Abstract: Hydraulic turbines are widely used in the energy recovery of high residual pressure fluid. The distribution of blade angle from blade inlet to outlet, an important parameter for impeller design, is featured with uncertainty and diversity. To study its influence on hydraulic turbine performance, six different forms of blade angle distribution are examined and summarized: linear, concave, convex, and three types of piecewise smooth curves. Numerical simulations and comparative analysis show that the head-flow curves of the six schemes are nearly the same, while the concave scheme offers a wider zone of higher turbine efficiency. Different schemes have little influence on impeller inlet velocity circulation. Compared with the others, the concave scheme shows a better overall performance of the impeller–lower impeller head loss, smaller non-uniform vortices in the impeller passage, better flow field, and better blade pressure features such as higher surface pressure and mild pressure gradient from blade inlet to outlet.

Key words: hydraulic turbine, blade angle, distribution type, simulation, optimization