Numerical Simulation On The Injection Process And Surrounding Complex Flow Fields Of Underwater Supersonic Gas Jets

Underwater supersonic gas jet is a gas jet from the orifice or nozzle into the liquidenvironment at a supersonic speed, which diffused in the water flow and caused a complexgas-water mixing and interface instabilities phenomenon. Underwater supersonic gas jet is afairly complex physical processes which is widely used in the defense industry, petrochemical,aerospace and other engineering practices. Early studies about underwater supersonic gas jet wasfrom underwater rocket ignition technology to the underwater submarine-launched missilelaunch broken water and air mixing in metallurgical processes later. Relevant research has beenattracting the attention of scholars at home and abroad. Underwater supersonic gas jet is animportant basic theory research. The main contents include the evolution of the situation of thejet, the gas-liquid boundary movement of evolution, instability of the gas-liquid two-phaseinterface, gas-liquid mixing and the nature of mechanical on the inside of gas-liquid flow jet.Today abroad studies about the two-phase flow focus on heat and mass transfer between the twophases. Less land focus on blending between gas and liquid or instabilities in gas-liquid interface.Therefore, the study of underwater gas jets, including experimental and numerical studies willenrich the content of the research on gas-liquid two-phase flow. Particularly, the research on themechanism and kinetics of two-phase flow in the mechanical behavior of the gas-waterinteractions is significant expansion for the development of two-phase flow discipline.Ax-symmetric model was established based on ANSYS FLUENT as the numerical model inthe thesis. Using this model, numerical simulation of underwater supersonic gas jets was donebased on VOF method. It showed the early evolution of bubble motion of underwater supersonicgas jet. It got the ordinary law of the process of a bubble from generating, growing to beingbroken by the next one, bulging and back-attack phenomenon occurs in the injection process. Itfocused on analysis of the structure of under-expanded supersonic gas jet and over-expansion ofthe jet and the distribution and variation of working parameter such as pressure and speed in theflow field during the injection in different conditions. Finally, the results of numerical simulationwere compared with the experimental studies to get good conformity conclusions：Complexshock-wave cell structures exist in the field of underwater supersonic gas jets, and whichinfluence the parameters in the flow fields, causing the phenomenon such as bulging，back-attack and pressure shock. It confirmed the theory about complex shock-wave structure in the flow fields from related experimental studies.