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为了研究叶栅分离旋涡的非定常流动特性,选取亚声速叶栅为研究对象,进行了基于延迟分离涡模拟方法 (DDES)的非定常数值模拟。针对进口Ma0.3的情况,对比分析了进口攻角、叶栅稠度、叶片弯角、叶片中弧线弯度分布和叶片厚度等因素对于叶栅分离旋涡运动的影响。结果表明,当攻角增大时,尾迹附近流场会逐渐由定常模式转化为非定常对涡脱落模式,同时对涡脱落频率不断减小;随着攻角的进一步增大,叶背分离强度不断增加,叶背分离涡开始单独脱落,并主导流场旋涡运动。强烈的叶背分离涡脱落引起了叶片气动力的剧烈脉动,其幅值是小攻角状态下由尾迹对涡脱落引起叶片气动力脉动的30倍以上。叶栅几何参数的改变对于流场旋涡运动同样有很大影响,流场同样呈现出“定常尾迹”、“对涡脱落”、“叶背分离涡脱落”这三种主要的旋涡运动形式之一。叶背分离点的相对位置则是影响旋涡非定常运动形式和旋涡脱落频率的主要内在因素。
In order to study the unsteady flow characteristics of vortex shedding vortex, a subsonic cascade was chosen as the research object, and the unsteady numerical simulation based on DDES was carried out. Aiming at the condition of imported Ma0.3, the influences of the angle of attack, the angle of blade, the bending angle of the blade, the curvature distribution of the blade in the blade and the thickness of the blade on the vortex motion of the cascade were analyzed. The results show that when the angle of attack increases, the flow field near the wake changes from steady mode to unsteady vortex shedding mode, and the vortex shedding frequency decreases continuously. With the further increase of angle of attack, Increasingly, leaf dorsal segregation vortex began to separate off and dominated the vortex movement in the flow field. The strong leaf dorsal detachment vortex shedding caused the dramatic aerodynamic pulsation of the leaf, which amplitude is 30 times more than that caused by the wake vortex shedding due to the small angle of attack. The change of the geometry parameters of the cascade also has a great influence on the vortex motion of the flow field. The flow field also shows the three main types of “steady wake”, “vortex shedding” and “vortex shedding vortex shedding” One of the vortex forms of movement. The relative position of leaf back separation point is the main internal factor that influences the unsteady vortex motion and vortex shedding frequency.