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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 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Highly loaded multi-stage fan drive turbine-tandem blade configuration design

The results of the tandem blade configuration design study are reported. The three stage constant-inside-diameter turbine utilizes tandem blading in the stage two and stage three vanes and in the stage three blades. All other bladerows use plain blades. Blading detailed design is discussed, and design data are summarized. Steady-state stresses and vibratory behavior are discussed, and the results of the mechanical design analysis are presented.

Evans, D. C.↗
NASA NTRS1972

Rotor design of high tip speed low loading transonic fan.

This paper describes the design concepts, principles and details of a high tip speed transonic rotor having low aerodynamic loading. The purpose of the NASA sponsored investigation was to determine whether good efficiency and large stall margin could be obtained by designing a rotor to avoid flow separation associated with strong normal shocks. Fully supersonic flow through the outboard region of the rotor with compression accomplished by weak oblique shocks were major design concepts employed. Computer programs were written and used to derive blade sections consistent from the all-supersonic tip region to the all-subsonic hub region. Preliminary test results indicate attainment of design pressure ratio and design flow at design speed with about a 1.6 point decrement in efficiency and large stall margin.

Erwin, J. R.↗
NASA NTRS1973

Acoustic properties of a supersonic fan

Tests of supersonic rotors designed to reduce forward propagating pressure waves and the accompanying blade passing tones and multiple pure tones showed the wave propagation and noise reduction to have been obtained at the expense of increased noise radiation rearward. Outlet guide vanes served to muffle the noise propagating rearwards, but did not affect forward propagation at all.

Goldstein, A. W.↗
NASA NTRS1973

Highly loaded multi-stage fan drive turbine-cascade test program

Test results are presented for 19 cascades involving five plain and two tandem blade sections. High camber and/or negative reaction is associated with six of the sections. Exit Mach numbers range up to slightly above sonic. Cascade efficiency, exit flow angle and static pressure, and blade surface pressure data are reported with incidence angle, Mach number, solidity, and relative position of the tandem blades as independent variables.

Cherry, D. G.↗
NASA NTRS1973

Space shuttle: Pressure investigation of a space shuttle launch configuration consisting of a delta-wing orbiter and a swept-wing booster with canard and tip fans (M equals 0.6 to 1.3). Volume 1, part A: Booster data

Wind tunnel tests to determine the pressure distribution on a space shuttle launch configuration consisting of a delta wing orbiter and a swept wing booster with canard and tip fins were conducted. Pressure data were obtained for the combined orbiter and booster and for the booster alone at Mach numbers from 0.6 to 1.3, angles of attack from minus 8 degrees to plus 10 degrees, and sideslip angles from minus 6 degrees to plus 6 degrees. Pressure data were also obtained for the booster alone without canard at Mach numbers of 0.9 and 1.1. The pressure taps were distributed primarily over the booster upper surface and the orbiter lower surface.

Rampy, J. M.↗
NASA NTRS1973

Effect of crossflow velocity on the generation of lift fan jet noise in VTOL aircraft

Analytical studies based on a turbulent mixing noise prediction technique indicate that jet noise power levels are increased when a jet is situated in a crossflow. V/STOL model transport acoustic test data obtained in the NASA Ames 40 ft. x 80 ft. wind tunnel confirmed this jet noise power level increase due to crossflow. Increases up to 6 db at a Strouhal number of 2.5 and crossflow velocity to jet velocity ratio of 0.58 were observed. The power level increases observed in the experimental data confirm the predicted power level increases.

Stimpert, D. L.↗
NASA NTRS1973

Aerodynamic effects of five lift-fan pod arrangements on an unpowered V/STOL transport model

An investigation was conducted in the Langley V/STOL tunnel to determine the effect of longitudinally oriented wing-mounted pods on the longitudinal and lateral aerodynamic characteristics in the cruise flight condition of a high-wing V/STOL transport model. Five pod arrangements were tested - three configurations with in-line pods at 20, 40, or 60 percent semispan and two split pod configurations with rear pods at 20 percent semispan and front pods at 40 or 60 percent semispan. In general, addition of the pods to the model decreased the stability, increased the lift-curve slope, and alleviated the abrupt stall of the basic model. The configuration with pods at 20 percent semispan had an abrupt instability at 10 deg angle of attack, All the configurations had lateral stability at sideslip angles from 5 to -5 deg. Very little difference in results existed between the configurations with pods at 40 and 60 percent semispan. Of the split pod configurations, the configuration with front pods at 40 percent semispan offered the best trimmed lift and lift-induced drag characteristics at high angles of attack. The configuration with in-line pods at 40 or 60 percent semispan provided the best cruise characteristics of all the pod configurations.

