Device of an aircraft engine for separating oil from an air-oil volume flow

Abstract

A device of an aircraft engine for separating oil from an air-oil volume flow and an apparatus for introducing oil into the air-oil volume flow. An outlet area of the apparatus for introducing oil is provided in a closed line section, into which the air-oil volume flow can be introduced via an inlet area. In accordance with the invention, a flow cross-section of the line section downstream of the outlet area of the apparatus tapers at least partially like a nozzle and at least in some sections inside a confusor area.

Claims

1. A device of an aircraft engine for separating oil from an air-oil volume flow of the aircraft engine, comprising: a closed line section including an inlet area for introducing the air-oil volume flow into the closed line section; an apparatus for introducing oil into the air-oil volume flow in the closed line section of the aircraft engine, the apparatus for introducing oil including an outlet area positioned in the closed line section, wherein the closed line section includes a diffusor area upstream of the outlet area where a flow cross-section of the closed line section flares to have an enlarged cross-section in a direction of flow through the closed line section; wherein the closed line section includes a confusor area downstream of the outlet area where the flow cross-section of the closed line section tapers to have a reduced cross-section in the direction of flow through the closed line section.

2. The device in accordance with claim 1, wherein the flow cross-section of an intermediate area of the closed line section, which extends between the outlet area and the confusor area, includes a cross-section which is at least one chosen from approximately constant and gradually enlarging to prevent a positive acceleration of the air-oil volume flow.

3. The device in accordance with claim 1, wherein the closed line section further comprises a deflection area adjoining the confusor area downstream of the confusor area, the deflection area including a bend and at least one chosen from a separate oil outlet and a combined air-oil outlet of the closed line section.

4. The device in accordance with claim 1, and further comprising a cyclone connected to the closed line section for receiving oil from the air-oil volume flow.

5. The device in accordance with claim 4, and further comprising an oil separator positioned downstream of the closed line section, the oil separator including an air inlet.

6. The device in accordance with claim 5, wherein the cyclone includes an air inlet and an air outlet and the closed line section includes an air outlet, wherein the air inlet of the cyclone is connected to at least one chosen from the air outlet of the closed line section and an air outlet of an engine area supplied with oil, wherein the air outlet of the cyclone is connected to at least one chosen from the inlet area of the closed line section, the air inlet of the oil separator and an external environment of the aircraft engine.

7. The device in accordance with claim 4, wherein the cyclone includes separate air and oil outlets, where the oil outlet of the cyclone in the installation position of the cyclone is provided in a lower area of the cyclone, while air can be removed from the cyclone via the air outlet from a center area of an interior of the cyclone.

8. The device in accordance with claim 6, wherein an air-oil volume flow introduced into the cyclone via the air inlet is directed tangentially to a wall area of the cyclone.

9. The device in accordance with claim 1, wherein the outlet area is positioned to introduce oil into the closed line section approximately centrally in the closed line section.

10. The device in accordance with claim 1, wherein the outlet area includes a nozzle for introducing the oil into the closed line section formed as at least one chosen from a spray cone and a cone-shaped oil film.

11. The device in accordance with claim 10, wherein an opening angle of the at least one chosen from the spray cone and the cone-shaped oil film is settable such that the oil introduced in conical form impacts in a wall area of the confusor area, the wall area facing the outlet area.

12. The device in accordance with claim 1, wherein the air-oil volume flow is introduced into the closed line section via the inlet area tangentially to the wall area of the closed line section and substantially perpendicular to the introduction direction of the oil from the outlet area.

13. The device in accordance with claim 1, and further comprising a further oil introduction conduit positioned in an area of the closed line section close to a wall area of the closed line section and upstream of the outlet area, to generate in the wall area of the closed line section an oil film and a flow in the oil film in a direction of an oil outlet of the closed line section.

