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 coefficientCD,mean lift coefficient CL0,T.m.s.lift coefficient CL Tms,maximum lift coefficient CL max andfluctuating lift coefficients C’L Tms,C’L max,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 from4.5×103 to 1.76×105.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.