GB673961A - Improvements relating to gas turbine power plant installations - Google Patents

Abstract

673,961. De-icing aircraft. ROLLS-ROYCE, Ltd. July 3, 1950 [April 5, 1949], No. 9302/49. Class 4. [Also in Groups XXVI and XXXV] In gas turbine plant comprising an air compressor, combustion equipment and a turbine in which air is tapped off from the compressor and supplied to a separate combustion chamber the hot gases of which are used for de-icing purposes, the fuel supply to the separate combustion chamber is controlled so as to maintain the temperature of the gas at the outlet side of the combustion chamber constant and the air supply to the separate combustion chamber is controlled by a temperature determined in part by the ambient air temperature and in part by the temperature of the de-icing gases. The temperature determined in part by the ambient air temperature and in part by the temperature of the de-icing gases may be the temperature of a surface on which ice is liable to form and which is arranged to be de-iced or the temperature of the air in the intake passage between the mouth of the nacelle and the compressor rotor. Air from the compressor discharge manifold 11c is led through a duct 16 to a separate combustion chamber 14 which supplies hot gases to the air flowing into the nacelle through struts 18. The air supply to the combustion chamber is controlled by a throttle valve 20 operated by an electric motor 32 which receives power from an electronic amplifier 31 in response to signals from a thermocouple element 30 located in the air intake passage to the compressor. The fuel supply to the combustion chamber is controlled by a throttle valve 23 operated by an electric motor 26 which receives power from an electronic amplifier 25 in response to signals from a thermocouple element 24 located in the discharge duct 15 from the combustion chamber. The power supplies to the amplifiers 25 and 31 are controlled by a relay 28 which is energised when a pilot-operated push button 29 is depressed. The relay 28 also energises ignition means 22 and solenoids controlling valves bypassing the throttle valves 23 and 20. The flow through the by-passes 40, 43 are arranged to give a predetermined ratio of fuel to air which is ignited by means 22 at starting. Under these conditions the combustion chamber is not alight and the thermocouples 24, 30 are inoperative. Arrangements in which the fuel supply is controlled by a valve in a by-pass pipe around the fuel pump and in which the thermocouples 24, 30 are replaced by electrical resistance elements are described. In a modification the electronic amplifiers are replaced by actuator and follower elements of the selsyn type connected to the thermometric device and air throttle respectively. In a further modification, the thermometric device is used to control the air throttle by closing electrical contacts and an actuator device, moved in accordance with the movement of the air throttle may cause movement of a follower element which breaks the power circuit to the air throttle. Specification 618,224 is referred to.