Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
  • F02M55/04—Means for damping vibrations or pressure fluctuations in injection pump inlets or outlets
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02K—JET-PROPULSION PLANTS
  • F02K9/00—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof
  • F02K9/42—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof using liquid or gaseous propellants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
  • B01F25/12—Interdigital mixers, i.e. the substances to be mixed are divided in sub-streams which are rearranged in an interdigital or interspersed manner
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02K—JET-PROPULSION PLANTS
  • F02K9/00—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof
  • F02K9/42—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof using liquid or gaseous propellants
  • F02K9/44—Feeding propellants
  • F02K9/52—Injectors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M43/00—Fuel-injection apparatus operating simultaneously on two or more fuels, or on a liquid fuel and another liquid, e.g. the other liquid being an anti-knock additive
  • F02M43/04—Injectors peculiar thereto
• • 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
  • F05D2260/00—Function
  • F05D2260/96—Preventing, counteracting or reducing vibration or noise
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R2900/00—Special features of, or arrangements for continuous combustion chambers; Combustion processes therefor
  • F23R2900/00014—Reducing thermo-acoustic vibrations by passive means, e.g. by Helmholtz resonators

Definitions

• the present invention relates to an injection element of two propellants in a combustion chamber, more particularly designed for a rocket engine with at least one combustion chamber, of the type comprising an injector grouping one or a plurality of such injection elements.
• the invention relates more particularly to an improvement made to such an injection element, in its downstream part where the mixing of the two propellants is carried out, in order to reduce the acoustic noise in the combustion chamber.
• Patent document FR 2,712,030 A1 describes an injector of two propellants in a rocket engine combustion chamber comprising a feed structure where the two propellants feed a plurality of injection elements arranged parallel to each other, in an axisymmetric configuration on the surface of a so-called “injection plate” circular structure forming part of the injector.
• injection plate can thus be associated with a large number of injection elements, for example up to a hundred or more, combining their unit rate to provide the overall flow of the engine.
• each injection element comprises a first conduit for the injection of the first propellant, and a second conduit for the injection of the second propellant, the second duct being annular, coaxial and externally adjacent. at the first conduit.
• annular duct means a duct whose radial section shows an annular flow section
• tubular duct means a duct to the solid section.
• upstream and downstream are defined according to the flow direction of the propellants.
• the propellants are injected into the combustion chamber through coaxial ducts of the injection elements of the FR injector, the turbulences caused in the boundary layers between the concentric and adjacent flows can ensure homogeneous mixing.
• two propellants by shear in their flow.
• such a combustion chamber can generate, in operation, a combustion noise that could even enter into strong acoustic coupling with the vibratory eigenmodes of the chamber. Such acoustic vibrations can thus resonate, reaching amplitudes likely to cause irreversible damage to the combustion chamber and the injector.
• damping devices at the periphery of the injection plate.
• the most commonly used damping devices are the baffles and the acoustic cavities.
• these damping devices have considerable disadvantages of increasing the mass, size, complexity and manufacturing costs of the combustion chamber, and will require, in addition additional validation tests, in particular their thermomechanical behavior in an extremely environment demanding.
• the invention therefore aims at providing an injection element which makes it possible to remedy these drawbacks.
• the first duct is also annular, surrounding a central body of the injection element, said central body having at least one cavity in communication with an external surface of the central body and configured to damp at least a predetermined acoustic frequency f.
• said acoustic dampening cavity is configured as a Helmholtz resonator, with a volume V in communication with an outer surface of the central body through a port of section A and length l 0 .
• a Helmholtz resonator has its own acoustic frequency according to the following equation:
• a Helmholtz resonator tuned to a predetermined excitation frequency f makes it possible to dissipate at least part of the acoustic wave energy at this frequency.
• the orifice connecting the cavity to the outer surface of the central body is substantially coaxial with said first and second conduits. In this way the orifice is oriented in the direction from which most of the combustion noise proceeds.
• the cavity communicates directly with the first conduit through the orifice, which is pierced, laterally, in the outer surface of the central body. This allows damping acoustic waves propagating upstream by the first conduit.
• said cavity is configured as an axial bore in the central body with a depth l p substantially equivalent to a quarter of the wavelength ⁇ corresponding to the acoustic frequency. f predetermined.
• the term axial orientation is that of the flow of propellant. The cavity thus forms a quarter-wave tube for attenuating acoustic waves of frequency f.
• an injection element in order to further improve the mixing of the two propellants downstream, further comprises a third duct, able to also inject the first propellant, said third conduit being annular and coaxial with the first and second conduits and externally adjacent to the second conduit.
