Numerical Simulation of Cavitation of Water Jet Nozzle Based on Realizable k-ε Model

Abstract

In order to study the cavitation characteristics of water jet nozzles, a realizable  model was selected to simulate the flow field inside the nozzle at the inlet pressure of 15 MPa. The pressure at the starting point of the nozzle throat section dropped to the minimum, and the liquid velocity reached the maximum. From the vapor volume distribution map of the nozzle, it can be seen that the vapor fraction is the largest on the wall of the expansion section, and a local reflux is formed in the expansion section, which results in the gradual diffusion of the vapor fraction distribution along the wall of the expansion section. In addition, the influence of nozzle inlet pressure on the vapor fraction and vapor fraction distribution region in the expansion section is analyzed. The results show that the larger vapor fraction and vapor fraction distribution region can be produced under the 25 MPa inlet pressure. At the pressure inlet of 25 MPa, six groups of numerical simulations were carried out with different the length to diameter ratio of the nozzle throat section (L4/d0). The results show that when L4/d0 is 2, it is more conducive to the formation of cavitation and the quality of cavitation is better.