Proceeding International Conference and Exhibition on Sustainable Energy and Advanced Materials (ICE SEAM 2011) Solo-Indonesia. October 3-4, 2011 ISSN 2088 8864. 174 The investigation on the effect of the blade numbers on the performance of a horizontal axis wind turbine utilizing a parametric study of the Blade Element Momentum theory Ridway Balaka 1),* , Aditya Rachman 2) , Jenny Delly 3) 1,2, 3) Department of Mechanical Engineering of Haluoleo University, Kendari Southeast Sulawesi, Indonesia * Corresponding author. Tel: +62 271632163, Fax: +62 271632163, E-mail: aditya_rchmn@yahoo.com Abstract The mechanism of the kinetic energy conversion has been utilized in many applications in renewable energy technologies. One of the applications is a horizontal axis wind turbine. In deciding the number of the blade to be put into the turbine design, instead of the design costs and the construction constraints, the effect of the number on the performance also is one of the aspects needed to be considered. Many studies attempt to investigate theoretically, computationally and experimentally the effect of blade number on the turbine performance. But, it seems that less comprehensive information is derived from these studies regarding to the factor contributing to the results of the investigation. This study investigates the effect the number of blades on the performance of the horizontal axis wind turbine in a variation of a rotation operation and a wind velocity, and attempts to explore comprehensively the reason behind the results of the investigation. The method utilized is a parametric study using the mathematical model of the Blade Element Momentum theory. The results show that in all variation of the velocity, turbines with high blade numbers reach its maximum performance at a low rotation, while the turbines with the lower blade numbers reach its maximum performance at a higher rotation. Other fact form this investigation is that for all blade number turbines, at a low wind velocity, turbines reach its maximum performance at a low rotation, while at a high velocity turbines reach its peak performance at a higher rotation. It is found that a torque, a velocity at rotor and a wind relative angle generated contribute in shaping the phenomena in the results of the investigations. Keywords: Performance, Blade Number, Wind Turbine 1. Introduction The conventional fossil fuel energy is a finite resource that will gradually disappear and its utilizations inevitably pose the concerns on the climate change. The clean renewable energy technologies can be an alternative option in delivering the energy in more sustainable and environmentally friendly. One of the technologies which meet these criteria is the mechanism of a harnessing of the kinetic energy of a natural moving fluid for a power generation. The wind turbine, one of the technologies using the kinetic energy mechanism, has been developed rapidly and are about to play important role in a new energy field (Ohya 2010). A horizontal axis wind turbine is one of the technologies which is believed to offer some beneficial features, including the high efficiency, easy starting, less torque fluctuation, and high speed operation (Anyi 2010) (Khan 2009). In dealing with a decision on the number of blades to be put into a design of a horizontal axis wind turbine, it is not only considering the design costs and the construction constraints, but also its effect on the turbine performance. It is apparently reasonable that the more blades mean the more performance derived. But the modern horizontal wind turbines generally have only a small number of blades. Some works has been conducted to investigate theoretically, computationally and experimentally the effect of the blade number on the performance of the horizontal axis wind turbine.