真空环境下高温气体静密封界面泄漏特性分析

文章基于气体热流润滑理论，建立高温气体静密封混合润滑分析模型，通过数值计算分析温度和表面粗糙度相关因素对静密封界面泄漏特性的影响。结果表明：考虑气体温黏效应和稀薄效应后，温度对气体静密封的泄漏率影响显著，温度从200 K升高到400 K时，泄漏率可降低20%以上；泄漏率亦受表面粗糙度大小、方向和分布形式的影响，其中粗糙度大小是主要因素，粗糙度越低泄漏率越小，表面粗糙度由0.8 μm减小到0.1 μm时，泄漏率可降低约3个数量级。可见，真空低泄漏静密封设计时气体热黏效应不可忽略；低泄漏率静密封表面的工程实现依赖于表面粗糙度的合理设计和工艺实现。

Leakage characteristics of thermal interface of hydrostatic gas seal in vacuum environment

Based on the theory of the thermos-gas-lubrication, an analytical mixed lubrication model for the high-temperature gas hydrostatic seal is established. The influence of the temperature and the surface roughness factors on the gas leakage rate is numerically analyzed. It is shown that the influence of the temperature on the leakage is significant in view of the viscosity effect and the rarefaction effect. The higher the temperature, the lower the leakage will be. When the temperature increases from 200 K to 400 K, the leak rate can be reduced by more than 20%. Besides, the leakage rate is also affected by the surface roughness in value, orientation and distribution pattern. The surface roughness value is the main factor affecting the leak rate of the gas static seal. The lower the roughness is, the smaller the leak rate will be. When the surface roughness R a decreases from 0.8 mm to 0.1 mm, the leakage rate can be reduced by about 3 orders of magnitude. The engineering realization of the low leakage rate static sealing surface depends on the reasonable design and machining for the surface roughness.