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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

An experimental investigation of the impingement of a planar shock wave on an axisymmetric body at Mach 3

An experimental study of the flow caused by a planar shock wave impinging obliquely on a cylinder is presented. The complex three dimensional shock wave and boundary layer interaction occurring in practical problems, such as the shock wave impingement from the shuttle nose on an external fuel tank, and store carriage interference on a supersonic tactical aircraft were investigated. A data base for numerical computations of complex flows was also investigated. The experimental techniques included pressure measurements and oil flow patterns on the surface of the cylinder, and shadowgraphs and total and static pressure surveys on the leeward and windward planes of symmetry. The complete data is presented in tabular form. The results reveal a highly complex flow field with two separation zones, regions of high crossflow, and multiple reflected shocks and expansion fans.

Brosh, A.↗
NASA NTRS1991

Shock waves and nucleosynthesis in type II supernovae

In the study of nucleosynthesis in type II SN, shock waves are initiated artificially, since collapse calculations do not, as yet, give self-consistent shock waves strong enough to produce the SN explosion. The two initiation methods currently used by light-curve modelers are studied, with a focus on the peak temperatures and the nucleosynthetic yields in each method. The various parameters involved in artificially initiating a shock wave and the effects of varying these parameters are discussed.

Aufderheide, M. B.↗
NASA NTRS1989

Experimental study of pressure and heating rate on a swept cylindrical leading edge resulting from swept shock wave interference

The effects of cylindrical leading edge sweep on surface pressure and heat transfer rate for swept shock wave interference were investigated. Experimental tests were conducted in the Calspan 48-inch Hypersonic Shock Tunnel at a nominal Mach number of 8, nominal unit Reynolds number of 1.5 x 10 to the 6th power per foot, leading edge and incident shock generator sweep angles of 0, 15, and 30 deg, and incident shock generator angle-of-attack fixed at 12.5 deg. Detailed surface pressure and heat transfer rate on the cylindircal leading edge of a swept shock wave interference model were measured at the region of the maximum surface pressure and heat transfer rate. Results show that pressure and heat transfer rate on the cylindrical leading edge of the shock wave interference model were reduced as the sweep was increased over the range of tested parameters. Peak surface pressure and heat transfer rate on the cylinder were about 10 and 30 times the undisturbed flow stagnation point value, respectively, for the 0 deg sweep test. A comparison of the 15 and 30 deg swept results with the 0 deg swept results showed that peak pressure was reduced about 13 percent and 44 percent, respectively, and peak heat transfer rate was reduced about 7 percent and 27 percent, respectively.

Glass, Christopher E.↗
NASA NTRS1961

Constant Density Approximations for the Flow Behind Axisymmetric Shock Waves

The incompressible rotational flow equations are used to obtain solutions for the flow behind axisymmetric shock waves with conic longitudinal sections. The nonlinear part of the term due to rotation is retained in the analysis. Numerical results for standoff distance and stagnation point velocity gradient are presented for the case in which the shock wave is a paraboloid, a sphere, or an oblate or prolate ellipsoid. A similarity parameter is proposed which correlates approximately the flow behind geometrically similar shock waves at different free-stream conditions.

Munson, Albert G.↗
NASA NTRS1993

Portable fiber optic coupled Doppler interferometer system for detonation and shock wave diagnostics

Testing and analysis of shock wave characteristics such as detonators and ground shock propagation frequently require a method of measuring velocity and displacement of the surface of interest. One method of measurement is Doppler interferometry. The VISAR (Velocity Interferometer System for Any Reflector) uses Doppler interferometry and has gained wide acceptance as the preferred tool for shock measurement. An important asset of VISAR is that it measures velocity and displacement nonintrusively.

