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  • Inorganic Chemistry  (83,671)
  • Cell & Developmental Biology  (25,032)
  • Aerodynamics
  • Aircraft Propulsion and Power
  • Industrial Chemistry
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  • 1
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    Active Flow Control: Recent Advances in Fundamentals and Applications (2023)
    MDPI - Multidisciplinary Digital Publishing Institute
    Details
    Publication Date: 2023-11-30
    Description: Active flow control (AFC) utilizes local active perturbations to induce changes in global flow behavior that result in aero/hydrodynamic performance improvement. It has been a vibrant research area with potential applications in a wide range of engineering fields. This Special Issue is a collection of 11 excellent research papers published in Actuators, showcasing and discussing new advances in both fundamental and applied AFC technologies.
    Keywords: Active flow control ; Actuators ; Aerodynamics ; Synthetic jets&nbsp ; bic Book Industry Communication::T Technology, engineering, agriculture::TB Technology: general issues
    Language: English
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  • 2
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    Hypersonic Vehicles (2022)
    IntechOpen | IntechOpen
    Details
    Publication Date: 2024-04-11
    Description: Some sixty years after the experimental flights of the North American X-15 hypersonic rocket-powered aircraft, sustained hypervelocity travel is still the next frontier in high-speed transportation. Today, there is much excitement and interest regarding hypersonic vehicles. In fact, many aerospace agencies, large industries, and several start-ups are involved in design activities and experimental campaigns both in wind tunnels and in-flight with full-scale experimental flying test beds and prototypes to make hypersonic travel almost as easy and convenient as airliner travel. Achieving this goal will radically revolutionize the future of civil transportation. This book contains valuable contributions that focus on various design issues related to hypersonic aircraft.
    Keywords: Aerodynamics ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science::TGMF Engineering: Mechanics of fluids::TGMF1 Aerodynamics
    Language: English
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  • 3
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    Frontiers in Chemistry: Rising Stars (2021)
    Frontiers Media SA
    Details
    Publication Date: 2024-04-04
    Description: The Frontiers in Chemistry Editorial Office team are delighted to present the inaugural “Frontiers in Chemistry: Rising Stars” article collection, showcasing the high-quality work of internationally recognized researchers in the early stages of their independent careers. All Rising Star researchers featured within this collection were individually nominated by the Journal’s Chief Editors in recognition of their potential to influence the future directions in their respective fields. The work presented here highlights the diversity of research performed across the entire breadth of the chemical sciences, and presents advances in theory, experiment and methodology with applications to compelling problems. This Editorial features the corresponding author(s) of each paper published within this important collection, ordered by section alphabetically, highlighting them as the great researchers of the future. The Frontiers in Chemistry Editorial Office team would like to thank each researcher who contributed their work to this collection. We would also like to personally thank our Chief Editors for their exemplary leadership of this article collection; their strong support and passion for this important, community-driven collection has ensured its success and global impact.
    Keywords: Green and Sustainable Chemistry ; Analytical Chemistry ; Theoretical and Computational Chemistry ; Polymer Chemistry ; Medicinal and Pharmaceutical Chemistry ; Organic Chemistry ; Nanoscience ; Catalysis and Photocatalysis ; Supramolecular Chemistry ; Electrochemistry ; Inorganic Chemistry ; Chemical Biology ; thema EDItEUR::P Mathematics and Science::PD Science: general issues
    Language: English
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  • 4
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    Environmental Democracy at the Global Level: Rights and Duties for a New Citizenship (2021)
    De Gruyter
    Details
    Publication Date: 2023-12-20
    Description: Giulia Parola’s Environmental Democracy at the Global Level: Rights and Duties for a New Citizenship can be seen as a manifesto that is both traditional and revolutionary at the same time. It calls for the construction of a new civilisation centred on the environment, while drawing on the traditional notions of democratic government. It adopts an approach that is focused on the power of individuals rather than governments, as ways to protect and improve the environment. It proposes that environmental rights and ecological duties are self-evident and inalienable, and should be treated as the cornerstones of a new democracy. Parola’s book is a thought provoking and intriguing work that will be of interest to scholars of environmental studies as well as to legal practitioners and non-specialists. Giulia Parola has studied Environmental Law at the University of Torino, at the University of René Descartes in Paris, (where she obtained PhD in Public Law) and at the University of Iceland ( LLM in Natural Resources Law and International Environmental Law). In 2011, she was appointed by the University of Laval (Canada, Quebec) as a researcher and a lecturer in Environmental Law.
    Keywords: GE1-350 ; K ; International Law ; Materials Science ; Industrial Chemistry ; Law ; Comparative Law ; Foreign Law ; Environment ; Natural Sciences ; German Civil Code ; Pollution Control ; bic Book Industry Communication::K Economics, finance, business & management::KC Economics::KCN Environmental economics
    Language: English
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  • 5
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    Aerodynamics (2021)
    IntechOpen | IntechOpen
    Details
    Publication Date: 2024-04-11
    Description: Aerodynamics, the study of air motion around solid objects, allows us to understand and measure the dominating forces acting on aircrafts, buildings, bridges, automobiles, and other structures. The forces that result in an aircraft overcoming gravity and drag are called thrust and lift. Various parameters such as geometrical configurations of objects, as well as physical properties of air, which may be functions of position and time, affect those forces. This book covers some of the latest studies regarding the application of the principles of aerodynamics to the design of many different engineered objects. This book will be of interest to mechanical and aerospace engineering students, academics, and researchers who are looking for new insights into this fascinating branch of fluid mechanics.
    Keywords: Aerodynamics ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 6
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    Disposable Bioprocessing Systems (2021)
    Taylor & Francis | CRC Press
    Details
    Publication Date: 2024-03-31
    Description: Because of many misconceptions, the biological drug manufacturing industry does not fully utilize disposable components, despite their wide availability. These misconceptions include concerns for the quality of materials, running costs, scalability, the level of automation possible, and the training of staff needed to include these components in existing bioprocessing systems. Not fully realizing the long-term benefits, many manufacturers are unwilling to discard investments made in fixed equipment and traditional stainless steel systems. Regulatory and environmental concerns, however, will eventually compel manufacturers to adopt disposable systems. Making a strong case for disposables, Disposable Bioprocessing Systems demonstrates the true potential of these systems. Written by a researcher and professor with hands-on experience in designing, establishing, and validating biological manufacturing facilities worldwide, and creating model facilities using maximum disposable technology, this book is the first comprehensive introduction to understanding disposable systems. It gives an overview of the current state of the disposable bioprocessing industry, resolves all controversial issues, and guides readers in choosing disposable components that meet their needs. An important chapter on safety addresses facts and myths about the use of plastics and elastomers—including the issue of leaching—and how to ensure regulatory compliance. Helping readers understand their choices, the book describes the equipment and systems available to prepare the starting materials for the manufacturing of biological drugs—from disposable containers to filters. The author also discusses costs, regulations, and concerns about waste disposal, and shares his predictions for the future of the disposable bioprocessing industry. A practical manual for those interested in the transition to disposable systems, this book will also interest students of bioprocessing. It offers a timely view of disposable bioprocessing technology as a "game changer" that will facilitate developing new drugs and conducting research in the emerging field of stem cells and gene therapy.
    Keywords: Biotechnology ; Pharmaceutical Science ; Industrial Chemistry ; PHARMACEUTICAL ; BIOSCIENCE ; CHEMLIB ; SCI-TECH ; BIOMEDICALSCIENCE ; CHEMICALENGINEERING ; STM ; bags ; bioreactors ; cleaning ; disposal ; downstream ; single ; stainless ; steel ; use ; validation ; thema EDItEUR::M Medicine and Nursing::MF Pre-clinical medicine: basic sciences ; thema EDItEUR::M Medicine and Nursing::MK Medical specialties, branches of medicine::MKG Pharmacology ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TD Industrial chemistry and manufacturing technologies::TDC Industrial chemistry and chemical engineering ; thema EDItEUR::M Medicine and Nursing::MQ Nursing and ancillary services::MQW Biomedical engineering
    Language: English
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  • 7
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    Applied Aerodynamics (2021)
    IntechOpen | IntechOpen
    Details
    Publication Date: 2024-04-11
    Description: Aerodynamics, from a modern point of view, is a branch of physics that study physical laws and their applications, regarding the displacement of a body into a fluid, such concept could be applied to any body moving in a fluid at rest or any fluid moving around a body at rest. This Book covers a small part of the numerous cases of stationary and non stationary aerodynamics; wave generation and propagation; wind energy; flow control techniques and, also, sports aerodynamics. It's not an undergraduate text but is thought to be useful for those teachers and/or researchers which work in the several branches of applied aerodynamics and/or applied fluid dynamics, from experiments procedures to computational methods.
    Keywords: Aerodynamics ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 8
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    Wind Tunnel Designs and Their Diverse Engineering Applications (2021)
    IntechOpen | IntechOpen
    Details
    Publication Date: 2024-04-11
    Description: This book is intended to be a valuable addition to students, engineers, scientists, industrialists, consultants and others providing greater insight into wind tunnel designs and their enormous research potential. It is a compilation of works from world experts on subsonic and supersonic wind tunnel designs, applicable to a diverse range of disciplines. The book is organised in two sections. The first section comprises of three chapters on various aspects of stationary and portable subsonic wind tunnel designs, followed by one chapter on supersonic wind tunnel and the final chapter discusses a method to address unsteadiness effects of fan blade rotation. The second section contains four chapters regarding wind tunnel applications across a multitude of engineering fields including civil, mechanical, chemical and environmental engineering.
    Keywords: Aerodynamics ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 9
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    Low Reynolds Number (2021)
    IntechOpen | IntechOpen
    Details
    Publication Date: 2024-04-11
    Description: This book reports the latest development and trends in the low Re number aerodynamics, transition from laminar to turbulence, unsteady low Reynolds number flows, experimental studies, numerical transition modelling, control of low Re number flows, and MAV wing aerodynamics. The contributors to each chapter are fluid mechanics and aerodynamics scientists and engineers with strong expertise in their respective fields. As a whole, the studies presented here reveal important new directions toward the realization of applications of MAV and wind turbine blades.
    Keywords: Aerodynamics ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 10
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    Advances in Spacecraft Attitude Control (2021)
    IntechOpen
    Details
    Publication Date: 2024-04-04
    Description: Spacecraft attitude maneuvers comply with Euler's moment equations, a set of three nonlinear, coupled differential equations. Nonlinearities complicate the mathematical treatment of the seemingly simple action of rotating, and these complications lead to a robust lineage of research. This book is meant for basic scientifically inclined readers, and commences with a chapter on the basics of spaceflight and leverages this remediation to reveal very advanced topics to new spaceflight enthusiasts. The topics learned from reading this text will prepare students and faculties to investigate interesting spaceflight problems in an era where cube satellites have made such investigations attainable by even small universities. It is the fondest hope of the editor and authors that readers enjoy this book.
    Keywords: Science ; Mechanics ; Aerodynamics ; bic Book Industry Communication::P Mathematics & science::PH Physics::PHD Classical mechanics::PHDF Fluid mechanics ; thema EDItEUR::P Mathematics and Science::PH Physics::PHD Classical mechanics::PHDF Physics: Fluid mechanics
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  • 11
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    Unit Operations of Particulate Solids (2021)
    Taylor & Francis | CRC Press
    Details
    Publication Date: 2024-04-11
    Description: Suitable for practicing engineers and engineers in training, this book covers the most important operations involving particulate solids. Through clear explanations of theoretical principles and practical laboratory exercises, the text provides an understanding of the behavior of powders and pulverized systems. It also helps readers develop skills for operating, optimizing, and innovating particle processing technologies and machinery in order to carry out industrial operations. The author explores common bulk solids processing operations, including milling, agglomeration, fluidization, mixing, and solid-fluid separation.
    Keywords: Industrial Chemistry ; Food Chemistry ; FOOD ; CHEMLIB ; SCI-TECH ; CHEMICALENGINEERING ; CHEMISTRY ; STM ; bed ; distribution ; fluidized ; industry ; mass ; material ; particle-size ; processing ; technology ; transfer ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TD Industrial chemistry and manufacturing technologies::TDC Industrial chemistry and chemical engineering ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TD Industrial chemistry and manufacturing technologies::TDC Industrial chemistry and chemical engineering::TDCT Food and beverage technology ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
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  • 12
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    Wind Tunnels (2021)
    IntechOpen | IntechOpen
    Details
    Publication Date: 2024-04-11
    Description: Although great advances in computational methods have been made in recent years, wind tunnel tests remain essential for obtaining the full range of data required to guide detailed design decisions for various practical engineering problems. This book collects original and innovative research studies on recent applications in wind tunnel tests, exhibiting various investigation directions and providing a bird’s eye view on this broad subject area. It is composed of seven chapters that have been grouped in two major parts. The first part of the book (chapters 1–4) deals with wind tunnel technologies and devices. The second part (chapters 5–7) deals with the latest applications of wind tunnel testing. The text is addressed not only to researchers but also to professional engineers, engineering lecturers, and students seeking to gain better understanding of the current status of wind tunnels.　Through its seven chapters, the reader will have an access to a wide range of works related to wind tunnel testing.
    Keywords: Aerodynamics ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 13
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    Advances in Spacecraft Attitude Control (2021)
    IntechOpen | IntechOpen
    Details
    Publication Date: 2024-04-11
    Description: Spacecraft attitude maneuvers comply with Euler's moment equations, a set of three nonlinear, coupled differential equations. Nonlinearities complicate the mathematical treatment of the seemingly simple action of rotating, and these complications lead to a robust lineage of research. This book is meant for basic scientifically inclined readers, and commences with a chapter on the basics of spaceflight and leverages this remediation to reveal very advanced topics to new spaceflight enthusiasts. The topics learned from reading this text will prepare students and faculties to investigate interesting spaceflight problems in an era where cube satellites have made such investigations attainable by even small universities. It is the fondest hope of the editor and authors that readers enjoy this book.