Description

(1) In the drawing,

(2) FIG. 1a shows a highly schematized longitudinal sectional view of an aircraft engine with an accessory gearbox arranged in the fan casing,

(3) FIG. 1b shows a representation—corresponding to FIG. 1a—of an aircraft engine with an accessory gearbox mounted in the area of the engine core,

(4) FIG. 2 shows a highly schematized partial representation of the aircraft engine according to FIG. 1a or FIG. 1b with an oil separator arranged in the area of the accessory gearbox,

(5) FIG. 3 shows an enlarged representation of an area III shown in more detail in FIG. 2,

(6) FIG. 4 shows the area illustrated in FIG. 3 from a view IV shown in more detail in FIG. 3,

(7) FIG. 5 shows a representation—corresponding to FIG. 3—of a second embodiment of the device in accordance with the present invention,

(8) FIG. 6 shows a representation—corresponding to FIG. 3—of a third embodiment of the device in accordance with the present invention,

(9) FIG. 7 shows a representation—corresponding to FIG. 3—of a fourth embodiment of the device in accordance with the present invention,

(10) FIG. 8 shows a schematized top view onto a cyclone which in the present case is arranged downstream of a line section of the device in accordance with FIG. 3, and

(11) FIG. 9 shows a sectional view of the cyclone shown in FIG. 8 along a sectional line IX-IX shown in more detail in FIG. 8.

(12) FIGS. 1a and 1b each show an aircraft engine or a jet engine 1 in a longitudinal sectional view. The aircraft engine 1 is provided with a bypass duct 2 and an intake area 3, where a fan 4 adjoins downstream the intake area 3 in a manner known per se. Again downstream of the fan 4, the fluid flow in the aircraft engine 1 splits into a bypass flow and a core flow, with the bypass flow flowing through the bypass duct 2 and the core flow into an engine core 5 which is in turn designed in a manner known per se with a compressor device 6, a burner 7 and a turbine device 8.

(13) The turbine device 8 has in the present invention three rotor devices 9, 10 and 11, which have a substantially comparable design and are connected to an engine axis 12.

(14) In the design of the aircraft engine 1 according to FIG. 1a, an accessory gearbox 13 is arranged in an outer engine casing 14, delimiting the bypass duct 2 and representing the outer circumferential area of the jet engine 1. The accessory gearbox 13 in the present invention is connected via a drive shaft 15 running in the radial direction of the jet engine 1 and via an inner gearbox 16A to the engine axis 12 and is thus driven/subjected to torque by the engine axis 12 during operation of the jet engine 1. Various auxiliary units 16 and an oil separator 17, which is also referred to as breather, are subjected to torque to the required extent by the accessory gearbox 13. Additionally, an oil tank 18 is provided in the area of the accessory gearbox 13, which represents a hydraulic fluid reservoir, from which oil is tapped for cooling and lubricating various areas of the aircraft engine 1 such as bearing devices, gear pairings of the inner gearbox 16A and of the accessory gearbox 13, and further assemblies of the aircraft engine 1 that are to be cooled and lubricated.

(15) In contrast to this, the accessory gearbox 13 with the auxiliary units 16 and the oil separator 17 is arranged, in the design of the aircraft engine 1 according to FIG. 1b, in the radial direction between the bypass duct 2 and the engine core 5 in a component 19 delimiting both the bypass duct 2 and the engine core 5.

(16) FIG. 2 shows an embodiment of the aircraft engine 1 according to FIG. 1a in a highly schematized form in the area of the accessory gearbox 13, the auxiliary units 16 and the oil separator 17, the latter being in the present invention connected to the oil tank 18 and two further areas 20, 21 as well as to an interior 24 of a casing 25 of the accessory gearbox 13, all of which representing areas of the aircraft engine 1 supplied with oil. The areas 20, 21 here represent the bearing chambers of the aircraft engine 1 and are supplied during operation of the aircraft engine 1 with oil from the oil tank 18 for lubrication and cooling. The area 20 here represents the bearing chamber of the front bearing and the area 21 the bearing chamber of the rear bearing of the aircraft engine 1. The aircraft engine 1 according to FIG. 1b shows the aspects described in more detail in the following with reference to FIG. 2 and to FIGS. 3-9 to a substantially identical extent.

