蚁穴式节流元件控压机理和空化特性研究

Research on the Pressure Control Mechanism and Cavitation Characteristics of Ant-hole Throttling Element

针对高压大流量条件下控制阀节流元件减压控速不平稳、空化气蚀严重等问题,提出一种新型空间蚁穴式节流元件。基于计算流体动力学(Computational fluid dynamics,CFD)仿真分析,详细对比研究节流元件级间压力、速度及气体体积分数在不同降压级数、不同压力等级下的变化规律,获得不同降压级数的临界空化压力值,与常规迷宫式节流元件的流场特征进行对比。搭建试验系统测得不同降压级数节流元件在不同阀口压降条件下的级间压力和流量并与仿真结果对比。结果表明,相比迷宫式节流结构,蚁穴式节流元件减压控速更平稳,具有更好的线性度。蚁穴式节流元件空化主要发生在最后一级,阀口压降与降压级数之间呈线性关系。基于所获得的阀口压降与降压级数之间的线性关系表达式,可为设计最佳的降压等级与降压级数组合提供理论指导,避免空化气蚀的发生,提高控制阀的使用寿命。试验测得数据与仿真数据一致性较好,验证了仿真模型的准确性。

Under the conditions of high pressure and large flow,the throttle element of the control valve has problems such as unstable decompression and speed control and serious cavitation erosion.A new type of ant-hole throttling element(ATE)is proposed.Based on the CFD simulation analysis,the variation laws of the inter-stage pressure,velocity and vapor phase volume fraction of the throttling element under different pressure reduction stages and different pressure levels were studied in detail.The critical cavitation pressure values of different depressurization stages are obtained and compared with the flow field characteristics of conventional labyrinth throttling elements.An experimental system is built to measure the inter-stage pressure and flow of throttling elements with different pressure reduction stages under different valve port pressure drop conditions and compared with the simulation results.The results show that:Compared with the labyrinth type throttling structure,the ant-hole type throttling element is more stable in decompression and speed control,and has better linearity.The cavitation of the ATE mainly occurs in the last stage,and there is a linear relationship between the pressure drop at the valve port and the number of pressure reduction stages.Based on the obtained expression of the linear relationship between the pressure drop at the valve port and the number of pressure reduction stages,theoretical guidance is provided for designing the optimal combination of pressure reduction levels and pressure reduction stages.Thereby avoiding the occurrence of cavitation and improving the service life of the control valve.The experimental data is in good agreement with the simulation data,which verifies the accuracy of the simulation model.