多级离心压缩机无叶扩压器内气动性能的数值研究

Numerical Investigation for Aerodynamic Performance of the Vaneless Diffusers inside a Multistage Centrifugal Compressor

对某多级离心压缩机的气动性能进行了整级CFD数值模拟,重点研究并比较了级间与级后无叶扩压器内的气动特点。计算方法基于Jameson格式,湍流模型选择Spalart-Allmaras模型。结果表明,在多级离心压缩机中,无叶扩压器的性能对整个机组的总体性能影响很大。级间与级后无叶扩压器内的能量损失都很高,但后者以摩擦损失为主,而前者由于受其下游弯道的影响,流动发生分离,因而其能量损失来源于摩擦与分离的共同作用。

The numerical flow analysis in a multistage centrifugal compressor is presented, The importance of research is attached on the aerodynamic performance of the two vaneless diffusers inside a multistage centrifugal composer. Jameson central scheme with Spalart-Allmaras turbulence enclosure is applied to Reynold＇s time-Averaged N-S equations. Results indicate： the aerodynamic performance of the vaneless diffuscrs has an intensive influence on the total performance of the whole machine. There is a large amount of energy loss inside the two diffusers resulted from different reasons. Frictional loss is the main factor for the energy loss in the vaneless diffuser at the end of stages while in the vaneless diffuser between the stages, flow separation occurs resulted from the distm-bance of the crossover so the energy loss comes from both friction and separation.