Milad Mohammadnejad - Department of Mechanical Engineering Urmia University of Technology Urmia, Iran Urmia, Iran
Reza Karimi - Department of Mechanical Engineering Urmia University of Technology Urmia, Iran Urmia, Iran
Salar Radman - Department of Mechanical Engineering Urmia University of Technology Urmia, Iran Urmia, Iran

In recent decades, due to the global energy crisis and the high emissions of greenhouse gases, research and development have led to increasing global activity in the field of renewable energy, especially wind energy. Due to the simplicity of design and manufacture, self-starting characteristics and operating independently of wind direction, Savonius wind rotors have been considered by many scientists. In the present article, using numerical simulation, the effect of a valve with a dynamic function on the blades has been investigated to reduce the impact of the force on the blade, whose concave surface lies behind the inlet flow. The results show that the average dynamic power coefficient has the maximum value at three different velocities and in all different ratios of the valve size, the tip speed ratio of the blade is equal to 0.8. At best, the ratio of the size of the valve is G/d= 0.025, as compared to the one without the valve, it can increase the dynamic power coefficient by 20.86%.