Modelling the Performance of a Vertical Axis Wind Turbine with Cambered Tubercle Leading Edge Blades

Abstract

Numerical simulations using computational fluid dynamics (CFD) to solve the Reynolds-Averaged Navier-Stokes (RANS) equations in vertical axis wind turbine (VAWT) systems has been remarkably helpful in the performance improvement of VAWTs. In this study, a 5 kW three-bladed H-rotor Darrieus VAWT with cambering and tubercle leading edge (TLE) incorporated as blade passive motion controls was modeled in computer-aided design geometry and fluid environment mesh, and simulated in a solver to predict its aerodynamics and performance. TLE modification on a cambered airfoil VAWT was shown to be detrimental to flow and performance using torque, lift and drag data. Results were further verified using the vorticity profiles of z-vorticity and Q-criterion where the baseline cambered VAWT showed streamlined flow generally throughout one full VAWT rotation while the TLE VAWT generated explicitly massive vortices the size of the blade chord at blade wakes that increased drag and reduced torque. Negative torque values reaching −3.59Nm were monitored to cause the overall performance degradation. TLE blades in the VAWT generated turbulence instead of reducing it. The TLE VAWT harnessed only 9.28 W of the 137.8 W available wind power.