オリフィス自由噴流に関するDSMC計算 : DSMC法による垂直衝撃波と樽形衝撃波の再現

抄録

The direct simulation Monte Carlo method is applied to the study of the structures of supersonic jets through a thin circular orifice. Three cases with different Knudsen numbers Kn are investigated, based on the stagnation conditions and the orifice diameter, 1/Kn=50, 500, and 2500. The pressure ratio is 50 in all cases. The Mach disk and barrel shock are not observed at all in the case of 1/Kn=50, but they appear slightly at 1/Kn=500 and are clearly observed at 1/Kn=2500 in the density, velocity and temperature profiles. The Mach disk is obtained at the expected axial location for 1/Kn=2500, which demonstrates that our DSMC calculation is reasonable. The DSMC results are also compared with experimental results obtained by a mass-sampling technique and qualitative agreement is recognized in the broadening of the barrel shock with decreasing density.