Observation of the Starting and Low Speed Behavior of Small Horizontal Axis Wind Turbine

This paper describes the starting behavior of small horizontal axis wind turbines at high angles of attack and low Reynolds number. The unfavorable relative wind direction during the starting time leads to low starting torque and more idling time. Wind turbine models of sizes less than 5 meters were simulated at wind speed range of 2？m/s to 5？m/s. Wind turbines were modeled in Pro/E and based on the optimized designs given by MATLAB codes. Wind turbine models were simulated in ADAMS for improving the starting behavior. The models with high starting torques and less idling times were selected. The starting behavior was successfully improved and the optimized wind turbine models were able to produce more starting torque even at wind speeds less than 5？m/s. 1. Introduction From ancient times the kinetic energy of the wind is used for various household activities like milling of wheat and corns. In the 1980s blade element momentum theory was presented. Based on blade element momentum theory various wind turbine designs were proposed for various wind conditions. In areas of high wind speeds large wind turbines can be installed. For areas of low and medium wind speeds small wind turbines are installed. It is not possible to start wind turbine at low wind speeds, so changes should be made in the existing wind turbine models in order to increase their sensitivity [1, 2]. The wind turbine material should be such that it can withstand the environmental impacts and also it should have a density in a specific range [3]. To increase the lift force in order to start the wind turbine at wind speeds various designs must be tested. In developing countries the practical experimentation is not possible so computer simulations are usually carried out to get the optimized design for a specific area [4]. Clausen and Wood [5] also worked on improving the starting behavior of horizontal axis wind turbines and they concluded that the root region of the wind turbine blade is responsible for generating the initial torque. Singh and Ahmed [6] practically made various wind turbine models of wood with low Reynolds number and they suggest various models for low and medium wind speed areas. Singh and Ahmed [7] tested various low Reynolds profiles for various low wind speeds and at various pitch angles. Habali and Saleh [8] carried out the static proof-load and field performance tests and then they designed a wind turbine model with 41.2% power coefficient. Song and Tan [9] designed 20？kW wind turbine blades. The optimized blade parameters were produced using MATLAB and the dynamic