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  • General Chemistry  (1,562)
  • Aircraft Propulsion and Power
  • 2015-2019  (300)
  • 1940-1944  (1,578)
  • 1
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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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  • 2
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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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  • 3
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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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  • 4
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    NASA Acoustic Stirling IRAD: Thermal Recovery Energy Efficient System (TREES) Energy Conversion and Management in Aircraft (2018)
    In:  CASI
    Details
    Publication Date: 2020-01-03
    Description: 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-TN68023 , Annual S&T Electrical Systems and Wiring Interagency; Dec 13, 2018; Houston, TX; United States
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  • 5
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    Hydrothermal Ethanol Flames in Co-Flow Jets (2018)
    In:  CASI
    Details
    Publication Date: 2019-12-21
    Description: Results on the autoignition and stabilization of ethanol hydrothermal flames in a Supercritical Water Oxidation (SCWO) reactor operating at constant pressure are reported. The flames are observed as luminous reaction zones occurring in supercritical water; i.e., water at conditions above its critical point (approximately 22 MPa and 374 C). A co-flow injector is used to inject fuel (inner flow), comprising an aqueous solution ranging from 20%-v to 50%-v ethanol, and air (annular flow) into a reactor filled with supercritical water at approximately 24.3 MPa and 425 C. Results show hydrothermal flames are autoignited and form diffusion flames which exhibit laminar and/or turbulent features depending upon flow conditions. Two orthogonal camera views are used; one providing a backlit shadowgraphic image of the co-flow jet and the other providing color images of the flame. In addition, spectroscopic measurements of flame emissions in the UV and visible spectrum are discussed.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN72746 , The Journal of Supercritical Fluids (ISSN 0896-8446) (e-ISSN 1872-8162); 145; 192-200
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  • 6
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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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  • 7
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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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  • 8
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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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  • 9
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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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  • 10
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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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  • 11
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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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  • 12
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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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  • 13
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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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  • 14
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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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  • 15
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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: NASA/TM-2019-220353 , GRC-E-DAA-TN73066
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  • 16
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    Dynamic Analysis of the STARC-ABL Propulsion System (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-07
    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: NASA/TM-2019-220352 , AIAA–2019–4182 , GRC-E-DAA-TN73064 , AIAA Propulsion and Energy Forum; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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  • 17
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    Evaluation of Electrical System Requirements for Implementing Turbine Electrified Energy Management (2019)
    In:  CASI
    Details
    Publication Date: 2019-11-07
    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: NASA/TM-2019-220354 , Paper AIAA–2019–4502 , GRC-E-DAA-TN73068 , AIAA/IEEE Electric Aircraft Technology Symposium (EATS); Aug 22, 2019 - Aug 24, 2019; Indianapolis, IN; United States
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  • 18
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    Dielectric Barrier Discharge (DBD) Plasma Actuators for Flow Control in Turbine Engines: Simulation of Flight Conditions in the Laboratory by Density Matching (2018)
    In:  CASI
    Details
    Publication Date: 2019-10-26
    Description: We address requirements for laboratory testing of AC Dielectric Barrier Discharge (AC-DBD) plasma actuators for active flow control in aviation gas turbine engines. The actuator performance depends on the gas discharge properties, which, in turn, depend on the pressure and temperature. It is technically challenging to simultaneously set test-chamber pressure and temperature to the flight conditions. We propose that the AC-DBD actuator performance depends mainly on the gas density, when considering ambient conditions effects. This enables greatly simplified testing at room temperature with only chamber pressure needing to be set to match the density at flight conditions. For turbine engines, we first constructed generic models of four engine thrust classes; 300-, 150-, 50-passenger, and military fighter, and then calculated the densities along the engine at sea-level takeoff and altitude cruise conditions. The range of chamber pressures that covers all potential applications was found to be from 3 to 1256 kPa (0.03 to 12.4 atm), depending on engine-class, flight altitude, and actuator placement in the engine. The engine models are non-proprietary and can be used as reference data for evaluation requirements of other actuator types and for other purposes. We also provided examples for air vehicles applications up to 19,812 m (65,000 ft).
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN60543 , International Journal of Turbo and Jet-Engines (ISSN 0334-0082) (e-ISSN 2191-0332); 36; 2; 157-174
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  • 19
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    Propulsion System Optimization for a Turboelectric Tiltwing Urban Air Mobility Aircraft (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-22
    Description: An emerging potential market within the aviation industry is short, frequent air taxi flights within the urban airspace. These air taxis (also called urban air mobility or UAM vehicles) are envisioned to be vertical take-o and landing designs which are capable of carrying 1 to 15 passengers in an intra-urban environment with less than 50 nautical miles of range. Numerous vehicle conceptual designs have been proposed by various industry and government organizations to fulfill these potential missions. These concepts are enabled by recent advancements in a number of areas including propulsion and power systems. While new technologies are making these vehicles possible, this new UAM design space is large, unexplored, and multidisciplinary in nature. New challenges exist in identifying and creating optimized designs for these unique vehicles with new propulsion technologies. This work presents the development of a suite of propulsion system analysis tools, which when coupled together, can improve the multidisciplinary conceptual design and optimization of UAM vehicle propulsion systems. These analysis tools are then applied to the design optimization of a turboelectric propulsion system for a notional UAM tiltwing concept. The optimization demonstration for this vehicle shows how a tightly-coupled multidisciplinary design can be developed which considers both physical design characteristics and operating schedules. Furthermore, the results explore trade-o s in the thermal management system design and how those trade-o s impact the overall vehicle.
