An Experimental Study of Fluid Forces Applied on a Circular Cylinder in Air Flow with 1/7 Power Law Velocity Distribution through Horizontal and vertical Duct

摘要

The present paper discusses the effects of the velocitygradient of air flow and the clearance between circularcylinder and inner surface of duct wall on the fluid forceapplied on a circular cylinder immersed in air flow with1/7 power law velocity distribution in a horizontal andvertical duct. The pressure distributions on a circularcylinder and duct walls are measured and the pressure liftand drag are analysed, using jointly a pendant method. Theconclusions attained are summarized as follows:(1) The 1ift due to the flow velocity gradient is appliedin the direction from the side of the higher velocitytoward the side of the lower velocity, and increasesas the velocity gradient becomes steeper.(2) The lift due to the clearance between circular cylinderand duct wall is applied in the opposite direction tothe lift due to the velocity gradient, and increasesas the clearance becomes smaller.(3) The resultant lift due to the velocity gradient anddue to the clearance vanishes at a clearance ratio,and turns over the applying direction across it.(4) The drag applied on the circular cylinder is almostindependent of the velocity gradient.