US3899883A - After burner - Google Patents

After burner Download PDF

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Publication number
US3899883A
US3899883A US365402A US36540273A US3899883A US 3899883 A US3899883 A US 3899883A US 365402 A US365402 A US 365402A US 36540273 A US36540273 A US 36540273A US 3899883 A US3899883 A US 3899883A
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United States
Prior art keywords
afterburner
gas flow
duct
exhaust gas
fuel
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US365402A
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English (en)
Inventor
Ratko Stakic
Marc Francois Bernard Buisson
Gilbert James Rousseau
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Safran Aircraft Engines SAS
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SNECMA SAS
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Publication date
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    • 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
    • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
    • F23R3/28—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply
    • F23R3/30—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply comprising fuel prevapourising devices
    • F23R3/32—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply comprising fuel prevapourising devices being tubular
    • 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
    • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
    • F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
    • F23R3/16—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration with devices inside the flame tube or the combustion chamber to influence the air or gas flow
    • F23R3/18—Flame stabilising means, e.g. flame holders for after-burners of jet-propulsion plants
    • F23R3/20—Flame stabilising means, e.g. flame holders for after-burners of jet-propulsion plants incorporating fuel injection means

Definitions

  • An afterburner installation for a gas turbine engine including an expansion turbine from which, in operation, there is discharged a high-velocity hightemperature exhaust gas flow, which installation comprises an afterburner duct located downstream of such expansion turbine, through which duct the exhaust gas flow passes, a source of afterburner fuel, and at least one hollow structure arranged within the afterburner duct in order to be in a heat transfer relationship with the high-velocity high-temperature exhaust gas flow; such hollow structure, having its interior connected to the fuel source and comprising an entry portion with an intake orifice facing upstream relative to the direction of exhaust gas flow and through which a fraction from the exhaust gas flow is collected and penetrates into the interior of such hollow structure, the intake portion extending in the longitudinal direction of the afterburner duct, and a discharge portion comprising at least one exit orifice through which a
  • the present invention relates to an afterburner installation designed for fitting to a gas turbine engine comprising an expansion turbine from which, in operation, there is discharged at high-velocity high-temperature exhaust gas flow.
  • the invention relates more particularly to highpower installations for use in high-performance turbojet propulsion engines designed for the propulsion of aircraft at high speeds, in which the temperature of the exhaust gas flow can reach a very high level, for example in the order of 850 to 950C, which is well above the level generally reached in conventional machines designed for the propulsion of aircraft at lower speeds.
  • the afterburner installation is of the kind comprising an after burner duct located downstream of the expansion turbine, through which duct the exhaust gas flow passes, a source of afterburner fuel, and at least one hollow structure arranged within the afterburner duct in order to be in a heat transfer relationship with the high-velocity high-temperature exhaust gas flow; hollow structure, the interior of which is connected to such fuel source, comprising an entry portion with an intake orifice facing upstream relative to the direction of exhaust gas flow and through which a fraction from the exhaust gas flow is collected and penetrates into the interior of the hollow structure.
  • Such intake portion extending in the longitudinal direction of the afterburner duct, and a discharge portion comprising at least one exit orifice through which a high-temperature jet of a mixture of gas and fuel escapes from the hollow structure and enters the afterburner duct where it spontaneously ignites and forms a stabilised flame front.
  • the object of the invention is to overcome the aforesaid drawbacks or difficulties by providing a device which makes it possible to trigger and maintain combustion of a fuel in a high-velocity high-temperature exhaust gas flow, without it being necessary to have recourse to stabilising obstacles and to a special ignition device.
  • the discharge portion of the hollow structure extends transversely relative to the longitudinal direction of the afterburner duct, and the exit orifice or each of such orifices of the discharge portion faces down stream relative to the exhaust gas flow direction.
  • the discharge portion of the hollow structure is disposed immediately in succession to the intake portion thereof.
