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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Experimental investigation of wingtip aerodynamic loading

An experimental investigation was performed to obtain the aerodynamic loading of a series of wingtips. The wingtips varied in taper ratio (1.0, 0.6, and 0.3) and in sweep angle (0, 20, 30, 35, and 45 deg). The wingtips were tested separately (wingtip only configuration) and while mounted on a semi-span wing. The quarter-chord sweep angle of the wing was varied from 30 deg forward sweep, to unswept, to 30 deg. aft sweep. Wingtip loading was obtained from a six component strainguage balance mounted in the wingtip. The effect of wing sweep and wingtip taper and wingtip sweep on the wingtip lift curve slope, drag polar, and pitching moment behavior is discussed. The obtained wingtip data was used to define blade tip platforms, suitable for use in the Free-Tip Rotor configuration. The Free-Tip Rotor has blade tips, which are allowed to weathervane into the blade tip's relative wind. A passive control moment is applied to the blade tip's pitch axis so as to cause blade tip motion around a prescribed null point providing a finite blade tip lift.

Van Aken, Johannes M.↗
NASA NTRS1996

Study of Semi-Span Model Testing Techniques

An investigation has been conducted in the NASA Langley 14- by 22-Foot Subsonic Tunnel in order to further the development of semi-span testing capabilities. A twin engine, energy efficient transport (EET) model with a four-element wing in a takeoff configuration was used for this investigation. Initially a full span configuration was tested and force and moment data, wing and fuselage surface pressure data, and fuselage boundary layer measurements were obtained as a baseline data set. The semi-span configurations were then mounted on the wind tunnel floor, and the effects of fuselage standoff height and shape as well as the effects of the tunnel floor boundary layer height were investigated. The effectiveness of tangential blowing at the standoff/floor juncture as an active boundary-layer control technique was also studied. Results indicate that the semi-span configuration was more sensitive to variations in standoff height than to variations in floor boundary layer height. A standoff height equivalent to 30 percent of the fuselage radius resulted in better correlation with full span data than no standoff or the larger standoff configurations investigated. Undercut standoff leading edges or the use of tangential blowing in the standoff/ floor juncture improved correlation of semi-span data with full span data in the region of maximum lift coefficient.

Gatlin, Gregory M.↗
NASA NTRS1976

Investigation of two bifurcated-duct inlet systems from Mach 0 to 2.0 over a wide range of angles of attack

A 15.354 percent/scale lightweight fighter type inlet/forebody was tested over a Mach number range of 0 to 2.0. Model configurations consisted of side mounted normal shock and fixed overhead ramp type inlets. Each configuration consisted of two inlets ducted (bifurcated) to supply a single engine face. The normal shock inlet variables included a boundary layer splitter bleed system, alternate boundary layer splitter plates, alternate upper and lower cowl lip shapes, and a blow-in-door (auxiliary inlet) in one lower lip. The only variable of the fixed overhead ramp inlet was the boundary layer bleed flow. Reynolds numbers ranged from 7.6 x 1 million to 19.5 x 1 million/m. Angle of attack ranged from -10 to 35 deg and angle of sideslip from -8 to 8 deg. Test measurements included engine face total pressure recovery, steady state distortion, dynamic distortion, and surface static pressures on the forebody and inlet surfaces.

Latham, E. A.↗
NASA NTRS1976

Effects of upper-surface blowing and thrust vectoring on low speed aerodynamic characteristics of a large-scale supersonic transport model

Tests were conducted in a full scale tunnel to determine the low speed aerodynamic characteristics of a large scale arrow wing supersonic transport configured with engines mounted above the wing for upper surface blowing and conventional lower surface engines having provisions for thrust vectoring. Tests were conducted over an angle of attack range of -10 deg to 34 deg and for Reynolds numbers (based on the mean aerodynamic chord) of 5.17 x 1 million and 3.89 x 1 million. A limited number of tests were also conducted for the upper surface engine configuration in the high lift condition at an angle of sideslip of 10 deg in order to evaluate lateral directional characteristics and with the right engine inoperative in order to evaluate the engine out condition.

