Numerical Investigation on Influence of Nozzle Configuration on Underwater Detonation Gas Jets

Abstract

To investigate the effect of different nozzle configurations on the characteristic patterns of underwater detonation gas jet and shock wave propagation process,based on the VOF multiphase model, 2-D axisymmetric numerical simulations on the internal and external flow field during the detonation process of a detonation tube with no nozzle,diverging nozzle and converging nozzle were carried out by means of solving unsteady RANS equations. The effects of nozzle configuration on the propagation characteristics of transmitted and reflected shock waves as well as the morphological evolution of detonation gas jet formed therein were studied. The calculation results show that the diverging nozzle is capable of enhancing the directivity of the transmitted shock wave propagating downstream along the axis, while the converging nozzle will weaken the intensity of the transmitted shock wave and enhance the intensity of the reflected shock wave propagating upstream. The initial axial and radial velocities of detonation bubbles gradually attenuate with time,and the nozzle has little effect on the axial dimension of the gas bubble. On the other hand,the converging nozzle can significantly restrain the radial dimension of the gas bubble. Results in this paper can provide technical support for the subsequent engineering application of underwater detonation propulsion.