A STUDY ON THE LEAKAGE-FLOW-INDUCED VIBRATIONS IN A TWO-DIMENSIONAL NARROW PASSAGE

在泄漏流通道狭窄的机械结构中，经常发生严重的自激振动。在前人一维泄漏流诱发振动研究的基础上，将一维理论应用于二维泄漏流通道，数值计算了偏心环形通道内的压力分布，分析了二维狭窄通道内泄漏流诱发振动的稳定性。在偏心环形通道压力分布的计算中，采用泄漏流格式，忽略了扩散器在环向流动中的影响。计算得到的压力分布与实验结果吻合较好，证明了偏心环空通道压力分布计算中泄漏流格式的有效性。结果发现，在轴向平行和收敛通道中，作用在通道壁上的流体力为正恢复力，而在发散通道中，流体力为负恢复力。计算的颤振型不稳定临界速度与实验结果吻合较好。

Severe self-excited vibrations occur frequently in mechanical structures with narrow leakage-flow passages. Based on the previous studies on one-dimensional leakage-flow-induced vibrations, the authors have applied the one-dimensional theory to the two-dimensional leakage-flow-passages and calculated numerically the pressure distributions in an eccentric annular passage to analyze the stability of leakage-flow-induced vibrations in two-dimensional narrow passages.In the calculations of pressure distributions in the eccentric annular passages a leakage-flow scheme was applied, where diffuser effects were neglected in the circumferential flow. The calculated pressure distributions were in fairly well agreement with those by experiments, which has proven the validity of the leakage-flow scheme proposed in calculations of pressure distributions in eccentric annular passages.As a result, it is found that, in parallel and convergent passages in the axial direction, fluid forces acting on the passage walls are positive restoring forces and in divergent passages they become negative restoring forces. The calculated critical velocities for the flutter-type instability were also in good agreement with experiments.