Coe, P. L., Jr.↗
NASA NTRS2011

Turboelectric Distributed Propulsion in a Hybrid Wing Body Aircraft

The performance of the N3-X, a 300 passenger hybrid wing body (HWB) aircraft with turboelectric distributed propulsion (TeDP), has been analyzed to see if it can meet the 70% fuel burn reduction goal of the NASA Subsonic Fixed Wing project for N+3 generation aircraft. The TeDP system utilizes superconducting electric generators, motors and transmission lines to allow the power producing and thrust producing portions of the system to be widely separated. It also allows a small number of large turboshaft engines to drive any number of propulsors. On the N3-X these new degrees of freedom were used to (1) place two large turboshaft engines driving generators in freestream conditions to maximize thermal efficiency and (2) to embed a broad continuous array of 15 motor driven propulsors on the upper surface of the aircraft near the trailing edge. That location maximizes the amount of the boundary layer ingested and thus maximizes propulsive efficiency. The Boeing B777-200LR flying 7500 nm (13890 km) with a cruise speed of Mach 0.84 and an 118100 lb payload was selected as the reference aircraft and mission for this study. In order to distinguish between improvements due to technology and aircraft configuration changes from those due to the propulsion configuration changes, an intermediate configuration was included in this study. In this configuration a pylon mounted, ultra high bypass (UHB) geared turbofan engine with identical propulsion technology was integrated into the same hybrid wing body airframe. That aircraft achieved a 52% reduction in mission fuel burn relative to the reference aircraft. The N3-X was able to achieve a reduction of 70% and 72% (depending on the cooling system) relative to the reference aircraft. The additional 18% - 20% reduction in the mission fuel burn can therefore be attributed to the additional degrees of freedom in the propulsion system configuration afforded by the TeDP system that eliminates nacelle and pylon drag, maximizes boundary layer ingestion (BLI) to reduce inlet drag on the propulsion system, and reduces the wake drag of the vehicle.

Felder, James L.↗
NASA NTRS2016

Assessment of the Noise Reduction Potential of Advanced Subsonic Transport Concepts for NASA's Environmentally Responsible Aviation Project

Aircraft system noise is predicted for a portfolio of NASA advanced concepts with 2025 entry-into-service technology assumptions. The subsonic transport concepts include tube-and-wing configurations with engines mounted under the wing, over the wing nacelle integration, and a double deck fuselage with engines at a mid-fuselage location. Also included are hybrid wing body aircraft with engines upstream of the fuselage trailing edge. Both advanced direct drive engines and geared turbofan engines are modeled. Recent acoustic experimental information was utilized in the prediction for several key technologies. The 301-passenger class hybrid wing body with geared ultra high bypass engines is assessed at 40.3 EPNLdB cumulative below the Stage 4 certification level. Other hybrid wing body and unconventional tube-and-wing configurations reach levels of 33 EPNLdB or more below the certification level. Many factors contribute to the system level result; however, the hybrid wing body in the 301-passenger class, as compared to a tubeand- wing with conventional engine under wing installation, has 11.9 EPNLdB of noise reduction due to replacing reflection with acoustic shielding of engine noise sources. Therefore, the propulsion airframe aeroacoustic interaction effects clearly differentiate the unconventional configurations that approach levels close to or exceed the 42 EPNLdB goal.

Thomas, Russell H.↗
NASA NTRS1987

A microgravity isolation mount

The design and preliminary testing of a system for isolating microgravity sensitive payloads from spacecraft vibrational and impulsive disturbances is discussed. The Microgravity Isolation Mount (MGIM) concept consists of a platform which floats almost freely within a limited volume inside the spacecraft, but which is constrained to follow the spacecraft in the long term by means of very weak springs. The springs are realized magnetically and form part of a six degree of freedom active magnetic suspension system. The latter operates without any physical contact between the spacecraft and the platform itself. Power and data transfer is also performed by contactless means. Specifications are given for the expected level of input disturbances and the tolerable level of platform acceleration. The structural configuration of the mount is discussed and the design of the principal elements, i.e., actuators, sensors, control loops and power/data transfer devices are described. Finally, the construction of a hardware model that is being used to verify the predicted performance of the MGIM is described.

