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
  • F02K1/46—Nozzles having means for adding air to the jet or for augmenting the mixing region between the jet and the ambient air, e.g. for silencing
  • F02K1/48—Corrugated nozzles
• • 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
  • F02K1/38—Introducing air inside the jet
  • F02K1/386—Introducing air inside the jet mixing devices in the jet pipe, e.g. for mixing primary and secondary flow
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2250/00—Geometry
  • F05D2250/10—Two-dimensional
  • F05D2250/11—Two-dimensional triangular
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2250/00—Geometry
  • F05D2250/10—Two-dimensional
  • F05D2250/13—Two-dimensional trapezoidal
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2250/00—Geometry
  • F05D2250/10—Two-dimensional
  • F05D2250/18—Two-dimensional patterned
  • F05D2250/182—Two-dimensional patterned crenellated, notched
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2250/00—Geometry
  • F05D2250/10—Two-dimensional
  • F05D2250/18—Two-dimensional patterned
  • F05D2250/184—Two-dimensional patterned sinusoidal

Definitions

• Double flow turbocharger for aircraft with reduced noise emission Double flow turbocharger for aircraft with reduced noise emission.
• the present invention relates to a turbofan engine turbofan for aircraft with reduced noise emission. It is known that, at the rear of a nozzle, the jet emitted by the latter comes into contact with at least one other gas stream: in the case of a single-flow turbine engine, the latter comes into contact with the air ambient, whereas, in the case of a turbofan engine, the cold flow and the hot flow come into contact not only with each other, but with the ambient air.
• jet in aeronautical technology.
• GB-A-766,985 discloses a nozzle whose outlet port is provided at its periphery with a plurality of rearwardly extending projections having a general direction of at least approximately that of the jet emitted by said nozzle. Such projections are constituted by "teeth" that can have many different shapes.
• GB-A-2 289 921 proposes to make indentations in the edge of the outlet orifice of the nozzle. Such indentations are distributed at the periphery of said outlet orifice and each of them generally has the at least approximate shape of a triangle whose base coincides with said edge of the outlet orifice and whose the summit is in front of this exit edge. This results in the formation, between two consecutive indentations, of a tooth shaped at least approximate triangular or trapezoidal.
• Such protruding teeth are generally called “chevrons" in the aeronautical technique, whatever their precise form.
• such rafters are commonly arranged both at the rear of the hot nozzle and behind the cold nozzle.
• the turbofan engine for aircraft comprising, around its longitudinal axis:
• a nacelle provided with an outer nacelle cover and enclosing a blower generating the cold flow and a central generator generating the hot flow; an annular cold flow channel formed around said central hot flow generator;
• an external fan cowl delimiting said annular cold flow channel on the side of said nacelle outer cowl; an outlet orifice for the cold flow, the edge of which is determined by the said nacelle external cover and by the said external fan cowl converging towards each other;
• said chevrons are two to two spaced apart by providing passages between them;
• each chevron is inclined towards said longitudinal axis so as to penetrate into said cold stream with a penetration angle which, measured from said external fan cowl, is at least approximately equal to 30 °;
• said penetration angle and the length of each chevron from said edge of the outlet orifice of the cold flow are chosen so that the penetration height thereof in said cold flow is between 0.01 times and 0, 03 times the diameter of said outlet port of the cold flow.
• the periphery of said cold stream is subjected, at the outlet of the corresponding nozzle, to a splitting into jets of different orientations and structures, depending on whether said jets pass over the highly penetrating chevrons, although relatively short length, or in the passages between said rafters.
• the cold flow jets passing through said passages have a direction extending said external fan cowl and have, at the edge of said cold flow outlet orifice, an acceleration value equal to the value nominal of the nozzle.