Thomas, J. L.↗
NASA NTRS1973

Holographic studies of shock waves within transonic fan rotors

Pulsed laser holographic interferometry has been applied to the detection of shock patterns in the outer span regions of high tip speed transonic rotors. The first holographic approach used ruby laser light reflected from a portion of the centerbody just ahead of the rotor. These holograms showed the bow wave patterns upstream of the rotor and the shock patterns just inside the blade row near the tip. Much of the region of interest was in the shadow of the blade leading edge and could not be visualized. The second holographic approach, on a different rotor, used light transmitted diagonally across the inlet annulus past the centerbody. This approach gave a more extensive view of the region bounded by the blade leading and trailing edges, by the part span shroud and by the blade tip. These holograms showed the passage shock emanating from the blade leading edge and a moderately strong conical shock originating at the intersection of the part span shroud leading edge and the blade suction surface. Reasonable details of the shock patterns were obtained from holograms which were made without extensive rig modifications.

Benser, W. A.↗
NASA NTRS1973

Performance of transonic fan stage with weight flow per unit annulus area of 178 kilograms per second per square meter (6.5(lb/sec)/(sq ft))

The overall and blade-element performances are presented over the stable flow operating range from 50 to 100 percent of design speed. Stage peak efficiency of 0.834 was obtained at a weight flow of 26.4 kg/sec (58.3 lb/sec) and a pressure ratio of 1.581. The stall margin for the stage was 7.5 percent based on weight flow and pressure ratio at stall and peak efficiency conditions. The rotor minimum losses were approximately equal to design except in the blade vibration damper region. Stator minimum losses were less than design except in the tip and damper regions.

Moore, R. D.↗
NASA NTRS1973

Performance of transonic fan stage with weight flow per unit annulus area of 208 kilograms per second per square meter (42.6 (lb/sec)/sq ft)

Performance was obtained for a 50-cm-diameter compressor designed for a high weight flow per unit annulus area of 208 (kg/sec)/sq m. Peak efficiency values of 0.83 and 0.79 were obtained for the rotor and stage, respectively. The stall margin for the stage was 23 percent, based on equivalent weight flow and total-pressure ratio at peak efficiency and stall.

Urasek, D. C.↗
NASA NTRS1973

Performance of transonic fan stage with weight flow per unit annulus area of 198 kilograms per second per square meter (40.6(lb/sec)/sq ft)

The overall and blade-element performance are presented for an air compressor stage designed to study the effect of weight flow per unit annulus area on efficiency and flow range. At the design speed of 424.8 m/sec the peak efficiency of 0.81 occurred at the design weight flow and a total pressure ratio of 1.56. Design pressure ratio and weight flow were 1.57 and 29.5 kg/sec (65.0 lb/sec), respectively. Stall margin at design speed was 19 percent based on the weight flow and pressure ratio at peak efficiency and at stall.

Kovich, G.↗
NASA NTRS1973

Impact resistance of current design composite fan blades tested under short-haul operating conditions

Boron/epoxy and graphite/epoxy composite blades were impacted in a rotating whirligig facility with conditions closely simulating those which might be experienced by a STOL engine impacted with various foreign objects. The tip speed of the rotating blades was 800 feet per second. The blades were impacted with simulated birds, real birds, ice balls, and gravel. The results of composite blade impact tests were compared with a titanium blade tested under similar conditions. Neither composite material indicated a clear superiority over the other. Blades made from both composite materials showed more damage than the titanium blades.

Steinhagen, C. A.↗
NASA NTRS1974

Low-speed wind tunnel tests of a 50.8-centimeter (20-in.) 1.15-pressure-ratio fan engine model

At a typical STOL aircraft takeoff and landing velocity, wind tunnel aerodynamic and acoustic measurements demonstrated that an inlet lip-area contraction ratio of 1.35 was superior to a ratio of 1.26 at high incidence angles. A 17 percent reduction in net thrust and an increase of 9 decibels in sound pressure level at the blade passing frequency resulted from inlet flow separation at an incidence angle of 50 deg with the 1.26-contraction-ratio inlet. Reverse-thrust forces obtained with blade rotation through the feathered angle were 1.8 times larger than with blade rotation through the flat angle. Reverse-thrust force was reduced from 30 to 50 percent and sound pressure level increased from 3 to 7 decibels at the blade passing frequency between the wind-tunnel-off condition and a typical STOL aircraft landing velocity.

Wesoky, H. L.↗
NASA NTRS1974

Holographic studies of shock waves within transonic fan rotors

NASA has funded two separate contracts to apply pulsed laser holographic interferometry to the detection of shock patterns in the outer span regions of high tip speed transonic rotors. The first holographic approach used ruby laser light reflected from a portion of the centerbody just ahead of the rotor. These holograms showed the bow wave patterns upstream of the rotor and the shock patterns just inside the blade row near the tip. The second holographic approach, on a different rotor, used light transmitted diagonally across the inlet annulus past the centerbody. This approach gave a more extensive view of the region bounded by the blade leading and trailing edges, by the part span shroud and by the blade tip. These holograms showed the passage shock emanating from the blade leading edge and a moderately strong conical shock originating at the intersection of the part span shroud leading edge and the blade suction surface.

Benser, W. A.↗