Topic
Oblique shock
About: Oblique shock is a research topic. Over the lifetime, 6551 publications have been published within this topic receiving 119823 citations.
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TL;DR: In this article, a parametric experimental investigation has been made of the class of three-dimensional shock wave/turbulent boundary layer interactions generated by swept and unswept leading-edge fins.
Abstract: A parametric experimental investigation has been made of the class of three-dimensional shock wave/turbulent boundary layer interactions generated by swept and unswept leading-edge fins. The fin sweepback angles were 0-65 deg at 5, 9, and 15 deg angles of attack. Two equilibrium two-dimensional turbulent boundary layers with a freestream Mach number of 2.95 and a Reynolds number of 6.3 x 10 to the 7th/m were used as incoming flow conditions. All of the resulting interactions were found to possess conical symmetry of the surface flow patterns and pressures outside of an initial inception zone. Further, these interactions were found to obey a simple conical similarity rule based on inviscid shock wave strength, irrespective of fin sweepback or angle of attack. This is one of the first demonstrations of similarity among three-dimensional interactions produced by geometrically dissimilar shock generators.
104 citations
TL;DR: In this article, a drag expression was proposed, extending Cunningham's method to higher velocities and Knudsen numbers for high-speed flow, which is valid from continuum to free molecule conditions, for Re≲200 and M≲1.
Abstract: Factors that may act on particle motion in high-speed flow are investigated. The classical expressions of drag coefficient C
D
for a sphere are reviewed. Then, a drag expression is proposed, extending Cunningham’s method to higher velocities and Knudsen numbers. This law, valid from continuum to free molecule conditions, for Re≲200 and M≲1 (where Re and M are, respectively, the Reynolds and Mach numbers based on relative velocity), is used to compare calculated and experimental values of the drag coefficient, as well as the particle velocities across an oblique shock wave. Calculated results are found to be in agreement with experiments.
104 citations
TL;DR: In this paper, the shape of diffracting waves is calculated by modifying Whitham's theory for the calculation of the shape and the flow pattern of diffracted waves in gases.
104 citations
TL;DR: In this paper, the Laplace transformation of the perturbation results in an equation which has a simple solution for weak shock waves, and for strong shocks the solution is given by a power series.
Abstract: The solution for the perturbation growth of a shock wave striking a density discontinuity at a material interface is developed. The Laplace transformation of the perturbation results in an equation which has a simple solution for weak shock waves. The solution for strong shock waves may be given by a power series. It is assumed that the equation of state is that of an ideal gas. The four independent parameters of the solution are the ratio of specific heat for each material, the density ratio at the interface, and the incoming shock strength. Properties of the solution which are investigated include the asymptotic behavior at large times of the perturbation velocity at the interface, the vorticity near the interface, and the rate of decay of the solution at large distances from the interface. The last is much weaker than the exponential decay in an incompressible fluid. The asymptotic solution near the interface, in addition to a constant term, consists of a number of slowly decaying discrete frequencies. The number is roughly proportional to the logarithm of the density ratio at the surface for strong shocks, and decreases with shock strength. For weak shocks the solution is compared with results for an incompressible fluid. Only interface perturbation velocities which tend to zero at large times lead to a limited deformation of the interface. It is found that these are possible only for density ratios less than about 1.5.
103 citations
TL;DR: In this article, a simplified model of particle transport at a quasiparallel one-dimensional collisionless shock is suggested, where the MHD-turbulence behind the shock is dominated by a circularly polarized, large amplitude Alfv\'en wave originated upstream from the turbulence excited by particles leaking from the downstream medium.
Abstract: A simplified model of particle transport at a quasiparallel one-dimensional collisionless shock is suggested. In this model the MHD-turbulence behind the shock is dominated by a circularly polarized, large amplitude Alfv\'en wave originated upstream from the turbulence excited by particles leaking from the downstream medium. It is argued that such a wave having significantly increased its magnetic field during the transmission through the shock interface can effectively trap thermal ions, regulating their leakage upstream. Together with a background turbulence this wave also plays a fundamental role in thermalization of the incoming ion flow. The spectrum of leaking particles and the amplitude of the wave excited by these particles are selfconsistently calculated. The injection rate into the first order Fermi acceleration based on this leakage mechanism is obtained and compared with computer simulations. The related problem of shock energy distribution between thermal and nonthermal components of the shocked plasma is discussed. The chemical composition of the leaking particles is studied.
103 citations