增压器无叶蜗壳内三维可压湍流流场的数值模拟

Simulation of Three dimensional Compressible Turbulent Flow in Scroll of a Turbocharger

用心形线表征了一种增压器无叶蜗壳双梨形流道横截面轮廓 ,用有限差分法对蜗壳内三维可压湍流流场进行了数值模拟计算 ,通过与 IFA30 0型热膜风速仪的测量结果相比较 ,表明两者具有良好的一致性。分析了其喷嘴出口处及流道截面上的速度分布 ,结果表明 ,蜗壳尾段喷嘴出口处的速度较低 ,其余部位处速度分布较均匀 ;在蜗舌与初始截面处的流道中存在涡流。

The pear shaped flow section contour of a turbocharger scroll was described by a function of heart shaped line. The numerical calculation grid of flow field was constructed with algebraic transformation of body fitted coordinate. Three dimensional compressible turbulent flow in such a scroll was simulated by FDM. The computed results are consistent with the values measured by an IFA300 anemometer. The nozzle outlet velocity is uniformly distributed except that the velocity in the end segment of scroll is lower. The flow angle is also evenly distributed in the area of azimuth 60 to 300 degree; however it decreases sharply after azimuth 300 degree. From the starting section the flow in the path exhibits an equal potential trend, near the nozzle the velocity is higher and near the wall the velocity is lower because of the boundary layer effect. The vortex exists in the flow path between the scroll tongue and the starting section, and it results in a local flow loss.