Large eddy simulation and experimental study on vortex characteristics of water jet in submerged condition

Key words:  submerged water jet  vortex  large eddy simulation  particle image velocimetry

Abstract:

The large eddy simulation was used to numerically simulate the vorticity field of submerged water jet in submerged condition, through which the mechanism of vortex generation and diffusion in the flow field was analyzed. And the simulation results and methods were validated using the particle image velocimetry (PIV) measurement test of vorticity field under the same conditions. In this way the effect of pump pressure and confining pressure on vortex characteristics of submerged jet were studied. The results show that a series of point vortexes with large vorticity are generated by the nozzle exit in the jet flow field. With the progress of jet development, vortexes spread gradually and entrain the surrounding medium to transfer energy, which causes the scope of entrainment expanded gradually and the entrainment ability decayed exponentially along the jet axis. With the pump pressure increasing, the vorticity of entire flow field increases significantly and the length of vortex diffusion climbs straight. While confining pressure has no effect on the magnitude of the vorticity, and the increase of confining pressure leads to reduce the length of the vortex diffusion.