Experimental Study of the Effect of Static Pressure on Turbulent Friction Reduction in Gas Saturation of Boundary Layer

Abstract

The article presents the results of an experimental study of the effect of static pressure on reduction of turbulent friction on a plate in gas saturation of the boundary layer. The experiments were carried out on the hydrodynamic stand of the Research Institute of Mechanics of the Moscow State University in the flow rate range U = 4–11 m/s and the static pressure range P = 10–200 kPa, the Reynolds number varied in the range of (3–8)×106. The local friction was measured with a “floating wall” sensor on a strain gage balance, and the gas was blown through a special permeable coating. It was shown that increase in the gas flow rate through a porous wall of flat plate test model could make the reduction of the local friction as high as 80–90%. However, increase in the static pressure in the flow significantly lowered the efficiency of control of the turbulent shear stresses. The friction reduction due to gas saturation of boundary layer depends on the gas flow rate (ceteris paribus) and the static pressure in the flow, which one should take into account when performing integral estimate of the efficiency of the method and assessing the energy loss for gas inlet into the flow.