  • the hollow structure comprises four portions disposed in accordance with the sides of a quadrilateral and traversed in series by the mixture of gas and fuel, namely: a first portion constituted by the intake portion of the hollow structure, a second portion extending transversely of the longitudinal direction of the afterburner duct, a third portion extending in the longitudinal direction of the afterburner duct, and extending upstream of the second portion, and a fourth portion constituted by the discharge portion.
  • the hollow structure comprises, over at least part of its length, a tubular structure.
  • the tubular structure comprises, over at least part of its length, at least two tubular portions supplied in parallel by the same intake orifice.
  • the discharge portion of the hollow structure extends substantially radially relative to the axis of the afterburner duct.
  • the radial spacing between two successive exit orifices decreases progressively with increasing distance from the axis of the afterburner duct.
  • the discharge portion of the hollow structure extends in the circumferential direction of the afterburner duct.
  • the gas turbine engine can be of the single-flow or multiflow type, for example of the dual-flow type, namely a primary high-temperature high-velocity gas flow escaping from the expansion turbine, and a secondary gas flow which is passed around the expansion turbine.
  • the hollow structure in accordance with the invention is designed to enable afterburning of fuel in the primary gas flow, downstream of the expansion turbine, and to this end is arranged in the junction zone in order to be in a heat transfer relationship on the one hand with the primary gas flow and on the other with the pilot combustion chamber.
  • FIGS. 1 and 2 are experimental graphs illustrating the conditions under which ignition of a mixture of fuel and comburrent agent injected into a high-velocity hightemperature flow of gaseous comburrent agent takes place.
  • FIG. 3 is a half-section in an axial plane, on the line IIIIII of FIG. 4, through an afterburner installation in accordance with a first embodiment of the invention.
  • FIG. 4 is a transverse section, on the line IV-IV, through the installation shown in FIG. 3.
  • FIG. 5 is a view on a larger scale and in section on the line V-V, illustrating a detail of the installation shown in FIG. 3.
  • FIG. 6 is a half-section in an axial plane, through an installation in accordance with a second embodiment of the invention.
  • FIG. 7 is a perspective view, partially cut-away, of an afterburner installation in accordance with a variant of the embodiment shown in FIG. 6.
  • FIG. 8 is a half-section in an axial plane, through an afterburner installation in accordance with a third embodiment of the invention.
  • FIG. 9 is a view in transverse section, of a variant of a detail of the invention.
  • the Applicants were confronted with the problem of achieving the triggering and maintenance of combustion of a fuel in a high-velocity, high-temperature flow of gaseous comburrent agent (the temperature being for example between 850C and 950C), without having to slow down the flow and without having to have recourse to a special ignition device.
  • Combustion is triggered, therefore, without the need for a special ignition device and is maintained in the gas flow without it being necessary to have recourse to stabilizing obstacles in order to slow down the flow.
  • the temperature T of the mixture of fuel and conburrent agent at the instant at which it enters the high-velocity, high-temperature gas flow.
  • the reference T will signify the temperature of the gas flow after injection of the fuel.
  • the graphs of FIGS. 1 and 2. illustrate the influence of this temperature T on the one hand upon the time t (in seconds) required to achieve spontaneous ignition, and on the other hand upon the rate of the spontaneous ignition, for the same temperature (850C) of the high-velocity high-temperature flow of gaseous comburrent agent.
  • These graphs demonstrate very well that it is essential, in order for the spontaneous ignition time to be as short as possible, that the temperature T of the mixture of fuel and comburrent agent, should be as high as possible.
  • the general reference 1 has been used to designate an afterburner installation designed to operate in a gas turbine engine such as a turbojet propulsion engine, comprising an expansion turbine 2 from which, in operation, there is discharged a highvelocity, high-temperature exhaust gas flow F containing a certain proportion of comburrent agent oxygen F.
  • This installation comprises, downstream of the turbine 2, an afterburner duct 3 having an axis X'X, externally delimited by a wall 4. At its upstream portion, the afterburner duct 3 has a divergent configuration due to the presence of a fixed turbine cone 5 supported by the wall 4 through the medium of profiled struts 6.
  • the afterburner installation likewise comprises a source 7 supplying afterburner fuel, connected to an annular collector or manifold 8 which externally girdles the afterburner duct 3.
