Flow Topology Over an Airfoil at Low Reynolds Number

Temperature Sensitive Paint (TSP) and InfraRed Thermography (IRT) have been employed to investigate the flow topology over the DU89-134 airfoil at chord based Reynolds numbers 𝑅𝑒𝑐 = 2.5 × 10^5 and 𝑅𝑒𝑐 = 5 × 10^5. Spanwise-averaged surface temperature distributions and their gradients were analyzed to determine the locations of flow separation, transition, and reattachment. Results indicate that at lower angles of attack, the flow is characterized by the separation-induced transition caused by the Laminar Separation Bubble (LSB), which decreases in size as the angle of attack and Reynolds number increase. At higher angles of attack, the flow transition from laminar to turbulent occurs without prior separation and the transition location shifts significantly upstream.