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针对带有不同前缘角的凹腔内流动和燃烧过程,分别在冷态和燃烧条件下探讨了前缘角对凹腔内流动损失及阻力特性的影响.研究表明:在壁面垂直喷射的喷口上游和凹腔内部均会形成低速、高温回流区,有利于点火及火焰稳定,燃烧反压通过边界层的亚声速区域上传,形成激波/边界层干扰结构.减小前缘角,可使剪切层分离位置提前,更偏向凹腔内部,导致凹腔后壁面再附激波增强,进而增大了总压损失,降低了总压恢复系数;亦可导致凹腔前、后壁面压差阻力增大,阻力系数上升.进一步认识了凹腔内部流场及稳焰增混机理,进而为优化凹腔结构设计提供依据.
The effects of the leading edge angle on the flow loss and the resistance characteristics in the cavity were discussed under the condition of cold state and combustion, respectively, for the flow and combustion process in the cavity with different leading edges. The results show that: Both the upstream and the inside of the cavity will form a low-speed and high-temperature recirculation zone, which is conducive to ignition and flame stabilization, and the combustion back pressure is uploaded through the subsonic region of the boundary layer to form a shock / boundary layer interference structure. The separation of the shear layer advances earlier and more towards the inside of the cavity, resulting in the re-attachment of the shock wave on the back wall of the cavity, thereby increasing the total pressure loss and reducing the total pressure recovery coefficient. The pressure difference between the front wall and the back wall of the cavity can also be caused The resistance increases and the drag coefficient increases.Furthermore, the internal flow field in the concave cavity and the stabilizing flame mixing mechanism are further understood, which provides the basis for optimizing the structural design of the cavity.