Device for controlling the bleed of air from a gas turbine engine compressor

摘要

1,115,968. Valves. ROLLS-ROYCE Ltd. 17 Oct., 1966, No. 46378/66. Heading F2V. [Also in Division G3] A bleed valve for controlling the bleed of air from a gas turbine compressor comprises a valve closure 33 controlling bleed ports 32, the valve being connected to a piston 28 which is actuated by a pure fluid switch. The pure fluid switch comprises a main jet 20 fed from a second stage compressor 13 and control jets 62, 65 fed from a first stage compressor 12. The jet 62 is fed from a chamber 63 supplied through a restrictor 64 and the pressure at 65 is normally below the pressure at 62 so that the main jet flows through duct 22 and acts in a chamber 24 on piston 28 to close the bleed valve. In the event of surge, the pressure P 2 supplied to the control jets drops suddenly causing a rapid drop at jet 62 and the higher pressure at 65, due to the chamber 63, switches the main jet to duct 23. The main jet then flows past non-return valve 57 to chamber 25, thus opening the bleed valve, while part of the flow in duct 23 flows through passage 66 to provide a further or holding switching action on the main jet. The valve acts as a quick opening, slow closing valve. When the valve opens, the fluid in chamber 24 is exhausted first through a duct 55 and then through non- return valve 41, after the port 55 has been closed by the piston 53. When the valve closes, the fluid in chamber 25 can only exhaust through an adjustable bleed 45. The bleed valve may be actuated for a normal control function instead of as a surge control by the control jets being connected to certain pressure sources such as compressor pressure, down stream pressure or ram pressure. In a modification, the movement of the bleed valve varies a restriction in one of the control jet supplies to oppose closing movement of the bleed valve.