槽口深度对U型节流阀空化流场的影响

采用数值计算的方法对U型节流阀内部流场进行了研究,分析了不同节流槽深度对节流阀内部油液压力场、速度场及空化区域的影响.研究结果表明:流道内压力较大区域位于上游流道,压力较小区域位于下游流道;U型节流槽是压力及速度突变区,在节流槽出口处出现压力骤降并在节流阀口处形成高速射流;在相同工况下,随着节流槽深度的增加,槽内流量增多,迫使油液急速流过节流口,从而造成射流方向发生改变,且高速射流的角度呈现不断减小的趋势,但是油液最大流速逐渐增大.节流槽出口靠近阀腔壁面处产生空化,且随着槽口深度加深时,节流槽内部压力恢复变慢,空化区域的面积逐渐增大,且径向截面空化较强的区域逐渐向节流槽中心扩展.因此,合理地控制U形节流槽的深度或增加节流槽内部阻力,可以有效地抑制空化发生.

Effects of groove depths on cavitation flow field in a U-shaped throttle valve

A CFD numerical calculation model was established in order to study the flow field inside U-shaped throttle valve. The velocity, pressure drop and cavitation region in throttle with different groove depths were also obtained. The numerical results showed that the maximum pressure is located at the upstream of the flow channel and the minimum pressure is located at the downstream of the flow channel. The pressure drops a lot and a high-speed jet forms when the fluid passes through the throttle outlet. Under the same working conditions,with the increase of groove depth, the flow in the notch increases. This situation forces the oil to flow rapidly through the orifice, which results in a change in the direction of the jet.The angle of high-speed jet shows a decreasing trend, but the maximum flow rate of oil gradually increases. At the outlet of the throttle groove, cavitation occurs near the wall of the valve cavity, and with the depth of the groove increasesing, the internal pressure of the throttle notch is recovered slowly, the cavitation area increases gradually, and the strong cavitation area in the radial section gradually expands toward the center of the throttling tank.Therefore, a reasonable control of the U-groove depth or increasing the internal resistance of the throttle can effectively inhibit the occurrence of cavitation.