基于双向流固耦合的混流泵叶轮力学特性研究

Mechanical Properties of Mixed-flow Pump Impeller Based on Bidirectional Fluid-structure Interaction

基于双向同步求解方法对混流泵内流场和叶轮结构响应进行联合求解,研究流固耦合作用下混流泵叶轮转子的力学特性。流场计算采用雷诺时均方法和标准k-ε湍流模型,结构响应采用弹性体结构动力学方程。通过对比分析流固耦合前后流道内不同位置压力监测点的压力脉动、外特性变化,研究流固耦合作用对混流泵流场的影响,并基于双向流固耦合分析了叶轮叶片的变形与动应力分布。研究结果表明,流固耦合作用对导叶出口处压力脉动幅值影响较大,耦合后扬程和功率波动幅值有所增加,而效率有所下降。考虑流固耦合作用,叶片最大变形发生在叶片出口边背面靠近轮缘处,最大变形量约为0.062 7 mm;最大等效应力发生在叶片背面靠近轮毂出口边附近,最大等效应力约19.85 MPa;采样点耦合动应力呈现周期性变化,轮缘与轮毂上动应力幅值相差3个数量级,轮毂处相比其他位置更易发生疲劳破坏。研究结果为混流泵叶片的结构设计和可靠性分析提供了参考依据。

With the aim to study the mechanical properties of the mixed-flow pump impeller rotor under the fluid-structure interaction,the flow field and impeller structure response in the mixed-flow pump were cooperatively solved based on the bidirectional synchronization solving method. The Reynolds-averaged Navier-Stokes equations and k-ε turbulent model were used for the simulation of the flow field,while the elastic structural dynamics equations were used for the structural dynamic response. The influence before and after fluid-structure interaction on the flow field in the mixed-flow pump was studied by comparison of pressure fluctuation and external characteristic changes at different monitoring points between flow channels. Meanwhile,the deformation of blade and the dynamic stress distribution on blade were analyzed based on the bidirectional fluid-structure interaction. The results showed that fluid-structure interaction had greater influence on the pressure pulsation amplitude at the vane outlet. After the coupled interaction,the amplitude of the head and power fluctuation were increased while the efficiency was decreased. The largest deformation location of blade occurred at the back side near to the rim of impeller with the maximum deformation of 0. 062 7 mm. The maximum equivalent stress was detected on the back side nearby the outlet of the hub with the maximum equivalent stress of about 19. 85 MPa. The coupling dynamic stress of the sample point was changed periodically and the amplitude value of the dynamic stress on the rim and the hub had a difference by 103 magnitudes,which meant that fatigue damage was easier to happen in the hub region. The results of the research provide reference basis for the structure designand reliability analysis of the mixed-flow pump.