非绝热壁面边界在离心压气机数值模拟中的应用

Application of Non-adiabatic Wall Boundary Condition in Numerical Simulation for Centrifugal Compressor

随着离心压气机级负荷与温升水平的提高,为了提升对离心压气机的数值模拟精度,在数值模拟中需要采用非绝热壁面边界条件。本文以一台设计良好的现役离心压气机为研究对象,对其数值模拟的壁面边界条件中分别应用了绝热壁面边界条件,以及等温和给定传热系数这两类常用的非绝热壁面边界条件,对比分析了非绝热壁面边界条件对数值模拟精度的影响及其原因。采用给定传热系数壁面边界条件的数值模拟结果中,效率计算误差最小,设计点效率误差较绝热计算下降46.6%,且计算结果对传热系数偏差有一定容忍度;产生上述差异的原因主要源于叶顶损失相关计算。采用等温壁面边界条件的设计点数值模拟结果中,参考温度偏差使等温边界相比绝热边界效率计算误差增大93.2%,说明等温边界对参考温度敏感,其进一步应用需依靠更精确的参考温度。

With the improvement of stage load and temperature level of centrifugal compressor,in order to improve numerical simulation accuracy of centrifugal compressor,it’s necessary to study the influence of non-adiabatic boundary condition on numerical simulation.In this work,numerical simulation of a well-designed active centrifugal compressor was carried out.Adiabatic and two widely used non-adiabatic boundary conditions,isothermal and heat transfer coefficient(HTC)imposed boundary conditions were employed.Numerical accuracy of non-adiabatic simulation was analysed in detail.Simulation with HTC imposed boundary condition reduces46.6%of error in efficiency at design point,in despite of the deviation of the HTC in a certain range.Detailed analysis shows that main difference between HTC imposed and adiabatic boundary conditions comes from tip loss related simulation.Numerical simulation with isothermal boundary condition shows that the efficiency error raises93.2%compared with adiabatic results because of the deviation of the reference temperature.Isothermal boundary condition is sensitive to the reference temperature,and thus the selection of reference temperature should be carefully considered in further study.