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扰动的产生、放大和反馈这一过程的不断重复和剪切层分离迹线与腔室内壁所围空气团的脉动,是引起自激振动的必要条件;腔室几何参数和下游壁形状是在自激振动中起重要作用。为此,我们研究了四种碰撞壁形状,即截锥面形、外球面形、内球面形和平面形。实验发现,对于截锥面形碰撞壁,自激振动幅值很大;对于内球面形碰撞壁,几乎没有自激振动。为了研究由射流-碰撞壁相互作用引起的不连续涡旋对压力脉动的影响,文中提出了涡旋-碰撞壁相互作用的数学模型。
The constant repetition of the process of generation, amplification and feedback of disturbances and the separation of the shear layer traces and the pulsation of the air masses surrounding the chamber walls are necessary conditions for causing self-excited vibration; the geometrical parameters of the chamber and the shape of the downstream wall are Self-excited vibration plays an important role. For this reason, we have studied four kinds of collision wall shapes, namely, the truncated cone shape, the outer spherical shape, the inner spherical shape and the planar shape. The experimental results show that the amplitude of self-excited vibration is very large for the frustoconical collision wall and almost no self-excited vibration for the inner spherical collision wall. In order to study the effect of discontinuous vortex on pressure pulsation caused by the interaction of jet-collision wall, a mathematical model of vortex-collision wall interaction is proposed in this paper.