Mean Flow and Pressure in a Straight Suction Duct with Porous Walls

Abstract

SummaryThe mean flow of an incompressible fluid in a straight suction duct with porous walls is considered and relations between the inflow and the pressure difference required to produce it are established on the basis of an elementary momentum analysis. It is assumed that bom the velocity and the pressure across planes normal to the direction of the mean flow inside the duct are distributed uniformly everywhere and that the effect of obstructions, which do not alter significantly the area of the duct cross section at any position, can be described in terms of losses of total pressure which are proportional to the square of the local speed within the duct. A variety of cases is discussed and it is shown that calculation of the internal pressure is straightforward and in agreement with experiment, at least for the case of a pipe having uniform porosity.