Investigation of the pulsed waterjet flow field inside and outside of the nozzle excited by ultrasonic vibration

Abstract

The pulsed waterjet flow inside and outside of the nozzle is investigated by numerical and experimental methods. This pulsed waterjet is generated by the external vertical vibration excitation at the end of the nozzle which causes the deformation of the nozzle inner wall. The pulsed waterjet flow distribution is simulated by CFD software FLUENT. The unsteady model of the solver is used. The simulation results express that there are alternative high-pressure zone and low-pressure zone inside and outside the waterjet nozzle, and the length of the waterjet core zone offset the nozzle also changes simultaneously. The pulsations of the waterjet velocity along the nozzle axis and at the outlet are more violent than which are without the boundary deformation vibration. By analyzing the influence of the amplitude and frequency of the vibration, the results show that the larger vibration amplitudes are, the greater pulsations of the waterjet velocity producing. And the maximum pressure of the high-pressure zone and low pressure zone is slowly reducing with the vibration frequency increasing. The experiment device has been set up to verify the simulation results of flow fields of the pulse waterjet; the images obtained in the experiment indicate that the flow field is well matched with the simulation result.