Prediction of cavitation erosion risk in regulating valve based on space-time distribution characteristics of cavitation

Aiming at the problem of poor cavitation resistance and short service life in the regulating valve of the key equipment in coal liquefaction engineering，these images of cavitation flow field in a regulating valve were captured by a high-speed camera，the characteristic parameter void fraction λ was proposed for quantitative analysis of a gas-phase volume fraction，and the change rate of void fraction β was also employed as the cavitation erosion risk to predict the cavitation damage on the regulating valve accurately．Results show that there is a positive correlation between the void fraction and the gas volume fraction．With the increase of inlet pressure，the void fraction at the spool head，the throat and the expansion section increase，cavitation develops fully and extends to the expansion section and then collapses．The cavitation in the regulating valve presents a periodic trend as birth，development，shedding and collapse．Furthermore，if the change rate of void fraction β＜0，it represents the collapse of cavitation．Therefore，the change rate of void fraction could be used to judge whether there is a risk of cavitation erosion．With the increase of inlet pressure，the attached cavitation is fixed at the spool head，which is the main reason for the cavitation damage of the spool．While the free cavitation damage area gradually extends downstream with the increase of inlet pressure．The cavitation damage area at the top and bottom part of the flow channel is asymmetric，and the cavitation damage area in the bottom part is overall ahead of it at the top part. © 2024 Huazhong University of Science and Technology. All rights reserved.