    Keywords: Aerodynamics ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 14
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    Development of an Aeroservoelastic Model for Gust Load Alleviation of the NASA Common Research Model Wind Tunnel Experiment (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-23
    Description: As aircraft move to using composite materials as their primary structure they become lighter and more flexible as well. This presents some significant challenges in association with gust load alleviation. In this paper we develop an aeroservoelastic model for use in developing controllers that utilize distributed control surfaces for active gust load alleviation in a set of wind tunnel experiments. The model is based on an preexisting aeroelastic wing tunnel model and compares the baseline functionality to it. We also provide simple full state feedback simulations for the model.
    Keywords: Aerodynamics
    Type: AIAA 2020-0211 , ARC-E-DAA-TN76375 , AIAA Scitech 2020 Forum; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
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  • 15
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    Development of Unsteady Pressure-Sensitive Paint Application on NASA Space Launch System (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-17
    Description: The key measurement to acquire for understanding unsteady flow is surface pressure. Unsteady Pressure-Sensitive Paint (uPSP) is an emerging optical technique used in wind tunnel testing to measure fluctuating surface pressures. Recently, tests were conducted on NASAs Space Launch System in NASA Ames Research Centers Unitary Plan Wind Tunnel to determine the aeroacoustics environment and assist in developing the buffet forcing functions. Unsteady PSP data was collected during this test campaign. Steady state PSP data, infrared thermography, shadowgraph, accelerometer data, and dynamic pressure transducer data were also collected. In all 50 TB of data were collected during the three days of testing. During these three days of testing, a repeating transonic and supersonic alpha sweep condition was acquired. This paper presents these two wind tunnel conditions and examines how the temperature influences the PSP data. In the first large demonstration of uPSP in 2015 on an NESC-, AETC-sponsored wind tunnel test, lifetime PSP results highlighted the influence the model temperature had on the PSP data. A best practice of heat soaking the model before acquiring calibration images was followed during the test campaign presented in this paper. An infrared thermography camera and thermocouples were installed in the model to collect more details of the model surface temperature. Data processing schemes for uPSP are still in development but will be briefly presented here as well.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN76119 , AIAA SciTech Forum; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
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  • 16
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    Preliminary Computational Assessment of Disk Rotating Detonation Engine Configurations (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-14
    Description: A rotating detonation engine (RDE) configuration whereby the working fluid enters and exits in a predominantly radial manner is examined using a quasi-two-dimensional computational fluid dynamic simulation. The simulation, based on a Cartesian coordinate system, was originally developed to examine the physics and performance of the more typical annular RDE. Modifications required to accommodate the radial and circumferential flowfield are discussed. The centripetal forces that arise in this disk RDE (DRDE) configuration create a different wave structure than that seen in the annular RDE. They also give rise to markedly different fluid behavior depending on whether the flow is radially inward or radially outward. Using an entropy-based measure of pressure gain, it is found that for the preliminary idealized calculations performed in this paper, the inward flowing DRDE outperforms the outward flowing variant. The inward flowing DRDE is further shown to outperform the equivalent annular RDE. The effects on performance of several parameters are examined, including inner-to-outer diameter ratio, inner-to-outer cross-sectional area ratio, and inlet throat-to-channel area ratio.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA 2020-2157 , GRC-E-DAA-TN75670 , AIAA Scitech 2020 Forum; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
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  • 17
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    AQUIFER Nano-Electrofuel Energy Economy and Powered Aircraft Operations (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-22
    Description: The Aqueous, QUick-charging battery Integration For Electric flight Research project is explained and the major subsystems are described, including nano-electric fluid, rim-driven motors, and integration concepts. The nano-electric fluid concept is a new type of aqueous flow battery that could reduce or retire the fire and explosion hazards of conventional batteries and fuel cells. The nano-electric fluid itself could enable energy storage and increased available energy per fuel weight ratios. The rim-driven motor is being developed to improve propulsion system safety and stability and to reduce noise. The rim-driven motor concept could enable motors that are more efficient both electrically and aerodynamically. The Energy Economy of the project concept is presented as a potential renewable or green energy sustainment for utilizing in-place infrastructure. The nano-electric fluid energy charge-use-recharge cycle is presented using renewable energy input from solar, wind, and hydroelectricity. Powered aircraft operations are presented, and the logistics of the new nano-electric fluid technology are explored. Powered aircraft operations topics include weight and balance, fueling, recharging, safety, and derivative considerations.
    Keywords: Aircraft Propulsion and Power
    Type: AFRC-E-DAA-TN74097 , SciTech Forum; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
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  • 18
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    Experimental Investigation of a One-Sided Ejector Nozzle (2019)
    In:  CASI
    Details
    Publication Date: 2019-05-07
    Description: A fundamental exploratory experiment is conducted assessing the performance of a one-sided ejector with the eventual goal of noise reduction for jet engines. The hardware is comprised of an 8:1 rectangular nozzle together with an ejector box whose lower surface is flush with the lower lip of the nozzle. Secondary flow is allowed through a gap between the upper lip of the nozzle and a flap that constitutes the upper surface of the ejector. Wall static pressures and Pitot probe surveys are conducted to evaluate the performance of the ejector with variation of geometric parameters. It is found that addition of vortex generating tabs at the upper lip of the nozzle significantly increases secondary flow entrainment. The entrainment is further enhanced by a divergence of the ejector upper surface. Limited noise measurements are done. The baseline ejector (without tabs) often encounters flow resonance with accompanying tones. The tabs have the additional benefit of eliminating those tones in all cases. However, for the tabbed case, addition of the ejector produces insignificant further noise reduction. This is due to the fact that the flow remains unmixed on the lower half of the ejector. The focus of ongoing and future efforts is to achieve sufficient mixing of the flow so that the exhaust velocities are uniformly low, while keeping the ejector hardware short and lightweight.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2019-220064 , GRC-E-DAA-TN65186 , E-19654
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  • 19
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    InSight's Reconstructed Aerothermal Environments (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-01
    Description: The InSight spacecraft was proposed to be a build-to-print copy of the Phoenix vehicle due to the knowledge that the lander payload would be similar and the trajectory would be similar. However, the InSight aerothermal analysts, based on tests performed in CO2 during the Mars Science Laboratory mission (MSL) and completion of Russian databases, considered radiative heat flux to the aftbody from the wake for the first time for a US Mars mission. The combined convective and radiative heat flux was used to determine if the as-flown Phoenix thermal protection system (TPS) design would be sufficient for InSight. All analyses showed that the design would be adequate. Once the InSight lander was successfully delivered to Mars on November 26, 2018, work began to reconstruct the atmosphere and trajectory in order to evaluate the aerothermal environments that were actually encountered by the spacecraft and to compare them to the design environments.The best estimated trajectory (BET) reconstructed for the InSight atmospheric entry fell between the two trajectories considered for the design, when looking at the velocity versus altitude values. The maximum heat rate design trajectory (MHR) flew at a higher velocity and the maximum heat load design trajectory (MHL) flew at a lower velocity than the BET. For TPS sizing, the MHL trajectory drove the design. Reconstruction has shown that the BET flew for a shorter time than either of the design environments, hence total heat load on the vehicle should have been less than used in design. Utilizing the BET, both DPLR and LAURA were first run to analyze the convective heating on the vehicle with no angle of attack. Both codes were run with axisymmetric, laminar flow in radiative equilibrium and vibrational non-equilibrium with a surface emissivity of 0.8. Eight species Mitcheltree chemistry was assumed with CO2, CO, N2, O2, NO, C, N, and O. Both codes agreed within 1% on the forebody and had the expected differences on the aftbody. The NEQAIR and HARA codes were used to analyze the radiative heating on the vehicle using full spherical ray-tracing. The codes agreed within 5% on most aftbody points of interest.The LAURA code was then used to evaluate the conditions at angle of attack at the peak heating and peak pressure times. Boundary layer properties were investigated to confirm that the flow over the forebody was laminar for the flight.Comparisons of the aerothermal heating determined for the reconstructed trajectory to the design trajectories showed that the as-flown conditions were less severe than design
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN70187 , International Planetary Probe Workshop (IPPW) 2019; Jul 08, 2019 - Jul 12, 2019; Oxford; United Kingdom
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  • 20
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    Computation Simulations of Electric Propulsion Aircraft: The X-57 Maxwell (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-03
    Description: Outline - Introduction: X-57 CFD task overview; Motivation. Part I, Computational simulations without propulsion: Establishing CFD (Computational Fluid Dynamics) Best Practices - Grid generation - Mesh refinement study - Numerical methods - Wind tunnel validation study; Power-Off Aerodynamic Database Results. Part II, Computational simulations with propulsion: Cruise Power-On Database; High-Lift Power-On Database. Summary.
    Keywords: Aircraft Propulsion and Power
    Type: ARC-E-DAA-TN69863 , NASA Advanced Supercomputing Advanced Modeling & Simulation (AMS) Seminar Series; Jun 13, 2019; Moffett Field, CA; United States
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  • 21
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    Geared Turbofan Engine Having a Reduced Number of Fan Blades and Improved Acoustics (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: A rotor blade comprises an airfoil extending radially from a root section to a tip section and axially from a leading edge to a trailing edge, the leading and trailing edges defining a curvature therebetween. The curvature determines a relative exit angle at a relative span height between the root section and the tip section, based on an incident flow velocity at the leading edge of the airfoil and a rotational velocity at the relative span height. In operation of the rotor blade, the relative exit angle determines a substantially flat exit pressure ratio profile for relative span heights from 75% to 95%, wherein the exit pressure ratio profile is constant within a tolerance of 10% of a maximum value of the exit pressure ratio profile.
    Keywords: Aircraft Propulsion and Power
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  • 22
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    Development of a Broadband Acoustic Emulator to Mature Propulsion Noise Reduction (CFANS-BB) (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: A simulator to artificially generate turbofan broadband signatures using the ANCF (Advanced Noise Control Fan) test article is presented. [Development of a Broadband Acoustic Emulator to Mature Propulsion Noise Reduction (CFANS-BB: Configurable Fan Artificial Noise Source- Broadband)]
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN67362 , Acoustics Technical Working Group (ATWG) Spring 2019 Meeting; Apr 10, 2019 - Apr 12, 2019; Hampton, VA; United States
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  • 23
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    Influence of Strain-Gage Balance Characteristics on the Precision Error of the Drag Coefficient (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Improvements and results of a new method are presented that computes a pre-test estimate of the precision error of the drag coefficient of a wind tunnel model. The error estimate is defined as the part of the drag coefficient's precision error that is primarily associated with the precision error of the angle of attack measurement and physical characteristics of the chosen strain-gage balance. The method indirectly describes the precision error of the angle of attack measurement by using an assumed balance gage output variation of one microV/V. The physical characteristics of the balance, on the other hand, are described by partial derivatives of the axial and normal forces with respect to the strain-gage outputs. These derivatives can directly be obtained from the data reduction matrix of the balance. The precision error estimate itself is calculated by applying a simple explicit equation that uses the model reference area, the dynamic pressure, the angle of attack, the coefficients of the linear terms of the data reduction matrix, and the electrical output variation of one microvolt per volt as input. Precision errors at constant angle of attack may be visualized as contour plots by plotting them, for example, versus the Mach number and the total pressure. Characteristics of NASA's MC60E balance are used in combination with the reference area of a generic wind tunnel model in order to demonstrate that error estimates are independent of both the balance load format and the units chosen for the description of balance loads, model reference area, and the dynamic pressure. Finally, experimental data from a wind tunnel test of the Ames Check Standard Model in the NASA Ames 11-foot Transonic Wind Tunnel illustrates the application of the method to real-world test data.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN63164 , AIAA SciTech 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Bowles-Tatnall Wake Vortex Encounter Hazard Metric (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Wake vortex spacing standards constrict the terminal area throughput and impose severe constraints on the overall capacity and efficiency of the National Airspace System. For more than two decades starting in the early 1990s, the National Aeronautics and Space Administration conducted extensive research on characterizing the formation and evolution of aircraft wakes. This multidisciplinary work included comprehensive field experiments (Pruis et al. 2016), flight tests (Vicroy et al. 1998), and wind tunnel tests (Rossow 1994; Chow et al. 1997). Parametric studies using large eddy simulations (Proctor 1998; Proctor et al. 2006) were conducted in order to develop fast-time models for the prediction of wake transport and decay (Ahmad et al. 2016). Substantial effort was spent on the formulation of acceptable vortex hazard metrics (Tatnall 1995; Hinton and Tatnall 1997). Several wake encounter severity metrics have been suggested in the past, which include the wake circulation strength, vortex-induced rolling moment coefficient (Clv), bank angle, and the roll control ratio (Tatnall 1995; Hinton and Tatnall 1997; Van der Geest 2012). The vortex-induced rolling moment coefficient introduced by Bowles and Tatnall (Tatnall 1995; Gloudemans et al. 2016) has been used extensively for risk and safety analysis of newly proposed air traffic management concepts and procedures. The original method of Bowles and Tatnall assumed a constant wing loading (the wing lift-curve slope, CL is constant), which resulted in an overestimation of the vortexinduced rolling moment coefficient. Bowles (2014) suggested a correction to the original method that provides more accurate values of Clv and which is also consistent with the underlying physics of the problem. The overestimation of Clv in the original method can be corrected by assuming an elliptical lift distribution. Figure 1.1 illustrates the correction in Clv achieved by the modified method.
