Global Wall Interference Correction and Control for the National Wind Tunnel Complex Transonic Test Section,
ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFS TN
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As part of the currently postponed National Wind Tunnel Complex NWTC program, a computational fluid dynamic CFD study of a large transport configuration was performed using the AEDC chimera-overset grid XAIR Euler code. Wall porosity, porosity control for the reduction of wall interference, correction approach, and the impact of reference point selection on wall interference at transonic conditions Mach Number 0.85 were studied. These effects were computationally investigated using a clean wing model representative of the MD-11 aircraft which spanned 80 percent of the test section width. Global wall corrections were determined by a stream tube calculation of the interference flow field. Results of these computations showed that global corrections for Mach number at the 14 chord, 50-percent semi-span location with angle-of-attack correction based on matching wing lift gave very low interference. Investigation of control of porosity showed that very few zones were required to achieve superior results for global corrections and for model pressure distribution. Residual blockage gradient and flow-curvature effects are shown to be treatable by very small changes in side-wall divergence angle and model geometric changes that are equivalent to shearing the coordinate system aft of the wing-fuselage juncture.
- Fluid Mechanics