• the streams of cold flow passing on the rafters are strongly deviated towards the axis of said turbine engine and penetrate deeply into said cold flow.
• the chevrons according to the present invention thus make it possible to influence both the turbulence (noise source) and the shock cells (amplification of this noise).
• the length of each chevron is at most equal to 150 mm.
• each chevron has the at least approximate shape of a trapezium with lateral sides converging towards each other while moving away from said edge of the outlet orifice of the cold flow, it is advantageous that each of said lateral sides of the rafters forms, with said edge, an angle of between 125 ° and 155 °.
• said rafters of the present invention are short and narrow and, like claws, penetrate strongly into the cold stream.
• the spacing between two consecutive chevrons is advantageous for the spacing between two consecutive chevrons to be greater than 1.5 times the width of a chevron along said edge of the outlet orifice of the cold flow. This spacing is preferably approximately equal to twice said width of a chevron.
• the small base of said trapezium spaced apart from said edge of the outlet orifice of the stream. cold has a central notch.
• said small base has two lateral projections separated by said central notch.
• it causes the formation of vortices promoting mixing between the external aerodynamic flow and said cold flow.
• each of the lateral projections of such a chevron generates a vortex, the two eddies of a chevron being interleaved and counter-rotating.
• the set of said chevrons thus generates a swirling system rapidly homogenizing the gas flows at the rear of the nozzle.
• each chevron has a rounded shape.
• the small base of the trapezium is undulated forming two rounded lateral bumps (the projections) separated by said notch, also of rounded shape; and - each of the lateral sides of the rafters is connected to the edge of the cold flow outlet orifice by a rounded concave line.
• Figure 1 shows, in schematic axial section, an improved turbomo- tor according to the present invention.
• Figure 2 is a rear view, schematic and partial, of the cold flow nozzle of the turbine engine of Figure 1, seen according to the arrow II of the latter figure.
• FIG. 3 is a diagrammatic section along the line III - III of FIG.
• Figure 4 is a partial schematic plan view of the edge of the outlet orifice of the cold flow nozzle provided with the chevrons according to the present invention.
• FIG. 5 is a diagram indicating, for a known engine and for this same known improved engine according to the invention, the variation of pressure P at the rear of said engine, as a function of the distance d along the axis of this latest.
• the turbofan engine 1 with longitudinal axis L-L and shown in Figure 1, comprises a nacelle 2 externally bounded by an outer shell nacelle 3.
• the nacelle 2 comprises, at the front, an air inlet 4 provided with a leading edge 5 and, at the rear, an air outlet orifice 6 having the diameter ⁇ and delimited by an edge 7 serving as trailing edge to said nacelle.
• a fan 8 directed towards the air inlet 4 and capable of generating the cold flow 9 for the turbine engine 1;
• a central generator 10 comprising in a known manner low and high pressure compressors, a combustion chamber and turbines at low and high pressure, and generating the hot flow 1 1 of said turbine engine 1;
• annular cold flow channel 1 formed around said central generator 10, between an inner fan cowl 13 and an outer fan cowl 14.
• the external fan cowl 14 forms a nozzle for the cold flow and converges towards the rear of the turbine engine 1, towards said cowl external of the nacelle 3, to form therewith the edge 7 of said orifice 6, which thus constitutes the outlet orifice of the cold flow.
• a plurality of chevrons 15 are distributed on said edge 7 of the orifice 6, around said axis L-L, projecting towards the rear of the turbine engine 1.
• the rafters 15 are two by two spaced apart, leaving passages 16 between them. Moreover, each chevron 15 is inclined towards the longitudinal axis LL so as to penetrate into said cold stream 9 with a penetration angle a (see Figure 3). Measured from the outer fan cowl 14, the penetration angle ⁇ is at least 20 °, and preferably about 30 °.
