Mitigation of unsteady peak fan blade and disc stresses in turbofan engines through the use of flow control devices to stabilize boundary layer characteristics

Abstract

Method and apparatus for providing a turbofan bladeadapted to initiate and control a boundary layer transition at a side surface of the bladeduring operation as a component in a turbofan assemblyThe turbofan bladeincludes a leading edgea trailing edgeand two side surfaces including a high-pressure side surfaceand a low-pressure side surfaceAt least one of the two side surfaces has an essentially smooth surface portionlocated between the leading and trailing edges, and the essentially smooth surface portion is interrupted by a surface deviationThe surface deviation is configured to fix a positionally unstable laminar to turbulent boundary layer transitionat a location toward the trailing edge from the surface deviation during operation of the turbofan blade in the turbofan assembly. In this manner, fatigue inducing and/or structurally damaging unsteady aerodynamic forces experienced upon the blade and/or fan disc during operation are controlled, and the resultant fluctuating fan blade and disc peak stresses are mitigated.