Simulated and Experimental Investigation into Coupled Wear of Cavitation and Erosion in Regulating Valves

In order to reveal the influence factors of regulating valve’s service life in coal liquefaction, and ensure the safety and stability of coal liquefaction system operation, numerical simulations were carried out based on turbulence model, cavitation model and discrete phase model to address the complex multiphase flow problem of gas liquid solid. In the investigation, the distribution characteristics of erosion wear and cavitation inside the valve were studied, and the coupled damage rate of cavitation erosion in key parts of the valve core was obtained. Then, the coupled cavitation erosion wear behavior of solid multiphase flow in the flow channel during the operation of the regulating valve was reproduced through experiments, and the damage morphology of the metal tin valve core under continuous cavitation erosion composite action was analyzed. Finally, the damage degree of tin valve cores under different working conditions was quantitatively evaluated using roughness values, and the impact fatigue and composite damage mechanism of valve core surfaces were explored. The results show that the main area where cavitation occurs in the coal liquefaction regulating valve is from the throttle port to the head of the valve core. The range of cavitation increases with the increase of inlet pressure, and the cavitation intensity also increases accordingly. Under different import pressures, the extreme value of the surface erosion rate of the valve core appears at the head of the valve core, with a maximum erosion wear rate of 1. 42 × 10^-4 kg/(m²·s), which is more than 10 times that of other erosion areas. The reason is that the high-speed fluid backflow at the head of the valve core carries particles and impacts the head of the valve core, while the collapse of bubbles impacts the surface of the valve core. In addition, it is also found that the surface of the regulating valve core, which works for a long time under the coupling effect of erosion and cavitation, exhibits characteristic morphology such as grooves and corrosion points.