Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02K—JET-PROPULSION PLANTS
  • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
  • F02K1/54—Nozzles having means for reversing jet thrust
  • F02K1/64—Reversing fan flow
  • F02K1/70—Reversing fan flow using thrust reverser flaps or doors mounted on the fan housing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02K—JET-PROPULSION PLANTS
  • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
  • F02K1/54—Nozzles having means for reversing jet thrust
  • F02K1/64—Reversing fan flow
  • F02K1/70—Reversing fan flow using thrust reverser flaps or doors mounted on the fan housing
  • F02K1/72—Reversing fan flow using thrust reverser flaps or doors mounted on the fan housing the aft end of the fan housing being movable to uncover openings in the fan housing for the reversed flow
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T50/00—Aeronautics or air transport
  • Y02T50/60—Efficient propulsion technologies, e.g. for aircraft

Definitions

• the present invention relates to a nacelle for turbofan engine with a high dilution ratio comprising an internal flow channel of a secondary flow generated by the turbojet engine and having an external structure equipped with a thrust reverser device.
• An aircraft is driven by several turbojets each housed in a nacelle also housing a set of ancillary actuators related to its operation and providing various functions when the turbojet engine is in operation or stopped.
• These ancillary actuating devices comprise in particular a mechanical system for actuating thrust reversers.
• a nacelle generally has a tubular structure comprising an air inlet upstream of the turbojet engine, a median section intended to surround a fan of the turbojet engine, a downstream section housing thrust reverser means and intended to surround the combustion chamber of the turbojet engine. , and is generally terminated by an ejection nozzle whose output is located downstream of the turbojet engine.
• the modern nacelles are intended to house a turbofan engine capable of generating through the blades of the rotating fan a flow of hot air (also called primary flow) from the combustion chamber of the turbojet engine, and a flow of cold air (secondary flow) flowing outside the turbojet through an annular passage, also called vein, formed between a shroud of the turbojet engine and an inner wall of the nacelle.
• the two air flows are ejected from the turbojet engine from the rear of the nacelle.
• the role of a thrust reverser is, during the landing of an aircraft, to improve the braking capacity thereof by redirecting forward at least a portion of the thrust generated by the turbojet engine.
• the inverter obstructs the cold flow vein and directs the latter towards the front of the nacelle, thereby generating a counter-thrust which is added to the braking of the wheels of the aircraft.
• an inverter comprises movable covers movable between, on the one hand, an extended position in which they open in the nacelle a passage for deviated flow, and secondly, a retracted position in which they close this passage.
• These covers can perform a deflection function or simply activation other means of deflection.
• a grid inverter also known as a cascade inverter
• the reorientation of the air flow is carried out by deflection grids, the hood having a simple sliding function aimed at discover or cover these grids.
• Additional locking doors activated by the sliding of the cowling, generally allow a closure of the vein downstream of the grids so as to optimize the reorientation of the cold flow.
• Modern propulsion systems are moving towards the implementation of turbofan engines with high dilution ratio, that is to say generating a flow rate of cold air much higher than the flow rate of hot air.
• the flow rate of the cold flow can be up to ten times higher than the flow rate of the hot flow.
• a nacelle associated with such a turbojet engine has a fan duct and a large cold flow vein adapted to such a flow rate.
• One of the direct consequences is therefore an increase in the size of the nacelle and the mass of the propulsion unit.
• a nacelle according to WO 96/19656 comprises a thrust reverser device which only partially blocks the inner channel so as to provide therein a leakage section allowing the circulation of a controlled leakage rate.
• a thrust reverser device which only partially blocks the inner channel so as to provide therein a leakage section allowing the circulation of a controlled leakage rate.
