In order to study the influence of acoustic impedance difference on the flow field structure of detonation tube exit in jet environment,an axisymmetric model of the flow field inside and outside the detonation tube was established.The rhoReactingCentralFoam solver of the OpenFoam platform was used to couple the flow field inside and outside the detonation tube.Three free jet regions of argon,hydrogen and air mixture,and helium were constructed outside the tube.Combining with the simulation results of the static air outside the tube,the influence of the acoustic impedance difference of the medium inside and outside the tube on the detonation flow field structure was analyzed.The results show that the argon jet and the static air will form a reflected shock wave on the acoustic impedance discontinuity surface when the detonation wave overflows outside the tube.The helium jet forms a reflected rarefaction wave on the acoustic impedance discontinuity surface when the detonation wave overflows outside the tube.The hydrogen and air mixture jet has no effect on the process.The Mach disk formed in the argon jet and the static air is reduced to almost disappear.The slip line and the subsequent supersonic region encounter near the Mach disk.The Mach disks in the hydrogen-air mixture jet and the helium jet remain a certain size after decreasing.The slip line and the subsequent supersonic region encounter far away from the Mach disk.The acoustic impedance difference between the free jet and the explosive mixture causes the leading shock wave to deform and change its directivity.The curvature of the leading shock wave near the central axis in an argon jet decreases,and the leading shock wave in still air roughly presents a spherical wave shape.The leading shock wave in a hydrogen air mixture jet and a helium jet protrudes.
OpenFoamdetonationflow field of tube exitacoustic impedance of jet flowflow field structure
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