高压共轨喷油器控制阀空化研究

Cavitation Analysis of Control-valve in High-pressure Common Rail Injector

为了研究较高轨压条件对共轨喷油器控制阀的影响,对典型的共轨喷油器进行了可靠性试验,而且针对控制阀及其上游流道进行了非定常气液两相流动模拟计算和分析。计算所需的动网格边界条件由执行器衔铁杆位移测量试验获得。通过测量喷油器的动态回油流量,对计算模型进行了试验验证。可靠性试验结果表明控制阀的阀座锥面存在空化穴蚀损伤。模拟计算结果表明,当入口压力条件达到250 MPa级别后,在控制阀上游的导流孔内出现明显的空化现象;在150 MPa、200 MPa和250 MPa 3个级别的入口压力条件时气液两相质量交换率的比值为1∶1.187∶1.437。为匹配250 MPa及以上级别的轨压条件,控制阀上游流道结构须改进。

In order to investigate the effect of high-pressure conditions on the control-valve of common rail injector, a sealing reliability test was carried out in a conventional type of common rail injector, and an unsteady vapor-liquid two-phase flow CFD simulation about the control-valve was performed with AVL- Fire. The displacement measurement of armature-pin of solenoid-actuator was accomplished for the boundary condition setting of computational dynamic grid. The simulation was validated against the experimental result of fuel backflow measurement in terms of mass flow rate. The reliability test result shows that cavitation damage appears on the conical seat surface of control-valve. The simulation result demonstrates that obvious cavitation phenomenon occurs in the guide-hole of the control-valve when inlet pressure boundary condition is increased to 250 MPa level. It also indicates that at three typical inlet pressure levels, viz. , 150 MPa, 200 MPa and 250 MPa, the ratio of mass exchange rate of vapor-liquid phases is 1： 1. 187： 1. 437. With respect to time dimension, the mass exchange rate reaches a peak at the incipient stage of closing course of the control-valve.