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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1953

Study of the supersonic propeller

In this paper a propeller having all sections operating at supersonic speeds is designated a supersonic propeller regardless of flight speed. Analyses assume subsonic flight speeds but very high rotational speeds. A very elementary analysis of the efficiency of a jet-propeller system is presented. A propeller analysis based on conventional vortex blade element theory is presented and reduced to a single point method which leads to an expression for optimum advance ratio in terms of hub-tip diameter ratio and airfoil fineness ratio. An expression for propeller efficiency in terms of advance ratio, hub-tip diameter ratio, and airfoil thickness ratio is also presented. Use is made of theoretical airfoil characteristics at supersonic speeds. A study of blade section interference, blade shock and expansion fields, at supersonic section speeds is presented. An example taken indicates that an efficiency of seventy percent can be obtained with a propeller having a tip Mach number of 2.3.

PROPELLERS, SUPERSONIC↗
NASA NTRS1980

Analytic development of improved supersonic cruise aircraft based on wind tunnel data

Data obtained from the MDC/NASA cooperative wing tunnel program were used to develop empirical corrections to theory. These methods were then used to develop a 2.2M supersonic cruise aircraft configuration with a cruise trimmed maximum L/D of 10.2. The empirical corrections to the theory are reviewed, and the configuration alternatives examined in the development of the configuration are presented. The benefits of designing for optimum trimmed performance, including the effects of the nacelles, are discussed.

Roensch, R. L.↗
NASA NTRS1974

Subsonic and supersonic indicial aerodynamics and aerodynamic transfer function for complex configurations

A general theory for indicial-potential-compressible aerodynamics around complex configurations is presented. The motion is assumed to consist of constant subsonic or supersonic speed (steady state) and small perturbations around the steady state. Using the finite-element method to discretize the space problem, a set of differential-difference equations in time relating the potential to its normal derivative on the surface of the body was obtained. The aerodynamics transfer function was derived by using standard method of operational calculus.

Morino, L.↗
NASA NTRS1979

Aerodynamic design and analysis of the AST-200 supersonic transport configuration concept

The design and analysis of a supersonic transport configuration was conducted using linear theory methods in conjunction with appropriate constraints. Wing optimization centered on the determination of the required twist and camber and proper integration of the wing and fuselage. Also included in the design are aerodynamic refinements to the baseline wing thickness distribution and nacelle shape. Analysis to the baseline and revised configurations indicated an improvement in lift-to-drag ratio of 0.36 at the Mach 2.7 cruise condition. Validation of the design is planned through supersonic wing tunnel tests.

Walkley, K. B.↗
DOE OSTI2022

Electronic states and transitions of PrO and PrO + probed by threshold ionization spectroscopy and spin–orbit multiconfiguration perturbation theory

The precise ionization energy of praseodymium oxide (PrO) seeded in supersonic molecular beams is measured with mass-analyzed threshold ionization (MATI) spectroscopy. Here, a total of 33 spin–orbit (SO) states of PrO and 23 SO states of PrO + are predicted by second-order multiconfigurational quasi-degenerate perturbation (MCQDPT2) theory. Electronic transitions from four low-energy SO levels of the neutral molecule to the ground state of the singly charged cation are identified by combining the MATI spectroscopic measurements with the MCQDPT2 calculations. The precise ionization energy is used to reassess the ionization energies and the reaction enthalpies of the Pr + O → PrO + + e – chemi-ionization reaction reported in the literature. An empirical formula that uses atomic electronic parameters is proposed to predict the ionization energies of lanthanide monoxides, and the empirical calculations match well with available precise experimental measurements.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1974

Deployment and performance characteristics of 1.5-meter supersonic attached inflatable decelerators

Attached-inflatable-decelerator (AID) canopies fabricated from lightweight Nomex cloth and tapes were deployed in a supersonic stream from the base of a 140 deg conical aeroshell. Characteristics of the deceleration system were obtained over a wide range of Mach number, dynamic pressure, and pitch angle. All models deployed rapidly by ram air and experienced only mild deployment shock loads. Steady-state drag coefficients as high as 1.3 were obtained in the supersonic stream and were relatively insensitive to Mach number, dynamic pressure, and pitch angle. All models were free of fluttering motion. Results also showed that the AID is aerodynamically more efficient without a burble fence in a supersonic stream. Though measured meridian-tape loads were higher than those predicted by theory, the ram-air deployment rates and steady-state drag coefficients were in good agreement with theory. These results indicate that the AID is a stable, efficient decelerator in a supersonic stream and its performance is readily predictable.

Bohon, H. L.↗
NASA NTRS1977

Unsteady subsonic and supersonic potential aerodynamics for complex configurations

A recently developed general theory for unsteady compressible potential fluid dynamics for complex-configuration aircraft is reviewed. The method is based on a combination of the following techniques: Green's function method (to transform the differential equation into an integral differential-delay equation), finite element method (to transform the equation into a set of differential-delay equations in time), and the Laplace transform method (to transform the differential-delay equations into algebraic equations).

