Abstract: An air inflow control device (10) simulates flight-like air inflow conditions into the intake (36) of a turbofan engine (18) during static ground tests. The device (10) has a truncated spherical portion (12) with a circular opening that is closed by a bellmouth (14). The bellmouth (14) provides an inwardly projecting conical surface having a central high-lite and throat portion (28, 35) that permits air to flow from inside the sphere (12) into the engine (18).

Abstract: A pair of cold air driven tubines are mounted in-line with each turbine driving one of two coaxial drive shafts. Each drive shaft is independently supported and separate drive air is supplied to each turbine such that the direction and speed of rotation of each drive shaft is independently controlled. Exhaust air from the forward turbine vents through an exhaust cavity that surrounds the aft turbine. Inlet drive air to the aft turbine is supplied via air ducts formed through the center of struts which extend radially from the inlet of the aft turbine, through the exhaust cavity and to an inlet port external to the turbine housing.

Abstract: A portable acoustic impedance measuring device 10 is provided for measuring the impedance properties of a panel 12. The device 10 includes a horn section 14 having a flexible plate 18. The plate 18 can assume the curvature of the duct panel 12. The horn section 14 is supported adjacent the panel's surface by a spindle shaft 28 which spans or bridges the inside diameter of the duct 12. The curvature of the plate 18 may be locked to hold the curvature of any of a variety of different panels having various sizes and shapes.

Abstract: Disclosed is a turbulence control structure for use during static noise testing of jet aircraft engines. A flow transparent substantially spherical geodesic dome defined by a modified 9-frequency icosahedral frame encloses the intake of a jet engine on a test stand. The surface of the dome is covered by flat flow panels constructed of aluminum honeycomb adhesively bonded to stainless steel perforated sheet. The combination of perforated sheet and honeycomb attenuate streamwise and transverse components of inflow distortions in the intake air entering the engine. As a result, clear inflow is achieved, engine speed is stabilized, and engine intake noise approximating that of in-flight operation are achieved.