EXPERIMENTAL STUDY ON THE CHARACTERISTICS OF THE NEAR WAKE OF A BLADE-LIKE BODY WITH AN AXISYMMETRIC CROSS-SECTION ROTATING ABOUT ONE END (2ND REPORT, INFLUENCES OF THE TIP CLEARANCE FLOW).

The characteristics of the wake of a blunt body near its tip were investigated experimentally. When the tip clearance is large, the downwash flow is so large that the radial component of the velocity in the wake promotes mixing and diffusion of the wake. Therefore the velocity recovery is rapid and the width of the wake increases quickly in the wake. The velocity fluctuation in the wake becomes irregular, and vortex shedding disappears near the tip of the body. On the other hand when the tip clearance is small, the downwash flow is weak and near the tip of the body the dead air region becomes large as a result of gathering the low energy fluid. So the mixing and diffusion in the wake are inactive, and the regularity of the velocity fluctuation in the wake is kept up to the tip of the body.