Wavelet analysis of the flow field around an oscillating airfoil undergoing pure pitching motion at low Reynolds number

This paper investigates the flow field around a NACA (National Advisory Committee for Aeronautics) 0012 airfoil undergoing pure pitching motion using continuous wavelet transform. Wind tunnel experiments were performed with test-stand that provides wide range of oscillation frequencies (f = 0–10 Hz). Sinusoidal was considered respect to quarter chord five reduced (K 0.05, 0.1, 0.15, 0.2, and 0.3) at Reynolds number Re 6 × 104. Mean angle attack pitch amplitude all cases 0° 6°, respectively. Unsteady surface pressure measurement conducted, lift coefficient calculated based on phase-averaged coefficient. The unsteady velocity distributions in wake have been measured employing rake. results indicate maximum value decreases by increasing frequency due “apparent mass” effects. For K close quasi-steady regime, cl-α loop approximately follows trend static case. Wavelet transform used as tool examine time series. Surface plots presence its superharmonics. Moreover, analysis shows third higher superharmonic are sensitive during cycle. reveals effective width gets smaller frequency. Furthermore, trailing edge vortices get weaker