    Keywords: Aerodynamics
    Type: NF1676L-33235 , NASA/TM-2019-220285 , L-21029
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    Numerical Investigation of a Shielded Chevron Nozzle (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Reynolds-Averaged Navier-Stokes simulations have been performed on a three-stream inverted velocity profile nozzle with and without various configurations of chevrons attached. The nozzle was mounted on a planform to imitate an engine mounted above a wing, shielding ground observers from engine noise. Several chevron designs intended to aggressively mix the jet and move noise sources upstream for shielding were examined to investigate there effects on noise and thrust. Numerical results for the baseline nozzle and one chevron configuration were compared with far-field noise and particle image velocimetry data obtained in NASA Glenn Research Center's Aero-Acoustic Propulsion Laboratory. A configuration in which chevrons alternate penetration into the primary stream and tertiary fan stream was explored using the Modern Design of Experiments approach. Short, high-penetration chevrons demonstrated a significant noise reduction for a relatively small thrust penalty.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-2019-220066 , E-19656
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    Multipoint Design and Optimization of a Turboshaft Engine for a Tiltwing Turboelectric Vertical Takeoff Landing Air Taxi (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: This paper describes the design of a turboshaft engine for a tiltwing air taxi application. In this case, the tiltwing air taxi is intended to fly a 400 nm mission with up to fifteen passengers. Engine requirements for the concept engine are taken from aircraft system studies where thrust is produced by four propellers driven by electric motors and powered by a single gas turbine engine. The purpose of this paper is to perform a cycle design optimization that minimizes fuel consumption and weight while respecting current technology limitations to meet mission requirements. To achieve results, the engine overall pressure ratio and maximum temperature at the exit of the combustor are set as the design parameters. Several sensitivity studies are also performed to visualize optimization trends. Results of the optimization study show solutions are heavily dependent on engine cooling flow requirements and exact mission requirements. This engine is intended for use in large system optimization research.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2019-220151 , AIAA Paper 2019-1948 , E-19671 , GRC-E-DAA-TN65425 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Overflow Simulations of Unmanned Aircraft Systems (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: National airspace, the management for access and operation of these vehicles is required. This management is being developed under the unmanned aircraft system traffic management system (UTM) program. To determine the aerodynamic characteristics of drones, wind tunnel experiments and computation fluid dynamic (CFD) analysis have been conducted. These experiments and analyses are undertaken to understand the flight capabilities of these vehicles in variable head and cross wind conditions. The results of these investigations will provide metrics for the safe operation of these vehicles in and around civil populations and in urban settings. The focus of this paper is to model a drone installed in a wind tunnel for varying pitch attitudes and rotor rpm settings. Specifically, the IRIS drone is modeled in the NASA-Ames 7x10 ft. W/T. The tunnel mounting hardware and the tunnel enclosure are modeled with the IRIS drone geometry. The rotors of the drone are modeled using two methodologies: a rotor disk model and individual blade representations. The results of the analysis are compared with available experimental data to validate the computational approach.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN64165 , AIAA Science and Technology Forum and Exposition 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Computational Modeling for Non-Equilibrium Shock Tube Flows (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-25
    Description: Time accurate simulation of non-equilibrium flows inside shock tube facilities presents several challenges from both physical and mathematical aspects. Furthermore, the large computational cost makes it impractical to support a real-time experimental test campaign. In this work, we explore other methods for modeling the shock tube problem with the main focus on the post-shock region and the absolute radiation emanating from it. The proposed alternative approach is several orders of magnitude less computationally expensive while still accurate enough with regards to the quantities of interest. Excellent agreement is found with the established stagnation-line approach. Comparison with time-accurate simulations shows good agreement close to the peak values and disagreement of the temperatures relaxation and radiance profiles toward equilibrium.
    Keywords: Aircraft Propulsion and Power
    Type: ARC-E-DAA-TN70861 , International Symposium on Shock Waves (ISSW32); Jul 14, 2019 - Jul 19, 2019; Singapore; China
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    Mid-Lift-to-Drag Ratio Rigid Vehicle 6-DOF EDL Performance Using Tunable Apollo Powered Guidance (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: The Mid-Lift-to-Drag ratio Rigid Vehicle (MRV) is a candidate in the NASA multi-center effort to determine the most cost effective vehicle to deliver a large-mass payload to the surface of Mars for a human mission. Products of this effort include six-degree-of-freedom (6DoF) entry-to-descent trajectory performance studies for each candidate vehicle. These high fidelity analyses help determine the best guidance and control (G&C) strategies for a feasible, robust trajectory. This paper presents an analysis of the MRV's G&C design by applying common entry and descent associated uncertainties using a Fully Numerical Predictor-corrector Entry Guidance (FNPEG) and tunable Apollo powered descent guidance.
    Keywords: Aerodynamics
    Type: JSC-E-DAA-TN64439 , 2019 AAS/AIAA Space Flight Mechanics Meeting; Jan 13, 2019 - Jan 17, 2019; Ka''anapali, HI; United States
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    Additional Comparison of Iced Aerodynamic Measurements on a Swept Wing from Two Wind Tunnels (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Artificial ice shapes of various geometric fidelity were tested on a wing model based on the Common Research Model. Low Reynolds number test were conducted at Wichita State University's Walter H. Beech Memorial Wind utilizing an 8.9% scale model, and high Reynolds number tests were conducted at ONERA's F1 wind tunnel utilizing a 13.3% scale model. Several identical geometrically-scaled ice shapes were tested at both facilities, and the results were compared at overlapping Reynolds and Mach numbers. This was to ensure that the results and trends observed at low Reynolds number could be applied and continued to high, near-flight Reynolds number. The data from Wichita State University and ONERA F1 agreed well at matched Reynolds and Mach numbers. The lift and pitching moment curves agreed very well for most configurations. This confirmed results from previous tests with other ice shapes that indicated the data from the low Reynolds number tests could be used to understand ice-swept-wing aerodynamics at high Reynolds number. This allows ice aerodynamics testing to be performed at low Reynolds number facilities with much lower operating costs and generate results that are applicable to flight Reynolds number.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN67168 , International Conference on Icing of Aircraft, Engines and Structures; Jun 17, 2019 - Jun 21, 2019; Minneapolis, MN; United States
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    Lessons Learned in Fabrication of a High-Specific-Torque Concentric Magnetic Gear (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Magnetic gearing is being investigated at NASA as a replacement to conventional mechanical gearing in aerospace applications. Some potential benefits of magnetic gears over mechanical gearing are torque transmission without mechanical contact, decreased transmission noise, and no required lubrication. However, in order to be a viable alternative for aerospace applications, magnetic gearing must be shown to provide high enough specific torque (torque per unit mass). NASA's second magnetic gearing prototype (PT-2) was able to achieve promising specific torque on par with low torque mechanical gearboxes. This work will briefly review the electromagnetic and structural design of PT-2, provide detailed information on fabrication and assembly, examine build errors, walk through rebuild efforts to improve operation, and conclude with remarks on build difficulties and opportunities for improvement in future prototypes.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN68518 , Annual Vertical Flight Society (VFS 2019) Forum and Technology Display (Forum 75); May 13, 2019 - May 16, 2019; Philadelphia, PA; United States
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    NASA Acoustic Stirling IRAD Thermal Recovery Energy Efficient System (TREES) Energy Conversion and Management in Aircraft (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA Acoustic Stirling IRAD (Internal Research and Development) Thermal Recovery Energy Efficient System (TREES) Energy Conversion and Management in Aircraft. Presentation on energy conversion on aircraft. Thermal energy recovery changes aircraft thermal management from being a necessary burden on aircraft performance to a desirable asset. It improves the engine performance by recycling waste heat and ultimately rejecting all collected aircraft heat out through the engine nozzle.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN68025 , Interagency Advanced Power Group (IAPG 2019) Mechanical Working Group (MWG) Meeting; May 14, 2019 - May 16, 2019; Houston, TX; United States
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    Modeling Turboshaft Engines for the Revolutionary Vertical Lift Technology Project (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Turboshaft engine performance and weight models were developed to support conceptual propulsion and vehicle mission design in support of the National Aeronautics and Space Administration's (NASA) Aeronautics Mission Research Directorate's (ARMD) Revolutionary Vertical Lift Technology (RVLT) Project. These models were developed using open data sources, assuming current and advanced technology levels, and range from 650 to 7,500 shaft output horsepower (485 to 5,600 kilowatts). Documenting the methodology, assumptions, and resulting performance realizes important benefits for NASA and the aviation community. NASA concept vehicle efforts using these propulsion models can more readily shared among the government, industry and university community as common baselines to support current and future work. Assessing the benefits of advanced technologies and new configurations can be facilitated using these models, which helps guide technology investment. As the various modeling conceptual vehicle and mission analysis environments advance, these models can be used directly for broader systems analysis studies, including optimization within the propulsion model itself. To perform this effort, the turboshaft engine is briefly discussed, highlighting the specific components and their expected performance characteristics over the power range and technology levels considered. Engine configurations will also be discussed as they will vary based on power output and assumed technology level. Engine performance, such as airflow, power output and weight will be reported, noting trends that are important for system studies. The effect of advanced propulsion technologies on RVLT-concept vehicles are also reported. Finally, potential future propulsion modeling work will be proposed.
    Keywords: Aircraft Propulsion and Power
    Type: VFS-Forum75-Paper-231 , GRC-E-DAA-TN68629 , Annual Vertical Flight Society (VFS 2019) Forum and Technology Display (Forum 75); May 13, 2019 - May 16, 2019; Philadelphia, PA; United States
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    PIV/Phased Array/Far-Field Noise Measurements of a Low-Noise Top-Mounted Propulsion Installation for a Supersonic Airliner (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A model-scale exhaust system was tested to validate low-noise concepts and noise prediction methods. The tests involved far-field acoustics, translating phased array, and particle image velocimetry; this report covers the far-field acoustic measurements. Data were acquired for a series of nozzles with different chevron designs, both uninstalled and installed on a representative aircraft planform. The impact of the various chevron treatments on the far-field noise was documented, along with the impact of the pylon and planform. For the baseline nozzle, installation produced a 2 EPNdB (Effective Perceived Noise in deciBels) reduction, as assumed in system studies. Chevrons were used to shift noise sources upstream to maximize the installation benefits and to reduce unshielded sources downstream. These resulted in reductions of 4-5 EPNdB...
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN67394 , Acoustics Technical Working Group (ATWG) Spring 2019 Meeting; Apr 10, 2019 - Apr 12, 2019; Hampton, VA; United States
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    Modeling Turboshaft Engines for the Revolutionary Vertical Lift Technology Project (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Turboshaft engine performance and weight models were developed to support conceptual propulsion and vehicle mission design and performance under the Revolutionary Vertical Lift Technology (RVLT) Project. These models were developed using open data sources, assuming current and advanced technology levels, and range from 650 to 7,500 shaft output horsepower (485 to 5,600 kW). Documenting the methodology, assumptions, and resulting performance realizes important benefits NASA and the aviation community. NASA concept vehicle efforts using these propulsion models can be more readily shared among the government, industry and university community as common baselines to support current and future work. Assessing the benefits of advanced technologies and new configurations can be facilitated using these models, which helps guide technology investment. As the various modeling conceptual vehicle and mission analysis environments advanced, these models can be used directly for broader systems analysis studies, including optimization within the propulsion model itself. To perform this effort, the turboshaft engine is briefly discussed, highlighting the specific components and their expected performance characteristics over the power range and technology levels considered. Engine configurations will also be discussed as they will vary based on power output and assumed technology level. Engine performance, such as airflow, power output and weight will be reported, noting trends that are important for system studies. The effect of advanced propulsion technologies on RVLT concept vehicles are also reported. Finally, potential future propulsion modeling work will be proposed.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN66991 , Annual Forum and Technology Display: The Future of Vertical Flight; May 13, 2019 - May 16, 2019; Philadelphia, PA; United States
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    New Test Rig to Measure Alternating Current Losses of Both Low and High Critical Temperature Superconductors (2019)
    In:  CASI
    Details
    Publication Date: 2019-06-18
    Description: This paper presents the design, development, operation, and test capabilities of a proposed superconducting coil testbed to measure alternating current (AC) losses at the NASA Glenn Research Center. Superconducting AC losses are important in the design of electric stators and rotors, power transmission lines, transformers, fault current limiters, magnets, and superconducting energy storage (not batteries). The new liquid-hydrogen-based rig will allow superconducting testing across a wide range of test parameters, including injected current up to 400 A, frequency (0 to 400 Hz), magnetic field (0 to 0.6 T), phase angle between induced voltage and injected current (180 to 180), coil coolant temperature (18 to 28 K), and AC power loss (5 to 30 W). While the target application of interest is 20 K superconducting MgB2 (the only superconductor that can presently be made with low losses) stator coils for future electric machines, the rig can accommodate test articles (TAs) with straight wire, tape, cables, coils of any shape, any allowable combination of superconducting wire and fluid (e.g., yttrium barium copper oxide (YBCO) coils and liquid nitrogen), and AC or direct current (DC) testing. The new spin rig builds upon the existing Air Force spin rig through a more flexible mode of fluid control, a wider gap space (up to 10.2 cm) for TAs, and the ability to accommodate TAs over a wider range of operating temperatures (18 to 95 K) using liquid hydrogen, gaseous helium, or liquid nitrogen as the working fluid, thus supporting direct cooled machines below 77 K.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN63356 , NASA/TM-2019-220046 , E-19642-TN63356
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    The Intermediate Wake of a Thin Flat Plate with a Circular Trailing Edge (2019)
    In:  CASI
    Details
    Publication Date: 2019-06-11
    Description: The intermediate wakes of thin flat plates with circular trailing edges (TEs) are investigated here with direct numerical simulations (DNSs). The separating boundary layers are turbulent in all cases. The near wake in two thin-plate cases (IN & NS), with a focus on the vortex shedding process, was explored in a recent article. Intermittent shedding was observed in Case IN. Case NS, with half the TE diameter of Case IN, was an essentially non-shedding case. A third case (ST) with a sharp trailing edge was also investigated and found to exhibit an intermittent wake instability. The objectives of the present study are twofold. The first is to determine if the wake instability found in Case ST exists in Cases IN and NS as well. The second is to provide the distributions of the turbulent normal intensities and shear stress in the wake and to understand these distributions via the budget terms in the corresponding transport equations. The results show that both Cases IN & NS exhibit a wake instability in the intermediate wake region, that is similar to that found earlier in Case ST. We note that in Case IN, the presence of an intermediate-wake instability results in the co-existence of two different types of instability within a single wake. The distributions of the turbulent normal intensities and shear stress, and the budget terms for the streamwise intensity are included and discussed here. All the budget terms contribute appreciably to the overall budget in the transport equation for streamwise normal intensity.
