Split Gap Effects on Rear Fuselage Flow

E. Valero, J. de Vicente, and L. Lacasa (Spain)

Keywords

Gap, Cavity problems, CFD, liverearend techniques.

Abstract

In wind-tunnel analysis of rear fuselage and empen nage flows it is usual to consider a twin-sting mount ing arrangement together with live-rear-end measuring technique. For this technique a split between the for ward and rear fuselage exists. The split gap allows for a secondary flow induced by the pressure field of the tail-plane and wing. The secondary flow would not only distribute the boundary layer on the rear fuselage but also induce a pressure change on the rear part, which can seriously affect the measurement precision and accuracy. Applying CFD techniques, numerical simulations of the flow around a simplified model are considered. These simulations solve the Navier-Stokes equations with specifical flow conditions -Reynolds and Mach numbersfor different configurations: gap width, gap location, and rear fuselage deflection. The re sults show that the crossflow appearing in the split gap is quasi-independent of the input free-stream only for symmetric gaps. A suction effect inside the gap is also put into relevance.

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