GB1504348A - Fuel distribution arrangement of a gas turbine engine - Google Patents

Abstract

1504348 Gas turbine engine fuel control systems V P DMITRIEV A M POLYAKOV A G TOMILIN AND S M SHUSHPAN 17 Sept 1975 38285/75 Heading F1G. The invention relates to a fuel supply system for a gas turbine engine, fuel being supplied to a pilot fuel manifold 8 having pilot burners 9 and to a main fuel manifold 5 having main burners 6. Fuel is supplied by a pump 30 to a metering device 4 comprising a metering valve 17 movable in a valve chamber 18, fuel discharging to line 3. The line 3 is connected through line 7 and valve 32 to the pilot manifold. The line 3 also connects through line 2 to a distributer 1 which comprises a fixed orifice 11, a spring-loaded valve 12, and a speed-controlled valve 13. At engine starting, fuel passes through lines 3, 7 to the pilot burners 9, also through lines 3, 2 and orifice 11 to the main burners 6 which are thus primed, the valves 12 and 13 both being closed at this stage. As the engine accelerates, the compressor discharge pressure increases, the metering valve 17 opens to allow increased fuel flow, the valve 12 opens against the loading of spring 15 whereby fuel now flows to the main burners 6. As the engine speed reaches a predetermined value, the valve 13 opens and fuel now passes through the valve 13 to the main burners, in effect by-passing the valve 12 and the orifice 11. The metering valve 4 is controlled in dependence on compressor discharge pressure P 2 , compressor inlet pressure P 1 and engine speed. Pressure P 2 is transmitted through line 25, chamber 24 and line 23 to the interior 22 of bellows 20 which is disposed in chamber 21 to which pressure P 1 is conveyed. As P 2 increases, the lower wall of the bellows moves downwardly whereby the metering valve 17 moves upwardly to increase fuel flow in lines 3, 2. Upon overspeed sensed by device 28, the valve 27 opens to allow pressure P 2 in chamber 24 and so in bellows chamber 22 to fall causing metering valve 17 to move to reduce fuel flow. The construction of the valve 12 is shown in detail in Fig. 2 (not shown) the valve comprising a sensor 41 responsive to ambient temperature which operates so that as ambient temperature falls, the spring force acting to open the valve is reduced whereby the fuel pressure required to open the valve is increased. The increased fuel pressure causes the swirl type pilot burners to correctly atomize the fuel whereby starting of the engine at low ambient temperature conditions is improved. The converse action occurs when ambient temperature increases.