    Keywords: Aerodynamics
    Type: NASA/TM-2019-220195 , ARC-E-DAA-TN67460
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    Shape and Angle-Of-Attack Measurements of Ram-Air Parachutes by Stereo Photogrammetry in the National Full-Scale Aerodynamics Complex (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-01
    Description: US Army MC-4/5 ram-air parachutes were tested in the 80- by 120-Ft test section of the National Full-Scale Aerodynamics Complex. Arrays of targets on the upper and lower surfaces of the central cell of the canopies were measured by stereo photogrammetry, and the target positions were used to estimate both the shape of the cell and angle of attack of the canopy. Forces and moments were measured by a six-axis load cell. Based on the photogrammetry and load-cell measurements, the relationships between lift, drag, and angle of attack were determined over a range of trailing-edge flap deflections, front riser lengths, and free-stream airspeeds. This paper describes the test, with an emphasis on the photogrammetry measurements, and presents a summary of results.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN68756 , 2019 AIAA Aviation and Aeronautics Forum and Exposition; Jun 17, 2019 - Jun 21, 2019; Indianapolis, IN; United States
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    ASPIRE Aerodynamic Models and Flight Performance (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-01
    Description: The Advanced Supersonic Parachute Inflation Research Experiments (ASPIRE) project waslaunched to develop the capability for testing supersonic parachutes at Mars-relevant conditions.Three initial parachute tests, targeted as a risk-reduction activity for NASA's upcomingMars2020 mission, successfully tested two candidate parachute designs and provided valuabledata on parachute inflation, forces, and aerodynamic behavior. Design of the flight tests dependedon flight mechanics simulations which in turn required aerodynamic models for the payload, andthe parachute. Computational Fluid Dynamics (CFD) was used to generate these models preflightand are compared against the flight data after the tests. For the payload, the reconstructedaerodynamic behavior is close to the pre-flight predictions, but the uncertainties in thereconstructed data are high due to the low dynamic pressures and accelerations during the flightperiod of comparison. For the parachute, the predicted time to inflation agrees well with the preflightmodel; the peak aerodynamic force and the steady state drag on the parachute are withinthe bounds of the pre-flight models, even as the models over-predict the parachute drag atsupersonic Mach numbers. Notably, the flight data does not show the transonic drag decreasepredicted by the pre-flight model. The ASPIRE flight tests provide previously unavailablevaluable data on the performance of a large full-scale parachute behind a slender leading bodyat Mars-relevant Mach number, dynamic pressure and parachute loads. This data is used topropose a new model for the parachute drag behind slender bodies to aid future experiments.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN68662 , AIAA Aviation Forum 2019; May 17, 2019 - May 21, 2019; Dallas, TX; United States
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    Adjoint-Based Mesh Adaptation and Shape Optimization for Simulations with Propulsion (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-31
    Description: Objectives: Reliable evaluation of mass flow rates through permeable boundaries - Estimate and control discretization error- Consider both computational domain outflow and inflow- Applicable to simulating propulsion-system effects, as well as secondary flow paths - Explore feasibility of handling more general outputs at domain boundaries. Design optimization subject to mass-flow-rate constraints - Improve aerodynamic performance and reduce noise due to sonic boom - Control discretization error in design space to improve confidence in final designs.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN69972 , AIAA Aviation and Aeronautics Forum (Aviation 2019); Jun 17, 2019 - Jun 21, 2019; Dallas, TX; United States
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    Preliminary Computational Assessment of Disk Rotating Detonation Engine Configurations (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: The pressure gain combustion (PGC) community is currently investigating rotating detonation engine (RDE) configurations where the flow direction is predominantly radial while the detonation travels circumferentially. These configurations are sometimes referred to as disk rotating detonation engines (DRDE) due to their nominal appearance as two disks in parallel with a gap between them. Having radial flow between disks, as opposed to the conventional RDE with axial flow in an annulus, may have profound effects on both the flow field and the performance. It may also yield extraordinarily compact devices which are well suited to particular propulsion and power applications. This presentation describes a preliminary effort to model the DRDE using a modified computational fluid dynamics (CFD) code originally written for analyzing ordinary RDE's. The quasi-two-dimensional code modifications are described, and some simple test flows are analyzed to insure that the modifications are functioning as envisioned. The code is then used to examine several DRDE scenarios such as radially inward and radially outward devices to see if stable operation is possible and if so, to assess the performance in terms of pressure gain. It is found that several flow scenarios are not only stable, but show superior performance to the ordinary RDE.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN68851 , Programmatic and Industrial Base (PIB); Jun 03, 2019 - Jun 07, 2019; Dayton, OH; United States|JANNAF Propulsion Meeting (JPM); Jun 03, 2019 - Jun 07, 2019; Dayton, OH; United States|Propulsion Systems Hazards Subcommittee (PSHS); Jun 03, 2019 - Jun 07, 2019; Dayton, OH; United States|Exhaust Plume and Signatures Subcommittee (EPSS); Jun 03, 2019 - Jun 07, 2019; Dayton, OH; United States|Combustion Subcommittee (CS); Jun 03, 2019 - Jun 07, 2019; Dayton, OH; United States|Airbreathing Propulsion Subcommittee (APS); Jun 03, 2019 - Jun 07, 2019; Dayton, OH; United States
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    Electric Aircraft Cryogenic Cooling with Thermo-Acoustic Exergy Management (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-21
    Description: No abstract available
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN68513 , 2019 Cryogenic Engineering Conference and International Cryogenic Materials Conference; Jul 21, 2019 - Jul 25, 2019; Hartford, CT; United States
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    Electromagnetic Mass and Efficiency of Magnetic Gears for Electrified Aircraft (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-30
    Description: Magnetic gears are currently being developed for use in a variety of industries such as wind and automotive, because of their higher reliability and lower maintenance cost than their mechanical counterparts. The bulk of magnetic gear development to date has focused on maximizing the technology's volumetric torque density. In contrast, the primary performance metrics for an aircraft's gear box are its mass and efficiency. To that end this paper presents a study of the achievable electromagnetic specific torque and efficiency of concentric magnetic gears. NASA's second magnetic gear prototype is used as the baseline for this study. Achievable electromagnetic specific torque and efficiency trends are presented with respect to higher level design variables such as gear ratio and radius.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70582 , AIAA/IEEE Electric Aircraft Technologies Symposium (EATS); Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN
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    Design of a Magnetic Gear for NASA's Vertical Lift Quadrotor Concept Vehicle (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-30
    Description: Magnetic gears are an attractive alternative to mechanical gears for electrified aircraft drive systems due to their ability to transmit torque without mechanical tooth contact. Consequently, magnetic gears enable electrified aircraft to take advantage of the benefits of gearing without introducing most of the contact-related reliability concerns associated with mechanical gearing. Magnetic gears however, have not been shown to match the specific torque (torque/mass) and efficiency of their mechanical counterparts in an aerospace application to date. In this paper, the design of a concentric magnetic gear for a personal air transport NASA reference vehicle is presented to demonstrate the feasibility of a magnetic gear for aerospace applications.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70579 , AIAA/IEEE Electric Aircraft Technologies Symposium (EATS); Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN; United States
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    Exit Boundary Layer Data for a Round Convergent Nozzle in Support of Numerical Simulation Efforts (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-30
    Description: An experiment is conducted with hot-wire anemometry to document the exit boundary layer characteristics of two nozzle configurations at jet Mach numbers up to 0.82. Far-field noise and jet plume experimental data from these two configurations have been used in Large Eddy Simulations (LES) of jets by colleagues at other Institutions. The current experiment provides the boundary layer data which have been identified as being critical for validation of the simulations since the initial conditions can significantly affect subsequent jet evolution and its radiated noise. The data exhibit fully turbulent boundary layers for the case with a pipe attached upstream of the nozzle. The case without the pipe involves Blasius-like mean velocity profiles but a highly disturbed laminar state with large turbulence intensities in a range of subsonic Mach numbers.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2019-220242 , E-19719 , GRC-E-DAA-TN70914
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    Further Development of the NASA X-57 Maxwell Mission Planning Tool for Mods II, III, and IV (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The experimental, fully electric X-57 Maxwell is designed to enable lower energy con-sumption at cruise compare to a fuel burning baseline. This is to be achieved using a sumof subsystem benefits incorporated in the electric, airframe, and propulsion systems. AMission Planning Tool captures the three stages of X-57 development in order to assess thedesign of each subsystem in the context of the whole aircraft. The Mission Planning Toolfor the fully electric X-57 Maxwell captures the aerodynamics, propulsion, heat transfer,and power system of the aircraft with trajectory optimization capabilities. It is able tomodel these subsystems through all phases of flight, from taxi to landing. Through thismultidisciplinary approach, we are able to predict the benefit of each subsystem and theeffect of key design assumptions and how the aircraft will react if they are not met or ex-ceeded. As the aircraft progresses and systems are tested, we can use the Mission PlanningTool to continue to predict performance. This paper details the continued development ofthe X-57 Mission Planning Tool and demonstrates its capabilities.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN71098 , AIAA/IEEE Electric Aircraft Technologies Symposium (EATS); Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN; United States
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    Electrical Power System Sizing Within the Numerical Propulsion System Simulation (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Electrified aircraft propulsion seeks to address ambitious goals in the commercial airline industry, including significant decreases in fuel burn, emissions, noise, and takeoff field length. In order to move these electrified propulsion concepts forward, analysis tools are needed that can model propulsion systems containing both gas turbine and power system components. This work presents the definition of an electric port, a set of electrical power systems tools, and simulation examples for the Numerical Propulsion System Simulation (NPSS) software. NPSS is the industry standard modeling and simulation package for aircraft propulsion systems, and the ability to design, size, integrate, and analyze electric power systems will enable industry efforts towards the development of electrified aircraft propulsion.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70658 , AIAA Propulsion and Energy Forum and Exposition; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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    CFD Evaluation Of Lean-Direct Injection Combustors for Commercial Supersonics Technology (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-11
    Description: An overview is given of an effort that focused on using CFD analysis to complement design and configuration definition of Lean-Direct Injection (LDI) combustion concepts for NASA's Commercial Supersonic Transport (CST) program. The National Combustion Code (OpenNCC) was used to perform non-reacting and two-phase reacting flow computations for second and third generation LDI configurations at CST cruise conditions. All computations were performed with a consistent approach of mesh-generation, spray modeling, ignition and kinetics modeling. Emissions (EINOx) characteristics were predicted for CST cruise conditions, and compared with emissions data from experimental measurements to evaluate the fidelity of the CFD modeling approach to predict emissions changes in response to changes in supersonic cycle conditions.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN72416 , AIAA Propulsion and Energy Forum; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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    High Efficiency Megawatt Machine Rotating Cryocooler Conceptual Design (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-10
    Description: Some of the challenges associated with developing electric aircraft propulsion systems include developing powertrain components that are both efficient and light-weight. In particular, electric motors must simultaneously achieve high efficiency by minimizing electrical and mechanical losses while also achieving high specific power by increasing the torque and/or speed. Normally increasing torque or speed will increase electrical and mechanical losses. The High Efficiency Megawatt Machine (HEMM) minimizes electrical losses by incorporating a superconductor to enable increased current on the rotor. And the rotor spins in a vacuum to minimize thermal and mechanical losses. Some organizations have been developing superconducting rotors for similar reasons using either cryogenic fluid transfer systems, fully immersed cryogenic cooling, and in a few cases utilized built-in cryogenic cooling on the rotor using a Brayton or Stirling system but the implementation was too large or inefficient for effective motor integration. Instead, a new approach for cryogenically cooling the superconducting rotor coil with an embedded rotating cryocooler is presented that fits completely within the rotating shaft.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN71027 , AIAA/IEEE Electric Aircraft Technologies Symposium; Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN; United States
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    Computational Modeling for Non-equilibrium Shock Tube Flows (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-07
    Description: Time accurate simulation of non-equilibrium flows inside shock tube facilities presents several challenges from both physical and mathematical aspects. Furthermore, the drastic computational cost makes it non-practical to support real-time experimental test campaign. In this work, we explore other methods for modeling the shock tube prob- lem with the main focus on the post-shock region and the absolute radiation emanating from it. The proposed alternative approach is several orders of magnitude less computa- tionally expansive while still accurate enough with regards to the quantities of interest. Excellent agreement is found with the well-established stagnation-line approach. Comparison with the time-accurate simulation shows good agreement close to the peak values and disagreement of the temperatures relaxation and radiance profiles toward equilibrium, due to shock speed unsteadiness.
