Optimization Study of Shaft Tubular Turbine in a Bidirectional Tidal Power Station

The shaft tubular turbine is a form of tidal power station which can provide bidirectional power. Efficiency is an important turbine performance indicator. To study the influence of runner design parameters on efficiency, a complete 3D flow-channel model of a shaft tubular turbine was developed, which contains the turbine runner, guide vanes, and flow passage and was integrated with hybrid grids calculated by steady-state calculation methods. Three aspects of the core component (turbine runner) were optimized by numerical simulation. All the results were then verified by experiments. It was shown that curved-edge blades are much better than straight-edge blades; the optimal blade twist angle is 7, and the optimal distance between the runner and the blades is 0.75-1.25 times the diameter of the runner. Moreover, the numerical simulation results matched the experimental data very well, which also verified the correctness of the optimal results.