中文摘要：

对某车用涡轮增压器上使用的高速小流量离心压气机两种舌部形状下的性能以及蜗壳内部流场进行了研究，应用三维黏性N—S方程数值模拟计算了蜗壳舌部附近和蜗壳内部的流场，分析了蜗壳内一些特征截面和流向上的速度和压力分布。结果表明，对于小尺寸高转速离心压气机，舌尖形状的改变对压力的提升和效率的改进有更明显的作用；舌部气流流入方向受流量影响，在大流量时，气流射人方向对于舌尖有一定角度，小流量时，气流速度方向与舌尖的指向已基本平行，随着流量的减小，气流经过舌尖重新进入蜗壳的回流率增加；设计流量下在扩压器入口出现了一个低压区，位置在60°到120°之间，小流量时静压最小值的位置发生变化；蜗壳内，靠近内半径的气流速度较大，而速度越大的区域，静压恢复系数越低，越靠近蜗壳出口，蜗壳流道几何中心的损失越大。

英文摘要：

To understand the influence of volute on centrifugal compressor performance of turbocharger and the flow field inside the volute, a high-speed and low-mass flow rate centrifugal compressor with two different volute tongue shapes was simulated by 3D viscous Navier-Stokes equations. The flow fields in the vicinity of volute tongues and inside the volutes, the velocity and pressure distributions of streamwise and volute characterized cross-sections were analyzed. Results show that tongue modification has apparent effectiveness on of pressure raising and efficiency improvement. Mass flow rate has influence on flow incidence to the volute tongue. There has certain incidence angle at large mass flow rate and no incidence angle at low mass flow rate. Recirculation flow to volute increases as mass flow rate decreases. Low pressure region, locating from 60° to 120°circumferentially, appears at diffuser inlet under the designed condition and the location of minimum static pressure varies under low mass flow. In volute, the flow velocity is high at inner radius on cross-sections where the pressure recovery coefficient is low. Higher pressure loss at volute passage geometry center is presented with closing to the volute outlet.