Performance enhancement of Wells turbine: Combined radiused edge blade tip, static extended trailing edge, and variable thickness modifications

摘要

The Wells turbine is used in conjunction with an oscillating water column to harvest wave energy. It is a self-rectifying axial flow reaction turbine which consists of symmetrical blades aligned normal to the incoming flow. A narrow operating range due to flow separation restricts the power extracting capability of the turbine at a higher flow rate. To improve its performance, a turbine blade with combined design modifications such as radiused edge blade (RED) tip, static extended trailing edge (SETE) and variable thickness blade (VTB) was investigated through CFD analysis. Three-dimensional time independent Reynolds-averaged Navier-Stokes equations were solved in a commercial solver to obtain the turbine performance, which was given by non-dimensional torque, pressure drop and efficiency. The combined REB tip, SETE and VTB modifications enhanced relative average turbine power output by 97% and the relative operating range by 22%. However, the average efficiency is decreased by 7.7%, because of the increased pressure drop.