离心压缩机尺寸效应修正模型

A Correction Model of Centrifugal Compressor Scale Effects

针对离心压缩机在模化设计中因尺寸效应导致产品级相对于基准级的性能偏移难以定量预测的难题,提出一种可对模化设计中效率和流量系数偏移进行定量预测的离心压缩机尺寸效应修正模型,该模型包括效率修正模型和流量系数修正模型两部分。首先,基于边界层理论对离心级的黏性损失进行分析,提出基准级黏损比函数的概念,进而推导出效率修正方程的基本形式;接着通过数值模拟获得基准级黏损比函数的具体表达,从而完善效率修正方程,以预测模化设计中产品级相对于基准级效率的偏移;然后,通过引入边界层的影响对流道收缩效应模型进行改进,从而理论推导出流量系数修正方程,以预测模化设计中产品级相对于基准级流量系数的偏移量。该尺寸效应修正模型不仅可以准确预测模化设计中离心压缩机的性能偏移,且与现有的修正模型相比,具有更强的理论基础,修正方程具有鲜明的物理直观性,大大减少了对经验因素的依赖。采用该效率修正模型对流量系数分别为0.068和0.15的两个三元离心级的模化实验进行预测,结果表明,产品级相对于基准级效率偏移量的预测值与实测值之间的相对偏差在9%以内,产品级效率的预测值与实测值之间的相对偏差在0.2%以内;采用该流量系数修正模型对流量系数分别为0.065和0.085的两个三元离心级的模化数值模拟进行预测,结果表明,产品级高效点流量系数的预测值与数值计算值的相对偏差在1%以内。

In order to solve the problem that it is difficult to quantitatively predict the performance deviation of the product stage relative to the base stage due to the scale effects in the scaling design of the centrifugal compressor,a modified model for scale effects of centrifugal compressor that can quantitatively predict the deviation of the efficiency and flow coefficient in the scaling design is proposed.The model includes two parts:an efficiency correction model and a flow coefficient correction model.Firstly,based on the boundary layer theory,the viscosity loss of the centrifugal stage is analyzed,and the concept of the base stage viscosity-loss ratio function is proposed,then the basic form of the efficiency correction equation is derived.After that,the efficiency correction equation is improved by obtaining the specific expression of the base stage viscosity-loss ratio function through numerical simulation in order to predict the deviation of the efficiency of the product stage relative to the base stage in the scaling design.Next,by introducing the influence of the boundary layer,the model of flow path shrinkage effect is improved,and the flow coefficient correction equation is theoretically derived to predict the deviation of the flow coefficient of the product stage from the base stage in the scaling design.The scale effects correction model can not only accurately predict the performance deviation of the centrifugal compressor in the scaling design,but also has a stronger theoretical basis than the existing correction models.The correction equation has a distinct physical intuition and greatly reduces dependence on empirical factors.The efficiency correction model is used to predict the scaling experiments of two ternary centrifugal stages with flow coefficients of 0.068 and 0.15.The results show that the relative deviation between the predicted value and the measured value of the product stage efficiency offset from the base stage is less than 9%,and the relative deviation between the predicted value and the measured value of the product stage efficiency is less than 0.2%.The flow coefficient correction model is used to predict the scaling numerical simulation of two ternary centrifugal stages with flow coefficients of 0.065 and 0.085.The results show that the relative deviations between the predicted values to the product stage high-efficiency point flow coefficient and the numerically calculated values are within 1%.