Computational investigation of the effects of surface imperfections and excrescences on the crossflow instability
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This paper describes a computational investigation and companion to the current work at the Texas A&M Engineering Experiment Station (TEES) Flight Research Lab (FRL). The FRL is both operating an O-2A aircraft and conducting wind tunnel tests in the Klebanoff Saric Wind Tunnel (KSWT) in the investigation of surface excrescences on the transition of laminar to turbulent flow. Using a finite-element Navier-Stokes solution and a spectrally accurate boundary-layer solver, coupled with linear and nonlinear stability analyses, it is proposed to quantify the effect of surface imperfections and outer mold line (OML) non-uniformities on crossflow instabilities. The quantitative goal of the proposed research is to computationally evaluate a wide parameter space of step heights and gaps, and develop correlation models between geometry and estimated effect on transition for use by designers. The proposed computations will be validated against experiments on the physical model both in-flight and in the KSWT, and vice versa, in a tightly integrated program. This paper is a companion paper to Effects of Step Excrescences on Swept-Wing Tran- sition by Duncan et al. also submitted to the 31st Applied Aerodynamics Conference.
author list (cited authors)
Tufts, M. W., Duncan, G. T., Crawford, B. K., Reed, H. L., & Saric, W. S.