On the Static Performance of Two-Dimensional Intakes with Momentum Injection in the Form of Boundary-Layer Control by Blowing

摘要

A theoretical one-dimensional analysis has been used to calculate at zero forward speed the static pressure and total-pressure recovery far down the throat of two-dimensional intakes in terms of the mean inflow rate (or Mach number), the mean pressure on the forward-facing lip and the coefficient of con¬traction of the intake. Total pressure is lost at high mass flows with thin-lipped intakes, as it is impossible to satisfy the momentum equation with the intake running full and flow separation occurs.nAt a given intake Mach number, the effect of air injection at a downstream facing slot depends on its effect on the flow geometry. If the lip static pressure remains constant or changes only with the mass flow, the improvement in total-pressure recovery or in mass flow is in theory small and in practice the gains are outweighed by increased viscous losses associated with the blowing.