Heat Transfer Enhancement by Means of a Rotation Cylinder

Heat transfer measurement has been done for the low speed channel flow with an insertion of a rotation circular cylinder near the channel wall in order to find the ways to achieve the dynamic control of the wall heat transfer. It was found that the cylinder rotation was quite effective to achieve large heat transfer enhancement including the power loss required for the cylinder rotation. Counter clockwise rotation (the direction to accelerate the gap flow) intensifies the motion of the unsteady vortex shed from the cylinder and this enhances the wall heat transfer over relatively long downstream area of the cylinder. Heat transfer enhancement becomes large as the rotation speed becomes higher and then shows the largest at a certain rotation speed. On the other hand, clockwise rotation (decelerate the gap flow) suppresses the vortex formation and decreases the heat transfer at low speed rotation. However, high speed rotation induces the fast flow approaching near the wall and can achieve large heat transfer there.