Showing papers on "Supersonic speed published in 1973"

Structure of Shock Waves in Cylindrical Ducts

Abstract: Wall static and in-stream phot pressure distributions are presented for confined, nonreacting, supersonic flows in cylindrical sections wherein a shock structure has been stabilized. Based on an analysis of these measurements, the character of the wave structure is shown to be oblique rather than normal, with the flow remaining primarily supersonic downstream of the shock system. When additional cylindrical sections are either added or deleted the shock structure is, with the exception of slight changes due to the different initial conditions, independent of location in the duct. The parameters which govern the distance st, over which the pressure rise is spread, viz., Mach number, momentum thickness Reynolds number, duct diameter, and the momentum thickness of the upstream boundary layer, were varied as follows: 1.53 ^ Ma ^ 2.72, 5 x 10 ^ Ree ^ 6 x 10, 1.0 D 6.1 in., and 0.007 ^ 6 ^ 0.036 in. In each test the wave structure was generated by either lowering the pressure in the air supply system so that the cylindrical duct was, in effect, overexpanded when discharging to ambient conditions, or by throttling the flow leaving the duct. For a given pressure ratio across the disturbance, Pf/pa, st varies approximately directly with the product 0D and inversely with (Ma — l)Re0. A simple quadratic expression is presented which adequately represents this corespondence for the complete range of conditions tested and for data from the cited reference.

Mixing-Controlled Supersonic Combustion

Abstract: The technology of supersonic combustion and its practical significance for hypersonic flight are reviewed. It is shown that this technology makes possible a good qualitative and quantitative understanding of the physical phenomena related to the process of supersonic combustion. Some of the more important, summarized aspects of this technology include the physical description of the supersonic combustion flame, the chemical reaction rates and the diffusion process involved, the interaction between combustion and fluid dynamics, and the mathematical methods of supersonic combustion analysis.

Coating heat softened particles by projection in a plasma stream of Mach 1 to Mach 3 velocity

Abstract: An electric arc plasma spray gun provides optimum coating of substrates by projecting a stream of plasma at a velocity at or about Mach two, at ambient pressure, and entraining therein particles of material to be coated upon said substrate. Power, pressures and temperatures are employed together with a unique set of interchangeable supersonic nozzles to achieve particle exit velocities of from one to ten thousand feet per second, heating said particles to a temperature below their melting point but sufficient to soften the particles for enhanced coating. Unique parameters of particle size, particle injection angle and particle injection positions are identified for different materials to be entrained in the supersonic plasma stream.

Relaxation solutions for inviscid axisymmetric transonic flow over blunt or pointed bodies.

Abstract: A finite-difference relaxation method is presented for numerical solution of the full potential equation and exact boundary conditions for general axisymmetric bodies is inviscid, steady transonic flow. Body-normal coordinates are used in the nose region and sheared cylindrical coordinates are used on the afterbody to accommodate corners such as boattails and flares. An improved difference scheme is used which does not require that the flow be nearly alined with a coordinate direction in supersonic regions, and which treats either subsonic or supersonic free streams. Numerical results are illustrated for some simple classical shapes such as spheres and ellipsoids, and for more practical shapes like tangent-ogives with boattails. Special attention is given to bodies which have been studied for area-rule applications. Agreement with available experimental results is good in cases where viscous effects and wind-tunnel wall interference are not important.

Multishocked, Three-Dimensional Supersonic Flowfields with Real Gas Effects

Abstract: This program determines the supersonic flowfield surrounding three-dimensional wing-body configurations of a delta wing. It was designed to provide the numerical computation of three dimensional inviscid, flowfields of either perfect or real gases about supersonic or hypersonic airplanes. The governing equations in conservation law form are solved by a finite difference method using a second order noncentered algorithm between the body and the outermost shock wave, which is treated as a sharp discontinuity. Secondary shocks which form between these boundaries are captured automatically. The flowfield between the body and outermost shock is treated in a shock capturing fashion and therefore allows for the correct formation of secondary internal shocks . The program operates in batch mode, is in CDC update format, has been implemented on the CDC 7600, and requires more than 140K (octal) word locations.