    Keywords: Aircraft Propulsion and Power
    Type: ARC-E-DAA-TN70486 , International Symposium on Shock Waves (ISSW32); Jul 14, 2019 - Jul 19, 2019; Singapore; China
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    X-57 60kW Permanent Magnet Synchronous Cruise Motor Finite Element Electromagnetic Modeling (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-28
    Description: The X-57 60kW Permanent Magnet Synchronous Motor for cruise applications was modeled utilizing a two-dimensional electromagnetics simulation software called Finite Element Method Magnets (FEMM, D. Meeker). Through FEMM, the simulated induction and torque characteristics of the X-57 PMSM were obtained. These parameters and other values were compared to actual static laboratory measurements. A three-dimensional electromagnetic model of the X-57 cruise motor was created utilizing OperaFEA (Dassault Systemes SE, Velizy-Villacoublay, France). Torque, RPM, power, resistance, and inductance characteristics were examined along with establishing work to begin examining heat flow and heat dissipation for efficiency purposes.
    Keywords: Aircraft Propulsion and Power
    Type: AFRC-E-DAA-TN75616 , Southern California Conferences for Undergraduate Research (SCCUR); Nov 23, 2019; San Marcos, CA; United States
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    Large-Scale Boundary Layer Ingesting Propulsor Research (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-04
    Description: NASAs Advanced Air Transport Technology (AATT) project is investigating boundary layer ingesting (BLI) propulsors for advanced subsonic commercial vehicle concepts to enable the reduction of fuel burn. A multidisciplinary team of researchers from NASA, United Technologies Research Center (UTRC), Virginia Polytechnic University, and the Air Force Arnold Engineering Development Complex developed and tested an embedded BLI inlet and distortion-tolerant fan (BLI2DTF) system in the NASA Glenn Research Center (GRC) 8- foot by 6-foot (8x6) transonic wind tunnel. The test demonstrated the component performance goals necessary for an overall fuel burn reduction of 3 to 5 percent on a large hybrid wing body (HWB) aircraft. Special test equipment, including a raised floor with flow effectors and a bleed system, was developed for use in the 8x6 to produce the appropriate incoming boundary layer representative of an HWB application. Detailed measurements were made to determine the inlet total pressure loss and distortion, fan stage efficiency, and aeromechanic performance including blade vibration stress and displacement response. Results from this test were used as input to a vehicle-level system study performed by the AATT project to assess the impact of BLI on an alternative advanced concept aircraft referred to as the NASA D8 (ND8), which is somewhat similar to the HWB in its integration of the propulsor. This paper will provide an overview of the project timeline, special test equipment needed in the wind tunnel to develop the appropriate incoming boundary layer, and the difficulties in designing a propulsor for the test. The paper will conclude with some representative aerodynamic and aeromechanic data from the test itself and conclude with how this data was used in the ND8 system study.
    Keywords: Aerodynamics
    Type: ISABE-2019-24264 , GRC-E-DAA-TN72111 , International Society for Air Breathing Engines (ISABE) Conference; Sep 22, 2019 - Sep 27, 2019; Canberra; Australia
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    Design of Low Inductance Busbar for 500 kVA Three-Level ANPC Converter (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-08
    Description: The adoption of SiC devices in high power applications enables higher switching speed, which requires lower circuit parasitic inductance to reduce the voltage overshoot. This paper presents the design of a busbar for a 500 kVA three-level active natural clamped converter. The layout of the busbar is discussed in detail based on the analysis of the multiple commutation loops, magnetic cancelling effect, and DC-link capacitor placement. The loop inductance of the designed busbar is verified with simulation, impedance measurements and converter experiment. The results can match with each other and the inductances of small and large loop are 6.5 nH and 17.5 nH respectively, which is significantly lower than the busbars of NPC type converters in other references.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN68912 , 2019 IEEE Energy Conversion Congress and Exposition; Sep 29, 2019 - Oct 03, 2019; Baltimore, MD; United States
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    Electrical Propulsive Fuselage Concept for Transonic Transport Aircraft (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-08
    Description: NASA is broadly engaged in Electrified Aircraft Propulsion (EAP) efforts across air vehicle sizes and electric aircraft propulsion approaches. EAP enables a wide range of propulsion airframe integration options as well as the use of rechargeable energy storage in an aircraft. This paper is limited to a discussion of boundary layer ingestion (BLI) systems which are located on the fuselage of the aircraft and use electrical drive systems. We term that combination an "electrical propulsive fuselage". The benefits, challenges, and design parameters of an electrically driven fuselage BLI system are considered. Five existing types of fuselage BLI implementation approaches which can be implemented using either electrical or mechanical drive systems are reviewed. An overview of boundary layer types, fan response to boundary layer, and electrical system for aircraft propulsion is presented. An idea distributed electric propulsive fuselage is proposed.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN72037 , International Society for Air Breathing Engines (ISABE) 2019; Sep 22, 2019 - Sep 27, 2019; Canberra; Australia
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    FUN3D Manual: 13.6 (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-30
    Description: This manual describes the installation and execution of FUN3D version 13.6, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
    Keywords: Aerodynamics
    Type: NF1676L-34707 , NASA/TM-2019-220416
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    Pilot Injector Redesign to Reduce N+3 Cycle Emissions for a Gas-Turbine Combustor (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-11
    Description: An overview is given of an effort for the use of CFD analysis to complement design and configuration definition of third generation Lean-Direct Injection combustion concepts (LDI-3) for NASAs N+3 program. The National Combustion Code (OpenNCC) was used to perform non-reacting and two-phase reacting flow computations for a three-cup, nineteen-element flame tube array with redesigned pilot injectors to improve spray and emissions characteristics when compared to a previous LDI-3 design. All computations were performed with a consistent approach to mesh-generation, spray modeling, ignition and kinetics modeling for a medium-power cycle condition. Computational predictions of the aerodynamics of a new pre-filming pilot injector were used to arrive at an optimized aerothermal design that meets effective area and fuel-air mixing criteria. The newly designed pilot injectors were shown to provide considerable improvements in aerodynamic stability, flame-tube pattern factor and NOx emissions, when compared to the original design.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70810 , AIAA Propulsion and Energy Forum; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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    Electromagnetic Efficiency and Mass of Magnetic Gears for Electrified Aircraft (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-10
    Description: Magnetic gears are currently being explored to replace mechanical gears in various industries such as wind and automotive due to their higher reliability and lower maintenance requirements. In these applications volume minimization has been the goal of magnetic gear development. In contrast, the primary performance metrics for electrified aircraft drives are mass and efficiency. This paper presents the first ever study of design tradeoffs between electromagnetic mass and efficiency of concentric magnetic gears and the feasibility of achieving the low mass and high efficiency required for electrified aircraft applications. Higher level design variables are considered, including gear ratio, number of magnetic pole pairs, and number of magnets per pole pair.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN72224 , AIAA/IEEE Electric Aircraft Technologies Symposium (EATS); Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN; United States
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    Defining and Measuring Pressure Gain (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-10
    Description: This presentation describes experimental and computational approaches to measuring pressure gain in the various devices currently under investigation wherein the working fluid undergoes a pressure gain combustion (PGC) process. Pressure gain is essentially a measure of the fluid availability for work or thrust production. The devices covered are Resonant Pulse Combustors, Internal Combustion Wave Rotors, Pulse Detonation Engines, and Rotating Detonation Engines. The approaches to pressure gain measurement differ in each device. However, all of the approaches attempt to address the fundamental challenges of PGC system measurement: the extremely harsh environment which makes instrumentation difficult, and the temporal and spatial non-uniformity associated with the exhausting flow which makes assigning a single value to the total pressure difficult. As part of the two-day 2019 International Constant Volume and Detonative Combustion Workshop, held in conjunction with the 2019 AIAA Propulsion and Energy Forum, this presentation is intended to foster discussion and eventual consensus on acceptable measurement methods.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN71983 , International Constant Volume Detonation Combustion Workshop; Aug 17, 2019 - Aug 18, 2019; West Lafayette, IN; United States
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    Fuel Sensitivity of Lean Blowout in a RQL Gas Turbine Combustor (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-06
    Description: Transition from fossil fuels to synthetic drop-in fuels without the need to change existing combustors is the current research topic. The combustor performances such as cold-day ignition limits, lean blow-out (LBO) limits and altitude relight limits are the main focus points. The objective of this work is to evaluate the effect of different fuel candidates on the operability of gas turbines by comparing a conventional petroleum-based fuel with one other alternative fuel candidate. Time filtered Navier-Stokes simulations (TFNS) and K-LES are performed to examine the performance of these fuels at the stable conditions close to blow-out in a referee combustor rig.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70667 , AIAA Propulsion and Energy Forum 2019; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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    Combustion and Emissions Study Using a 7-Point Lean Direct Injector Array (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-02
    Description: This paper continues a parametric study in which we consider the effect of air swirler configuration on the flame structure and combustor performance using a circular 7-point Lean Direct Injector Array for gas turbine applications. The injector array consists of a center swirler element surrounded by six swirler elements. Parameters considered in this study include swirler angle (60 or 52), handedness (co-swirling or counter-swirling) and center swirler offset. The primary focus considers flame stability, comparing four key air swirler configurations: for 1) fuel-lean flames; 2) high cold flow air reference velocity flames. We determined that the baseline swirler configuration had the best lean stability and could sustain the highest reference velocity. For this baseline configuration, we also compare the lean-blowout limits of four aircraft gas turbine reference fuels. With regard to lean blow-out, we determined that C4 could sustain the leanest flame, followed closely by A2. A1 was a poor performer.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70824 , ISABE-2019-24404 , The International Society for Air Breathing Engines (ISABE) 2019 Conference; Sep 22, 2019 - Sep 27, 2019; Canberra; Australia
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    Results of NASA's Magnetic Gear Program to Date (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-26
    Description: In rotorcraft, one of the main sources of mechanical failure is the gearbox, because of the many wear and failure modes associated with tooth contact in traditional mechanical gear boxes. Magnetic gears transmit torque without mechanical tooth contact between gear bodies and therefore they have none of the tooth contact related failure modes associated with mechanical gearing. As a result, magnetic gears have the potential to enable more reliable rotorcraft gearboxes. However, magnetic gears have not been demonstrated to match the performance of mechanical gearboxes at a high enough technology readiness level (TRL) to be used on an aircraft to date. To that end, NASA's Revolutionary Vertical Lift Technologies project has made an investment in developing magnetic gearboxes specifically for electrified vertical lift vehicles (EVTOL). In this presentation, the results of that investment to date will be discussed.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN73679 , Vertical Flight Society (VFS) Propulsion and Power Technical Meeting; Oct 29, 2019 - Oct 30, 2019; Hampton, VA; United States
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  • 62
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    Large-Scale Boundary Layer Ingesting Propulsor Research (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-29
    Description: _NASA's Advanced Air Transport Technology (AATT) project is investigating boundary layer ingesting (BLI) propulsors for advanced subsonic commercial vehicle concepts to enable the reduction of fuel burn. A multidisciplinary team of researchers from NASA, United Technologies Research Center (UTRC), Virginia Polytechnic University, and the Air Force Arnold Engineering Development Complex developed and tested an embedded BLI inlet and distortion-tolerant fan (BLI2DTF) system in the NASA Glenn Research Center (GRC) 8-foot by 6-foot (8x6) transonic wind tunnel. The test demonstrated the component performance goals necessary for an overall fuel burn reduction of 3 to 5 percent on a large hybrid wing body (HWB) aircraft. Special test equipment, including a raised floor with flow effectors and a bleed system, was developed for use in the 8x6 to produce the appropriate incoming boundary layer representative of an HWB application. Detailed measurements were made to determine the inlet total pressure loss and distortion, fan stage efficiency, and aeromechanic performance including blade vibration stress and displacement response. Results from this test were used as input to a vehicle-level system study performed by the AATT project to assess the impact of BLI on an alternative advanced concept aircraft referred to as the NASA D8 (ND8), which is somewhat similar to the HWB in its integration of the propulsor. This paper will provide an overview of the project timeline, special test equipment needed in the wind tunnel to develop the appropriate incoming boundary layer, and the difficulties in designing a propulsor for the test. The paper will conclude with some representative aerodynamic and aeromechanic data from the test itself and conclude with how this data was used in the ND8 system study.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN73213 , International Society for Air Breathing Engines (ISABE) Conference; Sep 22, 2019 - Sep 27, 2019; Canberra; Australia
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    Micro-scale Artificial Weave Generation Capabilities for Thermal Protection System Material Modeling (2019)
    In:  CASI
    Details
    Publication Date: 2020-01-22
    Description: Thermal Protection System (TPS) modeling requires accurate representation and prediction of the thermomechanical behavior of ablative materials. State-of-the-art TPS materials such as Phenolic Impregnated Carbon Ablator (PICA) have a proven flight record and demonstrate exceptional capabilities for handling extreme aerothermal heating conditions. The constant push for lightweight materials that are flexible in their design and performance, and hence allow for a wide range of mission profiles, has led NASA over the past years to develop its Heatshield for Extreme Entry Environment Technology (HEEET). HEEET is based primarily on a dual layer woven carbon fiber architecture and the technology has successfully been tested in arc-jet facilities. These recent developments have sparked interest in the accurate micro-scale modeling of composite weave architectures, to predict the structural response of macro-scale heatshields upon atmospheric entry. This effort can be extended to incorporate in-depth failure mechanics analyses as a result of local thermal gradients or high-velocity particle impact.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN73345 , Ablation Workshop; Sep 16, 2019 - Sep 17, 2019; Minneapolis, MN; United States
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    NASA Investments in Electrified Propulsion (2019)
    In:  CASI
    Details
    Publication Date: 2020-01-18
    Description: Presentation to the International Forum on Aviation (IFAR) at the Electric Hybrid Propulsion Workshop #2 in Budapest, Hungary. This presentation is to provide an overview of NASA's investments in electrified propulsion as a starting point for the workshop, which will concentrate on the safety of electrified airplanes and potential for international collaboration.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN74945
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    Effect of Out-Gassing on the Onset of Hypersonic Boundary Layer Transition (2019)
    In:  CASI
    Details
    Publication Date: 2020-01-17
