间隙变化对压气机静叶叶栅气动性能的影响

利用压气机平面叶栅试验，在大负攻角工况、设计工况和角区失速工况下，研究间隙变化对叶栅气动性能的影响，并分析内部流动变化与气动性能变化的关联。试验结果表明，不同工况下间隙变化对流场结构的影响不同，因而对叶栅性能的影响规律也不同。大负攻角工况下，不同间隙叶栅内在压力面前缘附近都存在一对由端壁向叶展中部发展的分离涡，间隙增大可以使叶栅总损失近似线性减小，并使间隙侧气流折转能力略微提升。设计工况下，无间隙侧吸力面角区存在轻微的角区分离，小间隙（0.2%展长）的引入首先会加剧间隙侧角区分离，当间隙进一步增大时，角区分离消失并形成泄漏涡结构。叶栅总损失随间隙增大呈先增大后减小再增加的趋势，角区分离的消除有助于提高间隙侧气流折转能力。角区失速工况下，间隙的引入可以削弱并移除间隙侧角区失速结构，从而使叶栅总损失下降，并在0.5%展长间隙时达到最小值，同时间隙侧气流折转能力得到增强。当间隙进一步增大时，叶栅损失变化不大。在间隙变化过程中，两侧端部流动结构产生相互影响，使两侧流场性能变化呈相反趋势。通过对比全工况范围内的气动性能，叶栅在选取0.5%展长间隙时整体性能最优。

Influence of clearance variation on aerodynamic performance of a compressor stator cascade

In this paper, a linear compressor cascade is used to experimentally investigate the influence of clearance variation on the flow structures and cascade aerodynamic performance at the highly negative angle of attack, design condition and corner stall condition. The association between the flow structure and cascade performance is also analyzed. The experimental results show that the influence of clearance variation on flow structures and cascade performance is different at different working conditions. At highly negative angle of attack, a pair of three-dimensional separation vortexes near the pressure-side leading edge is originated from the end wall in different clearance cascades. With the increase of clearance size, the cascade total pressure loss decreases, and the clearance side cascade turning ability is slightly increased. At design condition, a slight corner separation exists between blade suction surface and end wall. By bringing in a small clearance (0.2% span), corner separation is first aggravated. As the clearance size continues to increase, the corner separation can be eliminated, and leakage vortex is formed. With the increase of clearance size, the cascade total pressure loss first increases, then decreases and finally goes up again. The elimination of corner separation will improve clearance side cascade flow turning ability. At corner stall condition, the introduction and increase of clearance can impair and eliminate the corner stall structure, and thus the cascade loss decreases and reaches the minimum value with a 0.5% span clearance size. But the cascade loss almost remains the same as clearance continues to increase. Flow structures at both enwalls can influence each other as clearance varies, and the change trends of performance near two end walls are opposite. By comparing the overall cascade aerodynamic performance at all working conditions, the 0.5% span clearance cascade shows an optimal performance.