• the invention also relates to an injector comprising at least one injection element as described above, a combustion chamber comprising at least one such injector, and a rocket engine comprising at least one such combustion chamber.
• combustion chamber is meant, in the present context, not only a single-element main combustion chamber of a rocket engine, but also, inter alia, one or more elements of a multi-element combustion chamber, a prechamber staged combustion engine, or a gas generator for, for example, the actuation of a propellant supply turbopump.
• the invention also relates to a method of damping a combustion noise in a combustion chamber, in which a predetermined acoustic frequency is damped in a cavity of a central body of an injection element of a mixture two propellants in the combustion chamber, said injection element comprising, at least, a first annular duct for the injection of a first ergol externally adjacent to the central body, and a second duct for the injection of a second annular propellant, coaxial and externally adjacent to the first duct.
• this injection element could further comprise a third duct, able to also inject the first propellant, said third duct being annular and coaxial with the first and second ducts and externally adjacent to the second duct.
• FIGS. 2a, 2b and 2c are longitudinal sections of injection elements according to first, second and third embodiments.
• FIGS. 3a, 3b and 3c are longitudinal sections of injection elements according to fourth, fifth and sixth embodiments.
• FIG. 1 A rocket engine 1 with liquid propellants, in particular cryogenic liquid propellants, is illustrated schematically in FIG. 1.
• This rocket engine 1 comprises a tank 2 for the first propellant, a tank 3 for the second propellant, a gas generator 4 powered. by the first and second propellants, a turbopump 5 actuated by the combustion gases from the gas generator 4, a main combustion chamber 6 fed with propellants by the turbopump 5, and a convergent-divergent nozzle 7 for the propulsive ejection of combustion gases generated in the main combustion chamber 6.
• these components comprise propellant injection elements making it possible to obtain a homogeneous mixture and distribution of the propellants.
• these injection elements are mounted on an injection plate fed by the injected propellants.
• FIG. 2a shows the end portion of an injection element 201 with a tri-coaxial structure for injecting and mixing two propellants E1, E2.
• the injection element 201 has an axis of symmetry X, which is also the main axis of flow propellants El, E2. The way in which the different constituent parts of this injection element are arranged relative to one another and held in their respective positions while being connected to the two propellant supply circuits El, E2, is not shown.
• the injection element 201 comprises, in its end portion, three tubular walls 202, 203, 204 concentric around a central body 205 so as to form a first, second and third annular and coaxial ducts 206, 207, 207.
• a shrinkage RE is defined between the end of the outer shell, i.e., the outermost tubular wall 204 and the intermediate walls 202, 203.
• the outer wall 204 may be part of the injection plate itself, and the walls Intermediates 202,203 could be integrated into a single united body upstream.
• the first and third ducts 206, 208 are configured for the injection of the first ergol El, while the second duct 207, located radially adjacent to the outside of the first duct 206 and inside the third duct 208, is configured for the injection of the second propellant E2.
• the first and the second propellants El, E2 being injected at different speeds during the operation of the injection element 201, the shears inside and outside the annular flow of the second propellant E2 in the recess RE, produce turbulence in the flows of the two propellants E1, E2 ensuring a homogeneous mixture of the two propellants E1, E2.
• the three ducts 206, 207 and 208 are annular, the dimensioning of the injection element 201 can easily be adapted to the total flow rate of propellants required.
• the central body 205 has a cavity 209 of volume V, closed by a plate 210 perforated by an orifice 211 substantially aligned with the central axis X of the injection element.
• the orifice 211 has a section A and a length l 0 and communicates the cavity 209 with an outer surface 212 of the central body 205 facing the combustion chamber 213.
• the cavity 209 with the orifice 211 thus form a resonator of Helmholtz of proper frequency f according to the equation:
• a combustion noise of a predetermined frequency such as for example a frequency that can cause resonance effects with the structure of the combustion chamber, can be damped effective.
• the injection element 201 is also a tricoaxial type element with tubular walls 202, 203, 204 forming a first, second and third annular and coaxial ducts 206, 207, 207, around a body Central 205.
• a recess RE is defined between the end of the outer shell, i.e. the outermost tubular wall 204, and the intermediate tubular walls 202 and 203.
• the first and third ducts 206, 208 are also configured for the injection of the first ergol El, while the second duct 207, located radially adjacent to the outside of the first duct 206 and inside the third duct 208, is configured for the injection of the second propellant E2.
• the orifice 211 is not pierced in the plate 210 closing the cavity 209 of the central body 205, but laterally in the outer surface 212 of the central body 205, so as to put the cavity 209 in direct communication with the first conduit 206, and this to damp the acoustic waves propagating in the recess RE and in the first conduit 206.
