基于湍流模型的S-CO_(2)干气密封流场与稳态性能分析

Flow field and steady performance of supercritical carbon dioxide dry gas seal based on turbulence model

为探究湍流效应对S-CO_(2)干气密封性能的影响规律,以螺旋槽干气密封为研究对象,引用考虑离心惯性力效应的湍流Reynolds方程,选择Ng-Pan湍流系数表达式,采用物性软件REFPROP对CO_(2)真实物性进行计算。之后,根据普适能量方程,通过引入包含湍流效应、离心惯性力效应的平均速度,建立了可压缩流体简化能量方程。通过对湍流Reynolds方程与简化能量方程进行耦合求解,分析讨论了不同工况参数与平均膜厚下湍流效应对密封性能的影响。研究表明:湍流效应使得气膜流场内压力与温度分布发生显著变化,流场计算时不可忽略;在不同进口压力、进口温度下,湍流下的开启力和泄漏率显示出与层流一致的变化趋势;在不同平均膜厚下,考虑湍流效应后的开启力呈现出与层流不同的变化规律,而泄漏率表现出与层流相同的变化趋势;在不同进口压力、进口温度、平均膜厚下,湍流下的开启力和泄漏率均比层流下的低,且在两种流态下的这种差异随着进口压力、进口温度、平均膜厚的增大而逐渐增大;在不同转速下,开启力和泄漏率在湍流下分别表现出与层流不同的变化趋势。这些结果为进一步研究湍流效应对S-CO_(2)干气密封的影响提供了支撑。

In order to explore the influence of turbulence effect on the performance of S-CO_(2)dry gas seal,the spiral groove dry gas seal was taken as the research object.The Reynolds equation considering centrifugal inertia force effect was cited,the Ng-Pan turbulence coefficient expression was selected,and the real physical properties of carbon dioxide were calculated by using software REFPROP.Then,according to the universal energy equation,the simplified energy equation of the compressible fluid was established by introducing the average velocity including the turbulence effect and the centrifugal inertia force effect.By coupling the Reynolds equation and the simplified energy equation,the influence of the turbulence effect on the sealing performance under different working conditions and average film thickness was analyzed and discussed.The research has shown that the turbulence effect causes significant changes in the pressure and temperature distribution in the gas film flow field,hich cannot be ignored when calculating the flow field.Under different inlet pressure and inlet temperature,the opening force and leakage rate in turbulence show the same trend as that in laminar flow.Under different mean film thicknesses,the opening force after considering the turbulence effect shows a different variation rule from laminar flow,while the leakage rate shows the same variation trend as laminar flow.Under different inlet pressure,inlet temperature and average film thickness,the opening force and leakage rate in turbulent flow are lower than that in laminar flow,and the difference between the two flow states increases with the increase of inlet pressure,inlet temperature and average film thickness.At different rotational speeds,the opening force and leakage rate in turbulent flow show different trends from that in laminar flow.The results provide support for further research on the effect of turbulence on S-CO_(2)dry gas seal.