  • This fuel may be liquid or gaseous.
  • a hollow structure 9 is arranged within the afterburner duct 3 in order to be in a heat transfer relationship with the high-temperature, high-velocity exhaust gas flow F escaping from the turbine 2.
  • This hollow structure is represented (see FIG. 3) in the form of an L-shaped tubular structure held in position, in relation to the wall 4, by means of suspension struts (not shown).
  • the hollow structure 9 comprises a first tubular portion 9a extending in the longitudinal direction of the afterburner duct (for example parallel to the axis X'X) and a second tubular portion 9b extending transversely relative to the longitudinal direction (for example substantially radial).
  • the tubular section 9a is equipped with an intake orifice 9aa facing upstream relative to the direction of the gas flow F, through which a fraction f of the flow is collected and enters, under its own dynamic pressure, the interior of the hollow structure 9.
  • the tubular portion 9b advantageously has a streamlined contour (see FIG. 5) in order that the gas flow F is disturbed as little as possible. It is equipped with one or more exit orifices 9171: each of which faces downstream relative to the direction of the gas flow F, through which jets of a mixture of gas and fuel can escape from the hollow structure 9 to enter the afterburner duct 3. As FIGS. 3 and 4 show, the exit orifices 9ba are radially staggered so that the distance separating two successive orifices decreases progressively with increasing distance from the axis X'X of the duct.
  • the gas which enters the interior of the hollow structure 9 commences by cooling in contact with the fuel (this is especially so if the latter is injected in the liquid state and vaporises inside the hollow structure). Being in a heat transfer relationship with the high temperatun gas flow F, the fuel/gas mixture flowing through the hollow structure 9 subsequently becomes preheated to a temperature close to the temperature of self-ignition of the fuel.
  • the thus preheated mixture escapes through the exit orifices 9ba in the form of high-temperature jets which enter the afterburner duct 3 where they spontaneously ignite.
  • a combustion zone is developed which is delimited upstream by a stabilized flame front S located downstream of the exit orifices 91m.
  • the distance a separating the flame front S from the exit orifices 917a is a function of the time taken to achieve spontaneous ignition of the fuel/gas mixture entering the gas flow F, this time itself being a function of the temperature T, of this mixture.
  • the temperature T depends upon the heat transfer efficiency of the hollow structure 9 which will therefore be shaped and dimensioned accordingly.
  • hollow structures 9 could be used whose length and diameter are calculated to take account of the temperature T, which is to be achieved.
  • the arrangement shown in FIG. 3, in accordance with which the fuel/gas mixture is preheated by heat exchange with the exhaust gas flow F before the temperature of the flow has been increased as a consequence of afterburning in the duct 3, is particularly suitable for situations where the temperature of the exhaust flow from the expansion turbine 2 is quite high, higher than 900C for example.
  • the temperature T of the fuel/gas mixture entering the afterburner duct 3 will diminish correspondingly so that the distance d (and, consequently, the length of the afterburner duct) will increase.
  • FIG. 6 illustrates an arrangement which makes it possible to preheat the fuel/gas mixture by heat exchange with the high-velocity high-temperature exhaust gas flow F, after the temperature of the gas flow has been increased as a consequence of after-burning of fuel in the flow.
  • the hollow structure 9 comprises four tubular portions 90, 9b, 9c, 9d, arranged in series with one another.
  • the portions 9a and 90 each extend in the longitudinal direction of the afterburner duct 3, whilst the portions 9b and 9d both extent transversely relative to the longitudinal direction.
  • the hollow structure 9 is equipped as before with an intake orifice a.
  • the exit orifices 9:10 are arranged in the portion 9d, that is to say upstream of the rest of the hollow structure 9.
  • the jets of the fuel/gas mixture escaping from the exit orifices 9da ignite spontaneously in the gas flow F giving rise to a flame front S located at a distance d from the exit orifices 9da.
  • the fuel/gas mixture flowing through the hollow structure 9 experiences a substantially greater temperature rise than is the case with the embodiment illustrated in relation to FIG. 3, so that the ignition time and the ignition d, are considerably reduced.
