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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Aerodynamic interactions between a 1/6-scale helicopter rotor and a body of revolution

A wind-tunnel investigation was conducted in which independent, steady-state aerodynamic forces and moments were measured on a 2.24-m-diam, two-bladed helicopter rotor and a body of revolution. The objective was to determine the interaction of the body on the rotor performance and the effect of the rotor on the body aerodynamics for variations in velocity, thrust, tip-path-plane angle of attack, rotor/body position, and body nose geometry. Results show that a body of revolution near the rotor can produce significant favorable or unfavorable effects on rotor performance, depending on the operating condition. Body longitudinal aerodynamic characteristics are significantly modified by the presence of an operating rotor and hub.

Betzina, M. D.↗
NASA NTRS1951

A semi-empirical method for calculating the pitching moment of bodies of revolution at low Mach numbers

A semiempirical method, in which potential theory is arbitrarily combined with an approximate viscous theory, for calculating the aerodynamic pitching moments for bodies of revolution is presented. The method can also be used for calculating the lift and drag forces. The calculated and experimental force and moment characteristics of 15 bodies of revolution are compared.

FLOW, VISCOUS↗
NASA NTRS1985

Effects of body shape on the aerodynamics of a body of revolution at Mach numbers from 1.6 to 4.6

The aerodnamic characteristics for several bodies of revolution have been determined from wind tunnel tests at Mach numbers from 1.6 to 4.63. Six bodies, each having a length-to-diameter ratio of 6.67, were investigated. Geometric modifications included forebody shape, afterbody shape, and midsection slope. Significant aerodynamic changes were observed to be functions of geometric change and Mach number. Because of the aerodynamic dependence on geometry as well as Mach number, it is obvious that a number of trades must be considered in selecting a projectile shape.

Spearman, M. L.↗
NASA NTRS1991

On the measurement of subsonic flow around an appended body of revolution at cryogenic conditions in the NTF

Fluid mechanics scaling is briefly reviewed and testing ship models at high Reynolds numbers in the National Transonic Facility is discussed. Particular attention is given to the 1986 body of revolution experiment, the expanded model capabilities for a future body of revolution experiment, major features of a future flat plate experiment, the proposed liquid helium tunnel from the user's point of view, and a comparison of the NTF and the Conceptual Helium Tunnel.

Coder, David W.↗
NASA NTRS1957

Bodies of Revolution Having Minimum Drag at High Supersonic Airspeeds

Approximate shapes of nonlifting bodies having minimum pressure foredrag at high supersonic airspeeds are calculated. With the aid of Newton's law of resistance, the investigation is carried out for various combinations of the conditions of given body length, base diameter, surface area, and volume. In general, it is found that when body length is fixed, the body has a blunt nose; whereas, when the length is not fixed, the body has a sharp nose. The additional effect of curvature of the flow over the surface is investigated to determine its influence on the shapes for minimum drag. The effect is to increase the bluntness of the shapes in the region of the nose and the curvature in the region downstream of the nose. These shape modifications have, according to calculation, only a slight tendency to reduce drag. Several bodies of revolution of fineness ratios 3 and 5, including the calculated shapes of minimum drag for given length and base diameter and for given base diameter and surface area, were tested at Mach numbers from 2.73 to 6.28. A comparison of theoretical and experimental foredrag coefficients indicates that the calculated minimum-drag bodies are reasonable approximations to the correct shape.

Eggers, A J , Jr↗
NASA NTRS1982

Experimental study of surface pressures induced on a flat plate and a body of revolution by various dual jet configurations

The effect of the angle of a jet to a crossflow, the performance of dual jet configurations, and a jet injected from a body of revolution as opposed to a flat plate were investigated during experiments conducted in the 7x10 tunnel at NASA Ames at Velocities from 14.5 m/sec to 35.8 m/sec (47.6 to 117.4 ft/sec.). Pressure distributions are presented for single and dual jets over a range of velocity ratios from 2 to 10, spacings from 2 to 6 diameters and injection angles of 90, 75, 60, and 105 degrees. For the body of revolution tests, the ratio of the jet to body diameters was set as large (1/2) in order to be more representative of V/STOL aircraft applications. Flat plate tests involved dual jets both aligned and in side by side configurations. The effects of the various parameters and the differences between the axisymmetric and planar body geometrics on the nature, size, shape, and strength of the interaction regions on the body surfaces are shown. Some flowfield measurements are also presented, and it is shown that a simple analysis is capable of predicting the trajectories of the jets.

