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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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296 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Core/Combuster-Noise: Preparations for Future DART Tests

The DGEN AeroPropulsion Research Turbofan (DART) is a small engine representative of commercial transport propulsors. It is used at NASA to study, among other topics, core and combustor noise production mechanisms and propagation. This includes development/validation of robust and accurate instrumentation/techniques for evaluating noise production in the extreme environment of a turbofan core. This presentation highlights upcoming core-noise research activities contributing to or directly utilizing the DART facility during the remaining CY2018 and First Quarter CY 2019 period. The near-term aim is to further investigate features seen in the baseline DART core/combustor-noise test performed in the NASA GRC Aero-Acoustic Propulsion Laboratory (AAPL) during 2017 as well as to provide an improved documentation of the core noise emanating from the turbofan engine. The research is aligned with the NASA Ultra-Efficient Commercial Transport strategic thrust and is supported by the NASA Advanced Air Vehicle Program, Advanced Air Transport Technology Project, under the Aircraft Noise Reduction Subproject.

Turbofan Combustor Noise↗
NASA NTRS2020

Artificial Thickening of a Transonic Boundary Layer in the Presence of a Pressure Gradient Associated with a Boundary Layer Ingestion Concept

Boundary layer ingestion is an aeropropulsive concept associated with a propulsion airframe integration technique that integrates viscous aerodynamics into a propulsion system to achieve more efficient flight. The effectiveness of this concept is heavily dependent on how much of the boundary layer is being ingested into the propulsor. Scaling this concept for transonic wind tunnel testing is often plagued with blockage issues and requires a modification to the model dimensions such as fuselage length and diameter and wingspan. To simulate the boundary layer for these modified models requires a manipulation of the boundary layer height to achieve the appropriate ratio of boundary layer to propulsor inlet diameter or height. This paper will focus on 15 different transonic boundary layer manipulators to achieve varying turbulent boundary layer heights for a representative single-aisle transport utilizing Boundary Layer Ingestion.

Gregory S Jones↗
NASA NTRSDate not supplied

Preliminary Assessment of a Distributed Electric Propulsion System for the SUSAN Electrofan

The SUSAN Electrofan is a new hybrid electric large regional jet aircraft concept being studied by NASA that leverages advanced propulsion system technologies such as distributed electric propulsion (DEP) and boundary-layer ingestion (BLI) to reduce fuel consumption and emissions. In order to evaluate the individual benefits of these technologies toward the SUSAN Electrofan’s wing-mounted propulsion systems, three configurations are proposed. The first consists of two underwing pylon-mounted podded propulsors and serves as a baseline, while the second features an underwing pylon-mounted DEP concept with 16 ducted fans in a mail-slot nacelle. The third and final configuration mounts the mail-slot nacelle directly onto the pressure side of the wing to also take advantage of BLI. This paper presents preliminary investigations into the design and performance of the first two propulsion system configurations. This begins with an initial propulsor and mail-slot design where the aeropropulsive design space is explored, and adverse effects are addressed through iterative geometry modifications. The propulsion system configurations are then installed onto a wing–body model to account for integration effects and assess the relative aerodynamic and shaft power performance of each concept. Results indicate the potential benefits of DEP, which come from significant reductions in total drag, provided by operation at much lower propulsor fan pressure ratios.

ARMD↗
NASA NTRSDate not supplied

Evaluation of Silicon Carbide Pressure Sensor in Turbofan Engine Core Exhaust Nozzle

We report the results of the evaluation of single crystal 4H-silicon carbide piezoresistive pressure sensors that were directly inserted at the compressor and core exhaust nozzle exits, in shear contact with the engine-internal flow streams of the NASA DGEN Aeropropulsion Research Turbofan, where the operating temperatures at maximum power were ~230 oC, and ~460 oC, respectively. In addition to demonstrating sensor survivability during this maiden test, the frequency responses of the silicon-carbide sensors at the core-nozzle exit were compared against industry-standard silicon-based piezoresistive pressure transducers that externally placed, using an infinite-tube-probe arrangement. The low-voltage output of these early-development SiC sensors limited the frequency range with an acceptable signal-to-noise-ratio for the current application to less than about 2,500 Hz. The low output of the SiC sensors were due to a conservative burst-pressure diaphragm design that can be optimized to increase the frequency range. The results from this initial campaign offered insights to aspects of the sensor that would require further improvement, with the goal of achieving full-bandwidth capture of engine unsteady pressure fluctuations by direct interrogation of the flow field in hostile-environment engine-core components.

Silicon Carbide↗
NASA NTRSDate not supplied

Evaluation of SiC Pressure Sensors in Turbofan Engine Core Exhaust Nozzle

We report the results of the evaluation of single crystal 4H-silicon carbide piezoresistive pressure sensors that were directly inserted at the compressor and core exhaust nozzle exits, in shear contact with the engine-internal flow streams of the NASA DGEN Aeropropulsion Research Turbofan, where the operating temperatures at maximum power were ~230°C, and ~460°C, respectively. In addition to demonstrating sensor survivability during this maiden test, the frequency responses of the silicon-carbide sensors at the core-nozzle exit were compared against industry-standard silicon-based piezoresistive pressure transducers that externally placed, using an infinite-tube-probe arrangement. The low-voltage output of these early-development SiC sensors limited the frequency range with an acceptable signal-to-noise-ratio for the current application to less than about 2,500 Hz. The low output of the SiC sensors were due to a conservative burst-pressure diaphragm design that can be optimized to increase the frequency range. The results from this initial campaign offered insights to aspects of the sensor that would require further improvement, with the goal of achieving full-bandwidth capture of engine unsteady pressure fluctuations by direct interrogation of the flow field in hostile-environment engine-core components.

Silicon Carbide↗
NASA NTRS2019

How Certain Physical Considerations Impact Aerostructural Wing Optimization

Wing design optimization has been studied extensively and is of continued interest as optimization tools are developed and become more accessible. In each of these studies, certain assumptions and simplifications are made to make the design problem tractable. However, it is difficult to find systematic studies in which several considerations are added or removed one at a time to study how much impact they have. In this work, we examine how certain physical considerations (viscous drag, wave drag, thrust loads, and inertial relief from structural, fuel, and engine masses), impact the aerostructural optimization results for three distinct aircraft wings. The goal is to help develop a rough idea of how important these physical considerations are. We do this using gradient-based optimization and a multidisciplinary design optimization framework, OpenMDAO. We use the open-source tool OpenAeroStruct that couples a vortex lattice method to a finite element method. We establish a baseline aerostructural design optimization problem then perform a series of optimizations, each with one physical consideration removed from the baseline case. We find that depending on the size of the aircraft and flight conditions, the importance of some of these physical considerations varies considerably whereas the importance of others do not. Specifically, the optimal designs change radically without proper viscous and wave drag considerations and smaller aircraft with more distributed propulsion are more affected by the inclusion of engine loads.

Aeropropulsion↗