Flow Structure Past a Canonical Shape of Engine/Pylon/Wing Installation for Takeoff/Landing Conditions

Abstract

Here, a canonical model is proposed, which is able to represent the flow past a wing equipped with a pylon-mounted engine at low speed/moderate angle of attack. The vortices that develop past this model are described numerically and experimentally. For such configurations, the presence of a power-plant installation under the wing initiates a complex and unsteady vortical flowfield at the nacelle/pylon/wing junctions, responsible for a drop in aircraft performances. To gain insight into the underlying physics, the geometry is simplified into a symmetric two-dimensional extruded wing equipped with a symmetric, hemispheric-ended cylinder. The study was conducted at a Reynolds number of 200,000, based on the wing chord and on the freestream velocity. Two angle of attack angle configurations are investigated on the basis of unsteady Reynolds-averaged Navier–Stokes computations, oil-flow visualizations, and stereoscopic particle image velocimetry. The vortex dynamics thus produced is described in terms of vortex core position, intensity, and size. The analysis of the velocity flowfields obtained from the wind-tunnel measurements and the numerical computations highlights the influence of the longitudinal vortex initiated at the pylon/wing junction on the separation process of the boundary layer near the upper-wing leading edge.