Schetz, J. A.↗
NASA NTRS1950

An Analysis of the Applicability of the Hypersonic Similarity Law to the Study of Flow About Bodies of Revolution at Zero Angle of Attack

The hypersonic similarity law as derived by Tsien has been investigated by comparing the pressure distributions along bodies of revolution at zero angle of attack. In making these comparisons, particular attention was given to determining the limits of Mach number and fineness ratio for which the similarity law applies. For the purpose of this investigation, pressure distributions determined by the method of characteristics for ogive cylinders for values of Mach numbers and fineness ratios varying from 1.5 to 12 were compared. Pressures on various cones and on cone cylinders were also compared in this study. The pressure distributions presented demonstrate that the hypersonic similarity law is applicable over a wider range of values of Mach numbers and fineness ratios than might be expected from the assumptions made in the derivation. This is significant since within the range of applicability of the law a single pressure distribution exists for all similarly shaped bodies for which the ratio of free-stream Mach number to fineness ratio is constant. Charts are presented for rapid determination of pressure distributions over ogive cylinders for any combination of Mach number and fineness ratio within defined limits.

PRESSURE DISTRIBUTION - BODIES OF REVOLUTION↗
NASA NTRS1975

Experimental aerodynamic characteristics for a cylindrical body of revolution with side strakes and various noses at angles of attack from 0 degrees to 58 degrees and Mach numbers from 0.6 to 2.0

For a body of revolution with afterbody side strakes, an experimental investigation was conducted in the Ames 6- by 6-Foot Wind Tunnel to determine the effects on the aerodynamic characteristics of forebody geometry, nose strakes, body side strakes, Reynolds number, Mach number, and angle of attack. Aerodynamic force and moment characteristics were measured for the straked cylindrical afterbody (cylinder fineness ratio of 7) with tangent ogive noses of fineness ratio 2.5 to 5.0. In addition, the straked cylinder afterbody was tested with an ogive nose having a rounded tip and an ogive nose with two different nose strake arrangements. The data demonstrate that the aerodynamic characteristics for a body of revolution with side strakes can be significantly affected by changes in nose fineness ratio, nose bluntness, Reynolds number, Mach number, and, of course, angle of attack. Removing the strakes from the cylindrical aftersection greatly decreased the lift, but this removal hardly changed the maximum magnitudes of the undesirable side forces that developed at angles of attack greater than about 25 deg for subsonic Mach numbers.

Jorgensen, L. H.↗
NASA NTRS1971

Numerical calculation of transonic flow about slender bodies of revolution

A relaxation method is described for the numerical solution of the transonic small disturbance equation for flow about a slender body of revolution. Results for parabolic arc bodies, both with and without an attached sting, are compared with wind-tunnel measurements for a free-stream Mach number range from 0.90 to 1.20. The method is also used to show the effects of wind-tunnel wall interference by including boundary conditions representing porous-wall and open-jet wind-tunnel test sections.

Bailey, F. R.↗
NASA NTRS1953

A comparison of the experimental subsonic pressure distributions about several bodies of revolution with pressure distributions computed by means of the linearized theory

An analysis is made of the effects of compressibility on the pressure coefficients about several bodies of revolution by comparing experimentally determined pressure coefficients with corresponding pressure coefficients calculated by the use of the linearized equations of compressible flow. The results show that the theoretical methods predict the subsonic pressure-coefficient changes over the central part of the body but do not predict the pressure-coefficient changes near the nose. Extrapolation of the linearized subsonic theory into the mixed subsonic-supersonic flow region fails to predict a rearward movement of the negative pressure-coefficient peak which occurs after the critical stream Mach number has been attained. Two equations developed from a consideration of the subsonic compressible flow about a prolate spheroid are shown to predict, approximately, the change with Mach number of the subsonic pressure coefficients for regular bodies of revolution of fineness ratio 6 or greater.

Matthews, Clarence W↗
NASA NTRS1956

On boattail bodies of revolution having minimum wave drag

The problem of determining the shape of slender boattail bodies of revolution for minimum wave drag has been reexamined. It was found that minimum solutions for Ward's slender-body drag equation can exist only for the restricted class of bodies for which the rate of change of cross-sectional area at the base is zero. In order to eliminate this restriction, certain higher order terms must be retained in the drag equation and isoperimetric relations. The minimum problem for the isoperimetric conditions of given length, volume, and base area is treated as an example. According to Ward's drag equation, the resulting body shapes have slightly less drag than those determined by previous investigators.

Harder, Keith C↗
NASA NTRS1981

Unsteady Newton-Busemann flow theory. II - Bodies of revolution

A complete Newtonian flow theory is presented for unsteady flow past oscillating bodies of revolution of general shape at very high Mach numbers, consideration being given to a centrifugal force correction to the impact pressures. Expressions are obtained for the unsteady pressure and the stability derivatives are presented in closed form. It is stressed that the correction for the centrifugal force, which arises because of the curved trajectories that fluid particles follow along the surface subsequent to their impact, must not be neglected. If the correction is included, the theory is shown to be in excellent agreement with experimental results for relatively sharp cones. Theoretical results are in poor agreement with experimental results in air for bodies having moderate or large-nose bluntness.

Hui, W. H.↗