• the injection element 201 is also a tricoaxial type element with tubular walls 202, 203, 204 forming a first, second and third annular and coaxial ducts 206, 207, 207 around a central body 205.
• a recess RE is defined between the end of the outer shell, i.e. the outermost wall 204, and the intermediate walls 202 and 203
• the first and third ducts 206, 208 are also configured for the injection of the first ergol El, while the second duct 207, located radially adjacent to the outside of the first duct 206 and inside the third duct 208, is configured for the injection of the second propellant E2.
• the cavity 208 is not closed by a plate, but is configured as an axial bore of diameter d in the central body 205, open towards the combustion chamber 214 and blind, and having a depth l p substantially equivalent to a quarter of the wavelength ⁇ corresponding to the predetermined acoustic frequency f that is meant to be damped.
• the cavity 209 functions as a quarter-wave tube for damping combustion noise during operation of the combustion chamber 214.
• the injection element 201 comprises, in its end part, two concentric tubular walls 202, 204 around a central body 205 so as to form a first and a second ducts 206,207 annular and coaxial.
• a shrinkage RE is defined between the end of the outer shell, that is to say the outer tubular wall 204 and the intermediate wall 202.
• the wall 204 may be integrated into the injection plate itself.
• the first conduit 206 is configured for the injection of the first ergol El
• the second conduit 207 located radially adjacent to the outside of the first conduit 206, is configured for the injection of the second propellant E2.
• the first and the second propellants E1, E2 being injected at different speeds during the operation of the injection element 201, the shear between the annular flows of the two propellants El, E2 in the RE shrinkage produce turbulence ensuring a homogeneous mixture two propellants El, E2.
• the two ducts 206, 207 are annular, the dimensioning of the injection element 201 can easily be adapted to the total flow rate of propellants required.
• the central body 205 has a cavity 209 of volume V, closed by a plate 210 perforated by an orifice 211 substantially aligned with the central axis X of the injection element.
• the orifice 211 has a section A and a length l 0 and communicates the cavity 209 with an outer surface 212 of the central body 205 facing the combustion chamber 213.
• the cavity 209 with the orifice 211 thus form a resonator of Helmholtz of own frequency f.
• the injection element 201 also comprises, in its end part, two concentric tubular walls 202, 204 around a central body 205 so as to form a first and a second annular and coaxial conduits 206,207.
• a shrinkage RE is also defined between the end of the outer shell, that is to say the outer tubular wall 204 and the intermediate wall 202.
• the first conduit 206 is configured for the injection of the first ergol El, while the second conduit 207, located radially adjacent to the outside of the first conduit 206, is configured for the injection of the second propellant E2.
• the cavity 209 formed by an axial bore in the central body 205 is placed in direct communication with the first conduit 206 through an orifice 211 pierced, laterally, in the outer surface 212 of the central body 205, in order to put the cavity 209 in direct communication with the first conduit 206, and to form a Helmholtz resonator for damping the acoustic waves propagating in the recess RE and in the first conduit 206.
• the injection element 201 also comprises, in its end part, two concentric tubular walls 202, 204 around a central body 205 so as to form a first and an second ducts 206,207 annular and coaxial, respectively configured for the injection of a first and a second propellant El, E2.
• a shrinkage RE is also defined between the end of the outer shell, that is to say the outer tubular wall 204 and the intermediate wall 202.
• the cavity 209 is not closed by a plate, but is configured as an axial bore of diameter d in the central body 205, open towards the combustion chamber 214 and blind, and having a depth l p substantially equivalent to a quarter of the wavelength ⁇ corresponding to the predetermined acoustic frequency f that is meant to be damped.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Fuel-Injection Apparatus (AREA)
• Nozzles (AREA)
• Infusion, Injection, And Reservoir Apparatuses (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2011
  • 2011-07-07 FR FR1156143A patent/FR2977639B1/fr not_active Expired - Fee Related
• 2012
  • 2012-06-27 EP EP12738533.4A patent/EP2729691A1/de not_active Withdrawn
  • 2012-06-27 JP JP2014517888A patent/JP2014520997A/ja not_active Ceased
  • 2012-06-27 CN CN201280033681.0A patent/CN103649511A/zh active Pending
  • 2012-06-27 US US14/131,123 patent/US20140284394A1/en not_active Abandoned
  • 2012-06-27 RU RU2013157498/06A patent/RU2593315C2/ru not_active IP Right Cessation
  • 2012-06-27 WO PCT/FR2012/051473 patent/WO2013004949A1/fr not_active Ceased

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