螺杆膨胀机端面压力非均匀分布与轴封泄漏特性研究

Study of Non-uniform Pressure Distribution at End Face and Leakage Characteristics of Screw-expander Shaft Seal

螺杆机械的端面压力分布是计算轴封泄漏与动力特性的首要前提。不同于其它机型,螺杆机械的端面压力分布不仅与工况参数有关,还与转子设计参数密切相关。为研究螺杆机械轴封泄漏特性,本文建立了端面压力非均匀分布模型与轴封泄漏模型,通过实验数据的对比,验证了轴封模型的准确性,并进一步研究了不同工作压力、内容积比以及轴封出口压力下,端面压力分布与轴封泄漏量的变化规律。结果表明:螺杆膨胀机端面压力呈非均匀分布,且端面平均压力远小于工作压力。端面平均压力和泄漏量均随工作压力的增加而近似线性增大,随内容积比的增大而降低。当工作压力由500 kPa增至800 kPa时,端面平均压力增长12%,泄漏量变为原来的3.8倍;当内容积比由3增至5时,端面平均压力减小7.4%,泄漏量降幅高达50%。泄漏量随迷宫密封出口压力的增加而降低,且降幅逐渐增大,当出口压力由100 kPa升至300 kPa时,泄漏量降低37%。

The end-face pressure distribution of screw machinery is the premise of calculating the leakage and dynamic characteristics of shaft seals.Unlike other types of machinery,the pressure distribution on the suction end face of screw machinery is related to the operating parameters and the rotor design parameters.To study the leakage characteristics of the screw mechanical shaft seal,a nonuniform pressure distribution model of the end face and a shaft-seal leakage model were established.The accuracy of the model was verified through comparison with existing experimental data.The pressure distribution on the end face,leakage of the shaft seal under different working pressures,built-in volume ratios,and shaft-seal outlet pressures were studied.The results showed that the pressure on the screw-expander end face was nonuniformly distributed,and the average pressure was far less than the working pressure.The average pressure at the end face and the leakage increased approximately linearly to the working pressure.The average pressure of the end face and leakage decreased with an increase in the built-in volume ratio.When the working pressure was increased from 500 kPa to 800 kPa,the average pressure of the end face increased by 12%,and the leakage increased to 3.8 times that of the original value.When the built-in volume ratio increased from 3 to 5,the average pressure on the end face and the leakage decreased by 7.4% and 50%,respectively.The leakage decreased with increasing labyrinth-seal outlet pressure and reduced more distinctly at higher pressures.When the outlet pressure increased from 100 kPa to 300 kPa,the leakage decreased by 37%.