    Description: Prediction and control of the onset of transition and the associated variation in aerothermodynamic parameters in high-speed flows is key to optimize the performance and design of Thermal Protection Systems (TPS) of next-generation aerospace vehicles [1]. Boundary Layer Transition (BLT) characteristics can influence the surface heating budget determining the TPS thickness and consequently its weight penalty. Ablative heatshields are designed to alleviate the high heat flux at the surface through pyrolysis of their polymeric matrix and subsequent fiber ablation [2]. Pyrolysis leads to out-gassing and non-uniform ablation lead to surface roughness, both of which are known to influence the transition process. An ablator impacts BLT through three main routes: gas injecting into the boundary layer from the wall, changing the surface heat transfer due to wall-flow chemical reactions, and modifying surface roughness [3]. In preparation to Mars 2020 mission post-flight analysis, the predictive transition capability has been initiated toward hard-coupling porous material response analysis and aerothermal environment calculation.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN73347 , Ablation Workshop; Sep 16, 2019 - Sep 17, 2019; Minneapolis, MN; United States
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    Progress Towards Modeling the Ablation Response of NuSil-Coated PICA (2019)
    In:  CASI
    Details
    Publication Date: 2020-01-17
    Description: The Mars Science Laboratory (MSL) Entry, Descent and Landing Instrumentation (MEDLI) collected in-flight data largely used by the ablation community to verify and validate physics-based models for the response of the Phenolic Impregnated Carbon Ablator (PICA) material [1-4]. MEDLI data were recently used to guide the development of NASAs high-fidelity material response models for PICA, implemented in the Porous material Analysis Toolbox based on OpenFOAM (PATO) software [5-6]. A follow-up instrumentation suite, MEDLI2, is planned for the upcoming Mars 2020 mission [7] after the large scientific impact of MEDLI. Recent analyses performed as part of MEDLI2 development draw the attention to significant effects of a protective coating to the aerothermal response of PICA. NuSil, a silicone-based overcoat sprayed onto the MSL heatshield as contamination control, is currently neglected in PICA ablation models. To mitigate the spread of phenolic dust from PICA, NuSil was applied to the entire MSL heatshield, including the MEDLI plugs. NuSil is a space grade designation of the siloxane copolymer, primarily used to protect against atomic oxygen erosion in the Low Earth Orbit environment. Ground testing of PICA-NuSil (PICA-N) models all exhibited surface temperature jumps of the order of 200 K due to oxide scale formation and subsequent NuSil burn-off. It is therefore critical to include a model for the aerothermal response of the coating in ongoing code development and validation efforts.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN73344 , Ablation Workshop; Sep 16, 2019 - Sep 17, 2019; Minneapolis, MN; United States
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    NASA Electrified Propulsion Research Summary (2019)
    In:  CASI
    Details
    Publication Date: 2020-01-09
    Description: No abstract available
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN74525 , HQ-E-DAA-TN72474 , AIAA/IEEE Electric Aircraft Technologies Symposium (EATS); Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States|Energy Tech; Oct 22, 2019 - Oct 24, 2019; Cleveland, OH; United States
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    Applying Optical Diagnostics to Study Aircraft Gas Turbine Combustor Performance (2019)
    In:  CASI
    Details
    Publication Date: 2020-01-03
    Description: This is for an invited lecture at Cleveland State University for a combustion course. The presentation gives an overview of some of the optical diagnostic techniques the Combustion Branch uses to characterize research fuel injection concepts to reduce emissions. Examples are provided that come from previously presented conference papers
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN74916
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    Effective Oxidation Model for Light-Weight Carbon Preform Ablators (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-16
    Description: Porous Microstructure Analysis (PuMA) software is used to perform simulations of molecular beam scattering experiments of hyperthermal atomic oxygen striking FiberFormr, a carbon preform material used commonly as a precursor in thermal protection systems (TPS). The purpose of this study is to investigate the reactive interaction of fibrous carbon with atomic oxygen in a complex microstructure, which is the primary source of carbon removal at lower temperatures. The detailed micro-structure of FiberFormr obtained from X-ray micro-tomography is used in the PuMA simulations to capture the complexity of the porous and fibrous characteristic of FiberFormr. A finite-rate surface chemistry model recently constructed from the molecular beam scattering experiments on vitreous carbon is applied to each fiber of the FiberFormr material. This model consists of detailed surface reaction mechanisms such as adsorption, desorption, and several types of Langmuir-Hinshelwood (LH) reactions to characterize the oxygen-carbon interactions at the surface. Comparison between the experimental and PuMA time-of-flight (TOF) distributions of both O and CO show good agreement. It is also found that a significantly higher amount of CO is generated when the beam interacted with FiberFormr, when compared with vitreous carbon. This is postulated to be primarily a result of multiple collisions of oxygen with the fibers, resulting in an higher effective rate of CO production. Multiple collisions with the different fibers, resulting from the porous nature of FiberFormr is also found to thermalize the O atoms, in addition to the adsorption/desorption process. The effect of micro-structure is concluded to be crucial in determining the final composition and energy distributions of the products. Thus, an effective model for the oxygen interaction with FiberFormr, fully accounting for the detailed micro-structure, for use in Computational Fluid Dynamics (CFD) and material response codes, is presented.
    Keywords: Aircraft Propulsion and Power
    Type: ARC-E-DAA-TN64596 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Feasibility of Electrified Propulsion for Ultra-Efficient Commercial Aircraft Final Report (2019)
    In:  CASI
    Details
    Publication Date: 2019-12-18
    Description: MIT, Aurora Flight Sciences, and USC have collaborated to assess the feasibility of electric, hybridelectric, and turbo-electric propulsion for ultra-efficient commercial transportation. The work has drawn on the team expertise in disciplines related to aircraft design, propulsion-airframe integration, electric machines and systems, engineering system design, and optimization. A parametric trade space analysis has been carried out to assess vehicle performance across a range of transport missions and propulsion architectures to establish how electrified propulsion systems scale. An optimization approach to vehicle conceptual design modeling was taken to enable rapid multidisciplinary design space exploration and sensitivity analysis. The results of the analysis indicate vehicle aero-propulsive integration benefits enabled by electrification are required to offset the increased weight and loss associated with the electric system and achieve enhanced performance; the report describes the conceptual configurations than can offer such enhancements. The main contribution of the present work is the definition of electric vehicle design attributes for potential efficiency improvements at different scales. Based on these results, key areas for future research are identified, and extensions to the trade space analysis suitable for higher fidelity electrified commercial aircraft design and analysis have been developed.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN72076 , NASA/CR—2019-220382
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    A Control Strategy for Turbine Electrified Energy Management (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-07
    Description: Hybrid electric propulsion architectures provide the infrastructure to enable additional benefits to the propulsion system that are otherwise unrealizable with the sole use of the current, state-of-the-art, gas-driven, turbine engines. The presence of electric machines (EMs) coupled to the shaft(s) of the turbine engine provide the ability to actively alter the operation of the engine to the benefit of the propulsion system and the aircraft it propels. This is the goal of the Turbine Electrified Energy Management (TEEM) concept, which at its broadest level addresses the management of energy across the electrified propulsion system. Prior work has demonstrated the use of this concept to alter steady-state operation and improve transient operability of a hybrid-electric propulsion system. The main benefits previously illustrated include the elimination of stability bleeds and expansion of the turbomachinery design space in order to enable more efficient designs. This paper focuses on the development of control strategies to implement the TEEM concept, and it explores several possible architecture variants for applying this concept. Comparison studies are conducted between a purely gas-driven turbofan (baseline engine configuration) and TEEM augmented variants of the baseline engine. The variants are distinguished by the shaft(s) that possess an EM. The configurations consider EMs on both shafts, an EM on the high pressure spool (HPS) only, and an EM on the low pressure spool (LPS) only. These configurations are referred to as the dual-spool configuration, the HPS configuration, and LPS configuration, respectively. The studies expose several options in configuring and controlling the system, including the use of a single EM coupled to a single shaft of a two-spool engine to positively impact the operability of both shafts. The studies also demonstrate the use of independently designed controllers for the electric machine(s) that allow for a decoupled control design process.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70128 , AIAA/IEEE Electric Aircraft Technology Symposium (EATS); Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN; United States
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    NASA Electrified Aircraft Propulsion Efforts (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-14
    Description: NASA's broad investments in Electrified Aircraft Propulsion (EAP) are reviewed in this paper. NASA investments are guided by an assessment of potential market impacts, technical key performance parameters, and technology readiness attained through a combination of studies, enabling fundamental research, and flight research. NASA has determined that the impact of EAP varies by market and NASA is considering three markets: national/international, on-demand mobility, and short haul regional air transport. Flight research is underway to demonstrate integrated solutions and inform standards and certification processes. This paper focuses on the vehicle related activities, however there are related NASA activities in air space management and vehicle autonomy activities as well as a breakthrough technology project called the Convergent Aeronautics Solutions Project. A key finding is that sufficient technical advances in key areas have been made which indicate EAP is a viable technology for aircraft. Significant progress has been made to reduce EAP adoption barriers and further work is needed to transition the technology to a commercial product and improve the technology so it is applicable to large transonic aircraft. This paper will review the activities of the Hybrid Gas Electric Subproject of the Advanced Air Transport Technology Project, the Revolutionary Vertical Lift Technology Project, and the X-57 Flight Demonstration Project, and discuss the potential EAP benefits for commercial and military applications.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN72947 , Hybrid/Electric Aero-Propulsion Systems for Military Applications; Oct 07, 2019 - Oct 09, 2019; Trondheim; Norway
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    CFD Evaluation of Lean-Direct Injection Combustors for Commercial Supersonics Technology (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: An overview is given of an effort that focused on using CFD analysis to complement design and configuration definition of Lean-Direct Injection (LDI) combustion concepts for NASA's Commercial Supersonic Transport (CST) program. The National Combustion Code (OpenNCC) was used to perform non-reacting and two-phase reacting flow computations for second and third generation LDI configurations at CST cruise conditions. All computations were performed with a consistent approach of mesh-generation, spray modeling, ignition and kinetics modeling. Emissions (EINOx) characteristics were predicted for CST cruise conditions, and compared with emissions data from experimental measurements to evaluate the fidelity of the CFD modeling approach to predict emissions changes in response to changes in supersonic cycle conditions.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70736 , AIAA Propulsion and Energy Forum 2019; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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    High Efficiency Megawatt Machine Rotating Cryocooler Conceptual Design (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: Some of the challenges associated with developing electric aircraft propulsion systems include developing powertrain components that are both efficient and light-weight. In particular, electric motors must simultaneously achieve high efficiency by minimizing electrical and mechanical losses while also achieving high specific power by increasing the torque and/or speed. Normally increasing torque or speed will increase electrical and mechanical losses. The High Efficiency Megawatt Machine (HEMM) minimizes electrical losses by incorporating a superconductor to enable increased current on the rotor. And the rotor spins in a vacuum to minimize thermal and mechanical losses. Some organizations have been developing superconducting rotors for similar reasons using either cryogenic fluid transfer systems, fully immersed cryogenic cooling, and in a few cases utilized built-in cryogenic cooling on the rotor using a Brayton or Stirling system but the implementation was too large or inefficient for effective motor integration. Instead, a new approach for cryogenically cooling the superconducting rotor coil with an embedded rotating cryocooler is presented that fits completely within the rotating shaft.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70902 , AIAA/IEEE Electric Aircraft Technologies Symposium; Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN; United States
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    Exit Boundary Layer Data for a Round Convergent Nozzle in Support of Numerical Simulation Efforts (2019)
    In:  Other Sources
    Details
    Publication Date: 2019-08-22
    Description: An experiment is conducted with hot-wire anemometry to document the exit boundary layer characteristics of two nozzle configurations at jet Mach numbers up to 0.82. Far-field noise and jet plume experimental data from these two configurations have been used in Large Eddy Simulations (LES) of jets by colleagues at other Institutions. The current experiment provides the boundary layer data which have been identified as being critical for validation of the simulations since the initial conditions can significantly affect subsequent jet evolution and its radiated noise. The data exhibit fully turbulent boundary layers for the case with a pipe attached upstream of the nozzle. The case without the pipe involves Blasius-like mean velocity profiles but a highly disturbed laminar state with large turbulence intensities in a range of subsonic Mach numbers.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2019-220242/SUPP , E-19719 , GRC-E-DAA-TN70914
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    Control Technology Needs for Electrified Aircraft Propulsion Systems (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Electrified aircraft propulsion (EAP) systems hold potential for the reduction of aircraft fuel burn, emissions, and noise. Currently, NASA and other organizations are actively working to identify and mature technologies necessary to bring EAP designs to reality. This paper specifically focuses on the envisioned control technology challenges associated with EAP designs that include gas turbine technology. Topics discussed include analytical tools for the dynamic modeling and analysis of EAP systems, and control design strategies at the propulsion and component levels. This includes integrated supervisory control facilitating the coordinated operation of turbine and electrical components, control strategies that seek to minimize fuel consumption and lessen the challenges associated with thermal management, and dynamic control to ensure engine operability during system transients. These dynamic control strategies include innovative control approaches that either extract or supply power to engine shafts dependent upon operating phase, which may improve performance and reduced gas turbine engine weight. Finally, a discussion of control architecture design considerations to help alleviate the propulsion/aircraft integration and certification challenges associated with EAP systems is provided.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN69695 , ASME Turbo Expo 2019; Jun 17, 2019 - Jun 21, 2019; Phoenix, AZ; United States
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    Control Technology Needs for Electrified Aircraft Propulsion Systems (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Electrified aircraft propulsion (EAP) systems hold potential for the reduction of aircraft fuel burn, emissions, and noise. Currently, NASA and other organizations are actively working to identify and mature technologies necessary to bring EAP designs to reality. This paper specifically focuses on the envisioned control technology challenges associated with EAP designs that include gas turbine technology. Topics discussed include analytical tools for the dynamic modeling and analysis of EAP systems, and control design strategies at the propulsion and component levels. This includes integrated supervisory control facilitating the coordinated operation of turbine and electrical components, control strategies that seek to minimize fuel consumption and lessen the challenges associated with thermal management, and dynamic control to ensure engine operability during system transients. These dynamic control strategies include innovative control approaches that either extract or supply power to engine shafts dependent upon operating phase, which may improve performance and reduced gas turbine engine weight. Finally, a discussion of control architecture design considerations to help alleviate the propulsion/aircraft integration and certification challenges associated with EAP systems is provided.
