Interaction Of Incident Shock Wave Research Articles

The modeling of two-dimensional vortex flows in a cylindrical channel using parallel calculations on a supercomputer

Objectives . The study aimed to examine vortex structures formed during the interaction of incident and reflected shock waves in a cylindrical channel. The shock wave was described by the Hugoniot relations, which make it possible to determine the parameters of the gas behind the shock front by a given Mach number and the values of the gasdynamic parameters ahead of the pressure jump. The propagation of a strong shock wave (Mach number was 20) in argon was simulated. Methods . The methods of mathematical modeling were used. A parallel algorithm for solving two-dimensional equations of gas dynamics in cylindrical coordinates (r, z, t) was developed and a new version of the NUTCY_ps program created. The calculations were performed on an MVS-100K supercomputer. Results. Two methods of parallelization when solving a system of equations were considered. Using a specific task as an example, a comparison of the effectiveness of these methods was conducted. A parallel algorithm was developed and a program was upgraded for solving two-dimensional equations of gas dynamics in cylindrical coordinates (r, z are spatial coordinates, t is time). Numerical calculations were performed to simulate: 1) the shock wave incidence to and reflection from a metal screen; 2) the propagation of the shock wave through a hole in the screen; 3) the propagation of the shock wave through a cylindrical channel and its reflection from the bottom of the channel and interaction with the incident wave. The results obtained by the parallel supercomputer with different numbers of processors are presented. It is shown that using 16 processors, it is possible to reduce the computation time for getting a solution for the test problem by approximately 12 times. Conclusions . It is shown that the interaction of incident shock wave and the one reflected at an angle leads to the formation of regions with low and high gas densities, as well as vortex flows. The vortex interaction area (turbulence zone) gets a complex shape. The article discusses the possibility of carrying out full-scale experiments in shock tubes or using a laser shock tube. Such studies would make it possible to compare experimental data with the results of numerical simulation and, on their basis, to develop more advanced models of turbulent motions.

Strong interactions of incident shock wave with boundary layer along compression corner

The coherent structure and instability of the interaction of incident shock wave with boundary layer developing on a compression corner are experimentally studied. The experiments are carried out in a supersonic wind tunnel of Mach number 2. Particular attention is paid to shock patterns and unsteady shock motions induced by the separation bubble. The high-speed schlieren is used to visualize the flowfield evolution and to characterize the instability. The snapshot proper orthogonal decomposition of schlieren sequences is applied to investigate the primary coherent structure in the flowfield. Fast Fourier transform and continuous wavelet transformation are applied to characterize the instability. The results show that there are large-scale low-frequency oscillations of the shock waves and small-scale high-frequency pulsations in the separation region. The peak frequency of shock oscillation is mainly concentrated in the range of 100–1000 Hz. The pulsation of the small flow structure in the separation bubble is mainly concentrated above 12.5 kHz. Based on the results of experimental analysis, the preliminary mechanism of the large-scale instability of such interaction is obtained.

DIRECT NUMERICAL SIMULATION OF THE INTERACTION OF 2D SHOCKWAVE AND SHEAR LAYER

Direct numerical simulation (DNS) of the interaction of shock wave and shear layer was performed. The compressible unsteady two-dimensional Navier-Stokes equations were solved using the fifth-order WENO scheme combined with the third-order TVD Runge-Kutta scheme. The purpose of this paper is to reveal the mechanism of sound generation in the interaction of shock wave and shear layer. The results show that: (1) When incident shock wave is passing through the shear layer, the center of the vortex cores is shifted towards the lower side; (2) The interaction of incident shock wave and shear layer generates shocklet, and then acoustic wave is generated and radiated at the locus of contact of shocklet and shear layer; (3) Several arc-shocks are formed after reflected shock wave passing through shear layer; (4) When reflected shock wave is passing through shear layer, shock wave is leaking in the braid region and shock-associated noise is generated at the saddle points between vortices. This is a form of shock leakage mechanism.