Numerical study on cavitation in a globe control valve with different numbers of anti-cavitation trims

Abstract

Cavitation is a destructive phenomenon in control valves. In order to delay cavitation, a multi-series of perforated cylindrical plates, called trims, are used. Previously, the effects of orifice diameter and different types of trims have been investigated. In this study, by numerical analysis, a globe control valve was investigated by employing four different cases (without trim, with one trim, with two and three trims) and the impact of the number of these trims on the intensity, formation region and the initiation point of cavitation was analyzed. It was found that the addition of one stage or two stages of trims reduces the intensity and delays the onset of cavitation, relative to the valve without trim. However, no significant differences in terms of intensity and initiation point of cavitation were observed in the cases where two or three trims were used. Therefore, due to the high cost of producing the trims, and the severe drop in flow coefficient, it is not economically and technically justified to increase the number of trims to more than three.

摘要

空化是控制阀中的一种破坏性现象。为了延缓空化, 采用一种多孔圆柱板, 称为trim。在此之 前, 我们曾研究过孔板直径和不同类型的trim 的影响。本文采用4 种不同工况(无trim, 1, 2 和3 trims) 对球阀进行数值分析, 分析了trim 的数量对气蚀强度、形成区域和空化起始点的影响。结果表明, 与 不加trim 的阀门相比, 增加一个或两个trim 可以降低气蚀的强度, 延缓空化的发生。然而, 在使用 两到三个trims 的情况下, 空化的强度和起始点没有明显的差异。由于trim 生产成本高, 流量系数严 重下降, 将trim 数量增加到3 个以上在经济和技术上都是不合理的。