When a powerplant air intake is mounted close to an aircraft wing or body the possibility exists of it ingesting part of the boundary layer formed on the adjacent surface. Even if the boundary layer is not ingested directly, the spillage flow from a boundary layer diverter may under some conditions affect the main intake flow. In full-scale free-jet tests of an intake or powerplant it would be desirable to represent any adjacent surfaces, but usually the size of the test facility is insufficient to allow this.

This note describes the first tests of a device, developed at NGTE, which at supersonic speeds generates in a short axial distance a layer of low energy air with a pressure distribution approximating to that of a “natural” turbulent boundary layer.