Fleming, Kevin J.↗
NASA NTRS1978

Shock tube and shock wave research; Proceedings of the Eleventh International Symposium, University of Washington, Seattle, Wash., July 11-14, 1977

Papers are presented on the applications of shock-wave technology to the study of hydrodynamics, the use of the pressure-wave machine for charging diesel engines, and measurements of the heat-transfer rate in gas-turbine components. Consideration is given to shock propagation along 90-degree bends, the explosive dissemination of liquids, and rotational and vibrational relaxation behind weak shock waves in water vapor. Shock phenomena associated with expansion flows are described and stratospheric-related research using the shock tube is outlined. Attention is given to shock-wave ignition of magnesium powders, Mach reflection and boundary layers, and transition in the shock-induced unsteady boundary layer on a flat plate. Shock-tube measurements of induction and post-induction rates for low-Btu gas mixtures are presented and shock-initiated ignition in COS-N2O-Ar mixtures is described. Cluster growth rates in supersaturated lead vapor are presented and a study of laser-induced plasma motion in a solenoidal magnetic field is reviewed.

Ahlborn, B.↗
NASA NTRS1977

Spatially localized, shock-wave-induced continuous and very fast mixing between gases and liquid in parallel flow /An experimental study/

Shock-wave-induced patterns and turbulent supersonic shear flows over a stagnant bubble were determined for cases where recirculation and final mixing occurred within a very short time and within a distance of about 1 cm. The effect of a shock wave upon stratified laminas of gases in a shock tube was studied for a series of gases of different densities and molecular weights. Steady-state mixing of gas streams were investigated in wind tunnel experiments by means of a chemiluminescent reaction. Shock-wave-induced mixing which involves the introduction of a liquid jet into a supersonic gas stream is also described.

Devis, E.↗
NASA NTRS1979

Calculation of the three-dimensional flow field in supersonic inlets at angle of attack using a bicharacteristic method with discrete shock wave fitting

An analysis is presented for calculating the flow field in supersonic mixed-compression aircraft inlets operating at angle of attack. The flow field is computed by a steady three-dimensional bicharacteristic method. The bow shock wave and the reflected internal shock wave system are computed by a three-dimensional discrete shock wave fitting procedure. Viscous and thermal diffusion may be included as source terms in the bicharacteristic method. A production type computer program capable of determining the flow field in a variety of axisymmetric mixed-compression supersonic inlets is available. The results of the present analysis agree well with those produced by the two-dimensional method of characteristics when axisymmetric flow fields are computed. For three-dimensional flow fields, the results of the present analysis agree well with experimental data except in regions of high viscous interaction and boundary layer removal. The present analysis does not compute the boundary layer, nor does it account for boundary layer bleed.

Vadyak, J.↗
NASA NTRS1999

Numerical Simulation of Low-Density Shock-Wave Interactions

Computational Fluid Dynamics (CFD) numerical simulations of low-density shock-wave interactions for an incident shock impinging on a cylinder have been performed. Flow-field density gradient and surface pressure and heating define the type of interference pattern and corresponding perturbations. The maximum pressure and heat transfer level and location for various interaction types (i.e., shock-wave incidence with respect to the cylinder) are presented. A time-accurate solution of the Type IV interference is employed to demonstrate the establishment and the steadiness of the low-density flow interaction.

Glass, Christopher E.↗
DOE OSTI2025

Shock wave bending around a dusty plasma void

We report on experimental observations of the bending of a dust acoustic shock wave around a dust void region. This phenomenon occurs as a planar shock wavefront encounters a compressible obstacle in the form of a void whose size is larger than the wavelength of the wave. As they collide, the central portion of the wavefront, that is the first to touch the void, is blocked while the rest of the front continues to propagate, resulting in an inward bending of the shock wave. The bent shock wave eventually collapses, leading to the transient trapping of dust particles in the void. Subsequently, a Coulomb explosion of the trapped particles generates a bow shock. The experiments have been carried out in a Direct Current (DC) glow discharge plasma, where the shock wave and the void are simultaneously created as self-excited modes of a three-dimensional dust cloud. The salient features of this phenomenon are reproduced in molecular dynamics simulations, which provide valuable insights into the underlying dynamics of this interaction.

Dust acoustic waves↗