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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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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

BENEFIT AND CRITICAL FACTORS FOR THE PERFORMANCE OF THE BOUNDARY LAYER INGESTING PROPULSION

The benefit of the boundary layer ingestion(BLI)is described in the perspective of the propulsion and engine development. A power saving map of the BLI engines is derived based on the correlation of the wake velocity ratio of the ingested boundary layer profile and the propulsive efficiency. The ratio of the mass flow rate between BLI and non-BLI propulsors is introduced to quantify the power saving of the BLI engine relative to a clean inlet flow engine which generates same amount of thrust. The wake recovery factor from the jet flow out of the BLI engine is employed to find an adequate sizing of the BLI engine for the given design requirement. The effects of the fan pressure ratio on the power saving are also investigated to explore the feasible range of the BLI engine design. The derived correlation is validated with CFD analyses. A numerical experiment is carried out by varying the wake velocity ratio through different BLI engines sized with respect to an influencing body. Consequently, the propulsor efficiency is quantified and presented by the saving in the actual shaft power. The efficiency penalty, pressure ratio of the BLI fan stage are correlated with the power saving and the correlation is validated through BLI2DTF and R4 fan stage CFD analyses based on rig test data.

B J Lee↗
NASA NTRS1976

Wind Tunnel Design Studies and Technical Evaluation of Advanced Cargo Aircraft Concepts

In support of aerodynamic studies relating to the design and performance prediction of the National Transonic Facility, the following main tasks were accomplished: (1) estimation of aerodynamic losses of the tunnel circuits, (2) refinement of the high-speed diffuser loss prediction method utilizing experimental data generated for the purpose; (3) model studies of flow in the second-turn and measurements of the fan inlet distortion and overall pressure loss; (4) development of a shortened fan nacelle configuration of improved aerodynamic performance; and (5) evolution through model studies of an efficient rapid-diffuser system as the key to a circuit-modification proposal to reduce volume and minimize liquid-nitrogen consumption, at the same time saving on the shell cost.

Rao, D. M.↗
NASA NTRS1981

Experimental investigations on the V/STOL tunnel at NASA/Langley Research Center

The flow characteristics of the V/STOL tunnel were investigated. The results show an interaction between tunnel components. The flow around the tunnel circuit gradually deteriorated with increasing distance from the testing area. The flow in the first diffuser was still satisfactory at the beginning of the circuit, while at the end of the circuit, the flow approaching the contraction became entirely unsatisfactory. Deterioration of flow was due largely to turning the stream around the corners, with the resulting flow distortion affecting the diffusers downstream. The large end of the last diffuser stalled on one side and nearly stalled the flow at the tip of the fan. It was found that these adverse flow characteristics reduce the flow quality and the efficiency of the tunnel.

Barna, P. S.↗
NASA NTRS1982

Frequency and Time Domain Modeling of Acoustic Liner Boundary Conditions

As part of a research program directed at the acoustics of advanced subsonic propulsion systems undertaken at NASA Langley, Duke University was funded to develop a boundary condition model for bulk-reacting nacelle liners. The overall objective of the Langley program was to understand and predict noise from advanced subsonic transport engines and to develop related noise control technology. The overall technical areas included: fan and propeller source noise, acoustics of ducts and duct liners, interior noise, subjective acoustics, and systems noise prediction. The Duke effort was directed toward duct liner acoustics for the development of analytical methods to characterize liner behavior in both frequency domain and time domain. A review of duct acoustics and liner technology can be found in Reference [1]. At that time, NASA Langley was investigating the propulsion concept of an advanced ducted fan, with a large diameter housed inside a relatively short duct. Fan diameters in excess of ten feet were proposed. The lengths of both the inlet and exhaust portions of the duct were to be short, probably less than half the fan diameter. The nacelle itself would be relatively thin-walled for reasons of aerodynamic efficiency. The blade-passage frequency was expected to be less than I kHz, and very likely in the 200 to 300 Hz range. Because of the design constraints of a short duct, a thin nacelle, and long acoustic wavelengths, the application of effective liner technology would be especially challenging. One of the needs of the NASA Langley program was the capability to accurately and efficiently predict the behavior of the acoustic liner. The traditional point impedance method was not an adequate model for proposed liner designs. The method was too restrictive to represent bulk reacting liners and to allow for the characterization of many possible innovative liner concepts. In the research effort at Duke, an alternative method, initially developed to handle bulk reacting layers as described in Reference [2], was extended to apply to a broad range of liner types. This method included the effect of local gradients along the liner surface, and was particularly appropriate for situations with flow over the liner and grazing incidence acoustic fields. In order to utilize time domain computational methods to solve for the propfan acoustic field, corresponding liner boundary conditions were developed for time domain solutions rather than frequency domain solutions.

