Arrangement for the discharge of exhaust air separated from the lubricating oil de-aeration system of a gas-turbine engine

With an arrangement for the discharge of oil-contaminated exhaust air separated from the lubricating oil de-aeration system of a gas-turbine engine and led to the atmosphere via a venting line, the venting line (13) issues into an attenuation chamber (12) formed within the exhaust cone (9) of the gas-turbine engine and connected to a Venturi nozzle (14) via a discharge tube (17) for drawing off the oil-contaminated exhaust air and blowing it into the exhaust-gas flow, with the Venturi nozzle (14) being arranged in the exhaust gas-flow of the gas-turbine engine and oriented in a flow direction. The oil-contaminated exhaust air is completely discharged with the exhaust-gas flow without contacting visible engine parts.

This application claims priority to German Patent Application DE102009060051.5 filed Dec. 21, 2009, the entirety of which is incorporated by reference herein.

This invention relates to an arrangement for the discharge of oil-contaminated exhaust air separated from the lubricating oil de-aeration system of a gas-turbine engine and led to the atmosphere via a venting line.

In the bearing housings of gas-turbine engines, the lubricating oil mixes with sealing air which, as is generally known, is separated from the lubricating oil returned to the oil tank by a de-aeration system and discharged to the atmosphere via a venting line and a venting port issuing at the outside of the engine fairing (nacelle) or the fairing (pylon) of the engine mounting arrangement. However, the discharged air still contains oil particles which lead to considerable contamination of the fairing of the engine or the engine mounting arrangement on the aircraft fuselage, with this contamination being aggravated even more by adhering dirt and dust particles. Such contamination is aesthetically undesirable and, when burnt into the fairing by the high engine temperature, can only be removed by costly cleaning measures. The known proposals for the solution of this problem are aimed at discharging the oil-contaminated air (oil air) at a position as remote as possible from the surface of the fairing to avoid contact of the oil air with the surface of the fairing. The configuration of such air outlet openings, which must also be aerodynamically faired because of the high in-flight air drag and necessitate the provision of a long venting line extending up to the outside of the fairing of the engine or the engine mounting arrangement, incurs high investment and an increase in weight.

In a broad aspect, the present invention provides an arrangement for discharging the air issuing from the lubricating oil de-aeration system of a gas-turbine engine by which oil contamination of the fairing of the engine or the engine mounting arrangement is avoided and also a saving in weight is achieved. In other words, the present invention, in essence, provides that the oil-particle contaminated exhaust air (oil air) from the lubricating oil de-aeration system issues via a venting line, which is substantially reduced in length, directly into an attenuation chamber essentially formed by the exhaust cone of the gas-turbine engine, and the exhaust air in the attenuation chamber is connected via a discharge tube to a Venturi nozzle arranged in the exhaust-gas flow of the gas-turbine engine and oriented in flow direction. The low static pressure at the narrowest part of the nozzle body, and thus in the discharge tube, and the pressure difference relative to the high-pressure exhaust air in the attenuation chamber effect that the exhaust air is drawn off the attenuation chamber, then entrained by the gas flow in the nozzle body and introduced into the exhaust-gas flow and distributed therein. Thus, oil particles are prevented from depositing on any of the engine parts, in particular on visible surfaces. The reduced length of the venting line also enables a saving in weight to be achieved.

In development of the present invention, the attenuation chamber is confined by the exhaust cone as well as an exhaust-gas stator casing of the engine and a rear wall. The venting line directly issues into the attenuation chamber via an opening provided in the rear wall.

The nozzle body of the Venturi nozzle is positioned remotely from the inner surfaces of the exhaust flow duct. The position of the nozzle body is settable via the respective length of the discharge tube.

Preferably, the nozzle body is positioned centrally in the exhaust-gas flow so that the oil-contaminated exhaust air is completely absorbed in the exhaust-gas flow and discharged with the latter.

In further development of the present invention, a portion of the discharge tube issuing into the attenuation chamber conically widens towards the tube opening to ensure good suction effect.

The turbofan engine1shown inFIG. 1is enclosed by an engine fairing2at whose outer surface—on known engines—a venting line coming from the lubricating oil de-aeration system usually issues to discharge the oil air to the atmosphere. The engine includes a bypass duct4disposed downstream of the fan3as well as a core-flow duct5transiting downstream of the combustion chambers6and the turbines7into an exhaust flow duct8. The exhaust flow duct8is inwardly confined by the outer wall surface of the exhaust cone9. As shown inFIG. 2, the exhaust cone9, together with the exhaust-gas stator casing10and a rear wall11, forms a closed attenuation chamber12into which a venting line13issues which is connected to the lubricating oil de-aeration system and which is significantly shorter than in the afore-mentioned state of the art. Arranged in the exhaust flow duct8, actually remote and spaced apart from the wall surfaces confining the exhaust flow duct, is a Venturi nozzle14whose nozzle body15is directed in the direction of the exhaust-gas flow and whose discharge tube17, which is connected to the narrowest part16of the nozzle body15, communicates with the attenuation chamber12. A distance of the spacing of the nozzle body15remote from the adjacent wall surfaces is selected by choosing a certain length of the discharge tube17.

In operation of the turbofan engine1, part of the exhaust-gas flow passes around and through the Venturi nozzle14. The static pressure at the narrowest part16of the nozzle body15decreases according to the Venturi nozzle principle, with the pressure in the discharge tube17connected to the narrowest part16of the nozzle body15simultaneously decreasing, while the pressure of the oil air in the attenuation chamber12is at a significantly higher level. The pressure difference accordingly effects that the oil air is drawn off the attenuation chamber12and initially mixed with the exhaust-gas flow in the nozzle body15, and finally with the entire exhaust-gas flow, to be then discharged to the atmosphere without contacting any engine parts.

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