Investigation of Cavitation Near the Orifice of Hydraulic Valves

Abstract

Cavitating flows in the orifice of a poppet valve and a ball valve were investigated using an RNG k-ε turbulence model and a multi-phase flow cavitation model. The cavitation region, air volume fraction distribution, velocity distribution, and pressure distribution were obtained. Experimental flow visualization was conducted to catch cavitation images near the orifice of the poppet valve and the ball valve from two perpendicular directions, using a pair of industrial fibrescopes and high-speed video cameras-integrated visualization system. Besides, the vibrations of the valve body and the poppet induced by the cavitating flow are detected using a vortex displacement transducer, a laser displacement meter, and a digital strain device. The cavitation inception location and the cavitation cloud shape from both experiment and numerical simulations are in a good agreement qualitatively. Furthermore, the effects of outlet area, inlet velocity, and outlet pressure on cavitation were numerically investigated. The reduction of the outlet area by around 50 per cent is effective in reducing the cavitation near the orifice of the valve and suppressing the generation of cavitation. The cavitation region and the air volume fraction in the poppet valve increase greatly with an increased inlet velocity by 69 per cent on a certain condition. However, the increase in the outlet pressure can effectively suppress the cavitation inception in the poppet valve.