Experimental and Numerical Investigation to Assess the Performance of Helical Bach Vertical Axis Wind Turbine at Low Wind Velocity Conditions

Abstract

Many turbine models have been evolved to ameliorate the functioning of the small wind energy system. The newly developed helical Bach-type vertical axis wind turbine (VAWT) is used in this analysis with an idea to improve the overall performance. The shape of the conventional Bach-type vertical axis wind turbine is a modified form of a Savonius model which has both circular and straight portions to the blade profile. The simple Bach model has a maximum coefficient of performance corresponding to the blade arc angle of 45 deg and 225 deg. However, it consists of negative torque at the rotational angles of about 120–180 deg and 300–360 deg. Moreover, in the newly developed helical Bach, rotors can reduce the variation in torque in the rotational cycle; thereby, uniform torque is achieved in all angular position with improved performance. In this paper, experiments were conducted in the natural wind at Wind Turbine Research Station, Kayathar, Tamil Nadu, India. In addition to experimental work, the three-dimensional steady-state numerical investigations have been performed in the helical Bach vertical axis wind turbine. It is found that the numerical results are well matched with the experimental data. Based on the above computational study, it is found that helical Bach models have an increase in overall performance compared to the conventional Bach models and helical Savonius model.