Power and Ventilation Performance Study in a Modified Vertical Axis Wind Turbine Based on Semi-analytical Approach

In the current research, a novel vertical axis wind turbine producing both power and ventilation is presented. The idea is similar to an ancient wind catchers. The wind capacity of the Manjil city in Iran has been studied and a typical home-scale wind turbine has been assessed. To modify the geometry, a 3D semi-analytical code has been developed based on Double Multiple Stream Tube (DMST) theory. The validation analysis has been accomplished by the reference turbine. Using this code, the turbine performance including power coefficient and flow diversion index was studied. Particularly the effect of blade cone angle on the power deficiency and ventilation ratio was investigated. The results of the parameter study would reveal that for the optimal range of tip speed ratio, 2.9-3.2 based on the power curve, it is feasible to produce up to 400 m3/h ventilation flow and 50-200 W shaft power. It would be obtained by 20-degree blade inclination and is equivalent to 2.5% of the total flow entering the rotor. The power deficiency due to this change is 30% which is compromised by the ventilation capability. The results also revealed the optimal range of tip speed ratio is 2.9-3.2. . It is depicted that, power attenuation could be minimum when the suitable TSR and the appropriate geometry are selected. Finally, some generalized trends of the objective functions also have been drawn. The methodology is versatile for the ongoing problems in the field of vertical axis wind turbines.