• Penetration angle ⁇ the angle defined by the tangent T to the outer cover 14, near the edge 7, and the general direction D of the outer surface of the rafter 15.
• the length £ of each chevron 15 from edge 7 of the outlet orifice 6 is between 0.03 times and 0.06 times the diameter ⁇ of the latter. This length is, for example, at most equal to 150 mm.
• the penetration angle ⁇ and the length ⁇ are such that the height h of radial penetration of the rafters 15 in the cold stream 9 is between 0.01 times and 0.03 times said diameter ⁇ of the orifice of cold flow output 6.
• each chevron 15 has the at least approximate shape of a trapezium with lateral sides 17, 18 each of the lateral sides 17, 18 forms, with said edge 7, an angle b between 125 ° and 155 °.
• the spacing E between two consecutive chevrons 15 along the edge 7 is greater than 1.5 times the width L of the rafters 15 at said edge 7.
• the spacing E may be close to twice the width L.
• edge 7 of the outlet orifice 6 provided with the chevrons 15 of FIG. 4, we mean: by the angle b, the angle defined by the tangent S of the edge 7 and the straight line M, N extending a lateral side 17, 18 of a chevron 15;
• width L of a chevron 15 the distance separating the intersection 11 from the line M, extending a lateral side 17 of a chevron 15, with the tangent S of the edge 7 and the intersection 12 of the line N, extending the other side 18 of the chevron 15, with the tangent of the edge 7;
• the small base of the rafters 15, spaced from the edge 7, comprises a central notch 19.
• this small base has two lateral projections 20 and 21 separated by said notch 19.
• the notch 19 and the lateral projections 20 and 21 are rounded, so that said small base is corrugated with two lateral bumps (the projections 20 and 21) separated by the notch 19.
• each of the lateral sides 17, 18 of the rafters 15 is connected to the edge 7 of the orifice 6 by a rounded concave line 22 or 23, respectively.
• an aerodynamic flow V flows around the nacelle 2, in contact with the outer shell nacelle 3 (see Figures 1 and 3).
• jets 9.15 thereof are deflected by said rafters 15 towards the axis LL of the turbine engine 1, while other jets 9.16 said cold flow pass between the rafters 15, through the passages 16, an extension of the outer fan cowl 14, the acceleration of the jets 9.1 5 being much greater than that of the jets 9.16.
• the vortices generated by the bumps 20 and 21 of the rafters 15 there is an excellent mixture between the cold flow 9 and the aerodynamic flow V.
• the jet noise is reduced.
• the cold flow 9 is destructured at least peripherally, so that the noise shock cells are reduced.
• FIG. 5 is a diagram indicating the pressure oscillations P at the rear of the turbine engine as a function of the distance d thereto.
• the curve 24 in the solid line of FIG. 5 corresponds to said improved turbine engine according to the invention by arranging 14 chevrons 15 equi-parties at the periphery of the outlet orifice of its external blower cover, so as to provide as many passages 16
• the dotted curve of FIG. 5 corresponds to the same non-improved turbine engine according to the invention.

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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)

Applications Claiming Priority (2)

Publications (1)

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ID=39941857

Family Applications (1)

Country Status (9)

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Family Cites Families (29)

• 2008
  • 2008-05-07 FR FR0802540A patent/FR2930972B1/fr not_active Expired - Fee Related
• 2009
  • 2009-04-30 WO PCT/FR2009/000515 patent/WO2009138597A1/fr active Application Filing
  • 2009-04-30 RU RU2010149962/06A patent/RU2449150C1/ru not_active IP Right Cessation
  • 2009-04-30 JP JP2011507958A patent/JP2011520064A/ja active Pending
  • 2009-04-30 CN CN2009801162335A patent/CN102105670A/zh active Pending
  • 2009-04-30 EP EP09745916A patent/EP2297445A1/de not_active Withdrawn
  • 2009-04-30 CA CA2721227A patent/CA2721227A1/fr not_active Abandoned
  • 2009-04-30 US US12/990,733 patent/US20110047960A1/en not_active Abandoned
  • 2009-04-30 BR BRPI0908325A patent/BRPI0908325A2/pt not_active IP Right Cessation

Non-Patent Citations (1)

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