Experimental study on the directivity and noise reduction of the blade leading-edge noise using Inverse Method SODIX based on microphone array

Taking the NACA65(12)–10 blade as the object, a linear microphone array based on the SODIX (SOurce DIrectivity modeling in the cross-spectral matriX) method is used to study the leading-edge (LE) noise directivity of the baseline and the effect of the wavy LE on the LE noise directivity. First, a SODIX data processing program was developed, and the program was validated by numerical simulation. The validation results show that the data processing program has a good accuracy with an error less than 0.26 dB. Then, a linear array with 31 microphones is designed to identify the LE noise directivity of the baseline and the wavy LE blade experimentally in a semi-anechoic chamber. Within the measured degree range of 40°–142°, the directivity of LE noise shows a characteristic of typical dipole sound sources with a peak occurs at 130°. Besides, the higher the frequency is, the more obvious of the ‘lobe’ distribution of the LE noise directivity is. Further analysis shows that the wavy LE with various amplitudes and wavelengths especially with larger amplitudes can reduce LE noise in measured angle ranges especially among 90°–120°. And the maximum value is 7.71 dB for A30W20.