1- Isfahan Univ. of Tech.
Abstract: (7026 Views)
The ratio of lift to drag coefficient in wind turbine blades is within the most important parameters affecting the power coefficient of wind turbines. Due to the performance of Magnus wind turbines in low speed air flow; such turbines are attractive for research centers. In the present work, a new geometry for the blades of Magnus wind turbines is defined. The defined geometry is based on the geometry of a Treadmill with a difference that the diameter of its leading circle is greater than that of its trailing one. In the present work, the body is supposed to a low speed air flow while a tangential velocity is applied to the airfoil surfaces and then, its effect on the lift and drag coefficient is studied by numerical method. The effect of generated tangential velocity on the surfaces is investigated for different air flow speed and attack angles and then, its results are compared with that for stationary surfaces. The results show that generating tangential velocity along the surfaces caucuses the lift and drag coefficients and, their ratio to be varied, greatly. By the tangential movement of the surfaces, the maximum ratio of lift to drag coefficient occurs in zero attack angle which is equal to 109. Moreover, maximum magnitude of lift to drag coefficient for attack angles 5, 10, and 15 degrees are 81, 64, and 57; respectively.
Article Type:
Research Article |
Subject:
Aerodynamics Received: 2014/09/6 | Accepted: 2014/10/27 | Published: 2014/11/30