Performance enhancement of Wells turbine: Combined radiused edge blade tip, static extended trailing edge, and variable thickness modifications. (1st August 2019) - Kumar, P. Madhan
Abstract: 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 (REB) 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. Highlights: A combination of blade design modifications is introduced to improve the operating range and power of the Wells turbine. The combined blade design enhanced the torque and provided a wider operating range. The relative stall margin and the turbine power is enhanced by 22% and 97% respectively.