反向冲击下的液控单向阀多级节流特性研究

Study in Multistage Throttle Characteristic on Reverse Impact of Pilot-operated Check Valve

为了改善大流量液控单向阀在反向开启时的冲击特性、减小振动与空化、减少卸载时间。选取了3种不同结构的主阀芯,以冲击压力30 MPa、流量1 000 L/min作为基本参数,通过Fluent软件进行气液两相流分析,在此基础上对空化作了探讨并进行了实验验证,同时通过冲击实验系统对不同主阀芯的动态特性进行了研究。仿真结果表明:流体在流经阀芯区域时压力明显降低,且通过阀芯节流口时,由于过流面积突然变小,流速增大,在主阀芯侧产生了空化区域,而且阶梯式的节流结构能有效减小空化的区域、降低空化的产生。实验结果表明:冲击卸载时阶梯式的主阀芯压力振动较小,为28.41 MPa,流量上升梯度为4.86×10~5L/min^2,卸载时间为711 ms,说明其开启更加迅速,动态性能更优越;同时说明阶梯式的节流结构可以有效减少液控单向阀在卸载过程中的压力振动,提高响应速度,增强冲击性能,降低空化,验证了仿真的正确性和空化指数的合理性。

In order to improve the reverse impact characteristics of large-flow pilot-operated check valve at opening, reducing vibration, cavitations and unloading time, three different main poppets are selected. Setting impact pressure for 30 MPa, flow for 1 000 L/min as the basic parameters, the cavitations phenomenon was explored based on the analysis of gas-liquid two-phase flow by Fluent software, and then conducted the experimental verification. Meanwhile the dynamic characteristic of different pilot-operated check valve was studied by the impact test system. The simulation results show that the fluid pressure decreases obviously while flowing through pop- pet area. And the sudden decreasing of flow area at the orifice port of poppet results in the increasing of flow-velocity because of which the cavitations area appears on the side of main poppet. And stepped throttling structure can effectively reduce the cavitations area, decreasing the generation of cavitations. The experimental results show that pressure vibration of stepped main poppet is significantly reduced during process of unloading, for 28. 41 MPa, flow rise gradient for 4.86×10^5L/min^2, unloading time for 711 ms, indicating it 0 is opened more rapidly and dynamic performance is more superior. At the same time, the conclusion indicates that stepped throttling structure can effectively reduce the pressure vibration of pilot-operated check valve during process of unloading, improve response speed and enhance the impact properties, and reduce cavitations, which verified the correctness of simulation and the rationality of cavitations index.