斯特林发动机配气活塞气体的作用效应

Investigation on Gas Effect of Displacer for Free-Piston Stirling Engine

为了能够深入认识自由活塞斯特林发动机配气活塞的运动特性,对动力活塞固定不动时的配气活塞的气体作用效应进行了分析,并设计了配气活塞的单独运动实验,在此基础上提出了配气活塞固有频率的计算式。分析了工作腔压力波超前与滞后配气活塞位移两种情况下受到的气体力的作用情况,采用旋转矢量法阐述了气体力的作用机理。当压力波超前或滞后活塞位移小于90°时,认为一部分气体力发挥了气体弹簧的作用,使系统固有频率增大;当压力波超前或滞后活塞位移大于90°但小于180°时,认为一部分气体力发挥了惯性力的作用,使系统固有频率减小。热源温度越高,系统的固有频率越小。利用本实验室的一台自由活塞斯特林发动机进行实验,验证了上述气体力作用的效应与规律,且利用此理论计算了系统固有频率的准确性。

In order to have a deep understanding of the kinematical characteristics of the displacer of freepiston stirling engine,the effects of gas force,which is driven by the displacer only,is analyzed.And the running experiment of displacer individually is designed.During the course of the experiment a new calculation formula for natural frequency of displacer is proposed.In this paper,the gas force acting on the displacer is analyzed in the case of leading or lagging displacement of piston.And the acting mechanism of gas force is stated by means of rotation vector decomposition.The results show that a part of gas force is regarded as gas spring.The gas spring and the mechanical spring are parallelly arranged and the natural frequency of the system increases in the case of the pressure wave in advance or delaying the displacement of piston less than 90°.But the gas force is regarded as gas inertia force and the natural frequency of the system decreases in the case of the pressure wave in advance or delaying the displacement of piston greater than 90°but less than 180°.And the higher the temperature of the heat source,the smaller the natural frequency of the system.The accuracy of the effects of gas force and calculation formula for natural frequency are verified by an experimental text on a free-piston stirling engine which is designed by our laboratory.