    Keywords: Aircraft Propulsion and Power
    Type: ISABE-2019-24365 , GRC-E-DAA-TN71922 , International Society for Air Breathing Engines (ISABE) Conference; Sep 22, 2019 - Sep 27, 2019; Canberra, ACT; Australia
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  • 20
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    Introduction to Dynamic Propulsion System Modeling for Control Design, Analysis, and Simulation (2019)
    In:  CASI
    Details
    Publication Date: 2019-10-19
    Description: This is an oral presentation on dynamic propulsion system modeling for control design, analysis, and simulation. These tools have been developed at NASA Glenn Research Center.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN72034 , AIAA Propulsion and Energy Forum; Aug 19, 2019 - Aug 22, 2019; Indianapolis, IN; United States
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  • 21
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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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  • 22
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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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  • 23
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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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  • 24
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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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    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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  • 26
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    Green Propulsion Technologies for Advanced Air Transports (2015)
    In:  CASI
    Details
    Publication Date: 2019-09-20
    Description: Air transportation is critical to U.S. and Global economic vitality. However, energy and climate issues challenge aviation's ability to be sustainable in the long term. Aviation must dramatically reduce fuel use and related emissions. Energy costs to U.S. airlines nearly tripled between 1995 and 2011, and continue to be the highest percentage of operating costs. The NASA Advanced Air Transports Technology Project addresses the comprehensive challenge of enabling revolutionary energy efficiency improvements in subsonic transport aircraft combined with dramatic reductions in harmful emissions and perceived noise to facilitate sustained growth of the air transportation system. Advanced technologies and the development of unconventional aircraft systems offer the potential to achieve these improvements. The presentation will highlight the NASA vision of revolutionary systems and propulsion technologies needed to achieve these challenging goals. Specifically, the primary focus is on the N+3 generation; that is, vehicles that are three generations beyond the current state of the art, requiring mature technology solutions in the 2025-30 timeframe.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN20707 , OSU Aerospace Graduate Student Seminar; Jan 30, 2015; Columbus, OH; 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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  • 28
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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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  • 29
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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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    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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    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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  • 32
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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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    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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  • 36
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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-TN72121 , AIAA Propulsion and Energy Forum 2019; Aug 19, 2019 - Aug 22, 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: 2019-09-06
    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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    High Efficiency Megawatt Motor Conceptual Design (2018)
    In:  CASI
    Details
    Publication Date: 2019-09-06
    Description: The High Efficiency Megawatt Motor (HEMM) is being designed to meet the needs of Electrified Aircraft Propulsion (EAP). The key objective of this work is to establish a motor technology which simultaneously attains high specific power (〉16kW/kg ratio to electromagnetic weight) and high efficiency (〉98%) by judicious application of high temperature superconducting wire and integrated thermal management. Another important feature is to achieve the performance goals with an eye to aircraft integration constraints. An electromagnetic analysis was performed which shows that the proposed HEMM design meets the performance objectives if key current capability and mechanical constraints are achieved. Sensitivity of motor power and performance to those parameters is illustrated. The HEMM technology could be applied to a range of aircraft types that require megawatt level electrical power.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN57165 , AIAA Propulsion and Energy Forum and Exposition (AIAA Propulsion and Energy 2018); Jul 09, 2018 - Jul 11, 2018; Cincinnati, OH; United States
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  • 39
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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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    Implementation of a Body Force Model into OVERFLOW for Propulsor Simulations (2017)
    In:  CASI
    Details
    Publication Date: 2019-09-04
    Description: No abstract available
    Keywords: Aircraft Propulsion and Power
    Type: ARC-E-DAA-TN43279 , Applied Aerodynamic Conference, AIAA Aviation Forum; Jun 05, 2017 - Sep 09, 2017; Denver, CO; United States
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  • 41
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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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  • 42
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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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  • 43
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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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  • 44
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    Flame Holder System (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A flame holder system includes a modified torch body and a ceramic flame holder. Catch pin(s) are coupled to and extend radially out from the torch body. The ceramic flame holder has groove(s) formed in its inner wall that correspond in number and positioning to the catch pin(s). Each groove starts at one end of the flame holder and is can be shaped to define at least two 90 degree elbows. Each groove is sized to receive one catch pin therein when the flame holder is fitted over the end of the torch body. The flame holder is then manipulated until the catch pin(s) butt up against the end of the groove(s).
    Keywords: Aircraft Propulsion and Power
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  • 45
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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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  • 46
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    Conditionally Active Min-Max Limit Regulators (2017)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: A conditionally active limit regulator may be used to regulate the performance of engines or other limit regulated systems. A computing system may determine whether a variable to be limited is within a predetermined range of a limit value as a first condition. The computing system may also determine whether a current rate of increase or decrease of the variable to be limited is great enough that the variable will reach the limit within a predetermined period of time with no other changes as a second condition. When both conditions are true, the computing system may activate a simulated or physical limit regulator.
    Keywords: Aircraft Propulsion and Power
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  • 47
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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
    Format: application/pdf
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  • 48
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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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    Twin Target Thrust Reverser Module (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-26
    Description: A nozzle assembly for a dual gas turbine engine propulsion system includes a housing mountable proximate to a first bypass passage of a first gas turbine engine and a second bypass passage of a second gas turbine engine, first and second upper doors, and first and second lower doors. Each of the first and second upper doors and the first and second lower doors are pivotally mounted to the housing for movement between a stowed position and a deployed position in which airflow through the first and second bypass passages is redirected relative to respective centerline axes of the first and second gas turbine engines.
    Keywords: Aircraft Propulsion and Power
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  • 50
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    Small Scale High Speed Turbomachinery (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-26
    Description: A small scale, high speed turbomachine is described, as well as a process for manufacturing the turbomachine. The turbomachine is manufactured by diffusion bonding stacked sheets of metal foil, each of which has been pre-formed to correspond to a cross section of the turbomachine structure. The turbomachines include rotating elements as well as static structures. Using this process, turbomachines may be manufactured with rotating elements that have outer diameters of less than four inches in size, and/or blading heights of less than 0.1 inches. The rotating elements of the turbomachines are capable of rotating at speeds in excess of 150 feet per second. In addition, cooling features may be added internally to blading to facilitate cooling in high temperature operations.