Jones, D. I.↗
NASA NTRS1978

Evaluation of display and control concepts for a terminal configured vehicle in final approach in a windshear environment

A revised treatment of nonrandom inputs was incorporated in the model. Response behavior was observed for two display configurations (a pictorial EADI presentation and a flight-director configuration requiring use of a panel-mounted airspeed indicator), two control configurations (attitude and velocity control wheel steering), and two shear environments, each of which contained a head-to-tail shear and a vertical component. In general, performance trends predicted by the model were confirmed experimentally. Experimental and analytical results both indicated superiority to the EADI display with respect to regulation of height and airspeed errors. Velocity steering allowed tighter regulation of height errors, but control parameters had little influence on airspeed regulation. Model analysis indicated that display-related differences could be ascribed to differences in the quality of speed-related information provided by the two displays.

Levison, W. H.↗
NASA NTRS1978

Definition study of the Shuttle Imaging Radar-A (SIR-A) antenna on the second space shuttle mission (OFT-2)

A definition is derived for an antenna configuration fixed-mounted high in the payload bay on the hybrid OFT-2 pallet which is compatible with Orbiter interface requirements. Tests showed that the combination of the selected panels and the designed corporate feed meets SIR-A performance requirement of 33 db gain. The effects of Orbiter structure proximity on performance were determined by scale model tests to be negligible. The potential for improved performance during subsequent reflights includes a multiple-beam capability and dual polarization.

Nitschke, H. A.↗
NASA NTRS1978

Definition study of the Shuttle Imaging Radar-A /SIR-A/ antenna on the second Space Shuttle mission /OFT-2/

The study resulted in the definition of an antenna configuration fixed-mounted high in the payload bay on the hybrid OFT-2 pallet which is compatible with Orbiter interface requirements. Tests showed that the combination of the selected panels and the designed corporate feed will meet the SIR-A performance requirement of 33 dB gain. The effects of Orbiter structure proximity on performance were determined by scale model tests to be negligible. The potential for improved performance during subsequent reflights includes a multiple-beam capability and dual polarization.

Nitschke, H. A.↗
NASA NTRS1980

Application of advanced technologies to small, short-haul transport aircraft

The performance and economic benefits available by incorporation of advanced technologies into the small, short haul air transport were assessed. Low cost structure and advanced composite material, advanced turboprop engines and new propellers, advanced high lift systems and active controls; and alternate aircraft configurations with aft mounted engines were investigated. Improvements in fuel consumed and aircraft economics (acquisition cost and direct operating cost) are available by incorporating selected advanced technologies into the small, short haul aircraft.

Coussens, T. G.↗
NASA NTRS1981

Solar rotation measurements at Mount Wilson. II - Systematic instrumental effects and the absolute rotation rate

Possible sources of systematic error in solar Doppler rotational velocities are examined. Scattered light is shown to affect the Mount Wilson solar rotation results, but this effect is not enough to bring the spectroscopic results in coincidence with the sunspot rotation. Interference fringes at the spectrograph focus at Mount Wilson have in two intervals affected the rotation results. It has been possible to correlate this error with temperature and thus correct for it. A misalignment between the entrance and exit slits is a possible source of error, but for the Mount Wilson slit configuration, the amplitude of this effect is negligibly small. Rapid scanning of the solar image also produces no measurable effect.

Labonte, B. J.↗
NASA NTRS1989

Test techniques for cryogenic wind tunnels

Some of the testing techniques developed for transonic cryogenic tunnels are presented. Techniques are emphasized which required special development or were unique because of the opportunities offered by cryogenic operation. Measuring the static aerodynamic coefficients normally used to determine component efficiency is discussed. The first topic is testing of two dimensional airfoils at transonic Mach numbers and flight values of Reynolds number. Three dimensional tests of complete configurations and sidewall mounted wings are also described. Since flight Reynolds numbers are of interest, free transition must be allowed. A discussion is given of wind tunnel and model construction effects on transition location. Time dependent phenomena, fluid mechanics, and measurement techniques are examined. The time dependent, or unsteady, aerodynamic test techniques described include testing for flutter, buffet, and oscillating airfoil characteristics. In describing non-intrusive laser techniques, discussions are given regarding optical access, seeding, forward scatter lasers, two-spot lasers, and laser holography. Methods of detecting transition and separation are reported and a new type of skin friction balance is described.

