Experiments on incompressible turbulent boundary layers with distributed injection

Abstract

An extensive series of mean velocity measurements on the incompressible turbulent boundary layer with distributed injection is described. Boundary-layer developments have been measured along a porous flat plate under a variety of conditions, using 'Vyon' sintered polythene as the porous surface. The experiments included both zero and non-zero pressure gradients but were restricted to air-to-air injection without heat transfer. The boundary layer developments were measured with injection rates between 0 and 0.008 at free stream velocities of 50 and 150 ft/sec while some additional velocity profiles at one station only with injection rates up to 0.0145 were also measured. In addition, an experiment on a bounary layer where the injection rate was suddenly reduced to very nearly zero has been carried out. Direct measurements have been made to determine whether any significant convergence or divergence of the tunnel flow or significant static pressure variations through the boundary layer were present. The question of the aerodynamic smoothness of the porous surface used is also discussed. All the results obtained are presented in tabular form.