    Keywords: Aircraft Propulsion and Power
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    Variable Cycle Intake for Reverse Core Engine (2016)
    In:  CASI
    Details
    Publication Date: 2019-08-26
    Description: A gas generator for a reverse core engine propulsion system has a variable cycle intake for the gas generator, which variable cycle intake includes a duct system. The duct system is configured for being selectively disposed in a first position and a second position, wherein free stream air is fed to the gas generator when in the first position, and fan stream air is fed to the gas generator when in the second position.
    Keywords: Aircraft Propulsion and Power
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  • 52
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    Angled Core Gas Turbine Engine Mounting (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-26
    Description: A propulsion system for an aircraft includes first and second turbine engines mounted within a fuselage of the aircraft. The first turbine engine includes a first engine core that drives a first propulsor disposed about a first propulsor axis. The second turbine engine includes a second engine core and a second propulsor disposed about a second propulsor axis parallel to the first propulsor axis. The first engine core and the second engine core are mounted at an angle relative to corresponding ones of the first and second propulsor axes.
    Keywords: Aircraft Propulsion and Power
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  • 53
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    Gas Turbine Engine Having Fan Rotor Driven by Turbine Exhaust and with a Bypass (2016)
    In:  CASI
    Details
    Publication Date: 2019-08-26
    Description: A gas turbine engine has a core engine incorporating a core engine turbine. A fan rotor is driven by a fan rotor turbine. The fan rotor turbine is in the path of gases downstream from the core engine turbine. A bypass door is moveable from a closed position at which the gases from the core engine turbine pass over the fan rotor turbine, and moveable to a bypass position at which the gases are directed away from the fan rotor turbine. An aircraft is also disclosed.
    Keywords: Aircraft Propulsion and Power
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  • 54
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    Gas Turbine Engine Inlet Wall Design (2016)
    In:  CASI
    Details
    Publication Date: 2019-08-26
    Description: A gas turbine engine has an inlet duct formed to have a shape with a first ellipse in one half and a second ellipse in a second half. The second half has an upstream most end which is smaller than the first ellipse. The inlet duct has a surface defining the second ellipse which curves away from the first ellipse, such that the second ellipse is larger at an intermediate location. The second ellipse is even larger at a downstream end of the inlet duct leading into a fan.
    Keywords: Aircraft Propulsion and Power
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  • 55
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    NASA Acoustic Stirling IRAD: Thermal Recovery Energy Conversion in Aircraft (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-24
    Description: 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-TN68631
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  • 56
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    Gas Turbine Engine with Air/Fuel Heat Exchanger (2017)
    In:  CASI
    Details
    Publication Date: 2019-08-24
    Description: One embodiment of the present invention is a unique aircraft propulsion gas turbine engine. Another embodiment is a unique gas turbine engine. Another embodiment is a unique gas turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engines with heat exchange systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith.
    Keywords: Aircraft Propulsion and Power
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  • 57
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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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  • 58
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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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  • 59
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    Compressibility and Heating Effects on Pressure Loss and Cooling of a Baffled Cylinder Barrel (1944)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: Theoretical investigations have shown that, because air is compressible, the pressure-drop requirements for cooling an air-cooled engine will be much greater at high altitudes and high speeds than at sea level and low speeds. Tests were conducted by the NACA to obtain some experimental confirmation of the effect of air compressibility on cooling and pressure loss of a baffled cylinder barrel and to evaluate various methods of analysis. The results reported in the present paper are regarded as preliminary to tests on single-cylinder and multi-cylinder engines. Tests were conducted over a wide range of air flows and density altitudes.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-TR-783
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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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    Electrified Aircraft Propulsion (EAP) Educational Briefing (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: This is an educational briefing package for Electrified Aircraft Propulsion and Power (EAPP); this presentation will brief on NASA needs and challenges in Electrified Aircraft Propulsion and Power as well as the SBIR program and proposal guidance.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN63725
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    Jet-Surface Interaction Noise Models Comparison to TMP17 and Next Steps (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: A set of empirical jet-surface interaction noise models, developed for single-stream round nozzles exhausting over a simple surface in a static ambient, are evaluated for use in more realistic applications that include multi-stream nozzle systems with chevrons and dihedral surface geometries. The simple-single-stream models have several advantages when used in system-level noise studies: they are robust, they are quickly computed, and they are generally applicable to a wide range of configurations. However, these models rely on a fixed noise source distribution that does not account for the presence of chevrons at the nozzle exit. The effect of this omission on the prediction accuracy is shown by this comparison to experimental data. This motivates discussion of future work to develop a more robust modeling framework that can account for generalized source distributions and more complex airframe geometries. Re: Top-Mounted Propulsion (TMP17) Test Plans.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN54517 , Acoustics Technical Working Group (ATWG) Meeting; Apr 10, 2018 - Apr 11, 2018; Hampton, VA; United States
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    NASA Emissions Research Overview (2018)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: NASA Aeronautics is advancing a variety of technologies toward the objective of reducing aviation fuel burn and emissions. Specifically, the Advanced Air Transport Technology Project under the Advanced Air Vehicles Program is investing in technologies such as small core engines, fuel-flexible combustors, and electrified aircraft propulsion, all of which offer potential for reduced fleet fuel usage and harmful emissions. This presentation will provide a brief overview of these technical approaches as well as a NASA Aeronautics budget outlook.