• the present invention consists of a nacelle for a high dilution rate double flow turbojet engine comprising an internal flow channel of a secondary flow generated by the turbojet engine and having an external structure equipped with a reversing device.
• thrust adapted to move alternately from a closed position in which it allows the circulation of the secondary flow inside the direct channel in direct jet to an open position in which it discovers an opening in the external structure so as to allow a reorientation of the secondary flow according to a deflected jet by the activation of thrust reversal means
• the thrust reverser device in the open position, partially blocking the inner channel so as to provide a section therein leakage circuit for circulating a controlled leakage rate
• said nacelle being characterized in that when the inverter when in the open position, has a deviated jet inversion section and a leakage section through the inner channel whose sum is substantially equal to a direct jet discharge section of the secondary flow when the inverter thrust is in the closed position.
• the thrust reverser means such as deflection grids in the case of thrust reversers with grids. Furthermore, the space required to accommodate the thrust reverser means when the thrust reverser is in the closed position, can also be reduced, which allows substantial reductions in the overall dimensions of the nacelle.
• the total section dedicated to the passage of the secondary flow remains substantially constant in thrust reversal phase and direct jet, avoiding any increase or decrease in pressure secondary flow in the inner channel.
• the inversion section is obtained by moving a movable cowling having a reduced thickness and capable of ensuring, in the closed position, the external and internal aerodynamic continuity of the nacelle.
• the nacelle is intended to receive a turbojet having a dilution ratio close to ten and in that the leakage section is calculated so that the thrust reverser allows, in the open position, an inverted thrust substantially equal to twenty percent of the direct jet thrust when the inverter is in the closed position.
• the leakage section, when the thrust reverser is in the open position represents about thirty percent of the direct jet discharge section.
• the thrust reverser is a grid inverter.
• the thrust reverser is an inverter with natural locking grilles.
• the leakage section is obtained by reducing the section of the inner channel during the displacement of a movable cowl fitted to the thrust reverser device.
• the inner channel has a boss located downstream of the movable cowl in the open position.
• the inner channel has a boss located substantially at an upstream edge of the movable cowl in the open position.
• FIG. 1 is a diagrammatic representation in longitudinal section of a nacelle of a high dilution rate turbofan jet engine according to the prior art equipped with a thrust reverser with natural locking gates.
• FIG. 2 is a diagrammatic representation in longitudinal section of a nacelle of turbojet engine with a large dilution ratio according to a first variant embodiment of the invention.
• Figure 3 is a schematic representation in longitudinal section of a nacelle turbofan engine with a high bypass rate according to a second embodiment of the invention.
• inverter is not limited to a particular type of inverter. Although illustrated by a grid inverter comprising movable covers sliding along guide rails, it can also be implemented with inverters of different design, including doors.
• FIG. 1 represents a nacelle 1 for a double-flow turbojet engine with a high dilution ratio according to the prior art.
• the nacelle 1 is intended to constitute a tubular housing for a turbojet engine (not shown) double flow with a high dilution ratio and serves to channeling the air flows it generates through the blades of a fan (not shown), namely a hot air flow passing through a combustion chamber (not shown) of the turbojet, and a flow of cold air circulating outside the turbojet.
• the nacelle 1 has a structure comprising a front section forming an air inlet 4, a median section 5 surrounding the fan of the turbojet, and a rear section surrounding the turbojet and comprising a thrust reversal system.
• the air inlet 4 has an inner surface 4a for channeling the incoming air and an outer fairing surface 4b.
• the median section 5 comprises, on the one hand, an internal casing 5a surrounding the turbojet fan, and on the other hand, an outer casing fairing structure 5b extending the outer surface 4b of the air inlet section 5.
• the casing 5a is attached to the air intake section 4 that it supports and extends its inner surface 4a.
