Study On Surface Wave And Gas-liquid Interaction Of An Annular Swirling Viscous Liquid Jet Based On Large Eddy Simulation

Combustion is one of the most important processes in the thermodynamic cycle of internal combustion engines.And the breakup and atomization of fuel jet is the key to combustion process.At present,the pressure swirling atomizers are widely applied in gasoline direct injection engine,so it is very important for the study of an annular swirling viscous liquid jet generated by the pressure swirling atomizer.The annular swirling viscous liquid jet was set as the research object in this dissertation.Changes of morphology and breakup process of an annular swirling viscous liquid jet were studied.The surface wave structure and gas-liquid interaction were also researched in this paper.The research work was significant to the deepening and perfection of cognition of the annular swirling viscous liquid jet.The research results could provide important theoretical basis for more fully breakup of fuel jets.The research was based on large eddy simulation and selected an appropriate sub-grid model.The CLSVOF method was used to track and reconstruct the gas-liquid interface.The simulation model of annular swirling viscous liquid jet was established.To verify the accuracy of this model,the numerical simulation results were compared with the experimental results in a literature.The development of an annular swirling viscous liquid jet was numerically simulated.The characteristic parameters of an annular swirling viscous liquid jet were defined.The evolution of annular swirling viscous liquid jet morphology from the start-up stage to the full development stage was analyzed.The primary breakup process and the secondary breakup process of an annular swirling viscous liquid jet were studied.The mechanisms of liquid sheet breakup and liquid ligament breakup were given.The influence of injection parameters and physical parameters on various characteristic parameters of the annular swirling viscous liquid jet was researched.A study has been carried out on the surface wave structure of an annular swirling viscous liquid jet and its influencing factors.The formation mechanism of surface wave structure was analyzed and the spatial development of surface wave structure was studied.By changing the calculation conditions of the numerical simulation,the influence of axial velocity,swirling strength,primary turbulence intensity,liquid viscosity and liquid density on formation,breakup,morphology and wavelength growth rate of axial surface wave and circumferential surface wave were studied.A research on the gas-liquid interaction of an annular swirling viscous liquid jet was carried out.The gas-liquid interaction caused by the vortex structure and recirculation zone in still gas was analyzed.The influence of gas-liquid interaction on surface wave structure was studied.The development of an annular swirling viscous liquid jet in the moving gas was numerically simulated.And the effect of shear forces and pressures in cross flow and axial flow was studied.The effect of cross flow and axial flow on the annular swirling viscous liquid jet was investigated.