Investigation on The Flow Characteristics of Rotating Nozzle Cavitation Water Jet Flow Field

Abstract

Rotating cavitation water jet technology is widely used in many industrial fields such as pipeline cleaning, unblocking, cutting, etc. To more accurately analyse the flow characteristics of rotating cavitating water jets, the specific impact of the nozzle rotational velocity on the evolution of the whole flow field was systematically explored in this work. More specifically, a numerical simulation study of a three-nozzle rotating cavitation nozzle was carried out using the Large Eddy Simulation method of the WALE sub-lattice model. After determining 12MPa as the inlet pressure condition. The tangential velocity, vorticity, cavitation cloud development patterns, and wall pressure changes in the internal flow field at different rotational speeds were compared. From our analysis, it was demonstrated that as the nozzle rotates faster, the tangential velocity of the jet increases, leading to a deflection of the jet. The degree of deflection is positively related to the rotational speed. Under the action of shear, the vortex structure will gradually increase in size as the jet develops and finally breaks up and disintegrates. The period of cavitation cloud development and maximum volume fraction increases with increasing the rotational speed; When the rotational speed increases, the striking pressure of the rotating jet on the wall first increases and then decreases. The fitted jet curve can better reproduce the jet development pattern. The derived fitting formula allows the determination of the corresponding impact angle according to the magnitude of the rotational velocity. The existence of a higher nozzle rotation speed induces a greater curvature of the fitted curve, the deflection angle, and the impact angle. Our work provides a robust theoretical reference for the field application of the rotating nozzle cavitation water jet technology and can be used as technical support for industrial well-bore unblocking and pipeline descaling.

Keywords

• large eddy simulation
• rotating flow characteristics
• rotating cavitation
• vortex evolution
• curve fitting