自动进、排气气动发动机密闭气室的性能分析

Performance Analysis of Pneumatic Engine's Automatic Engine Air Supply

为了解密闭气室对自动进、排气气动发动机工作性能的影响,建立了带密闭气室和不带密闭气室两种结构的几何模型,采用重整化群(RNG)k-ε湍流模型对两种结构进行了模拟分析,得到了因结构改变而带来的缸内气体压力和流场的变化情况。对比分析表明,带密闭气室结构的发动机提高了进气过程中高压气体作用在排气阀上下表面的压力差,更好地满足了利用高压气体压力来自动关闭排气阀的功能;使气体在气门侯口处的流动更加顺畅,减少了因气体回流而产生的进气损失;带密闭气式结构系统在进气过程中因气体排气而带来的漏气损失得到了有效抑制。

To give a view of the impact of automatic engine air supply, the geometric model with sealed chamber and without sealed chamber was established, and the working process of them were simulated using renormalization group （RNG）k -e turbulence model. Simulation represented the change of in - cylinder flow field with the changes in the structure, e. g. cylinder pressure, exhaust flow. Calculation results show that the structure with sealed chamber improved the pressure difference of the exhaust valve＇ s upper and lower surfaces, which came from the high pressure gas in the process of inlet, improving the feature of the use of high -pressure gas pressure to automatically close the exhaust valve. Meanwhile,it made the gas flow more smoothly through the inlet valve port, and reduced the loss of inlet generated by the gas reflux and the loss of leak generated by the gas exhaust out of cylinder in the inlet process.