    Keywords: Aircraft Propulsion and Power
    Type: GT2019-91413 , GRC-E-DAA-TN65573 , ASME Turbomachinery Technical Conference & Exposition; Jun 17, 2019 - Jun 21, 2019; Phoenix, AZ; United States
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    Evaluating the Aerodynamic Impact of Circumferentially Grooved Fan Casing Treatments with Integrated Acoustic Liners on a Turbofan Rotor (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA is investigating the potential of integrating acoustic liners into fan cases to reduce fan noise, while maintaining the fans aerodynamic performance. An experiment was conducted to quantify the aerodynamic impact of circumferentially grooved fan cases with integrated acoustic liners on a 1.5 pressure ratio turbofan rotor. In order to improve the ability to measure small performance changes, fan performance calculations were updated to include real gas effects including the effect of humidity. For all fan cases tested, the measured difference in fan isentropic efficiency was found to be less than the measurement repeatability for a torque-based efficiency calculation (approx. = 0.2%), however, an unintended tip clearance difference between configurations makes it difficult to determine if circumferentially grooved fan cases degraded fan performance. Fan exit turbulence measurements showed a 1.5% reduction in total turbulence intensity between hardwall and circumferentially grooved fan cases in the tip vortex region, which is attributed to a disruption in the formation of the tip leakage vortex. This decrease in fan exit turbulence could potentially lead to a 1-2dB reduction in broadband rotor-stator interaction noise. Reduced aerodynamic performance losses associated with over-the-rotor liners could enable further fan noise reduction.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN62158 , ASME Turbo Expo 2019 Turbomachinery Technical Conference & Exposition; Jun 17, 2019 - Jun 21, 2019; Phoenix, AZ; United States
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    A New Recycling Method to Generate Turbulent Inflow Profiles (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The accuracy of the scale-resolving simulations for practical geometries strongly depends on the inflow boundary conditions. Imposing experimentally observed turbulent inflow profiles for the numerical simulations is a major challenge. Existing methods available in the literature assume self-similar behavior, which is not true for most of the experiments. In the present work, we formulate the turbulent inflow profile generation technique as an optimization problem. An adjoint technique is exploited to evaluate the sensitivities of multiple input parameters for the present problem. The present formulation is then tested to generate a laminar boundary layer profile, turbulent boundary layer profile, and turbulent jet profile.
    Keywords: Aircraft Propulsion and Power
    Type: ARC-E-DAA-TN69970 , AIAA Aviation 2019; Jun 17, 2019 - Jun 21, 2019; Dallas, TX; United States
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    Lessons Learned in Fabrication of a High-Specific-Torque Concentric Magnetic Gear (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Magnetic gearing is being investigated at NASA as a replacement to conventional mechanical gearing in aerospace applications. Some key benefits of magnetic gears over mechanical gearing are torque transmission without mechanical contact, decreased transmission noise, less frequent maintenance, and lack of lubrication. In order to take advantage of these benefits in aerospace applications, magnetic gearing must be shown to provide high enough specific torque (torque per unit mass). Prototype 2 (PT-2), developed to maximize specific torque, and fabricated at NASA Glenn Research Center, has shown promising specific torque comparable to low torque mechanical gears. This work will briefly review the electromagnetic and structural design of PT-2, provide detailed information on fabrication and assembly, examine build errors, walk through rebuild efforts to improve operation, and conclude with remarks on build difficulties and opportunities for improvement in future prototypes.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN67458 , Vertical Flight Society Annual Forum and Technology Display; May 13, 2019 - May 16, 2019; Philadelphia, PA; United States
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    Correlation of Full-Scale Isolated Proprotor Performance and Loads (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A full-scale isolated proprotor test is currently being conducted in the USAF National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel at NASA Ames. The test article is a 3-bladed research rotor derived from the right-hand rotor of the AW609; this rotor was manufactured by Bell Helicopter under contract to NASA. In this paper, this research rotor is referred to as "699". The test, nearly completed, is an integral part of the initial checkout test of the newly developed Tiltrotor Test Rig (TTR), whose purpose is to test advanced, full-scale proprotors in the NFAC. Figure 1 shows the TTR/699 installed in the 40- by 80-Foot test section. The TTR rotor axis is horizontal and the rig rotates in yaw on the wind tunnel turntable for conversion (transition) and helicopter mode testing. To date, a substantial amount of wind tunnel test data has already been acquired. The completed operational conditions include hover, airplane mode (cruise, wind tunnel airspeed V=61 to 267 knots), and the helicopter and conversion conditions (with a comprehensive sweep of the TTR yaw angle ranging, to date, from 90-deg yaw helicopter mode to 30-deg yaw conversion mode, at varying airspeeds). This 699 proprotor performance and loads correlation study uses these newly acquired wind tunnel test data. This paper represents the third analytical study, coming after two earlier analytical studies on the TTR/699; that is, a 2018 paper on pre-test predictions of 699 performance and loads, Ref. 1, and an upcoming January 2019 paper on aeroelastic stability analysis of the TTR/699 installed in the 40- by 80-Foot Wind Tunnel, Ref. 2. Reference 8 will present an overview of the entire TTR/699 test program. For completeness, Ref. 3 addresses the development and initial testing of the TTR. Background information on the TTR effort at NASA Ames can be found at the Aeromechanics website: https://rotorcraft.arc.nasa.gov/Research/Facilities/ttr.html. To the authors' knowledge, the full-scale results presented in this paper are the first of their kind. A literature survey brought up several existing correlation studies, but these were either based on small-scale test data (for example, the studies performed by the University of Maryland) or full-scale aircraft flight test data (for example, flight tests conducted by Bell Helicopter). Separately, the 2009 NASA study involving the JVX rotor is relevant (see Ref.4). The JVX is closely similar to the 699 in size and aerodynamics, and is accordingly a good reference for performance calculations. In Ref. 1 (as mentioned above), pre-test reality checks of the current analytical model were made by comparing JVX and 699 predictions in hover and forward flight (airplane mode).
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN61869 , Vertical Flight Society''s Annual Forum and Technology Display; May 13, 2019 - May 16, 2019; Philadelphia, PA; United States
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    Evaluation of Full Reynolds Stress Turbulence Models in FUN3D for Axisymmetric Jet Flow (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Two full seven-equation turbulence models have been implemented into the FUN3D code to evaluate their ability to improve the computation of challenging flows encountered in aerospace propulsion, including mixing flows. These models are the SSG/LRR and Wilcox full second-moment Reynolds stress models. They solve equations for the six components of the Reynolds stress and a seventh equation for the mixing length. Two standard eddy viscosity models are also evaluated for comparison, the Spalart-Allmaras (SA) one-equation model and the Menter Shear Stress Transport (SST-V) two-equation turbulence model. Flow through an axisymmetric reference nozzle is examined at three flow conditions: subsonic unheated, subsonic heated, and near sonic unheated. Centerline profiles of velocity and turbulent kinetic energy and radial profiles of velocity, turbulent kinetic energy and turbulent stresses are examined. characteristics, no significant changes in the downstream flow behavior compared to the baseline case are observed. Furthermore, the total power consumed by the fans for different incoming flow conditions also remain marginally the same. It is hoped that the results, albeit obtained at very low speeds. would serve as a database for this technologically interesting flow field that has not been explored adequately before.
    Keywords: Aerodynamics
    Type: GRC-E-DAA-TN63722 , AIAA Science and Technology Forum (AIAA SciTech); Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    The Effect of Incoming Boundary Layer Characteristics on the Performance of a Distributed Propulsion System (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An experimental study is conducted in an effort to advance the understanding of flow physics associated with a boundary layer ingesting, distributed propulsion system. The influence of incoming boundary layer thickness and flow distortions are studied on the flow downstream and the overall performance of the system. The propulsion model, fabricated using additive manufacturing and integrated with electrical fans, is mounted on a flat plate and tested at subsonic speeds. Detailed characterization of the incoming boundary layer and subsequent assessment of the downstream flow field is performed using hotwire anemometry. Modification of the incoming boundary layer is achieved by placing tripping devices, such as rods and vortex generating ramps, near the leading edge of the flat plate. The overall performance of the system for different incoming flow conditions is analyzed by comparing magnitudes of exhaust velocities as well as estimated propulsive power to the corresponding baseline values. For a constant input power to the fans, smaller upstream flow distortions and moderately thickened boundary layers result in marginal changes in the flow field downstream. On the other hand, notable reductions in downstream flow velocities and propulsive power are observed in the case of a significantly thicker and/or distorted incoming boundary layer. It is hoped that this study will serve as a database for this technologically relevant flow field that has not been explored adequately before.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM—2019-220068 , E-19658 , GRC-E-DAA-TN65193 , 2019 Science and Technology Forum (SciTech); Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Operational Stability Limits in Rotating Detonation Engine Numerical Simulations (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An instability is described which arises in computational fluid dynamic (CFD) simulations of semi-idealized rotating detonation engines (RDE) configured with a throat at the exit. Its existence is verified by examining output from two independently developed CFD codes simulating the same configuration and producing solutions that agree well. The instability is shown to be thermo-acoustic in that a spatial integral of the product of pressure and heat release fluctuations develops a regular oscillation which grows in time. The instability can become severe enough to cause detonation failure. Its onset is shown to be closely linked to the size of the exit throat and the size of the inlet restriction; both parameters that strongly influence RDE performance. It is shown that the instability places a cap on ideal RDEperformance, but that an optimized exhaust throat and inlet restriction combination still yields substantial pressure gain. Other parametric sensitivities are also examined in terms ofinstability growth. These include axial length, inlet manifold pressure, and air-fuel ratio.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN63619 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Experimental Investigation of a One-Sided Ejector Nozzle (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A fundamental exploratory experiment is conducted assessing the performance of a one-sided ejector with the eventual goal of noise reduction for jet engines. The hardware is comprised of an 8:1 rectangular nozzle together with an ejector box whose lower surface is flush with the lower lip of the nozzle. Secondary flow is allowed through a gap between the upper lip of the nozzle and a flap that constitutes the upper surface of the ejector. Wall static pressures and Pitot probe surveys are conducted to evaluate the performance of the ejector with variation of geometric parameters. It is found that addition of vortex generating tabs at the upper lip of the nozzle significantly increases secondary flow entrainment. The entrainment is further enhanced by a divergence of the ejector up-per surface. Limited noise measurements are done. The baseline ejector (without tabs) often encounters flow resonance with accompanying tones. The tabs have the additional benefit of eliminating those tones in all cases. However, for the tabbed case, addition of the ejector produces insignificant further noise reduction. This is due to the fact that the flow remains unmixed on the lower half of the ejector. The focus of ongoing and future efforts is to achieve sufficient mixing of the flow so that the exhaust velocities are uniformly low, while keeping the ejector hardware short and light-weight.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN62981 , SciTech 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Multi-Point Design and Optimization of a Turboshaft Engine for a Tiltwing Turboelectric VTOL Air Taxi (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper describes the design of a turboshaft engine for a tiltwing air taxi application. In this case, the tiltwing air taxi is intended to fly a 400-nautical mile mission with up to fifteen passengers. Engine requirements for the concept engine are taken from aircraft system studies where thrust is produced by four propellers driven by electric motors and powered by a single gas turbine engine. The purpose of this paper is to perform a cycle design optimization that minimizes fuel consumption and weight while respecting current technology limitations to meet mission requirements. To achieve results, the engine overall pressure ratio and maximum temperature at the exit of the combustor are set as the design parameters. Several sensitivity studies are also performed to visualize optimization trends. Results of the optimization study show solutions are heavily dependent on engine cooling flow requirements and exact mission requirements. This engine is intended for use in large system optimization research.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN62826 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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    Evaluation of Electrical System Requirements for Implementing Turbine Electrified Energy Management (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-05
    Description: Turbine Electrified Energy Management (TEEM) is a concept concerned with the management of energy in an electrified propulsion system. The management of energy in the hybrid-electric architecture has potential to benefit the turbomachinery and the aircraft it powers. The concept is particularly useful for improving operability during transient operation and could be leveraged to design a better performing engine. The concept utilizes electric machines coupled to the engine shafts and an electric power distribution system that includes energy storage. A controller is used to decide when and how energy is moved around the electrified propulsion system, particularly when considering energy conversion between mechanical and electrical forms. Prior work has shown that the electric machines can be used to supply/or extract supplemental power to/from the engine shafts to improve their operability and achieve or enable propulsion efficiency and performance benefits. However, the previous studies did not consider the practical constraints of the electrical machines and energy storage devices that are required for implementing the TEEM system architecture concept. This paper presents an integrated engine and electrical system model that is used to evaluate the electrical system requirements. The model captures the physics of the conceptual, Advanced Geared Turbofan 30,000lbf (AGTF30) engine, which features advanced technologies such as a compact gas turbine and a variable area fan nozzle. For this work, the engine is augmented with electrical system components that allow for the implementation of the TEEM concept. The evaluation presented suggests the potential of the TEEM concept to provide performance benefits for a turbofan engine.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70911 , AIAA/IEEE Electric Aircraft Technology Symposium (EATS); Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN; United States
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    Pilot Injector Redesign to Reduce N+3 Cycle Emissions for a Gas-Turbine Combustor (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-13
    Description: An overview is given of an effort for the use of CFD analysis to complement design and configuration definition of third generation Lean-Direct Injection combustion concepts (LDI-3) for NASA's N plus 3 program. The National Combustion Code (OpenNCC) was used to perform non-reacting and two-phase reacting flow computations for a three-cup, nineteen-element flametube array with redesigned pilot injectors to improve spray and emissions characteristics when compared to a previous LDI-3 design. All computations were performed with a consistent approach to mesh-generation, spray modeling, ignition and kinetics modeling for a "medium-power" cycle condition. Computational predictions of the aerodynamics of a new pre-filming pilot injector were used to arrive at an optimized aerothermal design that meets effective area and fuel-air mixing criteria. The newly designed pilot injectors were shown to provide considerable improvements in aerodynamic stability, flame-tube pattern factor and NOx emissions, when compared to the original design.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA 2019-4371 , GRC-E-DAA-TN72414 , AIAA/SAE/ASEE Joint Propulsion and Energy Forum and Exposition 2019 ; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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    Physical Simulation of Rocket Exhaust Aerodynamics Using Heated Ethane: Conceptual Foundations (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-13
    Description: Heated ethane (C2H6) has been proposed as an alternative to inert gases for use as a motive fluid in the experimental simulation of rocket exhaust plumes. By adjusting stagnation temperature, the isentropic exponent of ethane can be tuned to approximate those produced by common rocket propellants including hydrogen, hypergols, alcohols, and hydrocarbons. As a result, ethane can be made to follow a nozzle expansion process which is nearly identical to realistic rocket engine flow fields. Additionally, its high auto-ignition temperature and resistance to condensation enable the testing of expansion ratios much larger than conventional inertgas testing. NASA SSC has performed quasi-one-dimensional analyses using the Chemical Equilibrium with Applications (CEA) code as a preliminary means to compare flow fields produced by non-reacting ethane to those of reacting combustion products. A LO2/LH2 rocket engine operating at a chamber pressure of 5.0 MPa and a mixture ratio of 6.1 was used as an example case to demonstrate ethanes efficacy as a simulant. Errors for key similarity parameters were compared to legacy cold-flow test methods. Additional errors induced by machining tolerances and chemical impurities were also examined. Results suggest that at a 3% geometric scale and ~500 K ethane stagnation temperature, an error of less than 2.5% throughout the flow field is realistically achievable along the dimensions of Mach number, Reynolds number, pressure ratio, and isentropic exponent. The development of an experimental test bed for validation of this configuration is currently underway.
