Blades
Compressor fan blades have an isotropic core and composite fiber layers in an epoxy matrix. The fibers on opposite broad surfaces of the blade extend at an angle of between 25° and 35° to the blade length. The fibers on opposites sides of the blade are inclined in opposite senses such that extension force applied to the blade as it rotates produces opposing forces in the composite layers that resist untwisting of the blade. The thickness of the fiber layers varies from the leading edge to the trailing edge, being thicker towards the leading edge.
1. A blade for turbomachinery, said blade having a length, being twisted along its length and comprising:
a leading edge extending along the length of the blade;
a trailing edge extending along the length of the blade;
two opposed broad surfaces extending along the length of the blade and separated from one another by said leading and trailing edges; and
composite fiber layers adjacent respective ones of said opposed surfaces,
wherein said composite fiber layers on said opposed surfaces are arranged such that extension forces applied to said blade along its length produce opposing forces in said composite fiber layers resisting untwisting of said blade, and
wherein said fiber layers vary in thickness from said leading edge to said trailing edge, the lavers being thicker towards said leading edge than said trailing edge.
2. A blade according to claim 1 , wherein fibers in said composite fiber layers lie at an angle to said blade length of between about 25° and 35° in opposite senses on opposite sides of said blade.
3. A blade according to claim 1 , wherein said blade has an outer tip and a root, and wherein said outer tip is inclined at an angle of substantially 60° relative to said root when at rest.
4. A blade according to claim 1 , wherein fibers in said composite fiber layers are of a carbon material.
5. A blade according to claim 1 , wherein said composite fiber layers include fibers bonded into an epoxy matrix.
6. A blade according to claim 1 , wherein said blade has an isotropic core.
7. A blade according to claim 1 , including an outer surface layer of an impact-resistant material.
8. Turbomachinery including a plurality of blades according to claim 1 .
9. A gas-turbine engine including compressor fan blades according to claim 1 .
10. A blade for turbomachinery, said blade having a length, being twisted along its length and comprising:
a leading edge extending along the length of said blade;
a trailing edge extending along the length of said blade;
two opposed broad surfaces extending along the length of said blade and separated from one another by said leading and trailing edges; and
composite fiber layers adjacent respective ones of said opposed surfaces,
wherein fibers in said composite fiber layers on opposed surfaces are inclined with respect to one another such that extension forces applied to said blade along its length produce oppositely-directed shear forces in said composite fiber layers resisting untwisting of said blade, and
wherein said fiber lavers vary in thickness from said leading edge to said trailing edge, the lavers being thicker towards said leading edge than said trailing edge.
11. A blade according to claim 10 , wherein fibers in said composite fiber layers lie at an angle to the blade length of between about 25° and 35° in opposite senses on opposite sides of said blade.
12. Turbomachinery including a plurality of blades arranged for rotation about an axis, said blades each having a length extending radially of said axis, being twisted along its length and comprising:
a leading edge extending along the length of said blade;
a trailing edge extending along the length of said blade;
two opposed broad surfaces extending along the length of said blade and separated from one another by said leading and trailing edges; and
composite fiber layers adjacent respective ones of said opposed surfaces,
wherein said composite fiber layers on said opposed surfaces are arranged such that extension forces applied to said blades along their length produce opposing forces in said composite fiber layers resisting untwisting of said blades, and
wherein said composite fiber layers vary in thickness from said leading edges to said trailing edges, the layers being thicker towards said leading edges than said trailing edges.
13. Turbomachinery according to claim 12 , wherein fibers in said composite fiber layers lie at an angle to the blade length of between about 25° and 35° in opposite senses on opposite sides of said blade.
14. A gas-turbine engine including a plurality of compressor fan blades arranged for rotation about an axis, said blades each having a length extending radially of said axis and comprising:
a leading edge extending along the length of said blade;
a trailing edge extending along the length of said blade;
two opposed broad surfaces extending along the length of said blade and separated from one another by said leading and trailing edges; and
composite fiber layers adjacent respective ones of said opposed surfaces,
wherein said composite fiber layers on said opposed surfaces are arranged such that extension forces applied to said blades along their length produce opposing forces in said composite fiber layers resisting untwisting of said blades, and
wherein said composite fiber layers vary in thickness from said leading edges to said trailing edges, the layers being thicker towards said leading edges than said trailing edges.
15. A gas-turbine engine according to claim 14 , wherein fibers in said composite fiber layers lie at an angle to the blade length of between about 25° and 35° in opposite senses on opposite sides of said blade.