Investigation of low Reynolds number effects on a bidirectional hydrofoil for a tidal stream turbine

A bidirectional airfoil design has recently been proposed to efficiently exploit both the ebb and flow of a tidal stream. As part of laboratory scale testing, it can be challenging to achieve the high Reynolds numbers of the full scale design. In this work, the low Reynolds number effects on the hydrofoil is considered. CFD simulations are performed using OpenFOAM, where the Bas-Cakmakcioglu algebraic transition model is implemented to investigate low-Reynolds number effects. The implementation is first validated by simulation of the E387 airfoil, before the new hydrofoil design is simulated. The results show the presence of a laminar separation bubble that affect the performance of the hydrofoil at low Reynolds numbers, and a new design is proposed to alleviate these effects.