• the rear section comprises an external structure comprising a thrust reversal system and an internal engine fairing structure 8 defining with the external surface a vein 9 intended for the circulation of a cold stream in the case of a nacelle 1 of turbojet engine as shown here.
• the thrust reverser system comprises a movable cap 10 in translation adapted to pass alternately, on the one hand, from a closed position in which it houses deflection grids 11 and provides the structural continuity of the middle section 5 allowing thus the evacuation of the cold flow 3 through the vein 9 in direct jet 3a, and secondly, to an open position in which it discovers the deflection grids 11, then opening a passage in the nacelle 1, and blocks the vein 9 downstream of the deflection grids 11 thus allowing the reorientation of the cold flow in an inverted jet 3b.
• the gate reversal system presented here is a natural blocking gate reversal system. This means that the movable hood 10 naturally blocks the vein 9 in the open position without requiring the presence of complementary locking doors.
• the internal structure 8 of the rear section has downstream deflection grids 11, a hump 12 large enough to substantially reach the level of the casing 5a of the nacelle 1.
• the diameter DM1 interior of the nacelle 1 at the outlet of the casing 5a of the middle section 5 is substantially equal to the diameter DF1 of the internal structure 8 at the hump 12.
• the movable hood 10 has, on the one hand, an outer wall 13 capable of ensuring the external structural continuity of the nacelle 1 with the outer structure 5b of the fairing of the casing 5a, and on the other hand, a internal wall 14 adapted to ensure the internal structural continuity of the nacelle 1 with the housing 5a, the inner wall 14 substantially along the curvature of the internal structure 8 so that the vein 9 retains a substantially constant section and therefore has a hollow corresponding to the hump 12. Furthermore, the inner wall 14 and the outer wall 13 meet downstream of the movable cowl 10 to form an ejection nozzle capable of ensuring the ejection of the cold stream at a desired angle.
• the movable cowl 10 completely closes the vein 9, the hump 12 bringing the internal structure 8 in close contact with an upstream portion of said movable cowl 10 to the operating game near maneuver.
• the need to accommodate the hollow of the inner wall 14 of the movable hood while ensuring the aerodynamics of the nacelle requires a greater thickness between the external structures and the internal structures.
• the nacelle has a deflection section of the large cold flow so as to deflect a large part of this cold flow. This requires the presence of larger deflection grids 11, which results in an opening length of the larger movable hood 10 and a thickness and a corresponding interior volume to accommodate the deflection grids 11 when the movable hood 10 is in the closed position.
• This larger footprint also results in a larger mass and a difficulty of housing such a nacelle for turbojet engine with a high dilution rate under an aircraft wing.
• the object of the present invention is to provide a solution to this congestion and mass increase.
• the principle of the invention is based on the fact that nacelles for turbojet engines with a high dilution ratio have, due to their size, a greater natural resistance which tends to brake the aircraft. This resistance is called capturing trail. As a result, it is not FR2007 / 000616
• the solution provided by the invention lies in the fact, during a thrust reversal phase, to retain a part of the cold stream escaping in a direct jet thus allowing a reduction in the size of the inversion means, this leakage section of the secondary flow being controlled and determined so as to ensure the necessary and sufficient inversion.
• FIG. 2 shows a first solution consisting of keeping the hump 12 of a nacelle 1 according to the prior art but with a smaller length of the deflection gates and a corresponding reduction in the opening length of the movable cowl 10.
• a nacelle 100 differs from the nacelle 1 only in that it comprises deflection grids 111 having a length less than the deflection gates 11 of the nacelle 1.
• the diameter DF1 of the internal structure 8 at the hump 12 is always substantially equal to the inside diameter DM1 of the casing 5a at the outlet of the middle section 5.
