宽速域三种典型型槽油气密封泄漏与成膜特性对比研究

Comparative study on leakage and film-forming characteristics of oil-gas seal with three-typical groove in a wide speed range

如何实现涡轮增压器气膜密封在低速状态的低漏油和高速状态的低窜气、高刚度是其设计的关键问题。以泵出型螺旋槽、八字复合型槽和雷列台阶复合型槽油气密封作为研究对象,基于双相雷诺模型数值求解了三种型槽油气密封的流场分布,测试了不同工况下气膜密封的气膜厚度和介质泄漏,对比研究了宽速域范围内三种型槽油气密封的泄漏和成膜特性,重点分析了槽深、螺旋角和泵出槽长比等关键结构参数对八字复合型槽油气密封泄漏和成膜特性的影响规律。结果表明:泵出型螺旋槽密封因具有最小的漏油量可作为低速状态的优选方案,八字复合型槽密封因具有显著更低的窜气量和更大的气膜刚度可作为高速状态的优选方案,不过这依赖其槽深、螺旋角和泵出槽长比的合理设计;在一定的工况和结构参数时,复合型槽密封有望在端面形成明显的油气径向分界面,从而实现油气近零泄漏。

How to achieve both low oil leakage at low-speed condition and low gas consumption,high stability at high speed condition is the key problem in the design of the oil-gas seal used in vehicle turbocharger.Taking the oil-gas seals with pump-out spiral groove,splayed compound groove and Rayleigh compound groove as the research object,the two-phase Reynolds model derived from the continuity of oil and gas phase is used to solve the flow field distribution of the three different types oil-gas seals numerically,and the gas film thickness and medium leakage of the oil-gas seals under different working conditions are measured based on a special-designed test platform.The leakage characteristics and film-forming characteristics of the three different oil-gas seals in a wide speed range are compared,and the influence of key structural parameters,including groove depth,spiral angle and pump-out groove length ratio,on the leakage and film-forming characteristics of the splayed compound groove oilgas seal is emphatically analyzed.The results show that the pump-out spiral groove can be selected as the optimal scheme when oil-gas seal operates under low-speed condition because of its minimum oil leakage,and the splayed compound groove seal can be regarded as the optimal one in the high speed condition because of its significantly lower gas consumption and larger gas film stiffness.But it depends on the reasonable design of its groove depth,helix angle and pump out groove length ratio.Under certain working condition and structural parameters,the compound groove face seal is expected to form an obvious oil-gas interface on the seal face in the radial direction,so as to achieve near zero leakage for both oil and gas.