A preliminary 3D computational fluid dynamics analysis of the Wells Turbine has been carried out to investigate secondary flows of the actual blade geometry of the power plant on the island of Pico, and the effect of adding sweep and taper to the blade geometry. Gambit and Fluent are used for pre-processing, analysis and post-processing. The analysis was carried out at a blade tip Mach Number of 0.5 and inviscid, compressible flow is assumed. Results obtained indicate that the swept profile postpones separation on the blade tip for longer and also that the Pico blade gives rise to the most blade to blade interaction.
The Wells turbine has been a major focus since its invention in 1976 by Dr. A.A.Wells. Its unique ability to generate a uni-directional rotational motion out of an oscillating axial air flow of relatively low magnitude has made it the ideal tool to harness wave power. However, the air turbine has limited range of operation and low efficiency. Many researchers have concentrated on finding the right aerofoil and symmetrical profile to minimise these drawbacks. Feasible methods used are: classical axial flow machines prediction methods (radial equilibrium approach and actuator disc theory) Raghunathan (1995), experimental investigation using small-scale rigs and numerical analysis (CFD). Though CFD techniques were being used since 1960's, it was only in the 1990's that it was widely adopted as it was recognised to be economical, sufficiently complete and user-friendly. CFD has the advantage of being faster than the other two options as it is computerised and cheaper than experimental work. The purpose of this report is to analyse and compare qualitatively the performance of the turbine with the actual Pico profile, with addition of backward sweep and finally addition of taper to the blade.