    Keywords: Aircraft Propulsion and Power
    Type: HQ-E-DAA-TN56877 , FAA Aviation Emissions Characterization (AEC) Roadmap Meeting; May 22, 2018; Washington, DC; United States
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    Active Combustion Controls (2017)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: This presentation prepared for the upcoming NASA-Pratt/UTRC meeting describes background and developments on Active Combustion Control.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN49332 , NASA-Pratt/UTRC Aircraft Engine Controls Meeting; Nov 15, 2017; Hartford, CT; United States
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    Multilayered Functional Insulation System (MFIS) for AC Power Transmission in High Voltage Hybrid Electrical Propulsion (2017)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: High voltage hybrid electric propulsion systems are now pushing new technology development efforts for air transportation. A key challenge in hybrid electric aircraft is safe high voltage distribution and transmission of megawatts of power (〉20 MW). For the past two years, a multidisciplinary materials research team at NASA Glenn Research Center has investigated the feasibility of distributing high voltage power on future hybrid electric aircraft. This presentation describes the team's approach to addressing this challenge, significant technical findings, and next steps in GRC's materials research effort for MW power distribution on aircraft.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN48425 , EnergyTech 2017; Oct 31, 2017 - Nov 02, 2017; Cleveland, OH; United States
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    Overview of NASA GRC Electrified Aircraft Propulsion Systems Analysis Methods (2017)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: The accurate modeling and analysis of electrified aircraft propulsion concepts require intricate subsystem system component coupling. The major challenge in electrified aircraft propulsion concept modeling lies in understanding how the subsystems "talk" to each other and the dependencies they have on one another.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN48292 , EnergyTech 2017; Oct 31, 2017 - Nov 02, 2017; Cleveland, OH; United States
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    Overview of the NASA STARC-ABL (Rev. B) Advanced Concept (2017)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: No abstract available
    Keywords: Aircraft Propulsion and Power
    Type: NF1676L-26767 , One Boeing NASA Electric Aircraft Workshop; Mar 22, 2017; Washington, DC; United States
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    NASA Hybrid Gas-Electric Propulsion (HGEP) Subproject: Advanced Air Transport Technologies (AATT) (2017)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: No abstract available
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN40309 , Boeing/NASA Electric Aircraft Workshop; Mar 22, 2017; Washington, DC; United States
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    NACA Investigation of a Jet-Propulsion System Applicable to Flight (1943)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: Following a brief history of the NACA investigation of jet propulsion, a discussion is given of the general investigation and analysis leading to the construction of the jet-propulsion ground-test mock-up. The results of burning experiments and of test measurements designed to allow quantitative flight performance predictions of the system are presented and correlated with calculations. These calculations are then used to determine the performance of the system on the ground and in the air at various speeds and altitudes under various burning conditions. The application of the system to an experimental airplane is described and some performance predictions for this airplane are made.
    Keywords: Aircraft Propulsion and Power
    Type: NACA/TR-802
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  • 70
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    Sub-scale Waterflow Cavitation and Dynamic Transfer Function Testing of an Oxidizer Turbo-Pump Combined Inducer and Impeller (2016)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: In 2009 and 2010, Concepts NREC prepared for and performed a series of tests on a 52% scale of a version of the Pratt & Whitney Rocketdyne J-2X Oxidizer Turbopump under a Phase III SBIR with NASA MSFC. The test article was a combined inducer and impeller, tested as a unit. This paper presents an overview of the test rig and facility, instrumentation, signal conditioning, data acquisition systems, testing approach, measurement developments, and lessons learned. Results from these tests were presented in the form of two papers at the previous JANNAF joint propulsion conference, in December of 2011.
    Keywords: Aircraft Propulsion and Power
    Type: M16-5435 , Liquid Propulsion; Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States|Modeling and Simulation; Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States|JANNAF Joint Meeting; Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; United States|Spacecraft Propulsion; Dec 05, 2016 - Dec 08, 2016; Phoenix, AZ; 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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    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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  • 73
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    Experimental Investigation of Shrouding on Meshed Spur Gear Windage Power Loss (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-27
    Description: Windage power loss in high-speed gearboxes results in efficiency losses and increased heating due to drag on the gear teeth. Test results for meshed spur gear windage power loss are presented at ambient oil inlet temperatures, both with and without shrouding. The rate of windage power loss is observed to increase above a gear surface speed of 10,000 feet per minute (51 meters per second), similar to results presented in the literature. Shrouding is observed to become more effective above 15,000 feet per minute (76 meters per second), decreasing power loss by 10 percent at 25,000 feet per minute (127 meters per second). The need for gearbox oil drain slots limits the effectiveness of shrouding in reducing windage power loss. Windage power loss is observed to decrease with increasing gearbox temperatures and to increase with oil flow. Windage power losses for unshrouded meshed spur gears are 7 times greater than losses determined from unshrouded single spur gear tests. A 6- to 12-times increase in windage power loss is observed in the shrouded meshed spur gear data compared with shrouded single spur gear data. Based on this preliminary study, additional research is suggested to determine the effect of oil drain slot configurations, axial and radial shroud clearances, and higher gear surface speeds on windage power loss. Additional work is also suggested to determine the sensitivity of windage power loss to oil temperature and oil flow. Windage power loss for meshed spur gears tested in both the shrouded and unshrouded configurations is shown to be more than double versus windage power loss for the same spur gears run individually in the same shroud configurations. Further study of the physical processes behind these results is needed to optimize gearbox shrouds for minimum windage power loss.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2017-219536 , E-19395 , GRC-E-DAA-TN44777 , American Helicopter Society (AHS) Annual Forum and Technology Display (Forum 73); 9ý11 May 2017; Fort Worth, TX; United States
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    Sensor Selection for Aircraft Engine Performance Estimation and Gas Path Fault Diagnostics (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-27
    Description: This paper presents analytical techniques for aiding system designers in making aircraft engine health management sensor selection decisions. The presented techniques, which are based on linear estimation and probability theory, are tailored for gas turbine engine performance estimation and gas path fault diagnostics applications. They enable quantification of the performance estimation and diagnostic accuracy offered by different candidate sensor suites. For performance estimation, sensor selection metrics are presented for two types of estimators including a Kalman filter and a maximum a posteriori estimator. For each type of performance estimator, sensor selection is based on minimizing the theoretical sum of squared estimation errors in health parameters representing performance deterioration in the major rotating modules of the engine. For gas path fault diagnostics, the sensor selection metric is set up to maximize correct classification rate for a diagnostic strategy that performs fault classification by identifying the fault type that most closely matches the observed measurement signature in a weighted least squares sense. Results from the application of the sensor selection metrics to a linear engine model are presented and discussed. Given a baseline sensor suite and a candidate list of optional sensors, an exhaustive search is performed to determine the optimal sensor suites for performance estimation and fault diagnostics. For any given sensor suite, Monte Carlo simulation results are found to exhibit good agreement with theoretical predictions of estimation and diagnostic accuracies.
