螺旋槽结构对SCO2压气机轴端干气密封性能影响的数值研究

Effect of Spiral Structure on the Shaft End Dry Gas Seal Performance for Supercritical Carbon Dioxide Compressors

针对450MWe超临界二氧化碳(SCO2)压气机设计的轴端螺旋槽干气密封结构,采用数值求解三维雷诺时均Navier-Stokes(RANS)和SST湍流模型的方法研究了螺旋槽深度和角度对其性能的影响。基于与实验测量的空气介质的螺旋槽干气密封性能实验数据的对比,验证了数值方法的准确性。计算了5种螺旋槽深度和4种螺旋角下SCO2螺旋槽干气密封的泄漏量、开启力和开漏比。结果表明:螺旋槽深度的增加会显著提升干气密封螺旋槽根部的最高压力和高压力区域,进而导致具有更高的开启力,同时增加了泄漏量。螺旋角为20°时,螺旋槽深度从3μm增加至7μm,开启力最大增加9.07%;螺旋角为25°时,泄漏量最大增加18.67%;螺旋角为15°时,螺旋槽深度是3μm的干气密封具有最大的开漏比,此时干气密封在各螺旋槽深度下具有最好的综合性能。研究工作可为SCO2螺旋槽干气密封性能分析提供参考。

The spiral groove dry gas seal is designed according to the sealing requirements of the shaft end in 450 MWe supercritical CO2(SCO2)compressor.The influences of spiral angle and groove depth on the sealing performance of the designed dry gas seal are numerically investigated using three-dimensional Reynolds-Averaged Navier-Stokes(RANS)equations and SST turbulence model.The accuracy of the numerical method is validated by comparison of the experimental data for dry gas seal with air working fluid.The leakage flow rate,opening force and opening force leakage ratio of the spiral groove dry gas seal at five different spiral groove depths and four different spiral angles are numerically analyzed.The results show that the increase in the spiral groove depth leads to an intense increase in the maximum pressure and the high pressure area in the groove root region of the dry gas seal,which results in a higher opening force and bigger leakage rate.When the groove thickness increases from 3μm to 7μm,the maximum increase of opening force is 9.07%when the spiral angle is 20°;the maximum increase of leakage rate is18.67%when the spiral angle is 25°.The maximum opening force leakage ratio is reached when the spiral groove angle is 15°,which means the dry gas seal with this groove angle has the best comprehensive sealing performance.The performance analysis of the spiral groove dry gas seal at the shaft end of the compressor in this study provides a reference for the SCO2 power cycle seal design.