GB790292A - Improvements in or relating to gas-turbine engine combustion equipment - Google Patents

Abstract

790,292. Generating combustion products under pressure; combustion chamber walls. ROLLS-ROYCE, Ltd. Jan. 26, 1955 [Feb. 26, 1954], No. 5813/54. Class 51 (1). Gas-turbine engine combustion equipment comprises a first wall which defines a combustion space and a second wall spaced from the first on the side thereof remote from the combustion space, pressure cooling air being fed to the space between the walls, the first wall being formed of a multiplicity of relatively small pieces arranged mosaic-wise with their edges unjoined but close to one another. At least those edges of adjacent pieces which extend in directions transverse to the direction of gas flow through the equipment afford between them restricted air leakage flow passages into the combustion space whereby the leakage flow of air flows over substantially the whole of the interior surface of the first wall. The combustion equipment shown in Fig. 1 comprises an air casing 10a and a flame tube disposed therein, the flame tube wall comprising an outer wall 10 and an inner wall formed by a number of small mosaic pieces 12 which are formed with integral stems 13 which pass through apertures in the outer wall 10 and are welded or riveted thereto. The stems may be solid or may have air inlet bores 16 through them; the bores may be of venturi shape. The mosaic pieces may be of rectangular, triangular or hexagonal shape, and openings through the flame tube wall may be formed by apertures such as 11 in the outer wall 10 and by omitting the mosaic pieces in line therewith. In a second embodiment, Fig. 2, series of holes are drilled at right angles to each other in a thick plate and one surface of the plate is formed with series of slots 23, 24 in line with the axes of the drilled holes, thereby forming small mosaic pieces 25 which are supported by the stem pieces 22 from the continuous outer wall 26. In Fig. 3 a series of H- section metal strips are disposed side-by-side and the flanges 30 at one side are connected together by welding while a series of saw cuts 32 are made across the flanges 31 at the other side thereby forming a number of mosaic pieces 33. A series of holes 36 are drilled through the webs 35 of the H-section strips which thus divide the webs into a number of pieces, each supporting a mosaic piece 33 from the outer wall formed by the flanges 30. In Fig. 4 a plate 40 has a series of parallel fins thereon, the fins being slotted at 41 to produce a series of short webs 42. A second sheet 43 is attached by welding to the webs 42 and series of slots 44 are formed in the plate 40 to produce a number of mosaic pieces 45, each supported by a web 42. In Fig. 5a a flame tube wall is formed by winding a single strip of H-section spirally, the mosaic pieces 33 being formed as in the embodiment of Fig. 3. Fig. 6 shows a flame tube in which mosaic pieces are supported on a structure comprising longitudinal rods 62 mounted in end rings 63, 64, intermediate rings 65 being disposed between the end rings. The mosaic pieces comprise sheet metal pieces 66 having tabs at their circumferential ends, the tabs being hooked over the rods 62. In a similar construction the mosaic pieces are formed by casting, one end of each piece having a bore by which it is mounted on a rod 62, and the other end having a tongue which engages a groove formed in the end of the adjacent mosaic piece. The flame tube shown in Fig. 8, is formed by a number of H-section strips disposed longitudinally, similar to the construction of Fig. 3. Circumferentiallyextending slots 32a are formed in the inner flanges to provide the mosaic pieces 33, while similar slots formed in the outer flanges 30 and webs 35 have ring members 38 welded therein to divide the passages between the webs 35 into a number of axially separated sections. Air is admitted to the spaces between the webs 35 through holes 37. It is stated in the Provisional Specification that the constructions are applicable to furnace walls and combustion chambers generally. Specification 790,293 is referred to.