Abstract
Wells turbine has inherent disadvantages in comparison with conventional turbines: relative low efficiency at high flow coefficient and poor starting characteristics. To solve these problems, the authors proposed Wells turbine with booster turbine for wave energy conversion. This turbine consists of three parts: a large Wells turbine, a small impulse turbine with fixed guide vanes for bi-directional airflow, and a generator. It was conjectured that, by coupling the two axial flow turbines together, pneumatic energy from oscillating airflow is captured by Wells turbine at low flow coefficient and the impulse turbine gets the energy at high flow coefficient. The performance of turbines under steady flow conditions has been investigated experimentally by model testing. Furthermore, we estimated mean efficiency of the proposed turbine under oscillating flow conditions by quasi-steady analysis, in order to investigate the effect booster diameter on the mean efficiency.
