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  • 1
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    Acoustic Testing of a High-Tip-Speed Fan with Bypass-Duct Liners - Overview (2019)
    In:  CASI
    Details
    Publication Date: 2019-06-06
    Description: Under a pair of Space Act Agreements between NASA and Honeywell Aerospace, a model-scale (22 in.-diameter fan) acoustic wind tunnel test was carried out in the fall of 2014 in the NASA Glenn Research Center 9- by 15-Foot Low-Speed Wind Tunnel. The goal was to obtain acoustic pressure measurements for far-field, inlet and exit rotating rake, and in-duct microphone locations. This supersonic-tip-speed fan was tested in three bypass duct configurations: hard-wall, traditional liner, and advanced multiple-degree-of-freedom. Limited aerodynamic data was collected to verify the expected operating conditions. Preliminary analysis of the acoustic data finds it suitable for use in evaluating current NASA and Honeywell Aerospace acoustic tools and liner design practices. This report provides an overview of the test and some preliminary findings.
    Keywords: Acoustics; Aerodynamics
    Type: NASA/TM-2019-220162 , GRC-E-DAA-TN66525 , E-19678
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Euler analysis comparison with LDV data for an advanced counter-rotation propfan at cruise (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A fine mesh Euler solution of the F4/A4 unducted fan (UDF) model flowfield is compared with laser Doppler velocimeter (LDV) data taken in the NASA Lewis 8- by 6-Foot Supersonic Wind Tunnel. The comparison is made primarily at one axial plane downstream of the front rotor where the LDV particle lag errors are reduced. The agreement between measured and predicted velocities in this axial plane is good. The results show that a dense mesh is needed in the centerbody stagnation region to minimize entropy generation that weakens the aft row passage shock. The predicted radial location of the tip vortex downstream of the front rotor agrees well with the experimental results but the strength is overpredicted. With 40 points per chord line, the integrated performance quantities are nearly converged, but more points are needed to resolve passage shocks and flow field details.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 90-3033
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Investigation of advanced counterrotation blade configuration concepts for high speed turboprop systems. Task 5: Unsteady counterrotation ducted propfan analysis. Computer program user's manual (1993)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The primary objective of this study was the development of a time-marching three-dimensional Euler/Navier-Stokes aerodynamic analysis to predict steady and unsteady compressible transonic flows about ducted and unducted propfan propulsion systems employing multiple blade rows. The computer codes resulting from this study are referred to as ADPAC-AOACR (Advanced Ducted Propfan Analysis Codes-Angle of Attack Coupled Row). This report is intended to serve as a computer program user's manual for the ADPAC-AOACR codes developed under Task 5 of NASA Contract NAS3-25270, Unsteady Counterrotating Ducted Propfan Analysis. The ADPAC-AOACR program is based on a flexible multiple blocked grid discretization scheme permitting coupled 2-D/3-D mesh block solutions with application to a wide variety of geometries. For convenience, several standard mesh block structures are described for turbomachinery applications. Aerodynamic calculations are based on a four-stage Runge-Kutta time-marching finite volume solution technique with added numerical dissipation. Steady flow predictions are accelerated by a multigrid procedure. Numerical calculations are compared with experimental data for several test cases to demonstrate the utility of this approach for predicting the aerodynamics of modern turbomachinery configurations employing multiple blade rows.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-187125 , NAS 1.26:187125
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Holographic testing of composite propfans for a cruise missile wind tunnel model (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Each of the approximately 90 composite propfan blades constructed for a 55 percent scale cruise missile wind tunnel model were holographically tested to obtain natural frequencies and mode shapes. These data were used not only for quality assurance, but also to select sets of similar blades for each blade row. Presented along with the natural frequency data is a description of a computer-based image processing system developed to supplement the photographic based system for holographic image analysis and storage. The new system is quicker and cheaper, the holograms are indexed better, and several engineers can access the data simultaneously. The only negative effect is a slight reduction in image resolution, which does not influence the end use.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-105271 , E-8203 , NAS 1.15:105271
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Euler analysis of a swirl recovery vane design for use with an advanced single-rotation propfan (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Recent work has demonstrated the propulsive efficiency improvement available from single- and counter-rotation propfans as compared with current technology high bypass ratio turbofans. The concept known as swirl recovery vanes (SRV) is examined through the use of a 3-D Euler code. At high speed cruise conditions, the SRV can improve the efficiency level of a single-rotation propfan, but a concern is to have adequate hub choke margin. The SRV was designed with 2-D methods and was predicted to have hub choking at Mach 0.8 cruise. The 3-D Euler analysis properly accounts for sweep effects and 3-D relief, and predicts that at cruise the SRV will recover roughly 5 percent of the 10 percent efficiency loss due to swirl and have a good hub choke margin.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 88-3152
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Euler analysis of a swirl recovery vane design for use with an advanced single-rotation propfan (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Recent work has demonstrated the propulsive efficiency improvement available from single- and counter-rotation propfans as compared with current technology high bypass ratio turbofans. The concept known as swirl recovery vanes (SRV) is examined through the use of a 3-D Euler code. At high speed cruise conditions, the SRV can improve the efficiency level of a single-rotation propfan, but a concern is to have adequate hub choke margin. The SRV was designed with 2-D methods and was predicted to have hub choking at Mach 0.8 cruise. The 3-D Euler analysis properly accounts for sweep effects and 3-D relief, and predicts that at cruise the SRV will recover roughly 5 percent of the 10 percent efficiency loss due to swirl and have a good hub choke margin.