    Keywords: Aerodynamics
    Type: NASA/TM-2019-220446 , SREP-2220-0003
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    Design of a Magnetic Gear for NASA's Vertical Lift Quadrotor Reference Vehicle (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-11
    Description: Magnetic gears are an attractive alternative to mechanical gears for electrified aircraft drive systems due to their ability to transmit torque without mechanical tooth contact. Consequently, magnetic gears enable electrified aircraft to take advantage of the benefits of gearing without introducing most of the contact-related reliability concerns associated with mechanical gearing. Magnetic gears however, have not been shown to match the specific torque (torque/mass) and efficiency of their mechanical counterparts in an aerospace application to date. In this paper, the design of a concentric magnetic gear for a personal air transport NASA reference vehicle is presented to demonstrate the feasibility of a magnetic gear for aerospace applications.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN72227 , AIAA/IEEE Electric Aircraft Technologies Symposium (EATS 2019); Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN; United States
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    Fuel Sensitivity of Lean Blowout in a RQL Gas Turbine Combustor (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-17
    Description: Transition from fossil fuels to synthetic drop-in fuels without the need to change existing combustors is the current research topic. The combustor performances such as cold-day ignition limits, lean blow-out (LBO) limits and altitude relight limits are the main focus points. The objective of this work is to evaluate the effect of different fuel candidates on the operability of gas turbines by comparing a conventional petroleum-based fuel with one other alternative fuel candidate. Time filtered Navier-Stokes simulations (TFNS) and K-LES are performed to examine the performance of these fuels at the stable conditions close to blow-out in a referee combustor rig.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN72312 , AIAA Propulsion and Energy Forum 2019; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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    An Analysis of the Strayton Engine, a Brayton and Stirling Cycle Recuperating Engine (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-10
    Description: This paper explores the novel Strayton engine concept. This engine combines the cycles of a Brayton engine with that of a Stirling engine to create a highly efficient recuperating gas turbine engine. In the explored case, both Brayton cycle and Stirling cycle engines are used to generate electrical power. Additionally, the Stirling engine is used to draw heat out of the Brayton turbine (acting to cool the turbine blades), while also pumping heat into Brayton cycle just before combustion occurs (acting as the mechanism for recuperation). The purpose of this paper is to detail the system level modeling techniques used to generate the simulation, perform a cycle analysis of the combined cycle engine, identify key technologies and challenges associated with the concept, and compare potential performance gains with existing gas turbine engines and internal combustion engines. Topics such as controls, blade cooling effects, engine weight, and heat transfer using heat pipe are also explored. Results from this work show potential architectures that could provide the required heat transfer rates, potential control strategies, and performance benefits, including efficiency gains between 10% and 3% on engines ranging from 200HP to 670HP with the combined cycle engine.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN71720 , AIAA Propulsion and Energy Forum 2019; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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    Dynamic Analysis of the STARC-ABL Propulsion System (2019)
    In:  CASI
    Details
    Publication Date: 2019-09-10
    Description: In the pursuit of Electrified Aircraft Propulsion (EAP), much of the attention is on the development of hybrid electric concept vehicles and their propulsion systems from a steady state performance perspective. While it is steady-state performance that largely determines the efficiency of civil air transports, engine operability and transient performance define constraints for the steady state design that impact efficiency and system viability. Neglecting dynamics and control technologies can result in an over-designed, sub optimal propulsion system or a concept that is not feasible. Thus, dynamic system studies were conducted on the propulsion system of the conceptual aircraft design known as the Single-aisle Turboelectric AiRCraft with Aft Boundary Layer propulsor (STARC-ABL). This paper describes the development of a controller to verify the baseline concept's feasibility from an operability perspective. Further, studies were conducted to identify excessive stability margin in the baseline design that could be traded for potential benefits in efficiency through an engine re design. This study revealed the potential to reduce the high pressure compressor (HPC) stall margin by 3%. Finally, a study was conducted to investigate the potential benefit of adding energy storage to the STARC-ABL concept that further improves operability and enables more gains in engine efficiency and performance. The energy storage provided an additional 0.5% stall margin can be removed from the HPC.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN70106 , AIAA Propulsion and Energy Forum; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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    Control Technology Needs for Electrified Aircraft Propulsion Systems (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-04
    Description: Electrified aircraft propulsion (EAP) systems hold potential for the reduction of aircraft fuel burn, emissions, and noise. Currently, NASA and other organizations are actively working to identify and mature technologies necessary to bring EAP designs to reality. This paper specifically focuses on the envisioned control technology challenges associated with EAP designs that include gas turbine technology. Topics discussed include analytical tools for the dynamic modeling and analysis of EAP systems, and control design strategies at the propulsion and component levels. This includes integrated supervisory control facilitating the coordinated operation of turbine and electrical components, control strategies that seek to minimize fuel consumption and lessen the challenges associated with thermal management, and dynamic control to ensure engine operability during system transients. These dynamic control strategies include innovative control approaches that either extract or supply power to engine shafts dependent upon operating phase, which may improve performance and reduced gas turbine engine weight. Finally, a discussion of control architecture design considerations to help alleviate the propulsion/aircraft integration and certification challenges associated with EAP systems is provided.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2019-220296 , GRC-E-DAA-TN70505 , E-19721 , ASME Turbomachinery Technical Conference & Exposition; Jun 17, 2019 - Jun 21, 2019; Phoenix, AZ; United States
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    Design of a Slotted, Natural-Laminar-Flow Airfoil for a Transport Aircraft (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-03
    Description: A 13.49-percent-thick, slotted, natural-laminar-flow airfoil, the S207, for a transport aircraft has been designed and analyzed theoretically. The two primary objectives of high maximum lift, insensitive to roughness, and low profile drag have been achieved. The drag-divergence Mach number is predicted to be greater than 0.70.
    Keywords: Aerodynamics
    Type: NF1676L-34040 , NASA-CR-2019-220403
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    Reliability Requirements and Research Strategies for Urban Air Mobility Propulsion (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-21
    Description: An emerging new mission for aeronautics is Urban Air Mobility (UAM), a concept for air transportation around metropolitan areas with passenger-carrying operations. UAM vehicles must be capable of vertical take-off and landing, and this requirement presents unique technical challenges for electric and hybrid-based vertical take-off and landing (eVTOL). A critical challenge for UAM market growth is to gain public acceptance for being as safe as - or safer than - commercial air travel and automotive transportation. There is a lack of data for propulsion systems, components, and the associated thermal management systems for UAM eVTOL propulsion systems. The new mission, new propulsion system concepts, safety criticality of propulsion component performance during vertical take-off and lift operations, and lack of data presents many research challenges and opportunities. NASA has developed and published UAM vehicle concept studies. For a subset of the said concept vehicles, NASA has contracted for a study to identify failure modes and hazards associated with the propulsion systems of the concept vehicles and to perform functional hazard analyses (FHA) and failure modes and effects criticality analyses (FMECA) for each. From the completed study results, it was recommended for NASA to support research toward developing electric/hybrid-electric propulsion components with improved reliability and to explore powertrain architectures that can take advantage of higher reliability components to achieve inherent air-vehicle safety. NASA has started a research effort for UAM propulsion with a focus toward improving safety and reliability. Recent results and research strategy will be discussed toward the goals by means of: 1) improving individual component reliability through advanced materials and design methods, 2) improving the thermal management system, and 3) designing propulsion system architectures to provide inherent UAM vehicle safety.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN74347 , 2019 Propulsion and Power Technical Meeting; Oct 29, 2019 - Oct 30, 2019; Hampton, VA; United States
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    Near-Exit Pressure Fluctuations in Jets from Circular and Rectangular Nozzles (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-15
    Description: This article documents some experimental observations made for near-exit unsteady pressure fluctuations in high-speed jets. These fluctuations are apparently related to trapped waves within the jet potential core as investigated and reported recently by other researchers. Round nozzles of three different diameters and rectangular nozzles of three different aspect ratios are studied. The pressure fluctuations manifest as a series of peaks in the spectra. These trapped wave spectral peaks are found with all nozzles. Their characteristics and variations with axial and radial distances as well as with jet Mach number are documented. Effects of initial boundary layer state and the presence of a surface nearby as well as the scaling of the frequencies of the spectral peaks are studied and discussed.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM—2019-220383 , GRC-E-DAA-TN74374
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    Pressure Gain Combustion for High Speed Propulsion (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-15
    Description: This presentation contains notes for a one-hour lecture that is part of a two-day AIAA Short Course titled, Hypersonic Air-Breathing Propulsion: Emerging Technologies and Cycles. The presentation covers an introduction to Pressure Gain Combustion (PGC) and its applicability to high speed airbreathing propulsion (HSABP). The concept of PGC is discussed on a thermodynamic basis, the performance benefits are demonstrated, and methods of implementation are described. These include devices such as Resonant Pulse Combustors, Internal Combustion Wave Rotors, Pulse Detonation Engines, and Rotating Detonation Engines.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN71710 , Propulsion and Energy 2019; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN
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    NASA Electrified Aircraft Propulsion Efforts (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-14
    Description: No abstract available
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN72959 , Hybrid/Electric Aero-Propulsion Systems for Military Applications; Oct 07, 2019 - Oct 09, 2019; Trondheim; Norway
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    Aerodynamic Performance of Supersonic Parachutes Behind Slender Bodies (2019)
    In:  CASI
    Details
    Publication Date: 2019-08-09
    Description: NASA's ASPIRE (Advanced Supersonic Parachute Inflation Research Experiments) project was launched to investigate the supersonic deployment, inflation and aerodynamics of full-scale disk-gap-band (DGB) parachutes. Three flight tests (October 2017, March 2018 and July 2018) deployed and examined parachutes meant for the upcoming "Mars 2020" mission. Mars-relevant conditions were achieved by performing the tests at high altitudes over Earth on a sounding rocket platform, with the parachute deploying behind a slender body (roughly 1/6-th the diameter of the capsule that will use this parachute for descent at Mars). All three tests were successful and delivered valuable data and imagery on parachute deployment and performance. CFD simulations were used in designing the flight test, interpreting the flight data, and extrapolating the results obtained during the flight test to predict parachute behavior at Mars behind a blunt capsule. This presentation will provide a brief overview of the test program and flight test data, with emphasis on differences in parachute performance due to the leading body geometry.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN71648 , Annual Meeting of the APS Division of Fluid Dynamics; Nov 23, 2019 - Nov 26, 2019; Seattle, WA; United States
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