Morino, L.↗
NASA NTRS1981

Voyager and the origin of the solar system

A unified model for the formation of regular satellite systems and the planetary system is outlined. The basis for this modern Laplacian theory is that there existed a large supersonic turbulent stress arising from overshooting convective motions within the three primitive gaseous clouds which formed Jupiter, Saturn, and the Sun. Calculations show that if each cloud possessed the same fraction of supersonic turbulent energy, equal to about 5% of the cloud's gravitational potential energy, then the broad mass distribution and chemistry of all regular satellite and planetary systems can be simultaneously accounted for. Titan is probably a captured moon of Saturn. Several predictions about observations made by Voyager 2 at Saturn are presented.

Prentice, A. J. R.↗
NASA NTRS1990

Instability of a supersonic shock-free elliptic jet

A comparison of the measured and the computed spatial stability properties of an aspect ratio 2, supersonic, shock free, elliptic jet is presented. The shock free nature of the elliptic jet furnishes a perfect test of the validity of modeling the large scale coherent structures in the initial mixing region of noncircular supersonic jets with the linear hydrodynamic stability theory. Aerodynamic and acoustic data are measured to compute the mean velocity profiles and to provide a description of the spatial composition of pressure waves in the elliptic jet. The measured mean velocity profiles are employed to provide a qualitative model for the cross sectional geometry and the smooth velocity profiles utilized in the stability analysis. It is shown that the measured frequency associated with peak amplitude noise radiation agrees with that frequency predicted to dominate the large scale structure near the end of the potential core.

Baty, Roy S.↗
NASA NTRS1985

Study of an efficient long-range Mach 2.7 supersonic transport configuration concept

A long range Mach 2.7 supersonic transport configuration concept was studied utilizing linear theory methods. The configuration was sized to carry 290 passengers 6,000 nautical miles nonstop. The final configuration has a maximum takeoff gross weight of 687,200 pounds, a wing loading of 69.8 lbf/sq.ft. and a thrust weight ratio of .278. The most significant result is that a significantly improved trimmed maximum lift drag ratio of 11.04 can be obtained for a supersonic transport at Mach 2.62 and 55,000 feet.

Gall, P. D.↗
NASA NTRS1959

Investigation at Mach Numbers of 0.20 to 3.50 of a Blended Diamond Wing and Body Combination of Sonic Design but with Low Wave-Drag Increase with Increasing Mach Number

A diamond wing and body combination was designed to have an area distribution which would result in near optimum zero-lift wave-drag coefficients at a Mach number of 1.00, and decreasing wave-drag coefficient with increasing Mach number up to near sonic leading-edge conditions for the wing. The airfoil section were computed by varying their shape along with the body radii (blending process) to match the selected area distribution and the given plan form. The exposed wing section had an average maximum thickness of about 3 percent of the local chords, and the maximum thickness of the center-line chord was 5.49 percent. The wing had an aspect ratio of 2 and a leading-edge sweep of 45 deg. Test data were obtained throughout the Mach number range from 0.20 to 3.50 at Reynolds numbers based on the mean aerodynamic chord of roughly 6,000,000 to 9,000,000. The zero-lift wave-drag coefficients of the diamond model satisfied the design objectives and were equal to the low values for the Mach number 1.00 equivalent body up to the limit of the transonic tests. From the peak drag coefficient near M = 1.00 there was a gradual decrease in wave-drag coefficient up to M = 1.20. Above sonic leading-edge conditions of the wing there was a rise in the wave-drag coefficient which was attributed in part to the body contouring as well as to the wing geometry. The diamond model had good lift characteristics, in spite of the prediction from low-aspect-ratio theory that the rear half of the diamond wing would carry little lift. The experimental lift-curve slope obtained at supersonic speeds were equal to or greater than the values predicted by linear theory. Similarly the other basic aerodynamic parameters, aerodynamic center position, and maximum lift-drag ratios were satisfactorily predicted at supersonic speeds.

Holdaway, George H.↗
NASA NTRS1958

A Wind-Tunnel Investigation of the Aerodynamic Characteristics of a Full-Scale Supersonic-Type Three-blade Propeller at Mach Numbers to 0.96

An investigation of the characteristics of a full-scale supersonic-type propeller has been made in the Langley 16-foot transonic tunnel with the 6000-horsepower propeller dynamometer. The tests covered a range of blade angles from 20.2 degrees to 60.2 degrees at forward Mach numbers up to 0.96. The results showed that envelope efficiency at an advance ratio of 2.8 decreased from 86 percent to 72 percent when the forward Mach number was increased from 0.70 to 0.96. A comparison of the experimental results with calculated results showed that maximum propeller efficiency can be calculated with good accuracy by using ordinary subsonic strip theory when the blade-section speeds are supersonic. The investigation also showed favorable power-absorption properties of the supersonic-type propeller at high speeds.

Evans, Albert J↗
NASA NTRS1967

Nonlinear oscillations of a fluttering plate. II.

