Patent GB-790834-A (GB)
Title: Improvements in or relating to gas-turbine engine cooling arrangements
Inventor: LOMBARD ADRIAN ALBERT
IPC: F02C7/047
Filed: 1954-01-25
Abstract: 790,834. Gas-turbirse plant. ROLLSROYCE, Ltd. Jan. 7, 1955 [Jan. 25, 1954], No. 2248/54. Class 110 (3). [Also in Groups XXIX and XXXVII] A gas-turbine plant for a high - speed aircraft in which sealing or cooling air is supplied to the internal components of the engine through a duct which is fed with ram pressureized air has means associated with the duct to assist or create flow through the duct when the the pressure of the ram air is insufficient to cause the desired air flow. Ram pressurized air is stated to be air compressed solely by the motion of the engine relative to the atmosphere. Cooling air is distributed to the internal components of the engine such as the bearing 15, Fig. 1, by means of a hollow shaft 14 which is supplied with ram-pressurized air through an inlet duct 16 formed in the bullet 17. This air may also be used for sealing purposes at locations in the working fluid duct where the pressure of the working fluid is always below the pressure of the cooling and sealing air. When the aircraft is flying at low speeds or stationary, an injector 23, supplied with compressed air from the engine compressor by a pipe 24, is provided to induce an adequate flow of cooling air. An ejector at the downstream end of the shaft 14 may be provided instead of the injector 23. The flow through the pipe 24 is controlled by a valve 25 actuated in accordance with the flight Mach. No. by means of a pitot static tube 26. When the aircraft Mach. No. exceeds a preselected value, the diaphragm 27 closes the switch 28 and energizes the solenoid 29 which closes the valve 25 against the action of the spiing 31. In a modification the switch 28 is operated by means responsive to the temperature of the air in the air intake. If desired, the switch 28 may be operated by the difference between the intake temperature and the static ambient temperature or the absolute pressure of the ram air or the difference between the pitot and static pressures. In another modification, Fig. 4 (not shown), the control valve is regulated by means responsive to the ratio between the ram pressure at the intake and the pressure at which the cooling air is vented to atmosphere, which pressures are directly related to the rate of cooling air flow. These pressures are applied to a pair of diaphragms of unequal area actuating a leak off valve which controls a bellows power device operating a valve controlling the air supply through the duct 24. The pipe 24 may also be arranged to supply anti-icing air to the bullet 17. A ferrule 36 having ports 38 leading to a space 37 between the skins of the bullet is provided in the duct 24. In this case a valve controlled by-pass is arranged around the valve 25 so that air may be supplied to the bullet when the valve 25 is closed due to the ram pressure being high enough to avoid the use of the injector. When the aircraft is flying at high speed, the temperature of the ram air may be too high for efficient cooling. A butterfly valve 41 in the inlet passage 16, an inward flow turbine 42 and control sleeve valve 43 are therefore provided. The butterfly valve 41 and sleeve valve 43 are operated by a piston 50 so that when valve 41 is open, valve 43 is closed and vice versa. When the temperature of the ram air is too high, the temperature-sensitive element 60 actuates a piston valve 65 so that fluid from the pressure connection 67 is supplied to the left-hand side of piston 72 which moves to the right and operates a pair of valves 74, 75, connected to conduits 76, 77 leading to opposite ends of the ram cylinder 51, so that pressure fluid is supplied to the righthand end of the cylinder and the piston 50 moves to the left and opens the valve 43 and closes the valve 41. The cooling air then passes through the turbine 42 before entering the duct 14 and is thereby cooled. The power of the turbine 42 is used to assist the drive of the engine compressor. Instead of operating the valves 41, 43 simultaneously, the valve 43 may be opened before the valve 41 is closed and vice versa to avoid cutting off the cooling air supply. The valves 41, 43 may be operated by any of the variables referred to for controlling the valve 25 but will be operated at a selected value of the variable higher than that at.which the valve 25 is operated. In the compound gas turbine, Fig. 3, the low-pressure compressor rotor 113 is driven by the lowpressure turbine 116 through a hollow shaft 115 and the high-pressure compressor rotor 122 by the high-pressure turbine 124 through a hollow shaft 123. The rotors 113, 122 are supported by bearings 117, 125 in a housing 118. The shaft 123 is supported by a bearing 126 carried by a backbone structure 127. The shaft 115 is supported from the shaft 123 by a bearing 132. Cooling air is distributed through the engine by means of a sleeve 114 mounted in the low-pressure compressor rotor 113 and the shaft 115. The sleeve 114 is open at its forward end to receive the ram-pressurized air. Some of this air passes through ports 136 and around the bearings 117, 125 to ports 140 where it is exhausted to atmosphere. Another part of this air flows through ports 138 and around the bearings 132, 126 to passages 143 in the structure 127 from which it passes to atmosphere through the hollow nozzle guide rams 129 and ports 144. Another part of the air flowing through the shaft 115 may be arranged to flow through orifices at its downstream end to between the downstream face of the turbine disc 116 and the upstream face of the exhaust bullet 142 to provide sealing air which flows into the exhaust duct through the gap 141. To ensure an adequate flow of cooling air when the aircraft is flying at low speeds or stationary, air is tapped from the high-pressure compressor and led through a manifold 147, conduit 148, control valve 149, transfer manifold 151, duct 150 and the space between the skins of the nose fairing 134 to the injector 145. The valve 149 is controlled in a similar manner to the valve 25. In other arrangement, the inlet of the expansion turbine may be connected to the delivery of a stage of the compressor of the engine. Specification 790,836 is referred to.