    Keywords: AERODYNAMICS
    Type: NASA-TM-101357 , E-4387 , NAS 1.15:101357 , AIAA PAPER 88-3152
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    In-Flight Suppression of a Destabilized F/A-18 Structural Mode Using the Space Launch System Adaptive Augmenting Control System (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA's Space Launch System (SLS) Flight Control System (FCS) includes an Adaptive Augmenting Control (AAC) component which employs a multiplicative gain update law to enhance the performance and robustness of the baseline control system for extreme off nominal scenarios. The SLS FCS algorithm including AAC has been flight tested utilizing a specially outfitted F/A-18 fighter jet in which the pitch axis control of the aircraft was performed by a Non-linear Dynamic Inversion (NDI) controller, SLS reference models, and the SLS flight software prototype. This paper describes test cases from the research flight campaign in which the fundamental F/A-18 airframe structural mode was identified using frequency-domain reconstruction of flight data, amplified to result in closed loop instability, and suppressed in-flight by the SLS adaptive control system.
    Keywords: Launch Vehicles and Launch Operations
    Type: M15-4264 , 2015 American Institute of Aeronautics and Astronautics (AIAA) Guidance, Navigation, and Control Conference at the Science and Technology Forum and Exposition (SciTech); Jan 05, 2015 - Jan 09, 2015; Kissimmee, FL; United States
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    NASA TECHNICAL REPORTS
  • 8
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    Airborne Simulation of Launch Vehicle Dynamics (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In this paper we present a technique for approximating the short-period dynamics of an exploration-class launch vehicle during flight test with a high-performance surrogate aircraft in relatively benign endoatmospheric flight conditions. The surrogate vehicle relies upon a nonlinear dynamic inversion scheme with proportional-integral feedback to drive a subset of the aircraft states into coincidence with the states of a time-varying reference model that simulates the unstable rigid body dynamics, servodynamics, and parasitic elastic and sloshing dynamics of the launch vehicle. The surrogate aircraft flies a constant pitch rate trajectory to approximate the boost phase gravity turn ascent, and the aircraft's closed-loop bandwidth is sufficient to simulate the launch vehicle's fundamental lateral bending and sloshing modes by exciting the rigid body dynamics of the aircraft. A novel control allocation scheme is employed to utilize the aircraft's relatively fast control effectors in inducing various failure modes for the purposes of evaluating control system performance. Sufficient dynamic similarity is achieved such that the control system under evaluation is configured for the full-scale vehicle with no changes to its parameters, and pilot-control system interaction studies can be performed to characterize the effects of guidance takeover during boost. High-fidelity simulation and flight-test results are presented that demonstrate the efficacy of the design in simulating the Space Launch System (SLS) launch vehicle dynamics using the National Aeronautics and Space Administration (NASA) Armstrong Flight Research Center Fullscale Advanced Systems Testbed (FAST), a modified F/A-18 airplane (McDonnell Douglas, now The Boeing Company, Chicago, Illinois), over a range of scenarios designed to stress the SLS's Adaptive Augmenting Control (AAC) algorithm.
    Keywords: Spacecraft Design, Testing and Performance; Aircraft Stability and Control
    Type: AAS 15-097 , DFRC-E-DAA-TN20628 , Annual AAS Guidance and Control Conference; Jan 30, 2015 - Feb 04, 2015; Breckenridge, CO; United States
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    NASA TECHNICAL REPORTS
  • 9
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    Nonlinear Dynamic Inversion Baseline Control Law: Flight-Test Results for the Full-scale Advanced Systems Testbed F/A-18 Airplane (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A model reference nonlinear dynamic inversion control law has been developed to provide a baseline controller for research into simple adaptive elements for advanced flight control laws. This controller has been implemented and tested in a hardware-in-the-loop simulation and in flight. The flight results agree well with the simulation predictions and show good handling qualities throughout the tested flight envelope with some noteworthy deficiencies highlighted both by handling qualities metrics and pilot comments. Many design choices and implementation details reflect the requirements placed on the system by the nonlinear flight environment and the desire to keep the system as simple as possible to easily allow the addition of the adaptive elements. The flight-test results and how they compare to the simulation predictions are discussed, along with a discussion about how each element affected pilot opinions. Additionally, aspects of the design that performed better than expected are presented, as well as some simple improvements that will be suggested for follow-on work.
    Keywords: Aircraft Stability and Control
    Type: DFRC-E-DAA-TN3513 , DFRC-E-DAA-TN3908 , AIAA Modeling and Simulation Technologies Conference; Aug 08, 2011 - Aug 11, 2011; Portland, OR; United States|AIAA Guidance, Navigation, and Control Conference; Aug 08, 2011 - Aug 11, 2011; Portland, OR; United States|AIAA Atmospheric Flight Mechanics Conference; Aug 08, 2011 - Aug 11, 2011; Portland, OR; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Nonlinear Dynamic Inversion Baseline Control Law: Architecture and Performance Predictions (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A model reference dynamic inversion control law has been developed to provide a baseline control law for research into adaptive elements and other advanced flight control law components. This controller has been implemented and tested in a hardware-in-the-loop simulation; the simulation results show excellent handling qualities throughout the limited flight envelope. A simple angular momentum formulation was chosen because it can be included in the stability proofs for many basic adaptive theories, such as model reference adaptive control. Many design choices and implementation details reflect the requirements placed on the system by the nonlinear flight environment and the desire to keep the system as basic as possible to simplify the addition of the adaptive elements. Those design choices are explained, along with their predicted impact on the handling qualities.
    Keywords: Aircraft Stability and Control
    Type: DFRC-E-DAA-TN3409 , DFRC-E-DAA-TN3905 , AIAA Guidance, Navigation, and Control Conference; Aug 08, 2011 - Aug 11, 2011; Portland, OR; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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