Lawing, Pierce L.↗
NASA NTRS1989

Aerodynamic testing in cryogenic nitrogen gas - A precursor to testing in superfluid helium

Testing techniques for transonic cryogenic tunnels using nitrogen as the test fluid are presented. The measurement of static aerodynamic coefficients used to determine component efficiency is discussed, focusing on tests of two-dimensional airfoils at transonic Mach numbers. Also, three-dimensional tests of complete configurations and sidewall mounted wings are examined. Consideration is given to time-dependent phenomena, fluid mechanics, nonintrusive laser techniques, the detection of transition and separation, and testing for flutter, buffet, and oscillating airfoil characteristics.

Lawing, Pierce L.↗
NASA NTRS1991

Progress toward synergistic hypermixing nozzles

Mean flow measurements were obtained for air-to-air mixing downstream of swept and unswept ramp wall mounted hypermixing nozzle configurations. Aside from the sweep of the ramps, the two nozzle configurations studied are identical. The nozzles inject three parallel supersonic jets at a 15 deg angle (relative to the wind tunnel wall) into a supersonic freestream. Mach number and volume fraction distributions in a transverse plane 11.1 nozzle heights downstream from the nozzle exit plane were measured. Data are presented for a freestream Mach number of three at a matched static pressure condition and also at underexpanded static pressure condition (pressure ratio = 5). Surface oil flow visualization was used to study the near wall flow behavior. The results indicate that the swept ramp injectors produce stronger and larger vortex pairs than the unswept ramp injectors. The increased interaction between the swept ramp model's larger vortex pairs yields better mixing characteristics for this model.

Davis, D. O.↗
NASA NTRS1991

Progress toward synergistic hypermixing nozzles

Mean flow measurements have been obtained for air-to-air mixing downstream of swept and unswept ramp wall-mounted hypermixing nozzle configurations. Aside from the sweep of the ramps, the two nozzle configurations investigated are identical. The nozzles inject three parallel supersonic jets at a 15-deg angle (relative to the wind tunnel wall) into a supersonic freestream. Mach number and volume fraction distributions in a transverse plane 11.1 nozzle heights downstream from the nozzle exit plane were measured. Data are presented for a freestream Mach number of three at a matched static pressure condition and also at an underexpanded static pressure condition (pressure ratio equal to 5). Surface oil flow visualization was used to investigate the near-wall flow behavior. The results indicate that the swept ramp injectors produce stronger and larger vortex pairs than the unswept ramp injectors. The increased interaction between the swept ramp model's larger vortex pairs yields better mixing characteristics for this model.

Davis, D. O.↗
NASA NTRS1947

Wind-Tunnel Tests of a 0.182-Scale Model of an F4U-1 Airplane with External Stores

Tests were made in the Langley 7- by 10-foot tunnel on a 0.182-scale model of an F4U-1 airplane with external stores. This paper is concerned mainly with presenting the data obtained in this investigation and with a comparison of some of these data with flight-test results determining the feasibility of estimating flight buffet Mach number from tunnel data. The results of this investigation indicate that the incremental drag coefficient due to external stores may be used to estimate the maximum Mach number that the F4U-1 airplane may reach in flight when it is equipped with external stores. This estimation is conservative for the five configurations investigated by mounts varying from 0 to 10 percent of the flight limit Mach number. The free-stream tunnel Mach number corresponding to sonic flow over the lower surface of the wing in the region of the store is a good indication of the lower limit of buffet in flight of the F4U-1 airplane when equipped with external stores. The fluctuations of total pressure over the horizontal tail are not sufficiently large (maximum of 1 percent q(sub o) to cause buffeting of the airplane.

Silvers, H. Norman↗