Numerical investigation on the hydrodynamic performance of variable length blade tidal turbine: an attribute to enhance energy capture

In the marine industry, it is important to improve the performance of tida turbines to reduce power generation costs. Modification of existing tidal turbine models is necessary to boost performance. The main objective of the present study is to investigate the hydrodynamic performance of a model variable length blade tidal turbine by modifying the baseline rotor to improve the performance using blade element momentum theory (BEMT). The QBlade BEMT simulation results were validated with the available published data and are in good agreement. Furthermore, the key performance parameters (i. e. thrust, moment, and power coefficient) and power output were predicted using the BEMT code for different blade configurations of the model rotor. The simulation results were compared with a standard conventional fixed blade turbine model. Based on the results from the simulations, with the increase in the rotor blade lengths, the performance parameters, particularly peak power coefficients, were observed to be improved up to 10%. The power extraction was also enhanced up to 79% below-rated tidal velocities without any loss in performance at the rated condition. Hence, the model is more efficient compared to the conventional models.