A Simple Correlation for Incipient-Turbulent Boundary-Layer Separation due to a Skewed Shock Wave

Abstract: References 1 Fingerson, L. M., "A Heat Flux Probe for Transient Measurements in High Temperature Gases," Ph.D. thesis, 1961, Univ. of Minnesota, Minneapolis, Minn.; also ARS Journal, Vol. 13, No. 11, Nov. 1962, p. 1709. 2 McCroskey, W. J., "Density and Velocity Measurements in HighSpeed Flows," AIAA Journal, Vol. 6, No. 9, Sept. 1968, pp. 1805-1808. 3 Horstman, C. C. and Kussoy, M. I, "Hypersonic Viscous Interaction on Slender Cones," AIAA Paper 68-2, New York, 1968. 4 Vas, I. E., "An Experimental Investigation of the Flow About a Slender Cone at Hypersonic Speeds," Ph.D. thesis, 1970, New York Univ., New York. 5 Becker, M., Papanikas, D. G., and Schweiger, G., "Experimental Study of the Flow Field in Front of Hemispheres in the Transition and Shock Formation Regime," presented at the 7th RGDS, July 1970, Deutsche Forschungsurid Versuchsanstalt fur Luftund Raumfahrt, (DFVLR) Porz-Wahn, W. Germany. 6 Harbour, P. J. and Lewis, J. H., "Preliminary Measurements of the Hypersonic Rarefield Flow Field on a Sharp Flat Plate Using an Electron Beam Probe," Rarefied Gas Dynamics, Supp. 4, Vol. 1, Academic Press, New York, 1967. 7 Petraites, R. J., "An Experimental Investigation of the Effects of Three-Dimensionality on the Flow Over a Flat Plate at M ~ 25," MSE thesis, Aug. 1972, Dept. of Aerospace and Mechanical Sciences, Princeton Univ., Princeton, N.J. 8 Dewey, C. F., Jr., "A Correlation of Convective Heat Transfer and Recovery Temperature Data for Cylinders in Compressible Flow," International Journal of Heat and Mass Transfer, Vol. 8, 1965, pp. 245-252. 9 Rubin, S. G., Rudman, S., Lin, T. C, and Pierucci, M., "Hypersonic Viscous-Inviscid Interaction by a New Type of Analysis," AGARD CP 30, Hypersonic Boundary Layers and Flow Fields, May 1968. 10 Mayne, A. W., Jr., Gilley, G. E., and Lewis, C. H., "Binary Boundary Layers on Sharp Cones in Low-Density Supersonic and Hypersonic Flow," AIAA Journal, Vol. 7, No. 4, April 1969, pp. 699-706.

Aerodynamic Interference Induced by Reaction Controls

Abstract: : The literature pertaining to the interaction of a sonic or supersonic gaseous jet with a transverse external flow has been reviewed. The flowfields associated with these interactions are complex, and knowledge of them is based largely on results of experiments. Numerous examples of data from flat-plate experiments are presented. These include static pressure distribution, induced forces, flowfield survey, and flow visualization results. Analyses and correlation techniques for jet interaction flows are discussed. The region upstream of a jet in two-dimensional flow is similar to the flow upstream of a forward-facing step, and the flow associated with a jet from a circular nozzle in a flat plate resembles the flow past a blunt-nosed slender body. The single most important variable in determining the scale of these interactions is the ratio of jet momentum flux to the external-flow dynamic pressure.

Supersonic Generation of Atmospheric Waves

Abstract: Chimonas and Hines1 have pointed out that the Moon's shadow on the Earth's atmosphere during a solar eclipse constitutes a cooling region travelling at supersonic speeds, and may generate atmospheric gravity waves with periods from a couple of minutes up to twelve hours. Atmospheric wave generation by solar eclipses has been observed2–4, though within the source region (the region of total or partial eclipse) the gravity waves have substantially shorter period than outside it. Here I draw an analogy between the supersonic motion of the Moon's shadow and the supersonic motion of the Earth's terminator. The terminator is supersonic between ± 45° latitudes at all altitudes below 100 km and may therefore generate gravity waves in this region.

Viscous flow over a cone at moderate incidence. Part 2. Supersonic boundary layer

Abstract: A finite-difference method recently developed to study three-dimensional viscous flow is applied here to the supersonic boundary layer on a sharp cone at moderate angles of incidence (α/θ [les ] 2, angle of attack α, cone half-angle θ). The present analysis differs from previous investigations of this region in that (i) boundary-layer similarity is not assumed, (ii) the system of governing equations incorporates lateral diffusion and centrifugal force effects, and (iii) an improved numerical scheme for three-dimensional viscous flows of the type considered here is used. Solutions are shown to be non-similar at the separation streamline with local shear-layer formation. Detailed flow structure, including surface heat transfer, boundary-layer profiles and thickness, and the formation of swirling pairwise symmetric vortices, associated with cross-flow separation, are obtained. Good agreement is obtained between the present theoretical results and the existing experimental data.

Annular Truncated Plug Nozzle Flowfield and Base Pressure Characteristics

Abstract: The flowfield and base pressure characteristics of an internal-external-expansion, truncated plug nozzle are described over the pressure ratio range from "open" wake to "closed" wake conditions. The effect of plug length on these characteristics, including the process of wake "closure" is also presented. An existing method for calculating the flowfield and base pressure, for closed wake operation, is modified to include the internal shock wave generated near the shroud exit. The supersonic portion of the flow is calculated using rotational axisymmetric method of characteristics. The technique of Hartree is employed so that the downstream characteristic point locations can be chosen to fit the developing flowfield. An overexpansion technique is used to detect the internal shock wave in the vicinity of the shroud exit so that its effect on the plug base pressure could be determined. Good agreement between the analytical results and experimental data is obtained for closed wake operations.

