扩压叶栅角区-吸力面造型设计及流动控制机理

通过数值模拟,分别针对扩压叶栅的设计工况与角区失速工况进行叶身/端壁融合与吸力面优化造型设计,分析其流场结构与性能的变化,并探究两种优化造型对压气机性能改善的机理。优化结果表明:在设计工况下,优化造型吸力面凹陷,使得吸力面附面层厚度变薄,最大端壁融合位置靠近尾缘,角区低能流体在压力梯度的作用下转移并减少,分离结构得到明显控制,损失降低;在角区失速工况下,优化造型吸力面凸起,最大端壁融合位置靠近前缘,使得前缘分离结构显著减弱,当流体在进入吸力面前缘时提前附着,前缘分离区减小甚至消失,损失降低。根据两种造型流场结构特点与控制机理,可构造出在多工况下具有显著作用的叶身-端壁融合造型。

Flow control mechanism of diffuser cascade corner-suction surface profiling design

Through numerical simulation, the optimal profiling under the design point and near stall point were compared, allowing for analyzing the flow field structure and compressor performance changes and exploring the mechanism of the two kinds of optimized profiling to improve the compressor performance. The optimization results showed that the suction surface of the optimal profiling under the design point was sunken, which reduced obviously the thickness of the boundary layer on the suction surface; and blend blade and end wall was close to the trailing edge, which reduced the low energy fluid in the corner zone and produced transfer under the impact of the pressure gradient. For the optimal profiling under the near stall point, the blend blade and end wall was close to the leading edge and the suction surface was convex, which promoted the fluid adhesion in advance when fluid entered the leading edge, and the leading edge separation area decreased sharply or even disappeared. The optimal profiling adapted to all working conditions can be constructed based on the two profiling controlling mechanisms and structure features, yielding extremely positive effect on many working conditions.