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: 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.