Quasi-steady aerodynamic and von Karman large deflection plate theory equations of nonlinear oscillations of fluttering plate for single mode subsonic and sonic or coupled mode supersonic oscillations

VON KARMAN EQUATION↗
NASA NTRS1995

Large-Amplitude Long-Wave Instability of a Supersonic Shear Layer

For sufficiently high Mach numbers, small disturbances on a supersonic vortex sheet are known to grow in amplitude because of slow nonlinear wave steepening. Under the same external conditions, linear theory predicts slow growth of long-wave disturbances to a thin supersonic shear layer. An asymptotic formulation is given here which adds nonzero shear-layer thickness to the weakly nonlinear formulation for a vortex sheet. Spatial evolution is considered, for a spatially periodic disturbance having amplitude of the same order, in Reynolds number, as the shear-layer thickness. A quasi-equilibrium inviscid nonlinear critical layer is found, with effects of diffusion and slow growth appearing through nonsecularity condition. Other limiting cases are also considered, in an attempt to determine a relationship between the vortex-sheet limit and the long-wave limit for a thin shear layer; there appear to be three special limits, corresponding to disturbances of different amplitudes at different locations along the shear layer.

Messiter, A. F.↗
NASA NTRS1972

An experimental measurement of galactic cosmic radiation dose in conventional aircraft between San Francisco and London compared to theoretical values for conventional and supersonic aircraft

These direct measurements are in fair agreement with computations made using a program which considers both basic cosmic ray atmospheric physics and the focusing effect of the earth's magnetic field. These measurements also agree with those made at supersonic jet aircraft altitudes in Rb-57 aircraft. It is concluded that experiments and theory show that the doses received at conventional jet aircraft altitudes are slightly higher than those encountered in supersonic flights at much higher altitudes.

Wallace, R.↗
NASA NTRS1961

Aerodynamic Effects of Some Configuration Variables on the Aeroelastic Characteristics of Lifting Surfaces at Mach Numbers from 0.7 to 6.86

Results of flutter tests on some simple all-movable-control-type models are given. One set of models, which had a square planform with double-wedge airfoils with four different values of leading- and trailing-edge radii from 0 to 6 percent chord and airfoil thicknesses of 9, 11, 14, and 20 percent chord, was tested at Mach numbers from 0.7 to 6.86. The bending-to-torsion frequency ratio was about 0.33. The other set of models, which had a tapered planform with single-wedge and double-wedge airfoils with thicknesses of 3, 6, 9, and 12 percent chord, was tested at Mach numbers from 0.7 to 3.98 and a frequency ratio of about 0.42. The tests indicate that, in general, increasing thickness has a destabilizing effect at the higher Mach numbers but is stabilizing at subsonic and transonic Mach numbers. Double-wedge airfoils are more prone to flutter than single-wedge airfoils at comparable stiffness levels. Increasing airfoil bluntness has a stabilizing effect on the flutter boundary at supersonic speeds but has a negligible effect at subsonic speeds. However, increasing bluntness may also lead to divergence at supersonic speeds. Results of calculations using second-order piston-theory aerodynamics in conjunction with a coupled-mode analysis and an uncoupled-mode analysis are compared with the experimental results for the sharp-edge airfoils at supersonic speeds. The uncoupled-mode analysis more accurately predicted the flutter characteristics of the tapered-planform models, whereas the coupled-mode analysis was somewhat better for the square-planform models. For both the uncoupled- and coupled-mode analyses, agreement with the experimental results improved with increasing Mach number. In general, both methods of analysis gave unconservative results with respect to the experimental flutter boundaries.

Hanson, Perry W.↗
NASA NTRS1977

Nonlinear panel flutter - A finite-element approach

A finite-element approach has been developed for computing nonlinear flutter characteristics of rectangular isotropic panels with stream-alined side edges, based on aerodynamic forces from supersonic two-dimensional quasi-steady aerodynamic theory. Stress distributions and panel oscillation frequencies were determined from the analysis. The finite-element formulation, solution procedure, and convergence characteristics are presented. Comparisons are made with linear flutter and large-amplitude vibration results and demonstrate that good accuracy is obtained. Non-linear flutter results are presented for effects of aerodynamic damping, length-width ratio, initial in-plane forces and boundary-support conditions. Comparisons with experimental results are also presented.

Mei, C.↗
NASA NTRS1987

Prediction and control of transition in hypersonic boundary layers

In this paper, the role of compressible linear stability theory in prediction of boundary layer transition at supersonic and hypersonic speeds is investigated. Computations for sharp cones, using the e exp N method with N = 10, show that the first oblique Tollmien-Schlichting mode is responsible for transition at adiabatic wall conditions for freestream Mach numbers up to 7. For cold walls, the two-dimensional second mode dominates the transition process at lower hypersonic Mach numbers due to the well-known destabilizing effect of cooling on the second mode. It is shown that pressure gradient and suction may be used to stabilize this mode. Some results on the real gas effects on hypersonic boundary-layer stability are presented.

Malik, Mujeeb R.↗