Variable cycle gas turbine engine

Abstract: A variable cycle gas turbine engine for commercial supersonic aircraft is provided with variable geometry means to simultaneously control the bypass and pressure ratios for different engine flight conditions wherein the engine may be operated at supersonic speed with a lower bypass and higher pressure ratio than at subsonic speed. The relatively high noise levels generally associated with the supersonic mode of operation for conventional supersonic engines can be significantly reduced by controlling the variable geometry means in a manner which increases the bypass ratio and decreases the pressure ratio of the fan section of the engine. In this manner, supersonic aircraft may approach and take off from airports situated adjacent densely populated areas without unduly disturbing the local residents.

Supersonic Flow Aerodynamic Windows for High-Power Lasers

Abstract: The extraction of a laser beam from the cavity of a high-power laser through a solid window is difficult due to excessive heating of the window material by the absorbed laser flux. A class of devices is discussed and analyzed which uses the momentum of a supersonic jet to support the pressure difference between the laser cavity and the ambient atmosphere and permits the extraction of the laser beam through a nonabsorbing gas medium. The mass flow required for the operation of these devices and the optical quality of the window medium have been investigated as a function of operating conditions and the window design. Measurements of aerodynamic performance and optical quality have been made with a window of this type. This window has operated at a pressure ratio of 10 and measurements show that the beam quality degradation introduced by the window is small, in agreement with theoretical predictions.

Measurements of the Drag of Some Characteristic Aircraft Excrescences Immersed in Turbulent Boundary Layers

Abstract: : Measurements are described of the drag of various forms of excrescence mounted on balances installed in the walls of the working section of the RAE 8 ft x 8 ft wind tunnel. The tests cover a range of Mach numbers between 0.2 and 2.8 (but not transonic) and a range of Reynolds number. The excrescences tested include two-dimensional steps and ridges, circular cylinders and wings mounted normal to the surface, and holes and fairings. It is shown, for excrescences which are of height small compared with the boundary-layer thickness, that the scale effects on drag are well correlated in terms of the wall variables of the turbulent boundary layer, but that there is a dependence of drag on Mach number. For steps and ridges the effect of chamfering or rounding the upper corners was found to be beneficial at subsonic speeds but far less so at supersonic speeds. For circular holes the drag depends strongly upon the depth to diameter ratio. In an Appendix the oil-flow patterns obtained for a range of depth of circular holes are shown. The fairings tested were either half-bodies of revolution with pointed or rounded ends or of square or rectangular section with pointed ends. The effects of different amounts of immersion of the bodies into the boundary layer were found in some cases by testing geometrically similar bodies of different sizes.

On the atomization of a liquid by high-velocity gases: II

Abstract: Some assumptions in the author's earlier (1973) work on the gas atomization of liquids have been relaxed; also the work has been extended to cover the case of supersonic gas speeds. A prediction of the drop size of a spray can be made and good correlation with experimental work is found. Finally, for molten metals, a graphical method of prediction is developed.

Application of sonic-boom minimization concepts in supersonic transport design

Abstract: The applicability of sonic boom minimization concepts in the design of large supersonic transport airplanes capable of a 2500-nautical-mile range at a cruise Mach number of 2.7 is considered. Aerodynamics, weight and balance, and mission performance as well as sonic boom factors, have been taken into account. The results indicate that shock-strength nominal values of somewhat less than 48 newtons/sq m during cruise are within the realm of possibility. Because many of the design features are in direct contradiction to presently accepted design practices, further study of qualified airplane design teams is required to ascertain sonic boom shock strength levels actually attainable for practical supersonic transports.

Experimental Study of Slot Injection into a Supersonic Stream

Abstract: An experimental investigation of two-dimensional tangential-slot injection into a turbulent boundary layer at a freestream Mach number of 2.4 has been conducted. Nearly adiabatic surface temperatures were maintained during all tests. Static and pitot pressure profiles at four stations downstream of the slot were obtained. Skin friction was measured at the last three stations with a self-nulling balance. Schlieren photographs of the flow field were also obtained. Most of the data were obtained with slot Mach numbers of 0.31 and 0.66 corresponding to slot pressure less than and equal to stream static pressure, respectively. For the latter matched-pressure case, tangential slot injection reduced the surface shear at the three measuring stations by about 60 to 20 percent for increasing downstream distances from the slot of 12 to 28 slot heights. However, for the other case where slot pressure was less than stream static pressure, the effect of injection was to increase the shear by about 90 percent at the last downstream station of 28 slot heights. This increase in shear is attributed to the rapid acceleration of the low speed injectant stream by the high speed main stream and the increasing pressure through the recompression zone which is absent for the matched pressure case.

