초록 ▼

Method and apparatus for providing a turbofan blade 40 adapted to initiate and control a boundary layer transition at a side surface of the blade 40 during operation as a component in a turbofan assembly 35. The turbofan blade 40 includes a leading edge 55, a trailing edge 58, and two side surfaces

Method and apparatus for providing a turbofan blade 40 adapted to initiate and control a boundary layer transition at a side surface of the blade 40 during operation as a component in a turbofan assembly 35. The turbofan blade 40 includes a leading edge 55, a trailing edge 58, and two side surfaces including a high-pressure side surface 49 and a low-pressure side surface 52. At least one of the two side surfaces has an essentially smooth surface portion 61 located between the leading and trailing edges, and the essentially smooth surface portion is interrupted by a surface deviation 64. The surface deviation is configured to fix a positionally unstable laminar to turbulent boundary layer transition 24 at 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.

대표청구항 ▼

The invention claimed is: 1. A method for limiting stress levels in an aircraft-powering turbofan assembly by controlling unstable movement of laminar-to-turbulent boundary layer transition on fan blades of the turbofan assembly during aircraft flight, said method comprising: including on a flying a

The invention claimed is: 1. A method for limiting stress levels in an aircraft-powering turbofan assembly by controlling unstable movement of laminar-to-turbulent boundary layer transition on fan blades of the turbofan assembly during aircraft flight, said method comprising: including on a flying aircraft, an aircraft-powering turbofan assembly comprising multiple fan blades mounted on a fan disc and each of said fan blades having a leading edge, a trailing edge, and two side surfaces that comprise a high-pressure side surface and a low-pressure side surface, each blade also having a relatively long chord length, said turbofan assembly being configured such that a laminar-to-turbulent boundary layer transition range occurs on the low-pressure side surface of each of said fan blades during flight; providing a plurality of said fan blades each with a laminar-to-turbulent boundary layer transition control feature at the low-pressure side surface of the respective fan blade, positioning each said control feature on the respective blade at a position that will initiate and positionally stabilize the laminar-to-turbulent boundary layer transition to a location upon the respective fan blade between said control feature and the respective fan blade's trailing edge that will substantially maintain an aggregate limited stress occurring in the turbofan assembly at a mounting of the respective fan blade to the fan disc to below fifty megapascals during flight within the aircraft's operating envelope.