自激振动脉冲射流装置的理论分析和实验研究

THEORETICAL ANALYSIS AND EXPERIMENTAL STUDY A SELF-EXCITED OSCILLATION PULSED JET DEVICE

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。

Repeated process of 'disturbance generation, amplification and feedback, pulsation of air mass encircled by separation streamline of shear layer and cavity interior wall are the necessary condition for producing self-excited oscillation. The geometric parameters of cavity and shape of downstream edge play an important role in self-excited oscillation. Four types of impinging edge have been studied. They are truncated cone, convex spherical, concave spherical and plate types.It is found that for truncated cone type edge the amplitude of self-excited oscillation is very big, that for concave type edge there is little self-excitement. To examine the influence of discontinuous vortex,due to interaction of jet and impinging edge, on pressure fluctuation, a mathematic model is established to study interaction of vortex and impinging edge.