A methodology for designing Francis runner blade to find minimum sediment erosion using CFD

This paper reports on methodology for designing Francis runner blade. This involves finding best outlet angle (β2) and blade angle distribution (β-distribution) causing minimum possible erosion for given volume flow rate (Q = 14.34 m3/s), head (H = 40 m), rpm (N = 333.33 rpm) and eroding particle flow rate (0.08 kg/s). At first, the outlet angle β2 (designing parameter) was varied from 14° to 32° using linear blade angle distribution for all models. Then these models were simulated to find β2. In second, with that β2, blade angle distribution was varied and simulated to find the best blade angle distribution having minimum erosion rate with considerable efficiency. By using hydrodynamic theory for given Q and H, main dimensions were found out and 3D model was generated using β-distribution. Relation of designing parameters with erosion and efficiency was made. Optimum blade was obtained from proposed methodology and was compared with the reference blade in terms of erosion and efficiency.