    Keywords: Aircraft Propulsion and Power
    Type: ASME GT2015-43744 , GRC-E-DAA-TN18966 , ASME Turbo Expo 2015: Turbine Technical Conference and Exposition (GT 2015); 15ý19 Jun. 2015; Montreal, QC; Canada
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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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    Biofuel Blending Reduces Aircraft Engine Particle Emissions at Cruise Conditions (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-23
    Description: Aviation aerosol emissions have a disproportionately large climatic impact because they are emitted high in the relatively pristine upper troposphere where they can form linear contrails and influence cirrus clouds. Research aircraft from NASA, DLR, and NRC Canada made airborne measurements of gaseous and aerosol composition and contrail microphysical properties behind the NASA DC-8 aircraft at cruise altitudes. The DC-8 CFM-56-2C engines burned traditional medium-sulfur Jet A fuel as well as a low-sulfur Jet A fuel and a 50:50 biofuel blend. Substantial, two-to-three-fold emissions reductions are found for both particle number and mass emissions across the range of cruise thrust operating conditions. These observations provide direct and compelling evidence for the beneficial impacts of biojet fuel blending under real-world conditions.
    Keywords: Aircraft Propulsion and Power
    Type: NF1676L-25029 , Nature (ISSN 0028-0836) (e-ISSN 1476-4687); 543; 411-415
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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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    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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    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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    Meander-Like Shape Optimization of the Stator-Rotor Platform Cavity (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Recent progress in additive manufacturing has enabled opportunities to explore novel stator rim geometries which can be implemented to improve cooling strategies in turbomachinery. This paper presents a simplified stationary geometry optimization strategy to produce enhanced stator-rotor cavity sealing and highlights main driving mechanisms.The stator and rotor rims were designed using a design strategy based on inspiration from the meandering of rivers. A minimum thickness of 2 millimeters was maintained throughout the cavity to ensure a practical implementation. The computational domain comprised of the stator outlet, hub disk leakage cavity, and rotor platform was meshed using NUMECA Int. package, Hexpress. The numerical analysis required 3D Unsteady Reynolds Average Navier-Stokes to replicate vorticial structures using Ansys Fluent. The operating conditions were representative of engine-like conditions, exploring a wide range of mass flow ratios from 1 to 3 percent. The optimization yielded designs that provide 30 percent reduction in rear platform temperature while minimizing coolant mass flow. The applicability of the design was compared against 3D sector in both stationary and in rotation.
    Keywords: Aircraft Propulsion and Power
    Type: ASME GT2018-77167 , GRC-E-DAA-TN55691 , ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition (GT2018); Jun 11, 2018 - Jun 15, 2018; Oslo; Norway
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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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    Structural Configuration Analysis of Advanced Flight Vehicle Concepts with Distributed Hybrid-Electric Propulsion (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: Structural configuration analysis of two advanced aircraft concepts with distributed hybrid-electric propulsion is presented. These concepts are characterized by multiple wing-mounted electric propulsors, which are powered by turbo-generators. Based on lessons learned from previous structural analysis of unconventional concepts, high-fidelity finite element models of the aircraft wing with embedded electric propulsors are developed. Although a hybrid-electric propulsion system has noise and emission benefits, it also adds electrical power system weights. Hence, efficient structural integration of the wing and propulsors is investigated for design improvement, structural analysis, and weight reduction. Wing structural weights of the two designs are compared with a baseline conventional transport aircraft wing for benefit assessment. In one design, the wing structural weight reduction partially compensates for the additional weight associated with the distributed electric propulsion system.
    Keywords: Aircraft Propulsion and Power
    Type: NF1676L-27438 , AIAA SciTech Forum 2018; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
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    The Electrifying Future of Air Transportation (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: This presentation discusses the NASA Aeronautics Advanced Air Transport Technology Projects perspective on electric, hybrid-electric, and related distributed propulsion technologies for future generations of large transport aircraft. Recent system studies commissioned by NASA and other organizations have identified these technologies as promising approaches to dramatically reduce aircraft fuel consumption, noise, and emissions. These technologies are part of the Projects overall research portfolio aimed toward developing ultra-efficient commercial aircraft in conjunction with alternative low carbon propulsion and energy systems to enable safe and sustainable future growth in global aviation. It is anticipated that both room temperature and cryogenic electrical technologies will be needed in the future. Room temperature electrical systems are likely to impact aviation in the near term by making their way onto smaller aircraft and by augmenting traditional propulsion systems on larger aircraft, while cryogenic technologies will likely be needed in the far term to deliver the several tens of megawatts of propulsive power needed for large transport aircraft. The presentation outlines the opportunities and challenges for electric propulsion technologies for commercial aviation, and describes some of the related concepts and enabling technologies that are currently being developed.
