非平行壁面无叶扩压器失速的三维模型

A Three-dimensional Model on Rotating Stall in Unparallel Wall Vaneless Diffusers

为了研究离心压缩机系统内非平行壁面无叶扩压器的失速问题,提出了一种三维模型.首先采用强隐式方法(SIP)求解扩压器内的平均流动,然后采用奇异值分裂(SVD)方法求解离散后的线性化三维欧拉方程,得到了非平行壁面无叶扩压器失速时的临界流量系数和失速团相对转速.研究的非平行壁面轮盖型线包括单收缩型、先收缩后扩张型以及等面积收缩型.结果显示,无叶扩压器的轮盖型对临界流量系数和失速团相对转速都有重要影响,收缩型轮盖面可以有效抑制无叶扩压器失稳,对于较长的扩压器抑制效果更为明显.此外,非平行壁面无叶扩压器的失速临界流量系数还受到入口马赫数、扩压器出入口半径比的影响.

A 3D model wass presented to study the occurrence of weak rotating waves in unparallel wall vaneless diffusers in centrifugal compressors.The undisturbed flow was first calculated by strongly implicit procedure（SIP）,and the discrete linearlised 3D compressible Euler equations were then solved employing singular value decomposition（SVD） technique.The critical inlet mass flow rate for rotating stall and the relative rotating wave speed were predicted.Three different shapes of shroud wall： convergent,convergent and divergent,and constant area tapered shroud walls were studied.The results show the suppression effects on rotating stall of diffusers with contracting shaped shroud walls,especially of long diffusers.The critical mass flow rate also varies with inlet Mach number and diffuser outlet/inlet radius ratio.The results from the model developed agree qualitatively well with those in open literatures.