扩压叶栅中的旋涡流动

本文以旋涡作为研究线索 ,对扩压叶栅内旋涡流动作了较为全面的试验研究 ,提出了一个常规扩压叶栅内部近壁流动的物理模式 ,包括角涡与叶面附面层干涉的壁面拓扑流型 ,扩压叶栅流动中的旋涡结构 ,以及这个旋涡结构在不同攻角下与叶栅损失结构和负载结构的关系 ,从而解释了扩压叶栅角隅区高损区存在的原因。

EXPERIMENTAL INVESTIGATION ON VORTICAL TYPE FLOW IN COMPRESSOR CASCADES

A series of experiments to investigate the vortical flow in compressor cascades have been completed with a measuring and visualizing system.The phenomena observed include the gereration of corner vortexes and the interaction between corner vortexes and boundary layers on the blade suction surface in the compressor cascades.Based on these expermental results,the flow topology and vortex structure related to the flow pattern have been deduced at moderate incidences.However,at high incidences some important changes for the flow pattern appear and vortex breakdown and reversed flow represent the main characteristics of the vortical flow.Furthermore,the dynamic effects in the compressor cascade,such as the effects of the vortical flow on loading and losses, have been investigated.The results obtained are as follows: (1)At moderate incidences,a high loss region in the corner appears along with the formation of the corner vortex system.The principal loss mechanism comprises:(a)the three dimensional seperation of the corner vortex and secondary vortexes;(b)mixing of fluids with low and high momentum in the corner vortex system. (2)At high inidences,the reversed flow caused by vortex breakdown and strong adverse pressure gradient makes an important contribution to the loss increase. (3)At high incidences,the excessive increase of loading near the end wall appears mainly by the front part of the blade section. From the above mentioned research a physical model for the vortical flow in compressor cascades is obtained.