GB797360A - Improvements relating to fuel systems for use with gas turbine engines - Google Patents

Abstract

797,360. Gas turbine plant. DOWTY FUEL SYSTEMS, Ltd. May 24,1956 [March 7, 1955], No. 6631/55. Class 110 (3). A gas turbine fuel system comprising a circulatory circuit which includes an enginedriven pump supplying a plurality of spill-type atomizers and a throttle valve in the return flow conduit between the atomizers and the inlet of the pump has in the circuit a first heat exchanger constituting a cooler for a fluid coolant such as engine oil and a second heat exchanger having a fuel cooling element disposed in an air passage, the flow of air through which cools the fuel under conditions of low fuel consumption. Fuel from a source (not shown) is fed through a filter 2 to the inlet of an engine-driven high pressure fuel pump 3 which discharges to spill type atomizers 5. The return flow pipes are connected in parallel with a return pipe 6 containing a servomotoroperated throttle valve 7. Fuel may return from the pipe 6 to the inlet pipe 1 in two ways. One way is through the heat exchanger 15 and control valve 18 and the other is through the branch pipe 32 and regulating valve 33. The valve 18 is a balanced valve and is actuated by a spring-loaded capsule responsive to the pressure in the chamber 27. The valve 33 is responsive to the pressure drop across the heat exchanger 15. During low altitude or ground level operation the flow in the return pipe 6 will be small so that the valve 18 will tend to be closed by the spring 30. At increasing altitude the return flow will increase. The pressure in chamber 27 will, as a consequence, rise and the valve 18 will be opened. Up to a predetermined flow in the pipe 6 and heat exchanger 15 the valve 33 will remain closed. At higher rates of return flow the valve 33 by-passes increasing quantities of fuel direct to the pipe 1. The element 16 of the heat exchanger 15 is cooled by air which may be boundary layer air bled from the wing roots. A further heat exchanger 37 is provided to cool a fluid coolant such as lubricating oil. Another heat exchanger 39 for cooling a further coolant may be provided. The fuel may be used to cool cabin air or used as a heat sink for compressed air when the cabin air is cooled on a compression refrigeration cycle.