GB851304A - Fuel supply system - Google Patents

Abstract

851,304. Gas-turbine fuel systems. HOLLEY CARBURETOR CO. Jan. 30, 1958, No. 3089/58. Class 110 (3). A main fuel pump 16 delivers fuel from a tank 10 to the main combustion chamber 12 of a jet-propulsion engine through a metering valve 34 and can also deliver fuel to a reheat combustion chamber 14 by way of a throttle valve 106 and a metering valve 114. The metering valves 34, 114 are operated manually by a lever 46 and cams 42, 122 with, preferably, additional automatic control in accordance with compressor discharge pressure and (in the case of valve 34 only) engine speed and engine inlet air temperature. The pressure drop across the metering valve 34 is stabilized by a by-pass valve 64 which is subjected to the pressure drop and returns fuel to the tank 10 through a by-pass passage 60. Further by-pass valves 80 and 90, subjected to the pressure drop across a restriction 72 in the by-pass passage and therefore controlled by the flow through the by-pass valve 64, return fuel to the tank 10 respectively from the main fuel pump 16 and an auxiliary fuel pump 18. The relative strengths of the springs of the valves 80 and 90 are such that valve 90 is fully opened before valve 80 begins to open, so that the auxiliary fuel pump 18 is completely unloaded until the demand exceeds the capacity of the main fuel pump 16 (or a failure of the main fuel pump occurs). Check valves 26, 28 prevent recirculation of the output of one pump through the other pump. The throttle valve 106, subjected in the closing sense to the pressure drop across the metering valve 114, serves to stabilize the flow to the reheat combustion chamber 14. Preferably, an upper limit is set to the pressure drop across the restriction 72 by means of a valve 74, designed to open when the pressure drop reaches a predetermined value.