(17) In the embodiment of the aircraft engine 1 shown in FIG. 2, air-oil volume flows from the front bearing chamber 20 and from the rear bearing chamber 21 can each be guided in the direction of a line section 22. The enriched air-oil volume flows in the area of the bearing chambers 20 and 21 as well as in the area of the oil tank 18 and of the accessory gearbox 13 are routed—downstream of a line section node 30, into the area of which issue the line section 22 and a further line section 31 connected to the oil tank 18 as well as a line section 32 coupled to the accessory gearbox 13—in the direction of a device 40 provided in an area III shown in more detail.

(18) Generally speaking, it is also possible to route only one air-oil volume flow of the bearing chambers 20 and 21, of the oil tank 18 or of the accessory gearbox 13 in the direction of the device 40 and to clean it there in the manner described in detail in the following.

(19) FIG. 3 shows a first exemplary embodiment of the device 40 of the aircraft engine 1 provided for separating oil from the air-oil volume flows downstream of the line section node 30. The device 40 includes an apparatus 41 for introducing oil into the air-oil volume flow downstream of the line section node 30. An outlet area 42 of the apparatus 41 for introducing oil is provided in a closed line section 43, into which the air-oil volume flow can be introduced via an inlet area 44. A flow cross-section of the line section 43 tapers like a nozzle downstream of the outlet area 42 of the apparatus 41 in a confusor area 45 of the closed line section 43, so that the air-oil volume flow routed in the closed line section is accelerated in the confusor area 45. A flow cross-section of an intermediate area 46 of the closed line section 43 provided upstream of the confusor area 45 and extending at least between the outlet area 42 of the apparatus 41 and the confusor area 45, is designed at least approximately constant to prevent a positive acceleration of the air-oil volume flow, and can in further embodiments of the device 1 also widen at least approximately diffusor-like at least in some sections.

(20) The air-oil volume flow is introduced into the closed line section 43 via the inlet area 44 and in the manner indicated in FIG. 4 by the arrows A, B and C tangentially to the wall area of the closed line section 43 or of the intermediate area 46 and substantially perpendicular to the introduction direction of the oil, so that the air-oil volume flow starting from the inlet area 44 flows initially helically in the intermediate area 46 in the direction of the confusor area 45 through the intermediate area 46.

(21) The oil is introduced via the outlet area 42 of the apparatus 41 at least approximately centrally into the closed line section 43 or its intermediate area 46 in the form of a spray cone 47 or as a cone-shaped oil film. The opening angle of the spray cone 47 or of the cone-shaped oil film can be set using the outlet area 42 such that the oil introduced in conical form impacts in a wall area of the confusor area 45, said wall area facing the outlet area 42 of the apparatus 41. The flow cross-section of the inlet area 44, via which the air-oil volume flow can be introduced into the line section 43 upstream of the outlet area 42 of the apparatus 41, is smaller than the flow cross-section of the closed line section 43 upstream of the outlet area 42 of the apparatus 41.

(22) In addition, in this embodiment of the device 40 a further optional oil introduction means 48 is provided in an area of the line section 43 close to the wall upstream of the outlet area 42 of the apparatus 41, in order to create in the wall area of the line section 43 an oil film 49 and a flow in the oil film starting from the inlet area 44 in the direction of an oil outlet 50 of the closed line section 43, in the area of which oil droplets borne along by the air-oil volume flow are separated with high efficiency and a separation capacity of the device 40 is improved.

(23) In addition, air flowing into the closed line section 43 via the inlet area 44 is also discharged via the oil outlet 50 out of said closed line section 43, so that the oil outlet 50 represents a combined air-oil outlet.

(24) Alternatively, it is also possible here that only oil is discharged via the oil outlet 50 from the closed line section 43, while the air can be removed via a separate air outlet 51 from the closed line section 43, with the oil then having the level H indicated in FIG. 3 in the area of the oil outlet 50.

