Experimental Investigation of Pitching and Plunging Airfoils at Reynolds Number between 1x10^4 and 6x10^4

An experimental investigation was performed on a nominally two-dimensional pitching and plunging SD7003 and flat plate at Reynolds number 1 × 10, 3 × 10, and 6 × 10. The experiment was conducted at the University of Michigan water channel facility using phaseaveraged particle image velocimetry (PIV) technique to quantify the flow field. Two sets of airfoil kinematics were used in this study; a combined pitching and plunging motion, and a pure plunging motion. The flow topology and wall velocity profiles from the PIV measurements showed a Re dependence on a pitching and plunging SD7003 where the extent of flow separation is reduced at a relatively high Re. On the contrary, flat plate displayed a large leading edge separation flow characteristic that was independent of Re. For both airfoil cross-sections used in the experiment, turbulence statistics indicated laminar to turbulent transition phenomena at low Re. The study shows the leading edge shape effect on the flow transition and separation characteristics. A pure plunging motion of SD7003 and flat plate at Re = 60,000 showed the formation of the leading and trailing edge vortices. In addition, a quantitative analysis showed an apparent phase lag present on SD7003 relative to the flat plate. In order to validate the experimental data, a flow comparison between the University of Michigan and AFRL was performed.