自由活塞斯特林发动机间隙密封泄漏特性分析

摘要

间隙密封技术是自由活塞斯特林发动机的一项关键技术,间隙密封避免了摩擦损耗,不需要润滑,对自由活塞斯特林发动机整机性能的提高起到了重要的作用.本文建立了自由活塞斯特林发动机间隙密封双边运动的一维层流模型,结合施密特等温分析法,对一台输出功率为100 W的自由活塞斯特林发动机计算了工作腔与缓冲腔之间的泄漏率曲线和单个循环工作腔向缓冲腔泄漏的泄漏量,并比较了不同间隙宽度情况下泄漏损失所占的比重,得到了最大允许的密封间隙宽度.同时,建立带有进出口的二维模型,运用Fluent进行了数值模拟,并与一维层流模型计算结果进行对比,得出二者泄漏率基本一致的结果,但由于间隙流动处进出口体积骤变的存在,二维模型数值模拟结果泄漏率略低于一维层流模型,更接近实际情况.%Clearance seal technology is seen as a key technology of free piston Stirling engines. It avoids friction loss, needs no lubrication and makes large progress for improving performances of the free Stirling engines. A kind of one-dimensional laminar model with bilateral movement of seal gap for free piston Stirling engines is established and combined with Schmidt i-sothermal analysis to get mass leakage rate and mass leakage per cycle of a 100W free piston Stirling engines. Meanwhile, different seal gap widths are compared in order to study the impact from the seal leakage and a largest seal gap width allowed is got. Two-dimensional model of seal gap with the import and export for free piston Stirling engines is also established to get more precise mass leakage. Numerical simulation method is used to compute this two-dimensional model and get a similar mass leakage rate. Because of the influence of the import and export of seal gap, the numerical simulation results slightly lower than the results computed by one-dimensional laminar model.