超高速干气密封扰流效应及抑扰机制

干气密封在高速时优异的动压性能使其应用范围从传统的压缩机、离心机等中高速设备逐渐扩大到航空发动机、（微型）燃气轮机等超高速设备中。基于实际超高速工况特点，对转速范围为10 000~120 000 r/min时的干气密封性能进行了系统性仿真计算，结果发现：在一定几何参数和工况参数下，类似于气浮轴承的微振动现象，干气密封会出现疑似受气体压力波动流影响的开启力、泄漏量与转速非正相关变化的扰流现象，尤其在高压、大膜厚、小槽深时的扰流效应愈加显著；在转速持续增大过程中，干气密封微尺度流场会出现二次拐点现象，且一次拐点发生转速与设计参数有关，而二次拐点发生转速基本约为90 000 r/min。同时结合导流织构的设计思路，进一步研究了超高速下干气密封槽底导流织构的驱动导流效应，结果表明：加设导流织构后，承载效果明显提高，拐点发生工况延后且压力波动区域被压缩。表明导流织构具有良好的抑制扰流、维持开启力与转速持续正相关的作用，在此基础上，进一步阐释了导流织构的抑扰机制，以期为突破干气密封在超高速工况下的应用壁垒提供新思路。

Turbulence effect and suppression mechanism of dry gas seal at ultra-high speeds

The excellent dynamic pressure performance of dry gas seal at high speed enables its application range to gradually expand from the traditional compressor, centrifuge, and other medium-high speed equipment to gas turbine, aero-engine, and other ultra-high speed equipment. Based on the characteristics of actual working conditions of ultra-high speed, the systematic simulation of dry gas seal performance characteristic in the range of 10 000-120 000 r/min are carried out. The results show that under certain geometric parameters and operating conditions, similar to the micro-vibration phenomenon of gas bearing, the open force and leakage rate of dry gas seal are not positively correlated to the rotational speed, which is suspected to be affected by turbulence, and is more significant in high pressure, large film thickness, and small groove depth. In the process of continuous increase of rotating speed, a phenomenon with two flow inflection points will occur in micro-scale flow field of dry gas seal, and the corresponding rotation of the first inflection point varies with design parameters while the second one is almost at 90 000 r/min. Combined with the design thought of diversion texture at the same time, the driving-diversion effect of the diversion texture at the bottom of dry gas seal groove under ultra-high speeds is further studied, and the results show that the bearing effect is significantly improved, the working condition at the inflection point is delayed and the pressure fluctuation area is compressed after adding the diversion texture. The diversion texture has a good effect on suppressing turbulence and maintaining the positive correlation between opening force and rotational speed. On this basis, the disturbance suppression mechanism of diversion texture is further explained to provide a new idea for breaking through the application barrier of dry gas seal in ultra-high speed condition.