Abstract: To investigate the effects of slot jet of tandem cascade on the separation and cascade performance，the unsteady numerical simulation has been utilized to analyze the effects of axial overlap and pitch percent of tandem cascade on the cascade performance of one high-load compressor at large angle of attack 11°. The temporal-spatial evolution of the unsteady flow separation with the slot mixing flow was also investigated. One comprehensive parameter called slot contraction ratio was proposed to understand the influence of slot configuration on flow and separation. The results show that tandem blades can achieve good performance when the axial overlap is between -0.022 and 0.023 and the percent pitch is in the range of 0.6 to 0.9. Under the unsteady slow blowing，the separated bubbles on the suction surface of rear cascade are suppressed periodically while the influence of slot blowing on the front cascade is weak. The slot contraction ratio as one comprehensive parameter can reveal the effective working condition of the tandem cascade more clearly. Under the subsonic flow condition，contraction ratio greater than 1 is the prerequisite for the normal working of the tandem cascade. When the slot contraction ratio is less than 1，the slot acceleration effect disappears and the cascade performance got deteriorated. The optimal slot contraction ratio is between 1.1 and 1.4.

Key words: Tandem cascade；Unsteady flow；Separation bubbles；Pressure fluctuation；Slot contraction ratio

摘要： 为了研究串列叶栅前后叶缝隙流作用对流动分离和叶栅性能影响机制，通过非定常数值计算分析了串列叶栅轴向重合度和节距系数两种缝隙参数组合对高负荷压气机串列叶栅在大攻角11°下性能影响以及缝隙流掺混作用下前后叶流动分离的时空演化机制的影响规律，并且提出了缝隙流对串列叶栅流动及性能影响的综合性参数-缝隙收缩比。研究结果表明:轴向重合度在-0.022～0.023，节距系数在0.6～0.9时，串列叶栅能取得较好气动性能；在缝隙非定常吹除作用下，后叶吸力面分离泡被周期性抑制，前叶吸力面分离泡受缝隙射流源的影响较弱；提出的缝隙收缩比作为综合匹配参数可以更清晰揭示出串列叶栅有效工作条件，在亚声速来流工况下，缝隙收缩比大于1是串列叶片能正常工作的前提，缝隙收缩比小于1，缝隙加速作用消失，叶栅性能较差，最佳的缝隙收缩比范围是1.1～1.4。

关键词: 串列叶栅；非定常流动；分离泡；压力波动特征；缝隙收缩比