GB660007A - Improvements relating to turbine rotor blades - Google Patents

Abstract

660,007. Turbine blades. BOLSEZIAN, G. July 9, 1948 [July 9, 1947], 18504/48. Class 110(iii) In a hollow turbine blade formed of an assembly of at least three elements one of which is an at least partly inner element and at least two of which are outer elements in contact with the hot gas, the outer elements form an empty space around part of the at least partly inner element through which cooling medium flows and every leading edge or portion of the leading edge and every trailing edge or portion of the trailing edge has both its front and back faces on the same element. The blade, Fig. 1, comprises three blade elements 1, 2 and 4. The element 1 is integral with the rcot 3 and the element 2 is secured at its outer end to the rod or support 4 by means of a rivet 5 or welding. The rod 4 is secured to the root by a screw connection 12 or a dovetail. The rod 4 is isolated from the hot parts 1 and 2 by the provision of a space 7, through which cooling air supplied through ports 10 passes. This cooling air exhausts through slots 11 and blows off the boundary layer. To damp vibration in the blade, there is a friction fit between the interengaging end portions 8, 9 of the parts 1, 2. The element 2 may be formed in two halves of ceramic material which are separated by longitudinal gaps 11, Fig. 2. The two halves are assembled at their outer ends by a metallic cup member and at their inner ends by the blade element .1. In a modification. Fig. 4, the blade consists of two outer elements 25, 26 and a partly inner element 22 which is longer than the outer elements. The elements 25, 26 which form the blade profile are separated by a gap 29 and are assembled by a weld 28. Cooling air supplied through the conduit 30 exhausts through the outer end of the gap 23. In Another modification, Fig. 6, the blade is formed by a partly inner element having a core 37 which is integral with the root and the leading and trailing edges 45 and 46 of the blade. Two outer elements 42, 43, formed by profiled sheets are attached to the core 37 by welds 44: so as to form cooling air spaces 40, 41. The Specification as open to inspection under Sect. 91, comprises also a blade similar to that described with reference to Fig. 4 except that the parts 25, 26 are formed integral with one another and are attached to the root of the inner element 22. In another embodiment, the blade is also similar to that described with reference to Fig. 4 except that the two outer elements each constitute one face of the blade. In a modification of the arrangement described with reference to Fig. 6, the blade is formed from a single casting and the cooling air spaces 41, 42 may be divided into two or more passages. It is also stated that the internal surfaces of the elements 1, 2 and or the external surface of the rod 4 may be polished or provided with a polished stainless metal surface coating of nickel, chromium or platinum. This subject-matter does not appear in the Specification as accepted.