Title: Roughness receptivity in swept-wing boundary layers – computations

Authors: Richard G. Rhodes, Helen L. Reed, William S. Saric, Andrew L. Carpenter, Tyler P. Neale

Addresses: Aerospace Engineering, Texas A&M University, College Station, Texas 77843-3141, USA. ' Aerospace Engineering, Texas A&M University, College Station, Texas 77843-3141, USA. ' Aerospace Engineering, Texas A&M University, College Station, Texas 77843-3141, USA. ' Aerospace Engineering, Texas A&M University, College Station, Texas 77843-3141, USA. ' Aerospace Engineering, Texas A&M University, College Station, Texas 77843-3141, USA

Abstract: The crossflow instability responsible for transition over a swept wing has been found to be ultra-sensitive to micron-sized roughness at the leading edge. Transition-predictive tools are limited because of the lack of models connecting physical roughness characteristics with initial and boundary conditions needed by the computational codes. The Texas A&M Flight Research Lab (FRL) is currently conducting flight tests of a laminar flow 30° swept wing model (SWIFT – swept wing in flight tests) mounted vertically below the port wing hard-point of a Cessna O-2A Skymaster and operated at chord Reynolds numbers on the order of 7.5 million. Various roughness configurations are correlated with local skin-friction measurements downstream. As a companion to the flight experiments, the group has engaged in a computational study aimed at relating roughness features to the resulting initial amplitude of the instability. This will provide a critical connection between stability analysis design tools and transition location prediction.

Keywords: roughness receptivity; swept wings; 3D boundary layers; experiments; laminar flow control; discrete roughness elements; crossflow instability; hotfilm sensors; disturbance amplitude variations; disturbance wall shear stress.

DOI: 10.1504/IJESMS.2010.031878

International Journal of Engineering Systems Modelling and Simulation, 2010 Vol.2 No.1/2, pp.139 - 148

Published online: 27 Feb 2010 *

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