| 摘要 |
<p>839,883. Axial-flow compressors; gas turbine plant. ROLLS-ROYCE Ltd. Nov. 27, 1957 [Dec. 19, 1956], No. 38779/56. Classes 110 (1) and 110(3). A gas turbine engine comprises a compressor, an abstracting means permitting cooling or sealing air to be abstracted from the compressor at a number of pressure locations therein, and control means including valving controlling abstraction of air from a selected one of the pressure locations while preventing abstraction at the other pressure locations. In the axialflow compressor shown, forming part of an aircraft gas turbine engine, air for cooling and sealing purposes is bled from a low-pressure stage at a tapping 18, which may be of the form described in Specification 712,051, and passes from an annular manifold 20 into the hollow rotor shaft 10 through ports 22. The air leaves the shaft through ports 27 and enters a chamber 28 to cool the shaft bearing 17 and seal it against the inward flow of hot air, leaving through a port 28a to provide a cooling flow between the shaft and the combustion equipment. When a cylindrical valve 25 is moved axially to a position in which a flange 25a closes the ports 22, ports 26 in the valve register with ports 23 in the shaft to permit air to be bled from a higher-pressure tapping 19. A piston 29 formed in the valve 25 and enclosed by an enlarged cylindrical portion 30 of the shaft 10 is exposed on one side to the relatively high pressure of a tapping 32, and is exposed on the other side to a pressure which, when a valve 34 is in the position shown, is that of an atmospheric pressure location 36. When the valve 34 is in its alternative position, the pressure communicated to the piston 29 is that at a high-pressure tapping 35, and the piston is moved leftwardly to bring the valve 25 into its alternative position. The valve 34 may be operated manually or automatically in accordance with the pressure within the shaft 10, or the ratio of the pressure in the air intake 14 to the static ambient pressure, or the temperature at the intake 14 or within the shaft. In an alternative embodiment, the two bleed tappings are located at the outer casing of the compressor and are connected by separate pipes to a selector valve similar to the valve 34, a single pipe leading from the selector valve to the chamber 28. Specification 622,181 also is referred to.</p> |
