The effectiveness of tripping wire on boundary layer transition and turbulence measurement of the wire wake.

Abstract

Experimental studies were performed to investigate the effect of a tripping wire on the boundary-layer transition over a 15 degree wedge in an external free stream. Turbulence measurements were carried out in the range from the wake of the wires to the laminar-turbulent transition region. The results indicated that the tripping wire becomes effctive at the wire Reynolds number R-k (=U∞xk/ν) larger than Rk1 where Rk1=570 (zk/k) -4.3×103, and that the transition Reynolds number Rt (=U∞xt/ν) at the most effective condition is given as the formula Rt =1.06 Rk+1.33×104, in which U∞ denotes the free stream velocity, xk and xt the location of the wire and the transition point measured from the apex of the wedge, respectively, k the wire diameter andνthe kinematic viscosity of the fluid. The Reynolds number in the experiments ranged from U∞xk/ν=(0.09-2.0) ×105 and xk/k=25 to 200.