    Keywords: Aircraft Propulsion and Power
    Type: ARC-E-DAA-TN44463 , IEEE Energy Conversion Congress and Expo 2017; Oct 01, 2017 - Oct 05, 2017; Cincinnatti, OH; United States
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    Investigation of Spiral and Sweeping Holes (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-18
    Description: Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and Square holes. A patent-pending spiral hole design showed the highest potential of the non-diffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing ratios of 1.0, 1.5, 2.0, and 2.5 at a density ratio of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN35549 , Journal of Turbomachinery (ISSN 0889-504X) (e-ISSN 1528-8900); 138; 9
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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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    Aerodynamic Heat-Power Engine Operating on a Closed Cycle (1942)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Hot-air engines with dynamic compressors and turbines offer new prospects of success through utilization of units of high efficiencies and through the employment of modern materials of great strength at high temperature. Particular consideration is given to an aerodynamic prime mover operating on a closed circuit and heated externally. Increase of the pressure level of the circulating air permits a great increase of limit load of the unit. This also affords a possibility of regulation for which the internal efficiency of the unit changes but slightly. The effect of pressure and temperature losses is investigated. A general discussion is given of the experimental installation operating at the Escher Wyss plant in Zurich for a considerable time at high temperatures.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-TM-1034 , Zeitschrift des Vereines Deutscher Lagenieure; 85; 22; 491-500
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    Validation of an Integrated Airframe and Turbofan Engine Simulation for Evaluation of Propulsion Control Modes (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The National Aeronautics and Space Administration (NASA) has developed independent airframe and engine models that have been integrated into a single real-time aircraft simulation for piloted evaluation of propulsion control algorithms. In order to have confidence in the results of these evaluations, the integrated simulation must be validated to demonstrate that its behavior is realistic and that it meets the appropriate Federal Aviation Administration (FAA) certification requirements for aircraft. The paper describes the test procedures and results, demonstrating that the integrated simulation generally meets the FAA requirements and is thus a valid testbed for evaluation of propulsion control modes.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN19726 , SciTech 2015; Jan 05, 2015 - Jan 09, 2015; Kissimmee, FL; United States
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    An Integrated Architecture for Aircraft Engine Performance Monitoring and Fault Diagnostics: Engine Test Results (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper presents a model-based architecture for performance trend monitoring and gas path fault diagnostics designed for analyzing streaming transient aircraft engine measurement data. The technique analyzes residuals between sensed engine outputs and model predicted outputs for fault detection and isolation purposes. Diagnostic results from the application of the approach to test data acquired from an aircraft turbofan engine are presented. The approach is found to avoid false alarms when presented nominal fault-free data. Additionally, the approach is found to successfully detect and isolate gas path seeded-faults under steady-state operating scenarios although some fault misclassifications are noted during engine transients. Recommendations for follow-on maturation and evaluation of the technique are also presented.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2015-218448 , AIAA Paper 2014-3924 , E-19012 , GRC-E-DAA-TN17165 , Joint Propulsion Conference; Jul 28, 2014 - Jul 30, 2014; Cleveland, OH; United States
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    Re: Penetration Behavior of Opposed Rows of Staggered Secondary Air Jets Depending on Jet Penetration Coefficient and Momentum Flux Ratio (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The purpose of this article is to explain why the extension of the previously published C = (S/Ho)sqrt(J) scaling for opposed rows of staggered jets wasn't directly successful in the study by Choi et al. (2016). It is not surprising that staggered jets from opposite sides do not pass each other at the expected C value, because Ho/D and sqrt(J) are much larger than the maximum in previous studies. These, and large x/D's, tend to suggest development of 2-dimensional flow. Although there are distinct optima for opposed rows of in-line jets, single-side injection, and opposed rows of staggered jets based on C, opposed rows of staggered jets provide as good or better mixing performance, at any C value, than opposed rows of in-line jets or jets from single-side injection.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN33874 , International Journal of Heat and Mass Transfer (e-ISSN 0017-9310); 102; 435-444
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    A Requirements-Driven Optimization Method for Acoustic Treatment Design (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Acoustic treatment designers have long been able to target specific noise sources inside turbofan engines. Facesheet porosity and cavity depth are key design variables of perforate-over-honeycomb liners that determine levels of noise suppression as well as the frequencies at which suppression occurs. Layers of these structures can be combined to create a robust attenuation spectrum that covers a wide range of frequencies. Looking to the future, rapidly-emerging additive manufacturing technologies are enabling new liners with multiple degrees of freedom, and new adaptive liners with variable impedance are showing promise. More than ever, there is greater flexibility and freedom in liner design. Subject to practical considerations, liner design variables may be manipulated to achieve a target attenuation spectrum. But characteristics of the ideal attenuation spectrum can be difficult to know. Many multidisciplinary system effects govern how engine noise sources contribute to community noise. Given a hardwall fan noise source to be suppressed, and using an analytical certification noise model to compute a community noise measure of merit, the optimal attenuation spectrum can be derived using multidisciplinary systems analysis methods. The subject of this paper is an analytical method that derives the ideal target attenuation spectrum that minimizes noise perceived by observers on the ground.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN31751 , AIAA/CEAS Aeroacoustics Conference; May 30, 2016 - Jun 01, 2016; Lyon; France