Bliss, Donald B.↗
NASA NTRS2015

Materials, Manufacturing, and Test Development of a Composite Fan Blade Leading Edge Subcomponent for Improved Impact Resistance

Application of polymer matrix composite materials for jet engine fan blades is becoming attractive as an alternative to metallic blades; particularly for large engines where significant weight savings are recognized on moving to a composite structure. However, the weight benefit of the composite is offset by a reduction of aerodynamic efficiency resulting from a necessary increase in blade thickness; relative to the titanium blades. Blade dimensions are largely driven by resistance to damage on bird strike. Further development of the composite material is necessary to allow composite blade designs to approximate the dimensions of a metallic fan blade. The reduction in thickness over the state of the art composite blades is expected to translate into structural weight reduction, improved aerodynamic efficiency, and therefore reduced fuel consumption. This paper presents test article design, subcomponent blade leading edge fabrication, test method development, and initial results from ballistic impact of a gelatin projectile on the leading edge of composite fan blades. The simplified test article geometry was developed to realistically simulate a blade leading edge while decreasing fabrication complexity. Impact data is presented on baseline composite blades and toughened blades; where a considerable improvement to impact resistance was recorded.

Materials↗
NASA NTRS2009

Design and Testing of Braided Composite Fan Case Materials and Components

Triaxial braid composite materials are beginning to be used in fan cases for commercial gas turbine engines. The primary benefit for the use of composite materials is reduced weight and the associated reduction in fuel consumption. However, there are also cost benefits in some applications. This paper presents a description of the braided composite materials and discusses aspects of the braiding process that can be utilized for efficient fabrication of composite cases. The paper also presents an approach that was developed for evaluating the braided composite materials and composite fan cases in a ballistic impact laboratory. Impact of composite panels with a soft projectile is used for materials evaluation. Impact of composite fan cases with fan blades or blade-like projectiles is used to evaluate containment capability. A post-impact structural load test is used to evaluate the capability of the impacted fan case to survive dynamic loads during engine spool down. Validation of these new test methods is demonstrated by comparison with results of engine blade-out tests.

Roberts, Gary D.↗
NASA NTRS2009

Design and Testing of Braided Composite Fan Case Materials and Components

Triaxial braid composite materials are beginning to be used in fan cases for commercial gas turbine engines. The primary benefit for the use of composite materials is reduced weight and the associated reduction in fuel consumption. However, there are also cost benefits in some applications. This paper presents a description of the braided composite materials and discusses aspects of the braiding process that can be utilized for efficient fabrication of composite cases. The paper also presents an approach that was developed for evaluating the braided composite materials and composite fan cases in a ballistic impact laboratory. Impact of composite panels with a soft projectile is used for materials evaluation. Impact of composite fan cases with fan blades or blade-like projectiles is used to evaluate containment capability. A post-impact structural load test is used to evaluate the capability of the impacted fan case to survive dynamic loads during engine spool down. Validation of these new test methods is demonstrated by comparison with results of engine blade-out tests.

