AIRFOIL SELF-NOISE GENERATED IN A CASCADE

Self-noise from fans and rotors is generated by blade boundary-layer t urbulence interacting with the trailing edges of the blades. Previous theories describing this mechanism have considered only an isolated ai rfoil and have shown that acoustic scattering from the sharp trailing edge is responsible for the sound that propagates to the far field. In aeroengine applications, fans or stators have relatively high solidit y, and there will be acoustic scattering from adjacent blades as well as the blade locally excited by the how The theory is given for self-n oise from a fan modeled as a linear cascade of semi-infinite flat plat es. The magnitude of the self-noise mechanism is compared with the fie ld that would be generated by a single airfoil without adjacent blade scattering.