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    Impact of an Exhaust Throat on Semi-Idealized Rotating Detonation Engine Performance (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A computational fluid dynamic (CFD) model of a rotating detonation engine (RDE) is used to examine the impact of an exhaust throat (i.e. a constriction) on performance. The model simulates an RDE which is premixed, adiabatic, inviscid, and which contains an inlet valve that prevents backflow from the high pressure region directly behind the rotating detonation. Performance is assessed in terms of ideal net specific impulse which is computed on the assumption of lossless expansion of the working fluid to the ambient pressure through a notional diverging nozzle section downstream of the throat. Such a semi-idealized analysis, while not real-world, allows the effect of the throat to be examined in isolation from, rather than coupled to (as it actually is) various loss mechanisms. For the single Mach 1.4 flight condition considered, it is found that the addition of a throat can yield a 9.4 percent increase in specific impulse. However, it is also found that when the exit throat restriction gets too small, an unstable type of operation ensues which eventually leads to the detonation failing. This behavior is found to be somewhat mitigated by the addition of an RDE inlet restriction across which there is an aerodynamic loss. Remarkably, this loss is overcome by the benefits of the further exhaust restrictions allowed. The end result is a configuration with a 10.3 percent improvement in ideal net specific thrust.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN28815 , AIAA Aerospace Sciences Meeting (SciTech 2016); Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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    Turboelectric Aircraft Drive Key Performance Parameters and Functional Requirements (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The purpose of this paper is to propose specific power and efficiency as the key performance parameters for a turboelectric aircraft power system and investigate their impact on the overall aircraft. Key functional requirements are identified that impact the power system design. Breguet range equations for a base aircraft and a turboelectric aircraft are found. The benefits and costs that may result from the turboelectric system are enumerated. A break-even analysis is conducted to find the minimum allowable electric drive specific power and efficiency that can preserve the range, initial weight, operating empty weight, and payload weight of the base aircraft.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2016-218919 , AIAA Paper 2015-3890 , E-19104-1 , GRC-E-DAA-TN26012 , AIAA Propulsion and Energy Forum 2015; Jul 27, 2015 - Jul 29, 2015; Orlando, FL; United States
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    Large Eddy Simulation of High-Speed, Premixed Ethylene Combustion (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A large-eddy simulation / Reynolds-averaged Navier-Stokes (LES/RANS) methodology is used to simulate premixed ethylene-air combustion in a model scramjet designed for dual mode operation and equipped with a cavity for flameholding. A 22-species reduced mechanism for ethylene-air combustion is employed, and the calculations are performed on a mesh containing 93 million cells. Fuel plumes injected at the isolator entrance are processed by the isolator shock train, yielding a premixed fuel-air mixture at an equivalence ratio of 0.42 at the cavity entrance plane. A premixed flame is anchored within the cavity and propagates toward the opposite wall. Near complete combustion of ethylene is obtained. The combustor is highly dynamic, exhibiting a large-scale oscillation in global heat release and mass flow rate with a period of about 2.8 ms. Maximum heat release occurs when the flame front reaches its most downstream extent, as the flame surface area is larger. Minimum heat release is associated with flame propagation toward the cavity and occurs through a reduction in core flow velocity that is correlated with an upstream movement of the shock train. Reasonable agreement between simulation results and available wall pressure, particle image velocimetry, and OH-PLIF data is obtained, but it is not yet clear whether the system-level oscillations seen in the calculations are actually present in the experiment.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA Paper 2015-0356 , NF1676L-21651 , AIAA SciTech 2015; Jan 05, 2015 - Jan 09, 2015; Kissimmee, FL; United States
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    Development of a Premixed Combustion Capability for Scramjet Combustion Experiments (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Hypersonic air-breathing engines rely on scramjet combustion processes, which involve high speed, compressible, and highly turbulent flows. The combustion environment and the turbulent flames at the heart of these engines are difficult to simulate and study in the laboratory under well controlled conditions. Typically, wind-tunnel testing is performed that more closely approximates engine testing rather than a careful investigation of the underlying physics that drives the combustion process. The experiments described in this paper, along with companion data sets being developed separately, aim to isolate the chemical kinetic effects from the fuel-air mixing process in a dual-mode scramjet combustion environment. A unique fuel injection approach is taken that produces a nearly uniform fuel-air mixture at the entrance to the combustor. This approach relies on the precombustion shock train upstream of the dual-mode scramjet combustor. A stable ethylene flame anchored on a cavity flameholder with a uniformly mixed combustor inflow has been achieved in these experiments allowing numerous companion studies involving coherent anti-Stokes Raman scattering (CARS), particle image velocimetry (PIV), and planar laser induced fluorescence (PLIF) to be performed.
    Keywords: Aircraft Propulsion and Power
    Type: NF1676L-20579 , AIAA SciTech 2015; Jan 05, 2015 - Jan 08, 2015; Orlando, FL; United States
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    Vehicle Integrated Propulsion Research (VIPR) III Volcanic Ash Environment (VAE) Preliminary Visual and Teardown Observations (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This presentation will be used to develop a level of partnership that is not within the current NASA program for N+3 engine operations.
