混流式水轮机转轮叶片流激振动分析

结合小变形弹性理论和不可压缩粘性流体的最大功率耗散原理构造流体-叶片系统的功率泛函,通过广义变分原理建立了混流式水轮机转轮叶片在非定常湍流场中考虑流体-结构相互作用(FSI)的有限元模型,计算叶片在FSI情况下的流激振动。数值计算采用分离迭代格式,流动用大涡模拟(LES),叶片振动用直接积分法。试验模型以某型水轮机为原型设计制作,在一片叶片的正面和负面上分别装有5只Kulite的压力传感器,在另一片叶片上装有3只微加速度传感器。计算得到的叶片自振频率、频谱曲线以及加速度时程与试验实测结果是吻合的。

ANALYSIS OF FLOW-INDUCED VIBRATION OF BLADES FOR A FRANCIS HYDRO TURBINE

A fully coupled modeling and numerical simulation of flow-induced vibration of three-dimensional blades for a Francis hydro turbine in unsteady turbulent flow are presented. The methodology used is of the generalized variational principle on a power functional of the fluid-blade system. Three vibrating mechanisms of the blades, turbulent-induced vibration, vortex-induced vibration and fluid elasticity instability, are involved in the establishments with fluid-structure interaction (FSI). A working model turbine was designed and used to implement comparisons with experimental measurements. On the pressure and suction sides of one blade of this turbine, ten Kulite’s pressure transducers are mounted, and three acceleration transducers are rigged on other blade. An iterative scheme for the fluid and for the blade is implemented in turn. For the phase of the flow and for the phase of the vibration, large eddy simulation (LES) and step-by-step integral method are employed, respectively. The comparison shows that the computational results are agreeable with the experimental measurements.