The Eighth Asia-Pacific Conference on Wind Engineering, December 10–14, 2013, Chennai, India EFFECT OF PITCH ANGLE ON BLADE - TOWER INTERFERENCE ON HAWT N. I. Haroon Rashid 1 , S. Nadaraja Pillai 2 , C. Senthil Kumar 3 . 1 Research Scholar,Department of Aerospace Engineering, MIT Campus, Anna University Chennai, TN, India, aeroharoonrashid@gmail.com 2 Department of Aeronautical Engineering, J. J. College of Engineering & Technology, Tiruchirapalli, TN, India, aeropillai@gmail.com 3 Department of Aerospace Engineering, Madras Institute of Technology, Anna University, Chennai, TN, India, cskumar@annauniv.edu ABSTRACT In the wind turbine, the distribution of wind is altered by the presence of the tower. For upwind rotors, the flow of wind in front of the tower is redirected thereby reduces the torque at each blade. The performance of the wind turbine is affected by such influence of interference. Hence, it is important to understand the flow interference between blade and tower. In this research, the wind turbine blade with various pitch angles has been studied both computationally and experimentally. The result shows that the influence of interference leads to negative pressure region on the tower where the blade interference occurs. Hence this leads a slowdown of rotor locally for every 120 degree, this in turn affect the power performance and decrease the structural stability. Keywords: Tower Shadow, Interference, HAWT, pitch angle Introduction For horizontal axis wind turbine, the interaction between the tower and the blade creates flow complexity and leads to reduced power performance. Even though various unsteady effects in the wind turbines such as atmospheric boundary layer, turbulence intensity of the upstream flow, yaw effect of the nacelle, wake of the neighboring turbines, upstream blockage effect dominates; this has been discussed by many researchers. However the interference between the wind turbine blade and its tower and also the influence of the blade pitch angle interaction needs further more research attention. This effect is discussed widely as tower shadow and most of the effect on downwind turbine wake model is discussed by Wang and Coton. Also they concluded that the discrepancies arise when the angle of attack of the blade experiences higher value. Experimental study by Orlando et al., found that there is 35% of velocity reduction in the anemometer reading the anemometer is in the downstream of the turbine tower. Chattot studied with vortex model for the simulation of the tower shadow and its effect on the blade working conditions as analyzed with the blade root flap bending moment. The importance of rotor in the upwind and downwind configurations and its importance is discussed by chattot. Amada et al., showed the decrease in power output by around 6% due to the various effect including tower shadow. Dolan and Lehn discussed about the normalized power output and its effect in terms of wind shear and the tower shadow effect. They found that the tower shadow and wind shear combinely reduce 6% of the power output. In this research wind turbine model has been made both computationally and experimentally in order Proc. of the 8th Asia-Pacific Conference on Wind Engineering – Nagesh R. Iyer, Prem Krishna, S. Selvi Rajan and P. Harikrishna (eds) Copyright c  2013 APCWE-VIII. All rights reserved. Published by Research Publishing, Singapore. ISBN: 978-981-07-8011-1 doi:10.3850/978-981-07-8012-8 158 1172