A Numerical Model for the Flow Within the Tower of a Tornado-Type Wind Energy System

The two-equation k–ε turbulence model is used to predict numerically the flow within the tower of a tornado-type wind energy system. Calculations are carried out for a tower in a uniform flow. Both cases of closed-bottom tower and simulated turbine flow with a variety of turbine-to-tower diameter ratios and turbine flow rates are considered. Calculated values of pressure for closed-bottom tower are compared with experimental values. Considerable reduction of the pressure drop is found due to the interaction of the nonrotating axial flow from the turbine with the vortex within the tower. Values of the maximum power that can be extracted by the turbine are estimated for a given set of tower flow boundary conditions. The optimum ratio of turbine-to-tower diameters was found to be around 0.4.