Aeroacoustic analysis of a NACA 0015 airfoil with Gurney flap based on time-resolved PIV measurements

The present study investigates the feasibility of high-lift devices noise prediction based on measurements of time-resolved particle image velocimetry (TR-PIV). The model under investigation is a NACA 0015 airfoil with Gurney flap with height of 6% chord length. The velocity fields around and downstream the Gurney flap are measured by PIV and are used for the PIV-based noise predictions. The predictions are assessed via microphone measurements. Since the Gurney flap height is much smaller than the emitted acoustic wavelength, the source of noise can be considered compact and the integral implementation of Curle's analogy based on the unsteady aerodynamic loads can be followed. The results are compared with the simultaneous microphone measurements in terms of time histories and power spectra. The integral formulation of Curle's analogy yields acoustic sound pressure levels in good agreement with the simultaneous microphone measurements for the tonal component. All the calculated far-field noise power spectra reproduce the peak at vortex shedding frequency, which also agrees well with the microphone measurements.