    Keywords: Aircraft Propulsion and Power
    Type: DFRC-E-DAA-TN30644 , Aircraft Airworthiness and Sustainment Conference (AA&S 2016); Mar 21, 2016 - Mar 24, 2016; Grapevine, TX; United States
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    Sensor Selection for Aircraft Engine Performance Estimation and Gas Path Fault Diagnostics (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper presents analytical techniques for aiding system designers in making aircraft engine health management sensor selection decisions. The presented techniques, which are based on linear estimation and probability theory, are tailored for gas turbine engine performance estimation and gas path fault diagnostics applications. They enable quantification of the performance estimation and diagnostic accuracy offered by different candidate sensor suites. For performance estimation, sensor selection metrics are presented for two types of estimators including a Kalman filter and a maximum a posteriori estimator. For each type of performance estimator, sensor selection is based on minimizing the theoretical sum of squared estimation errors in health parameters representing performance deterioration in the major rotating modules of the engine. For gas path fault diagnostics, the sensor selection metric is set up to maximize correct classification rate for a diagnostic strategy that performs fault classification by identifying the fault type that most closely matches the observed measurement signature in a weighted least squares sense. Results from the application of the sensor selection metrics to a linear engine model are presented and discussed. Given a baseline sensor suite and a candidate list of optional sensors, an exhaustive search is performed to determine the optimal sensor suites for performance estimation and fault diagnostics. For any given sensor suite, Monte Carlo simulation results are found to exhibit good agreement with theoretical predictions of estimation and diagnostic accuracies.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2016-218926 , GT2015-43744 , E-19182 , GRC-E-DAA-TN27315 , ASME Turbo Expo 2015; Jun 15, 2015 - Jun 19, 2015; Montreal, Quebec; Canada
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    Environmentally Responsible Aviation: Propulsion Research to Enable Fuel Burn, Noise and Emissions Reduction (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA Environmentally Responsible Aviation (ERA) program is maturing technologies to enable simultaneous reduction of fuel burn, noise and emissions from an aircraft engine system. Three engine related Integrated Technology Demonstrations (ITDs) have been completed at Glenn Research Center in collaboration with Pratt Whitney, General Electric and the Federal Aviation Administration. The engine technologies being matured are: a low NOx, fuel flexible combustor in partnership with Pratt Whitney; an ultra-high bypass, ducted propulsor system in partnership with Pratt Whitney and FAA; and high pressure ratio, front-stage core compressor technology in partnership with General Electric. The technical rationale, test configurations and overall results from the test series in each ITD are described. ERA is using system analysis to project the benefits of the ITD technologies on potential aircraft systems in the 2025 timeframe. Data from the ITD experiments were used to guide the system analysis assumptions. Results from the current assessments for fuel burn, noise and oxides of nitrogen emissions are presented.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN27429 , International Symposium on Air Breathing Engines (ISABE 2015); Oct 25, 2015 - Oct 30, 2015; Phoenix, AZ; United States
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    Electric Motor Considerations for Non-Cryogenic Hybrid Electric and Turboelectric Propulsion (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA Glenn Research Center is investigating hybrid electric and turboelectric propulsion concepts for future aircraft to reduce fuel burn, emissions, and noise. Systems studies show that the weight and efficiency of the electric system components need to be improved for this concept to be feasible. However, advances in motor component materials such as soft magnetic materials, hard magnetic materials, conductors, thermal insulation, and structural materials are expected in the coming years, and should improve motor performance. This study investigates several motor types for a one megawatt application, and projects the motor performance benefits of new component materials that might be available in the coming decades.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN24480 , AIAA Propulsion and Energy Conference 2015; Jul 27, 2015 - Jul 29, 2015; Orlando, FL; United States
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    Investigation of Asymmetric Thrust Detection with Demonstration in a Real-Time Simulation Testbed (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The purpose of this effort is to develop, demonstrate, and evaluate three asymmetric thrust detection approaches to aid in the reduction of asymmetric thrust-induced aviation accidents. This paper presents the results from that effort and their evaluation in simulation studies, including those from a real-time flight simulation testbed. Asymmetric thrust is recognized as a contributing factor in several Propulsion System Malfunction plus Inappropriate Crew Response (PSM+ICR) aviation accidents. As an improvement over the state-of-the-art, providing annunciation of asymmetric thrust to alert the crew may hold safety benefits. For this, the reliable detection and confirmation of asymmetric thrust conditions is required. For this work, three asymmetric thrust detection methods are presented along with their results obtained through simulation studies. Representative asymmetric thrust conditions are modeled in simulation based on failure scenarios similar to those reported in aviation incident and accident descriptions. These simulated asymmetric thrust scenarios, combined with actual aircraft operational flight data, are then used to conduct a sensitivity study regarding the detection capabilities of the three methods. Additional evaluation results are presented based on pilot-in-the-loop simulation studies conducted in the NASA Glenn Research Center (GRC) flight simulation testbed. Data obtained from this flight simulation facility are used to further evaluate the effectiveness and accuracy of the asymmetric thrust detection approaches. Generally, the asymmetric thrust conditions are correctly detected and confirmed.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN24742 , AIAA Propulsion and Energy Forum 2015; Jul 27, 2015 - Jul 29, 2015; Orlando, FL; United States
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    Stage-by-Stage and Parallel Flow Path Compressor Modeling for a Variable Cycle Engine, NASA Advanced Air Vehicles Program - Commercial Supersonic Technology Project - AeroServoElasticity (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper covers the development of stage-by-stage and parallel flow path compressor modeling approaches for a Variable Cycle Engine. The stage-by-stage compressor modeling approach is an extension of a technique for lumped volume dynamics and performance characteristic modeling. It was developed to improve the accuracy of axial compressor dynamics over lumped volume dynamics modeling. The stage-by-stage compressor model presented here is formulated into a parallel flow path model that includes both axial and rotational dynamics. This is done to enable the study of compressor and propulsion system dynamic performance under flow distortion conditions. The approaches utilized here are generic and should be applicable for the modeling of any axial flow compressor design accurate time domain simulations. The objective of this work is as follows. Given the parameters describing the conditions of atmospheric disturbances, and utilizing the derived formulations, directly compute the transfer function poles and zeros describing these disturbances for acoustic velocity, temperature, pressure, and density. Time domain simulations of representative atmospheric turbulence can then be developed by utilizing these computed transfer functions together with the disturbance frequencies of interest.
    Keywords: Aircraft Propulsion and Power
    Type: GRC-E-DAA-TN25398 , AIAA/SAE/ASEE Joint Propulsion Conference; Jul 27, 2015 - Jul 29, 2015; Orlando, FL; United States
    Format: application/pdf
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