NACA0012 airfoil at Reynolds numbers between 50,000 and 140,000 — Part 1: Steady freestream

Abstract

The transitional flow past a NACA0012 airfoil at Reynolds numbers, $Re$, between 50,000 and 140,000 is investigated using experiments and low and high-fidelity numerical simulations. Variations in Reynolds number provide the quasi-steady response of the flow and resulting lift to dynamic inflow (varying freestream velocity) conditions addressed in a following paper. It is shown that non-linearity of the quasi-steady response in lift to changes in freestream velocity is highly dependent on angle of attack and is typically promoted when the flow transitions from laminar separation without reattachment to laminar separation with reattachment as the Reynolds number increases. The correlation between flow topology and lift is highlighted using the force partitioning method, which provides a new interpretation for the existence of a shift from negative to positive lift and slope breaks in the lift versus angle of attack (and Reynolds number) curve.