(25) Downstream of the confusor area 45, the closed line section 43 includes a deflection area 52, which has in the present invention a bend of 90° and in whose area the oil outlet 50 and the air outlet 51 are respectively provided. In further embodiments the deflection can also be designed with a bend of more or less than 90°. The deflection area 52 acts as an impingement filter, and oil borne along in the air-oil volume flow is separated mechanically there, thus further improving a separation capacity of the device 40 in turn.

(26) The oil particles or oil droplets in the air-oil volume flow downstream of the outlet area 42 of the apparatus 41 now enlarged by washing out the oil can be separated substantially more efficiently by introducing oil in the confusor area 45 and in the deflection area 52, so that oil losses of the aircraft engine 1 in the direction of an environment 28 of the jet engine 1 are minimized by the reduced emissions.

(27) FIG. 5 shows a representation—corresponding to FIG. 3—of a second embodiment of the device 40, where the air-oil volume flow downstream of the line section node 30 is introduced substantially in the axial direction of the closed line section 43. Unlike the embodiment of the device 40 according to FIG. 3, the device 40 according to FIG. 5 includes, upstream of the outlet area 42 of the apparatus 41 and of the intermediate area 46, a diffusor area 53 in the zone of which the flow cross-section of the closed line section 43 is designed widening diffusor-like to reduce a flow velocity of the air-oil volume flow and to generate in the intermediate area 46 a flow calmed as much as possible, preferably a laminar flow, which favours the joining or coalescence of small droplets of the air-oil volume flow with the oil introduced via the apparatus 41 inside the intermediate area 46. The coalescence of the oil droplets of the air-oil volume flow and of the introduced oil is favoured by the respectively applying forces of attraction between the individual oil droplets, where the tendency of the oil droplets to combine into larger oil droplets grows as the ratio between the diameters of the oil droplets increases.

(28) FIG. 6 shows a third embodiment of the device 40, which except for an asymmetrical design of the diffusor area 53 and of the confusor area 45 substantially matches the embodiment of the device 40 according to FIG. 5. In the embodiment of the device 40 according to FIG. 6, both the inlet area 44 of the closed line section 43 and the outlet area 50 in the deflection area 53 are arranged non-concentrically relative to the outlet area 42 of the apparatus 41, where the oil is introduced centrally via the outlet area 42 of the apparatus 41 into the intermediate area 46 in the form of the spray cone 47 or of the cone-shaped oil film. An oil film 49 which flows in the direction of the oil outlet 50 is in turn formed in the wall area of the closed line section 43 and improves the separation capacity of the device 40.

(29) The device 40 can be fitted both vertically in the manner shown in FIG. 6 and at least approximately horizontally to the extent shown in FIG. 7, in order to separate oil from the air-oil volume flow, where in the embodiment of the device 40 according to FIG. 7 the further oil introduction means 48 is provided in the lower wall area of the closed line section 43 in order to create there the oil film 49 for increasing the separation capacity of the device 40, and a flow in said oil film 49 in the direction of the oil outlet 50.

(30) With the substantially horizontal alignment of the device 40, a defined oil droplet diameter distribution is formed over the flow cross-section of the intermediate area 46 of the closed line section 43 and is favoured by the gravity effect acting on the oil droplets borne along in the air-oil volume flow. The gravity effect acting on the oil droplets leads to larger oil droplets increasingly collecting in the lower area of the flow area, while in the upper area of the flow area oil droplets with a smaller droplet diameter are borne along by the air-oil volume flow in the direction of the confusor area 45. With an increasing flow path of the air-oil volume flow in the intermediate area 46, the larger oil droplets separate in the lower wall area of the closed line section 43 in the area of the oil film 49, while the smaller oil droplets in the upper flow cross-section of the intermediate area 46 combine with the oil introduced via the apparatus 41 to form larger oil droplets, which are separated to a substantial extent mechanically at the latest in the confusor area 45 and in the deflection area 52 adjoining said confusor area 45.

