Patent GB-742485-A (GB)
Title: Improvements in or relating to gas-turbine power plant installations
Inventor: JOHNSON CHRISTOPHER LINLEY
IPC: F02C7/232
Filed: 1953-02-13
Abstract: 742,485. Gas-turbine plant. ROLLS-ROYCE, Ltd. Feb. 8, 1954 [Feb. 13, 1953], No. 4178/53. Class 110(3) [Also in Groups XXVIII and XXIX] A fuel drain arrangement of a gasturbine power plant installation comprises a sump for the collection of drainage fuel and an ejector pump having a Venturi passage to which pressure air is supplied from an engine of the installation to suck the drainage fuel from the sump and deliver it into the working fluid of an engine of the installation downstream of the turbine. In the arrangement shown, Figs 1 and 2, drainage fuel from the glands of the fuel pump 33, the oil cooler 34, throttle valve 31, main shaft off valve 32, manifold 35 and burners 30 is led through a pipe 72 into a peaked portion 38a of a first drainage fuel collector tank 38. An outlet connection 74 from this tank leads to a Venturi ejector pump 70. A vent pipe 73 having a number of bends in it leads from the peaked portion 38a through the bottom of the tank. A second drainage fuel collector tank 40 receives fuel from the compressor equipment 21 and turbine assembly 22 through a valve 41 mounted on the nozzle box structure of the turbine. The nozzle box structure comprises a large diameter ring 42, a 'second ring 43 formed with a series of hollow box-section arms 44 which extend one between each pair ot combustion chamber casings 28 and a third ring 46 of frusto-conical form which engages pads 44a formed on the extremities of the arms 44. The downstream part 46a of the third ring supports the nozzle guide vane assembly 47. The gases from the combustion chamber pass to the nozzle guide vane assembly 47 through nozzles 45. A cylindrical casing 48 surrounding the portion 46a defines a cooling air manifold through which cooling air which has passed over the bearings is delivered by elbow-shaped duct 49. Holes 50, Fig. 4, allow fuel accumulating in the nozzle guide vane assembly to drain into the lowermost part of the space between the nozzle box parts 42, 44 and then through passage 51 into the first valve chamber 53 of the drain valve 41. The drain valve 41 comprises a piston valve 56 which is held on to its seating 57, Fig. 5, by combustion chamber pressure and opened by a light spring 58. The chamber 53 also receives the drains from the combustion chambers 28 through conduits 60. The second valve chamber 54 on the downstream side of the piston valve 56 is connected through a conduit 62 to drain tank 40. Fuel leaking from the joint between the exhaust cone outer wall 24 and jet pipe 26 may be collected in a trough 65 from which it is led to the tank 40. One of the unions 59 connected to the conduit 60 has a side connection leading to a pipe 71 connected to the ejector pump 70. The pump 70 is formed in two parts 78, 79, Fig. 7. The part 78 has a pair of parallel Vanturi passages 80 connected to a common air inlet chamber 81 connected to the pipe 71, and has a pair of supporting lugs 83 by which it is mounted on the exhaust cone wall 24 so that the centre lines of the passage 80 make an angle of 45 degrees with the axis of the exhaust cone. The part 79 has a pair of nozzles 87 which terminate adjacent the throats of the Venturi passage 80. One of the nozzles 87 is connected to the pipe 74 leading to the tank 38 and the other is connected to the pipe 67 leading to the tank 40. A modified form of ejector pump is also described. The design of the Venturi and fuel nozzle may be such that sonic velocity occurs at the throat. The Venturi may be arranged to discharge into the jet stream downstream of the propelling nozzle and may be mounted on this nozzle. A modification in which there is a single drain tank having two pumps is also described. In a further modification having two drain tanks, one of the tanks is divided into two compartments one of which is connected to the other tank. The two ejector pumps are separately connected to each of these compartments. In another modification the two tanks each have an ejector pump and are connected by a conduit so that when an aircraft is in nose-down attitude one ejector pump is operating and when in tail-down attitude the other pump is working.