MEASUREMENT OF HYDRODYNAMIC FORCES ACTING ON A CIRCULAR CYLINDER NEAR A PLANE BOUNDARY IN STEADY FLOW

In this paper,the characteristics of hydrodyna(?) forces on a circular cylindernear a plane boundary have been studied experimentally in w(?) tunnels.The drag coefficientC,mean lift coefficient C,T.m.s.lift coefficient C,maximum lift coefficient Candfluctuating lift coefficients C’,C’,and lift(vortex shedding)frequency have been mea-sured on condition that the thickness of plane boundary layer,δ,was 0.1D(D is the diameter ofthe cylinder)at the station of the centre of the cylinder,and Reynolds number,Re,varied from4.5×10~3 to 1.76×10~5.The regularity of the change of these coefficients with Re and gap ratioG/D is found.The measurement of the lift frequency shows that a strong non-linear coupling ac-tion appears when the gap ratio between the circular cylinder and plane,G/D,reaches 0.5,andthe shedding of regular vortex is suppressed when G/D=0.2.