Numerical Optimization on Guide Vane Hydraulic Performance of Nuclear Main Pump Based on Orthogonal Test

In order to improve the hydraulic performance of nuclear main pump and accomplish the best matching between impeller, guide vane and circular delivery chamber, the AP1000 nuclear main pump was chosen as the study object. The geometry parameters of impeller and volute were kept unchanged, and the attack angle of diffuser inlet, the angle of diffuser and the outlet angle of diffuser as the three factors of the orthogonal test method were chosen, and the value range was ensured according to the value of each factor respectively. Based on Reynolds time-average N-S equation, RNG k-ε turbulence model and the SIMPLEC algorithm, the orthogonal experiment and numerical optimization were completed by CFD technology. Through orthogonal test and significance analysis of factors, it is shown that under the rated conditions, the optimized model pump will improve the pump driving head 0.55 m, with efficiency increasing 0.66%, compared to the original model pump. Under small flow condition, the driving head and efficiency are more significantly optimized. The angle of diffuser and the outlet angle of diffuser have obvious effects to hydraulic performance of the pump and the flow diffusion in diffuser determines hydraulic loss of the diffuser. The interactions among the inlet angle of diffuser, the outlet angle and the angle of diffuser have little effect to the hydraulic performance of pump, which can be ignored. The research on the angle of diffuser shows that under small flow condition, the angle of diffuser is proportional to the efficiency of the pump, however under large flow condition, which is inversely proportional to the efficiency of the pump.