(31) To permit further cleaning of the air flowing out of the closed line section 43, which still has a defined load—which is however lower than the load in the air-oil volume flow—and which is introduced into the closed line section 43 via the inlet area 44, it is provided in a further embodiment of the device 40 shown in FIG. 8 and FIG. 9 that the air-oil volume flow removed from the further line section 43 is introduced via an air inlet 55 into a cyclone 54 tangentially to a wall area of said cyclone 54. Alternatively, it can also be provided that the cyclone 54 is arranged upstream of the inlet area 44 of the closed line section 43 and a load in the air-oil volume flow downstream of the line section node 30 is reduced initially in the area of the cyclone 54, and then the pre-cleaned air-oil volume flow is routed via an air outlet 56 of the cyclone 54 in the direction of the inlet area 44 of the closed line section 43.

(32) The cyclone 54 has a separate air and oil outlet, where an oil outlet 57 of the cyclone 54 is provided in the installation position of the cyclone 54 in a lower area of said cyclone 54, while air can be removed from the cyclone 54 via the air outlet 56 from a center area of an interior 58 of said cyclone 54.

(33) The air outlet 56 of the cyclone 54 is coupled, like the combined air-oil outlet 50 or the separate air outlet 51 of the device 40 according to FIGS. 3-7, to the oil separator 17, so that an air-oil volume flow discharged out of the cyclone 54 via the air outlet 56 and laden with oil is introduced into the oil separator 17. The oil separated in each case from the air-oil volume flow oil in the area of the devices 40 according to FIGS. 3-9 is, depending on the respective application, either returned immediately into an oil circuit of the aircraft engine 1 or initially conveyed further in the direction of the oil separator 17 and returned there to the oil circuit.

(34) A porous area 26 is rotatably arranged in the interior of the oil separator 17 and can be flowed through by the air-oil volume flow exiting the cyclone 54. The porous area 26 can in the present invention and to the extent shown in FIG. 2 be driven by the accessory gearbox 13 via a gear 27 and acts as a centrifuge in order to reduce as far as possible the proportion of oil in the air-oil volume flow flowing through the porous area 26. The proportion of oil of the air-oil volume flow in the oil separator 17 is here reduced in the zone of the porous area 26 by separation of the oil from the air, on the one hand as when flowing through an impingement filter and on the other hand as in the area of a centrifuge, due to the rotation of the porous area 26. The oil filtered out of the air-oil volume flow in the zone of the porous area 26 is extracted in the outer area of the oil separator 17, in a manner not shown in detail, via a pump device and returned to the oil tank 18. The air flowing out of the oil separator 17 in the direction of the environment 28 has only a low oil load. The gear 27 is, in addition to further gears 27A to 27E, non-rotatably connected to a gear shaft 29 and arranged in the interior 24 of the accessory gearbox 13.

LIST OF REFERENCE NUMERALS

(35) 1 Aircraft engine, jet engine 2 Bypass duct 3 Intake area 4 Fan 5 Engine core 6 Compressor device 7 Burner 8 Turbine device 9, 10, 11 Rotor device 12 Engine axis 13 Accessory gearbox 14 Engine casing 15 Drive shaft 16 Auxiliary units 17 Oil separator 18 Oil tank 20 Area, front bearing chamber 21 Area, rear bearing chamber 22 Line section 24 Interior 25 Casing 26 Porous area 27 Gear 27A to 27E Gear 28 Environment 29 Gear shaft 30 Line section node 31 Line section 32 Line section 40 Device 41 Apparatus 42 Outlet area of apparatus 43 Closed line section 44 Inlet area of closed line section 45 Confusor area 46 Intermediate area 47 Spray cone 48 Further oil introduction means 49 Oil film 50 Oil outlet, combined air-oil outlet 51 Air outlet 52 Deflection area 53 Diffusor area 54 Cyclone 55 Air inlet 56 Air outlet 57 Oil outlet 58 Interior of cyclone A to C Arrow H Oil level