• the reduced length of the deflection grids 111 allows a smaller displacement of the movable cowl 10 when opening the thrust reversal system. As a result, the upstream portion of the movable cowl 10 no longer comes into close contact with the hump 12 but stops upstream of said hump 12, thereby leaving a leakage section S2 in the vein 9 between the moving cowl 10 and the internal structure 8. Furthermore, the deflection grids 111 being less difficult to accommodate inside the movable cowl 10 in the closed position, the total thickness of the movable cowl 10 upstream thereof can be reduced relative to to the prior art.
• the reduced opening length of the movable cowl 10 allows a reduction in the length of guide rails (not visible) of said movable cowl 10, installed in the upper and lower part of the thrust reverser structure. This results in a reduction of the fairing of said guide rails 00616
• the guide rails being shorter than on a thrust reverser system according to the prior art, they can be raised to the maximum side of the extrados of the movable cover 10, eliminating or reducing a portion of the flat located in the vein 9 at the inner wall 14 of the movable cowl 10 usually encountered at the passage of the guide rail.
• the outline of the nacelle 1 is shown in broken lines in Figure 2 for comparison purposes.
• FIG. 3 shows a second solution consisting in reducing the bump height 12 of a nacelle 1 according to the prior art and placing it further upstream.
• a nacelle 200 differs from the nacelle 1 in that it comprises an internal structure 208 having a smaller hump 212 and disposed further upstream than the bump 12 of the nacelle 1.
• the diameter DF2 of the internal structure 208 at the hump 212 is smaller than the internal diameter DM1 of the housing 5a. This allows to naturally provide a space between the boss 212 and the movable cover 10 in the open position, this space constituting a leakage section S3 for the cold air flow.
• the movable cowl 10 moves to the hump 212. This being located upstream relative to the bump 12 of the prior art, the moving length of the movable cowl 10 is reduced and accommodates deflection grids 211 also of reduced length since the flow of cold air to divert 3b is less important.
• the consequences on the overall dimension of the nacelle are the same as explained for the nacelle 100.
• the hollow formed by the inner wall 14 of the movable cowl 10 is also less important.
• the inner wall 14 thus has a smaller curvature that further reduces the gap between the inner wall 14 and the outer wall 13 of the movable hood upstream thereof and therefore the overall dimensions of the nacelle 200 relative to the nacelle 1.
• the outline of the nacelle 1 is shown in broken lines in Figure 3 for comparison purposes.
• the reduced opening length of the movable cowl 10 makes it possible to reduce the length of guide rails (no visible) of said movable cowl 10. This results in a reduction of the fairing of said guide rails which also reduces the overall dimensions of the movable cowl 10, and consequently, to minimize aerodynamic profile accidents, thereby gaining efficiency.
• the guide rails being shorter than on a thrust reverser system according to the prior art, they can be raised to the maximum side of the extrados of the movable cover 10, eliminating or reducing a portion of the flat located in the vein 9 at the inner wall 14 of the movable cowl 10 usually encountered at the passage of the guide rail.
• the leakage sections S2, S3 increase with the dilution ratio, so for a turbojet engine with a greater dilution ratio, the leakage section S2, S3 will be increased.
• the leakage section S2, S3 and the deflection section are calculated in such a way that their sum is substantially equal to the section of the vein 9 direct jet.
• the efficiency of the inversion obtained is a function of the ratio between the leakage section S2, S3 on the direct jet exhaust section.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Control Of Turbines (AREA)

Applications Claiming Priority (2)

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Family Applications (1)

Country Status (7)

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• 2006
  • 2006-05-10 FR FR0604113A patent/FR2900980B1/fr not_active Expired - Fee Related
• 2007
  • 2007-04-12 CA CA002651103A patent/CA2651103A1/fr not_active Abandoned
  • 2007-04-12 US US12/297,485 patent/US20090107108A1/en not_active Abandoned
  • 2007-04-12 CN CN2007800164461A patent/CN101438048B/zh not_active Expired - Fee Related
  • 2007-04-12 WO PCT/FR2007/000616 patent/WO2007128890A1/fr active Application Filing
  • 2007-04-12 RU RU2008147844/06A patent/RU2435056C2/ru not_active IP Right Cessation
  • 2007-04-12 EP EP07731284A patent/EP2016274A1/de not_active Withdrawn

Non-Patent Citations (1)

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