High-Fidelity Simulations of Transitional Flow Over Pitching Airfoils

Presented is a high-fidelity, computational study of transitional flow over an airfoil as it is pitched up from an initial zero incidence to 40 at a nominally constant pitch rate, held, and then returned in a similar manner. The Reynolds numbers were chosen to bracket the regions of laminar and transitional flows applicable to prototypical micro air vehicle conditions, 5 × 10 ≤ Rec ≤ 4 × 10. A high-order, implicit large eddy simulation technique was employed to show the degree of fidelity required to capture these highly transitional flows. Two-dimensional analyses examining the effects of Reynolds number and pitch rate were conducted and a discussion is provided. Additionally, the impact of transition and spanwise extent on the flowfield and force histories were explored through three-dimensional, spanwise periodic simulations. These simulations were shown qualitatively to compare extremely well with available experimental observations.

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