流体激发结构振动响应预测模型及激振力的识别

ESTABLISHMENT OF FLUID-INDUCED VIBRATION PREDICTION MODEL OF THE BEAM AND EXCITING FORCE IDENTIFICATION

本文引入模态分析方法用以建立流体诱发结构振动的应变响应予测模型。具体讨论了处于横向流作用下的单根圆柱的振动应变响应问题,推导了用模态参数表达的应变传递函数矩阵及应变响应的表达式,叙述了应用电阻应变计来测量应变响应和应变传递函数的方法。在此基础上,测量了在某一流场条件下的振动应变响应,据此识别了流体激励力谱。实验结果表明,在雷诺数为10~4左右时,流体的激振力主要来自旋涡脱落,湍流脉动所起作用则较小。

Based on the vibration equation of the beam under the action of cross flow, response prediction model expressed in terms of modal parameters which were recognized from the force-strain transfer function is established. Using this model, the identification method of exciting force spectrum in the meanings of least square erro is presented. The strain response of a single beam with circular cross section in the crossflow have been measured by means of strain gauges, and the spectrum of exciting force of flow have been identified. The result shows that the exciting force mainly because of the vortex shedding, and the turbleflce induced force is relatively small in the situation with Reynolds number around 10~4.