Numerical investigation on the performance of double layered h-rotor darrieus turbine

Abstract

Performance of wind turbine has been investigated for a long period of time.As a result,the design of both Horizontal Axis Wind Turbine and Vertical Axis Wind Turbine hasbeen improved. However, still there is opportunity to increase its efficiency. The Vertical Axis Wind Turbine (VAWT) has the advantage over Horizontal Axis Wind Turbine (HAWT) for working on omnidirectional air flow without any additional control system. A double layered H-rotor Darrieus type VAWT is investigated numerically in this thesis, which is a lift based wind turbine. The effect of solidity (i.e. chord length x no. of blades / radius of turbine) on power coefficient (CP) of H-rotor for different tip speed ratios has been numerically simulated and studied. The study has been conducted usingunsteady RANS equations and SST k-ω turbulence model. SIMPLE algorithm is used for pressure-velocity coupling and the second order upwind discretization scheme is chosen for getting accurate solution.Different parameters are compared, which depict the performance of the double layered H-rotor Darrieus type VAWT.The double layered H-Darrieus VAWT is found to be a higher speed lower torque machine compared to the single layered H-Darrieus VAWT, which can generate power at higher maximum power coefficient forhigher solidity vertical axis wind turbines. Double Layered staggered H-Darrieus VAWT offersmore stable power coefficient than the Double Layered in-line H-Darrieus VAWT withsolidity σ=1.5 near the tip speed ratio for maximum power coefficient.