Interaction between the normal shock wave and the turbulent boundary layer in a supersonic nozzle becomes complex with an increase of a Mach number just before the shock wave. When the shock wave is strong enough to separate the boundary layer, the shock wave is bifurcated, and the 2nd and 3rd shock waves are formed downstream of the shock wave. The effect of a series of shock waves thus formed, called shock train, is considered to be similar to the effect of one normal shock wave, and the shock train is called pseudo-shock wave. There are many researches on the configuration of the shock wave. However, so far, very few researches have been done on the asymmetric characteristics of the leading shock wave in supersonic nozzles. In the present study, the effect of nozzle geometry on asymmetric shock wave in supersonic nozzles has been investigated experimentally.
The supersonic flow fields with the pseudo-shock wave are observed in some apparatuses, such as the separation part of a SCRAM jet engine, a high pressure gas piping system, supersonic diffuser and so on.
In the supersonic internal flow, interaction between the shock wave and the boundary layer is very complex and induces the separation of boundary layer. When the shock wave is strong enough to separate the boundary layer, the shock wave is bifurcated and more shock waves are formed downstream of the leading shock wave. The series of shock waves are called shock train. This shock train and the resulting mixing region construct a pseudo-shock wave [
Neumann and Lustwerk [
Tamaki et al. [3,4] reported that with an increase of the main flow Mach number, the configuration of the pseudo-shock wave changed from λ-type shock wave to X-type shock wave and the range of the shock wave was expanded. However, the asymmetric characteristics of the leading shock wave have not been investigated satisfactorily.
Numerical and experimental researches on the symmetric and asymmetric shock wave system in a planar nozzle were presented by Xiao et al. [
The purpose of this study is to investigate the effects of the nozzle length with parallel part and the position of nozzle throat on the characteristics of asymmetric shock wave in supersonic nozzles experimentally.