1. A first stage turbine disk section for a gas turbine engine, comprising:
(a) a centrally disposed disk hub having a radially outwardly extending web terminating at an outer end; and
(b) the disk hub having a convex, continuously curved hub surface defining an apex positioned at a medial location on the hub surface opposite the outer end, the location of the apex selected so as to reduce the peak axial compressive stress by forcing the principal stress field to transition from being primarily axially oriented to primarily radially oriented, the continuously curved hub surface acting to reduce the effective axial constraint at the apex and to separate the peak axial and hoop stresses such that the surface effective stress is optimized to its minimum value, thereby mitigating the formation of undesirable axial stress in the disk hub.
2. A gas turbine section according to claim 1, wherein the disk hub includes only a convex, continuously curved hub surface and no cylindrical or frusto-conical hub surface areas thereon.
3. A gas turbine section according to claim 1, wherein the convex, continuously curved hub surface is positioned to shift maximum axial stress and hoop stress on the disk hub out of mutual alignment, thereby reducing the magnitude of the effective stress on the hub surface.
4. A method of reducing axial stress in a disk hub of a gas turbine disk, comprising the steps of:
(a) determining the location of stress gradients in a gas turbine disk hub;
(b) forming a convex, curved surface section in a disk hub surface of the disk hub that axially displaces peak axial stress relative to peak hoop stress and reduces the peak axial stress, thereby reducing the magnitude of the effective stress on the disk bore surface.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. In a fiber optic system, a method for aligning a beam of light and an optical fiber comprising
a central core and a cladding, comprising the steps:
directing said beam of light toward said optical fiber,
detecting light in the cladding of said optical fiber;
adjusting the relative orientation of said beam of light and said optical fiber until said light detected in said cladding reaches a minimum.
2. A method according to claim 1 further comprising determining a minimum
3. A method according to claim 2 wherein said determining a minimum step comprises:
sweeping said beam of light across a face of said optical fiber,
monitoring the amount of light detected by said cladding detector as said beam of light sweeps across said face, and
selecting a smallest value corresponding to light detected by said cladding detector during said sweeps.
4. A method according to claim 1 wherein said minimum corresponds to no light being detected in said cladding.
5. A method according to claim 1 wherein light travelling down the core of said fiber is not measured in connection with said adjusting step.
6. A method according to claim 1 wherein said beam of light is caused to move in a first axis at a first frequency and in a second axis at a second frequency, and the amount of light detected in said cladding is filtered according to said frequencies.
7. A method according to claim 1 comprising detecting light in said cladding from a plurality of locations around a circumference of said fiber.