Effect of fineness ratio on boattail drag of circular-arc afterbodies having closure ratios of 0.50 with jet exhaust at Mach numbers up to 1.30

Abstract: An investigation was conducted to determine the effect of fineness ratio on the drag of circular-arc boattails at subsonic and low supersonic speeds. The boattails had closure ratios of 0.50 and incorporated convergent nozzles. The investigation was conducted statically and at Mach numbers from 0.40 to 1.30 at 0 deg angle of attack with jet total-pressure ratios varying from jet off to about 6, depending on Mach number. Low-fineness-ratio boattails had large separated-flow regions and the highest drag at all Mach numbers. Subsonic pressure-plus-friction drag levels were generally similar for boattails which did not have large separated regions. Drag-rise Mach number increased as boattail fineness ratio increased.

Wave-like Disturbances in the Ionosphere

Abstract: BEER1 has recently suggested that atmospheric gravity waves could be expected to exist in the ionosphere as a result of the supersonic motion of the terminator. He reached this conclusion by drawing an analogy between the proposed production of gravity waves by the supersonic motion of the Moon's shadow on the Earth's atmosphere during a solar eclipse2, and the supersonic motion of the Earth's terminator. At the mesopause the extent of the terminator's supersonic motion can be as great as ±55° latitude.

Numerical solutions of the supersonic, laminar flow over a two-dimensional compression corner

Abstract: Numerical solutions of Navier-Stokes equations are presented for the supersonic laminar flow over a two-dimensional compression corner. A well-known time-dependent method has been used wherein the asymptotic steady solutions of the unsteady Navier-Stokes equations are obtained with the Brailovskaia (1965) finite-difference scheme.

Turbulent jet mixing at high supersonic speeds.

Abstract: The results of three related studies of turbulent jet mixing are presented and discussed. The major effort was the collection of mean-flow data at a much higher free stream Mach number than was previously available. The effects of initial swirl in the injectant were found to be minimal. Numerical predictions of the non-swirling experimental case obtained using an eddy viscosity approximation are found to be in reasonable agreement with the data. Lastly, an approximate analysis of the decay of the swirling velocity is developed. This analysis is based upon an eddy viscosity model for transport in the circumferential direction adapted from wing-tip vortex work.

Ballistic Range Investigation of Sonic-Boom Overpressures in Water

Abstract: An investigation of sonic-boom overpressures in water has been conducted by gun-launching small cone-cylinder models over water. Flights were conducted at Mach numbers of 2.7 and 5.7, in air, corresponding to Mach numbers of 0.6 and 1.3, respectively, in water. Shadowgraph pictures and underwater pressure measurements indicate that for horizontal flights at Mach numbers below Mach 4.4 in air (i.e., subsonic relative to the speed of sound in water) the resulting underwater disturbance is an acoustic wave whose peak pressure attenuates rapidly with water depth. In contrast, at supersonic Mach numbers, relative to water, the incident shock wave at the surface is transmitted into the water as a propagating shock wave and the peak pressure associated with it does not attenuate with water depth.

On Turbulent Stress and the Structure of Young Convective Stars

Abstract: It is pointed out on the basis of T Tauri star observations that there may exist strongly supersonic turbulent stresses beneath the surfaces of young convective stars which are of order l00 times the normal gas pressure. To account for this phenomenon an elementary dynamical theory of supersonic turbulent convection is presented which is an extension of the usual subsonic mixing-length theory. (WDM)

Aerodynamic noise emission from turbulent shear layers.

Abstract: The Phillips (1960) convected wave equation is employed in this paper to study aerodynamic noise emission processes in subsonic and supersonic shear layers. The wave equation in three spatial dimensions is first reduced to an ordinary differential equation by Fourier transformation and then solved via the WKBJ method. Three typical solutions are required for discussions in this paper. The current results are different from the classical conclusions. The effects of refraction, convection, Mach-number dependence and temperature dependence of turbulent noise emission are analyzed in the light of solutions to the Phillips equation.

Nonlinear stability of a liquid film adjacent to a supersonic stream

Abstract: The nonlinear stability of a liquid film adjacent to a supersonic gas stream is investigated. The gas is assumed to exert a mean shear stress at the liquid/gas interface which in turn establishes a linear mean velocity profile in the liquid. The analysis takes into account the pressure perturbation exerted by the gas on the liquid assuming the disturbed gas motion to be inviscid and the mean gas velocity profile to be uniform. The problem is formulated within the long wave approximation, and solutions are obtained for finite amplitude waves by using the method of multiple scales. The results predict the existence of finite amplitude periodic waves, in qualitative agreement with recent experimental observations.