高温下射流管伺服阀流量特性分析

Analysis of flow characteristics of jet pipe servo valve at high temperature

为分析射流管伺服阀的前置级能量转换特性,基于动量守恒和能量守恒定理,建立射流管伺服阀前置级数学模型,并对高温下射流管伺服阀流量特性与前置级结构参数之间的关系进行分析;分别对2种不同型号的射流管伺服阀进行试验研究,得到常温下射流放大器的恢复压力特性以及2种型号伺服阀在30℃和150℃下的小信号空载流量特性。研究结果表明:高温下油液黏度降低导致射流速度增大,恢复压力增加,空载流量变大;前置级结构参数会影响高温下射流碰撞面积的变化幅度,进而影响恢复压力和空载流量。当射流孔与接收孔直径之比在0.69附近时,高温下射流碰撞面积的变化幅度最大,碰撞损失的动量增加,此时空载流量的变化最小。在相同温差下,若空载流量的变化幅度未达到最大,则射流喷嘴的自由射流距离会影响射流碰撞面积的变化,进而影响空载流量的变化。2种伺服阀在120℃温差下空载流量的变化幅度分别为4%和16%,试验结果与理论计算结果一致,验证了所建立的前置级数学模型的正确性和有效性。

In order to analyze the energy conversion characteristics of the pre-stage of the jet pipe servo valve,a mathematical model of the pre-stage of the jet pipe servo valve was established based on the conservation of momentum and energy.The relationship between the flow characteristics of the jet pipe servo valve and the structural parameters of the pre-stage at high temperature was analyzed.Experiments on two types of jet pipe servo valves were carried out,and the recovery pressure characteristics of the jet amplifier at room temperature and the small signal no-load flow characteristics of the two types of servo valves at 30℃and 150℃were obtained.The results show that with the decrease of oil viscosity at high temperature,the jet velocity increases,the recovery pressure increases,and the no-load flow becomes larger.The structural parameters of the pre-stage affect the change amplitude of the jet collision area at high temperatures,and further affect the recovery pressure and noload flow.When the ratio of the diameter of the jet hole to the diameter of receiving hole is around 0.69,the jet collision area changes the most at high temperature,the momentum of the collision loss increases,and the change in the no-load flow is the smallest at this time.With the same temperature difference,if the change amplitude of the no-load flow does not reach the maximum,the free jet distance of the jet nozzle will affect the change of the jet collision area,which in turn affects the change of the no-load flow.The change rate of the no-load flow of the two servo valves at a temperature difference of 120℃is 4%and 16%respectively.The test results are consistent with the theoretical results,which verifies the correctness and effectiveness of the established pre-stage mathematical model.