WO1994012390B1

WO1994012390B1 - Coolable rotor blade structure

Info

Publication number: WO1994012390B1
Application number: PCT/US1993/010683
Authority: WO
Filing date: 1993-11-04
Publication date: 1994-10-13

Abstract

A coolable rotor blade (14) is disclosed. Various construction details are developed to decrease tensile stresses in critical regions of the airfoil (20). In one embodiment, the center of gravity of the airfoil sections (28) is shifted forwardly in the outward direction to decrease tensile stresses in the trailing edge region (36).

Claims

AMENDED CLAIMS [received by the International Bureau on 1 September 1994 (01.09.94); original claims 1, 4, 5 and 7 amended; remaining claims unchanged (3 pages)]

1. A coolable rotor blade structure for a rotor blade having a root, a tip, an airfoil extending spanwisely from the root to the tip about a radial line, the airfoil having a leading edge region and a trailing edge region, and a pressure side wall and a suction sidewall which are joined at the leading edge region and extend spanwisely to bound a cavity for cooling air on the interior of the blade the trailing edge region having a pressure sidewall surface and a suction sidewall surface and a plurality of openings for discharging cooling air from the airfoil, which comprises:

a spanwisely extending portion of the airfoil which extends from the root to a radial location between the root and the tip and which is formed of a plurality of airfoil sections, each airfoil section extending generally perpendicular to the radial line, extending parallel to the remaining airfoil sections in said portion and having a center of gravity which is disposed with respect to a plane parallel to the pressure sidewall surface in the trailing edge region such that the center of gravity of each section is rearwardly of the center of gravity of the remainder of the spanwisely extending portion of the airfoil that lies between said section and the tip; and,

a cooling air passage in flow communication with the cavity for cooling air in proximity to the leading edge region such that the leading edge region is cooled by cooling air in the cooling air passage;

wherein the trailing edge region has stress concentrations associated with the trailing edge openings under operative conditions;

wherein the stress in the trailing edge region under operative conditions is a tensile stress;

wherein the leading edge region is cooled by the cooling air which enables the leading edge region to better accommodate tensile stresses than the trailing edge region; and

wherein the location of the center of the gravities causes a

compressive force to be exerted by the airfoil in the spanwisely extending portion to decrease tensile stresses in the trailing edge region at the root region under operative conditions and to exert a tensile force in the leading edge region which increases tensile stresses in the leading edge region, the leading edge region being better able to acommodate tensile stresses than the trailing edge region because of cooling of the leading edge region and stress concentrations in the trailing edge region that result from the trailing edge openings.

2. The coolable rotor blade structure of claim 1 wherein the spanwisely extending portion of the airfoil extends from the tip.

3. The coolable rotor blade structure of claim 2 wherein the spanwisely extending portion of the airfoil includes the tip of the airfoil.

4. The coolable rotor blade structure of claim 1 wherein the trailing edge region is generally planar on the pressure sidewall surface and wherein the trailing edge region has a trailing edge and the trailing edge is curved forwardly over the spanwisely extending portion when viewed in a direction generally perpendicular to said planar surface.

5. The coolable rotor blade structure of claim 2 wherein the trailing edge region is generally planar on the pressure sidewall surface and wherein the trailing edge region has a trailing edge and the trailing edge is curved forwardly over the spanwisely extending portion when viewed in a direction generally perpendicular to said planar surface.

6. The coolable rotor blade structure of claim 4 wherein the trailing edge region has a plurality of slots which place the interior of the coolable rotor blade in flow communication with the exterior.

7. The coolabbl rotor blade structure of claim 5 wherein the trailing edge region has a plurality of slots which are the openings that place the interior of the coolable rotor blade in flow communication within the exterior.