喷水推进混流泵叶片径向力

Radial forces of waterjet propulsion mixed-flow pump

水力机械内的水压力脉动常常导致叶片的疲劳破坏及共振,为了研究叶片旋转交互作用引起的流体诱导水压力,基于CFD计算和模型试验开展导叶式喷水推进混流泵叶片交互作用径向力研究.建立了一个闭式的混流泵试验循环系统,在叶轮和泵轴内内置同步旋转测力计测量叶轮上的瞬时力和转矩.通过大量的标定确定试验轴系的动态特性.采用Fluent软件进行非定常数值模拟,并将模拟结果与试验结果进行了比较,分析了产生偏差的原因.结果表明:叶片旋转经过时的轴上径向作用力的频率与工况有关,同时叶片激发的径向力导致叶轮有与轴旋转方向相反旋转的趋势;计算的推进泵外特性与试验吻合较好,同时叶片交互作用径向力的量级也有较好的吻合度;从小流量到大流量工况,计算结果的变化趋势与试验结果一致.

Fluctuations of fluid pressure in hydraulic machinery can cause resonance and fatigue da-mage of blades.In order to study fluid-induced forces,which are caused by impeller-diffuser interaction,unsteady radial forces due such an effect was conducted in a mixed-flow pump with a vaned diffuser by using CFD computation and model experiment.A closed-loop test rig was built for the pump and a co-rotating dynamometer was installed between the impeller and the pump shaft to measure the instantaneous forces and moments on the impeller.The dynamic behavior of the experimental rotor-shaft system was determined by carrying out extensive calibrations.The measured forces at the blade passing frequency showed an unexpected dependency on flow rate.Another important observation was that the blade excitation forces cause the impeller to whirl in the direction opposite to shaft rotation.The computed global characteristics and the magnitude of blade interaction forces showed good agreement with measurements,respectively.The measured results were compared with the unsteady ones estimated by using CFD code-Fluent.Over a large range of flow rates,the trend of force variation agrees well with the measurements.The reasons for deviation of prediction from experiment were explained.