Oblique shock

About: Oblique shock is a research topic. Over the lifetime, 6551 publications have been published within this topic receiving 119823 citations.

Initiation of Detonation

Abstract: A conventional shock tube modified so as to prevent local early detonation from the diaphragm burst or from wall crevasses was used to study the initiation of detonation behind the reflected shock wave. Three types of initiation behavior were observed, two of which appear to be nicely one dimensional. In all cases stoichiometric hydrogen‐oxygen mixtures diluted with argon were used in the tube. In the first case a simple acceleration of the reflected shock occurred when the pressure wave generated by the adiabatic explosion reached the reflected shock. In the second case a typical accelerating wave pattern headed by a shock wave was formed behind the reflected shock while in the third case (which does not appear to be strictly one dimensional) the adiabatic explosion quickly produced a Chapman‐Jouguet detonation wave behind the reflected shock wave. A simple qualitative theory for the occurrence of the wave patterns observed is presented and the adiabatic explosion delays are compared to Schott and Kinsey's recent results using a different shock‐tube technique.

Onset of oblique detonation waves: Comparison between experimental and numerical results for hydrogen-air mixtures

Abstract: Stable delayed oblique detonation waves have been observed both numerically and experimentally in hydrogen-air stoichiometric mixtures for Mach numbers 6 and 7.5. The experimental results obtained using an oblique shock tube facility are compared to calculations made by solving the full conservation equations for a reactive gas. The overall flow structure obtained experimentally is compared to detailed computations of an oblique shock wave to oblique detonation-wave transition over a wedge, and resulting flow fields are analyzed on the basis of shock and detonation polars.

ISEE‐1 and ‐2 observations of laminar bow shocks: Velocity and thickness

Abstract: Thirteen bow shock crossings observed by ISEE-1 and -2 have been used to determine the thickness and velocity of the quasi-perpendicular laminar bow shock, i.e., those for which the Mach number and beta are low and the magnetic field is at large angles to the shock normal. The shock velocity ranges from a few kilometers per second to over 100 km/sec for these events. The shock thickness is found to be close to an ion inertial length, about 100 km for the conditions studied herein. In contrast to supercritical shocks, there is approximate equipartition of thermal energy between ions and electrons behind these shocks. Finally, there is a weak correlation between shock thickness and the angle between the interplanetary magnetic field and the shock normal, with more perpendicular shocks being thinner.

Delayed Detached-Eddy Simulation and Analysis of Supersonic Inlet Buzz

Abstract: Supersonic inlet buzz in a rectangular, mixed-compression inlet has been simulated on a 20 x 10 6 points mesh using the delayed detached-eddy simulation method, a version of detached-eddy simulation that ensures the attached boundary layers are treated using Reynolds-averaged Navier-Stokes equations. The results are compared with experimental data obtained during a previous campaign of wind-tunnel experiments. The comparison of unsteady data is performed thanks to phase averages, Fourier transforms, and wavelet transforms. The buzz observed at Mach 1.8, which occurred at a frequency of 18 Hz, is well reproduced. The shock oscillations, as well as the different flow features experimentally observed, are present in the simulation. The buzz frequency, as well as higher frequencies existing in the experimental pressure signals, are correctly predicted. The data issued from the simulation (time history of pressure fluctuations, pseudo-Schlieren, and three-dimensional visualizations) allow a better investigation of the inlet flowfield during buzz and a detailed description and physical analysis of this phenomenon. A description and an explanation of the mechanism at the origin of secondary oscillations that occur at a higher frequency during buzz are proposed. The crucial role of acoustic waves moving through the duct is shown.