The effect of a duct on the design and performance of a horizontal axis turbine is investigated. A new Blade Element Axial Momentum Theory, which is based on previous scholarly work, is proposed to design ducted horizontal axis turbines. The theory is general in the sense that it is applicable to both ducted and unducted horizontal axis turbines. Furthermore, the performance enhancement predicted by the theory is tested using a commercial Computational Fluid Dynamics (CFD) code. Finally, the blades are compared structurally using a commercial Finite Element Analysis (FEA) code. A good agreement between the improvements suggested by the theory and the CFD simulations is found and the importance of the back pressure coefficient is substantiated. Most importantly, the performance of the turbine is increased without producing additional thrust on the blades and the starting torque is improved significantly.