Roberts, Gary D.↗
NASA NTRS2014

Materials, Manufacturing and Test Development of a Composite Fan Blade Leading Edge Subcomponent for Improved Impact Resistance

Application of polymer matrix composite materials for jet engine fan blades is becoming attractive as an alternative to metallic blades; particularly for large engines where significant weight savings are recognized on moving to a composite structure. However, the weight benefit of the composite of is offset by a reduction of aerodynamic efficiency resulting from a necessary increase in blade thickness; relative to the titanium blades. Blade dimensions are largely driven by resistance to damage on bird strike. Further development of the composite material is necessary to allow composite blade designs to approximate the dimensions of a metallic fan blade. The reduction in thickness over the state of the art composite blades is expected to translate into structural weight reduction, improved aerodynamic efficiency, and therefore reduced fuel consumption. This paper presents test article design, subcomponent blade leading edge fabrication, test method development, and initial results from ballistic impact of a gelatin projectile on the leading edge of composite fan blades. The simplified test article geometry was developed to realistically simulate a blade leading edge while decreasing fabrication complexity. Impact data is presented on baseline composite blades and toughened blades; where a considerable improvement to impact resistance was recorded.

Ballistic Impact↗
NASA NTRS1980

Study of blade aspect ratio on a compressor front stage

A single stage, low aspect ratio, compressor with a 442.0 m/sec (1450 ft/sec) tip speed and a 0.597 hub/tip ratio typical of an advanced core compressor front stage was tested. The test stage incorporated an inlet duct which was representative of an engine transition duct between fan and high pressure compressors. At design speed, the rotor stator stage achieved a peak adiabatic efficiency of 86.6 percent at a flow of 44.35 kg/sec (97.8 lbm/sec) and a pressure ratio of 1.8. Surge margin was 12.5 percent from the peak stage efficiency point.

Behlke, R. F.↗
NASA NTRS1988

Impact of bypass ratio on thrust-to-weight for V/STOL

Issues involved in the selection of a V/STOL propulsion system are discussed. The effect of bypass ratio on thrust-to-weight, fuel flow, and hover efficiency is investigated for the cases of four representative tilt propulsion system aircraft. The effect of fan pressure ratio on engine selection is shown to be very mission dependent. It is noted that the FAA requires reserves based on fixed wing or helicopter operations, neither of which is found to be entirely appropriate for STOVL aircraft.

Wilson, Samuel↗
NASA NTRS2008

Fan Performance Testing and Oxygen Compatibility Assessment Results for Future Space Suit Life Support Systems

An advanced portable life support system (PLSS) for the space suit will require a small, robust, and energy-efficient system to transport the ventilation gas through the space suit for lunar Extravehicular Activity (EVA) operations. A trade study identified and compared ventilation transport technologies in commercial, military, and space applications to determine which technologies could be adapted for EVA use. Based on the trade study results, five commercially available, 24volt fans were selected for performance testing at various pressures and flow rates. Measured fan parameters included fan delta-pressures, input voltages, input electrical currents, and in some cases motor windings electrical voltages and currents. In addition, a follow-on trade study was performed to identify oxygen compatibility issues and assess their impact on fan design. This paper outlines the results of the fan performance characterization testing, as well as the results from the oxygen compatibility assessment.

Jennings, Mallory A.↗
NASA NTRS2003

Novel High Efficient Organic Photovoltaic Materials

Solar energy is a renewable, nonpolluting, and most abundant energy source for human exploration of a remote site or outer space. In order to generate appreciable electrical power in space or on the earth, it is necessary to collect sunlight from large areas and with high efficiency due to the low density of sunlight. Future organic or polymer (plastic) solar cells appear very attractive due to their unique features such as light weight, flexible shape, tunability of energy band-gaps via versatile molecular or supramolecular design, synthesis, processing and device fabrication schemes, and much lower cost on large scale industrial production. It has been predicted that supramolecular and nano-phase separated block copolymer systems containing electron rich donor blocks and electron deficient acceptor blocks may facilitate the charge carrier separation and migration due to improved electronic ultrastructure and morphology in comparison to polymer composite system. This presentation will describe our recent progress in the design, synthesis and characterization of a novel block copolymer system containing donor and acceptor blocks covalently attached. Specifically, the donor block contains an electron donating alkyloxy derivatized polyphenylenevinylene (RO-PPV), the acceptor block contains an electron withdrawing alkyl-sulfone derivatized polyphenylenevinylene (SF-PPV). The key synthetic strategy includes the synthesis of each individual block first, then couple the blocks together. While the donor block has a strong PL emission at around 560 nm, and acceptor block has a strong PL emission at around 520 nm, the PL emissions of final block copolymers are severely quenched. This verifies the expected electron transfer and charge separation due to interfaces of donor and acceptor nano phase separated blocks. The system therefore has potential for variety light harvesting applications, including high efficient photovoltaic applications.

