Title: Computational design of a test article to investigate 2-D surface excrescences on a swept laminar-flow wing

Authors: Matthew W. Tufts; Glen T. Duncan Jr.; Brian K. Crawford; Helen L. Reed; William S. Saric

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

Abstract: The construction of a spanwise-invariant swept-wing test article designed to facilitate the inclusion of a range of two-dimensional (2-D) step and gap excrescences in flight via an internal articulation mechanism has been completed. Using a finite-element Navier-Stokes solution and a spectrally accurate boundary-layer solver, coupled with stability analyses, the model has been designed to be subcritical to all instabilities except the crossflow instability. The model can be safely flown in a flight experiment, and be mounted in the Klebanoff-Saric Wind Tunnel at Texas A&M University. The model can be tested at multiple angles of attack (pressure gradients), as well as multiple Reynolds numbers, including unit Reynolds numbers typical of transports. Stability behaviour of the test article was designed to be conducive to a thorough examination of the interaction between an inherent crossflow instability and the shear layer created by the step and gap excrescences. The computations and experiments will together provide data and correlations complementing the previous studies of 2-D excrescences on an unswept flat plate and wedges subject to favourable pressure gradients by The Northrop Grumman Corporation. The current paper focuses on the design and stability analyses of the smooth-wing test article, that is, without excrescences present, as a baseline configuration.

Keywords: excrescences; 2-D roughness; laminar turbulent transition; crossflow instabilities; swept wings; flight research; computational fluid dynamics; CFD; linear stability theory; LST; parabolised stability equations; PSEs; finite element method; FEM; Navier-Stokes; angle of attack.

DOI: 10.1504/IJESMS.2014.063123

International Journal of Engineering Systems Modelling and Simulation, 2014 Vol.6 No.3/4, pp.181 - 190

Published online: 26 Jul 2014 *

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