Experimental Hydrodynamics of the Accelerated Turbulent Boundary Layer With and Without Mass Injection

Abstract

Mean velocity-profile data are reported for blown, unblown, and sucked accelerated turbulent boundary layers. The pressure gradients investigated are those corresponding to constant values of the pressure-gradient parameter K=νU∞2dU∞dx The two values of K considered in detail are 0.57 × 10−6 and 1.45 × 10−6. For each pressure gradient, the surface boundary conditions cover a range of constant blowing and sucking fractions from F = −0.002 to +0.004. Velocity profiles corresponding to these accelerated flows are shown to differ substantially from those characteristic of zero-pressure-gradient flows. For each case of a constant K acceleration, sequential values of the momentum-thickness Reynolds number approach a specific constant, and the velocity distributions near the wall are similar in both wall coordinates and outer coordinates. Results obtained here can be reproduced by a numerical integration of the boundary-layer equations using a modification of the van Driest damping factor, A+, derived from the data presented here. The A+ correlation is presented.