The distribution and characteristics of internal flow field of the impeller with crack damage in service environment was investigated via numerical simulation with RNG k-ε turbulence model. The diffuser and volute are added based on the original impeller to simulate the internal flow field comprehensively. It was found that along the flow direction, the pressure, velocity, and temperature of the fluid increase continuously, and the maximum value appears near the outlet of the impeller. The maximum pressure and velocity in the crack area are distributed around the middle section and the trailing edge of the crack. Entropy production theory was applied in the study of internal flow, which reveals that the entropy production becomes larger around the crack. The further propagation of the crack is promoted by the opening force perpendicular to the entrance direction of the middle crack, the corrosion propagation at the rear edge of the crack, and the thermal deformation of the blade. The accelerated crack process will finally lead to the blade fracture accident.

采用RNG k-ε湍流模型数值模拟研究了使用环境下裂纹损伤叶轮内部流场的分布和特征。在原有叶轮的基础上增加了扩压器和蜗壳，全面模拟内部流场。发现沿流动方向，流体的压力、速度和温度不断增加，最大值出现在叶轮出口附近。裂纹区域的最大压力和速度分布在裂纹中部和后缘附近。将熵产生理论应用于内部流动的研究，揭示了裂缝周围的熵产生变大。裂纹的进一步扩展是由垂直于中间裂纹入口方向的张开力、裂纹后缘的腐蚀扩展和叶片的热变形促进的。加速的裂纹过程最终会导致叶片断裂事故。