Sun, Sam↗
NASA NTRS1982

NASA ECI programs - Benefits to Pratt and Whitney engines

Proprietary research conducted under the NASA-sponsored Engine Component Improvement program is shown to have advanced the state of such component technologies as thermal barrier coatings, ceramic seal systems, advanced turbine clearance control, and JT9D engine fan design. In addition, the tests conducted have demonstrated the advantages of updated cooling, sealing and aerodynamic designs in the high pressure turbine and compressor of the JT8D engine. These technological advances are being transferred to such novel engine configurations as the PW2037 and NASA Energy Efficient Engine. Attention is given to the results of the thermal coating refinement tests of convectively cooled vanes, and to the development of a single shroud fan design applicable to the JT9D and next-generation engines.

Gaffin, W. O.↗
NASA NTRSDate not supplied

Optimal Control Allocation for Distributed Electric Propulsion in A Series/Parallel Partial Hybrid Powertrain

The SUbsonic Single Aft eNgine (SUSAN) Electrofan is a NASA concept transport aircraft representative of technology anticipated for a 2040 entry-into-service date. The powertrain consists of a single thrust-producing geared turbofan engine with generators driving a series/parallel partial hybrid power/propulsion system. The architecture includes 16 underwing contrarotating fans, eight on each side. The distributed fans can be used by the flight control system to augment or replace the rudder function. This paper sets up the optimal control problem of setpoint determination for individual wingfans in the distributed propulsion system, accounting for electrical string efficiencies, saturations, and failures. The solution minimizes power consumption while maintaining thrust and torque on the airframe for maneuvering. Additionally, thrust that would have been lost due to temporary fan speed or power saturation is optimally redistributed to maintain overall desired thrust and torque on the aircraft. A simulation of a coordinated turn utilizing the distributed electric propulsion for yaw rate control in a multiple wingfan failure scenario demonstrates the robustness of the powertrain design to failures and helps define its limitations.

Distributed Electric Propulsion↗
NASA NTRSDate not supplied

Optimal Control Allocation for Distributed Electric Propulsion in A Series/Parallel Partial Hybrid Powertrain

The SUbsonic Single Aft eNgine (SUSAN) Electrofan is a NASA concept transport aircraft representative of technology anticipated for a 2040 entry-into-service date. The powertrain consists of a single thrust-producing geared turbofan engine with generators driving a series/parallel partial hybrid power/propulsion system. The architecture includes 16 underwing contrarotating fans, eight on each side. The distributed fans can be used by the flight control system to augment or replace the rudder function. This paper sets up the optimal control problem of setpoint determination for individual wingfans in the distributed propulsion system, accounting for electrical string efficiencies, saturations, and failures. The solution minimizes power consumption while maintaining thrust and torque on the airframe for maneuvering. Additionally, thrust that would have been lost due to temporary fan speed or power saturation is optimally redistributed to maintain overall desired thrust and torque on the aircraft. A simulation of a coordinated turn utilizing the distributed electric propulsion for yaw rate control in a multiple wingfan failure scenario demonstrates the robustness of the powertrain design to failures and helps define its limitations.

Distributed Electric Propulsion↗
NASA NTRS1922

The Efficiency of a Wind Tunnel

If, by some means, a steady state of motion of a perfect fluid were established in an ideal wind tunnel, there would be no losses, and the motion would persist indefinitely. In the actual tunnel, the function of the motor-fan group is overcome by the total loss of head in the tube due to friction and eddies.

WIND TUNNELS - EFFICIENCY↗