阀后管道突扩对控制阀门流阻特性的影响

Influence of sudden expansion of pipelines after valve on flow resistance characteristics of control valve

为准确地描述非均匀流条件下控制阀门阀后采用突扩管道后的流阻特性,针对典型控制阀门(活塞式调流阀与固定式锥形阀),采用物理模型试验与理论分析方法,基于阀后突扩管道内的流场结构及试验段压力特性,研究阀后管道突扩对典型控流调压阀门流阻特性的影响规律。结果表明,不同阀型采用相同突扩体时的流阻特性变化程度不同,阀型的影响主要体现在改变了突扩体的入流、出流条件。在规范公式的基础上,考虑阀门出流流场结构(突扩体入流条件)与水流缩脉(突扩体出流条件)的影响,分析得到管道突扩比与阀门流量系数的定量关系,规范计算值与试验值的最大差异约为8%,优化公式计算值与试验值最大差异约为1%,说明改进后的突扩体流阻系数公式的计算精度较规范公式有所提高。研究结果可为高压差、大流量调流调压系统管路设计提供参考。

In order to accurately describe the flow resistance characteristics of control valve under the condition of non-uniform flow after use of sudden expansion pipeline behind the valve,physical model tests and theoretical analysis methods were adopted for typical control valves(VAG plunger valve and fixed cone valve).Based on the flow field structure in the sudden expansion pipeline behind the valve and the pressure characteristics of the test section,the influence of sudden expansion behind the valve on the flow resistance characteristics of typical flow control and pressure regulating valves were studied.The results show that the flow resistance characteristics of different valve types are different when the same sudden expansion body is used.The influence of the valve type is mainly reflected in the change of the inflow and outflow conditions of the sudden expansion body.On the basis of the standard formula and considering the influence of the valve outflow flow field structure(sudden expansion body inflow condition)and the influence of the water flow pulsation(sudden expansion body outflow condition),the quantitative relationship between the sudden expansion ratio and the valve flow coefficient was obtained.The maximum difference between the calculated value of the standard and the experimental value was about 8%,and the maximum difference between the calculated value of the optimized formula and the experimental value was about 1%,indicating that the calculation accuracy of the improved flow resistance coefficient formula was improved somewhat compared with the standard formula.The results can be used as reference for pipeline design of high pressure differential and large flow and pressure regulating system.