Curved blade turbomachinery noise reduction

Abstract From the Canadian patent

Abstract, A turbomachinery stage comprising two axially spaced blade rows, one of which is rotatable, wherein the blades of the upstream row are contoured to present a leaned wake to the downstream row. In the preferred embodiment, the blades of the upstream row extend radially from a central hub and, at a radius above the hub, are physically curved circumferentially from a radial line through the hub. The physical lean locally complements the inherent aerodynamic lean at each radius such that the integrated acoustic power of the stage is essentially at a minimum thus maximizing the acoustic, attenuation Preferably, the constraint is imposed that the blade physical curvature is essentially …