GB812557A - Improvements in or relating to gas turbine power plants - Google Patents

Abstract

812,557. Gas turbine jet propulsion plant. WESTINGHOUSE ELECTRIC INTERNATIONA.L CO. Oct. 10, W55, No. 28751/55. Class 110 (3). A gas turbine power plant fuel control comprises a speed governor for controlling the supply of fuel to the combustion chamber and a mechanism responsive to the pressure downstream of the compressor inlet for modifying the setting of the speed governor to limit the ratio of N/#T to a maximum value where N is the angular velocity of the power plant and T the absolute temperature at any point in the power plant upstream of the turbine inlet. The fuel supply to main combustion apparatus 22 is controlled by a speed governor 32 the controlled speed of which is set by a throttle or power lever 38 acting through a cam on an adjusting member 40. Electrical automatic temperature control apparatus 41 is used to control an actuator 31 which varies the area of the exhaust nozzle 15 in accordance with temperature conditions in the engine and the position of the power lever 38 by eyelid members 28a, 28b. The temperature control apparatus 41 has a temperature reference voltage unit 42 connected to a manual temperature scheduling potentiometer 43 and a control amplifier unit 46 connected to a thermocouple 47 disposed in the turbine exhaust. The contact member 50 of the potentiometer 43 is actuated by the power lever 38 and is electrically connected to one end of the temperature setting potentiometer 51. With the above arrangement, the area of the exhaust nozzle 15 is varied in accordance with the position of the power lever 38 to maintain a desired temperature in the engine for each position. of the power lever. To limit the stresses in the power plant the speed governor is modified to limit the ratio N/#T to a maximum value just below that at which the stresses reach their allowable limits. For this purpose a control unit 60 is provided. The control unit is responsive to the pressure difference between a pressure in the compressor obtained from a probe 63 and ambient pressure admitted to the housing 61 through an aperture 82. A rod 66 operated by the control unit 60 in response to this pressure difference rotates a shaft 67 which modifies the setting of the speed governor 32 to a lower value and at the same time varies the setting of the potentiometer 51 to reduce the temperature setting of the reference voltage unit 42. The control unit 60 also operates when fuel is injected through the spray pipe 24 into the turbine exhaust. To prevent further adjustment of the temperature scheduling potentiometer 43 in this range, a portion 43a having zero resistance is provided. The probe 63 may be disposed anywhere in the compressor between its inlet and outlet and the aperture 82 may be connected to a point upstream of the probe 63 and need not necessarily communicate with the ambient air. The thermocouple 47 may be disposed upstream of the location illustrated.