Experimental Investigation of Trailing-Edge Noise from a Linear Cascade of Cambered Airfoils

International audienceCascade broadband trailing-edge noise is investigated experimentaly in an aeracoustic linear cascade of seven cambered airfoils immersed in a low Mach number ($M=0.23$) - low Reynolds ($Re_c = 5.3 × 10^5$) quiet flow. The solidity of the cascade is $\sigma = c/s = 1.43$ and the blade chord $c = 0.1$ m. Far field acoustic PSD follows a classical $U^6$ power law and scales with a Helmholtz number rather than a Strouhal number. Suction side surface pressure spectra $\Phi_{pp}$ are analysed and fitting laws are proposed for the spanwise coherence length $l_z$ and the convection velocity $U_c$ to apply three analytical models. Amiet’s isolated airfoil noise model is used to assess the extent of the blade-to-blade interactions in the experiment. It is able to reproduce the far field noise when the acoustic wavelength is smaller than the cascade pitch. However in the low frequency range the “cascade effect“ is found important reaching 15dB at 200Hz. Howe’s cascade trailing-edge model is applied but this model in the present form is not able to reproduce the measured noise spectra. Glegg’s cascade trailing-edge model shows a very good agreement in the mid to high frequency range $f > 800$ Hz. This work is supported by the 7th Framework European Project ${\it FLOCON}$