  • FIG. 7 shows a variant embodiment of the invention, in accordance with which the hollow structure 9 comprises, over at least part of its length, at least two tubular portions 9c,9d, and 9c 9d supplied in parallel by the same intake orifices 9aa and each equipped with exit orifices 9da, and 9da
  • This arrangement has the advantage of making it possible to reduce the diameter of the radial tubular portions 9d, and 941 so that there is less disturbance to the high-velocity high- -temperature gas flow F.
  • FIG. 8 shows a further variant embodiment of the invention in accordance with which the fuel/gas mixture is preheated, in part at least, by heat exchange with an auxiliary heat source.
  • FIG. there is shown a portion of a by-pass or dual-flow gas turbine engine.
  • a primary high-velocity high-temperature gas flow F escapes from an expansion turbine 22, and a secondary gas flow or cold flow Z, passes around the expansion turbine.
  • the two flows F and Z mix in a junction zone located downstream of the turbine 22.
  • the auxiliary combustion chamber 23 directs into the secondary gas flow Z, through the flame-holders 28, gas jets in the course of combustion, and thus acts as a pilot combustion chamber making it possible to trigger and stabilize combustion in the secondary flow.
  • This chamber serves, at the same time, as an auxiliary heat source, as will be explained hereinafter.
  • the invention In order to permit afterburning of fuel in the highvelocity high-temperature primary gas flow F, the invention, as in the preceding cases, provides a hollow structure 29 which makes it possible to very substantially preheat the fuel/gas mixture.
  • This hollow structure comprises a portion 29a of generally annular shape, delimited, on the one hand, by the wall 20 of the pilot combustion chamber 23, and, on the other hand, by a wall 40.
  • the portion 29a contains an intake orifice 2911a likewise of annular form, through which a fraction f of the primary gas flow F can enter the interior of the hollow structure 29.
  • fuel injectors 30 connected by channels 31 to a fuel manifold 32 itself connected to a fuel source (not shown).
  • the lines 31 pass through the pilot combustion chamber 23 inside streamlined struts 33.
  • the hollow structure 29 passes a fuel/- gas mixture which is heated up by heat exchange, on the one hand with the primary gas flow F, and on the other hand with the auxiliary heat source constituted by the pilot combustion chamber 23.
  • the high intensity of combustion in the pilot combustion chamber contributes to a substantial increase in the temperature of the jets of fuel/gas mixture escaping, through the exit orifices 29ba, into the primary gas flow F. In this fashion, a very short ignition time for the afterburning of the fuel in the primary gas flow, is achieved.
  • the pilot combustion chamber 23 plays no other part whatsoever in the aforesaid af terburning process.
  • the hollow structure 29 through which the fuel/gas mixture in the course of preheating flows acts as a heat shield for the wall 20 of the pilot combustion chamber 23.
  • an afterburner installation comprising means bounding an afterburner duct located downstream of said expansion turbine and through which duct said exhaust gas flow passes, a source of afterburner fuel, and a system for supplying the afterburner duct with afterburner fuel from said fuel source to bring about combustion of said fuel in said afterburner duct and for stabilizing said combustion
  • said supplying and stabilizing system consisting of a plurality of hollow tubular structures each distinct from said means bounding the afterburner duct and arranged totally within said afterburner duct, so as to be immersed in said high-velocity, high-temperature exhaust gas flow, each said tubular structure comprising four portions arranged in series relationship including:
  • a first entry portion extending peripherally in the longitudinal direction of the afterburner duct and having one intake orifice which faces upstream relative to the direction of said exhaust gas flow, and through which a fraction from said exhaust gas flow is collected and penetrates into the interior of said tubular structure; the interior of said entry portion being further connected, in the vicinity of said intake orifice, with said source of afterburner fuel;
  • each tubular structure is traversed, along substantially its whole length extending from its first portion to its fourth portion, by a mixture of gas and fuel which is preheated by heat-transfer from the high-velocity, high-temperature exhaust gas flow in which said structure is immersed, which preheated mixture escapes in the form of a plurality of preheated jets which spontaneously ignite after entering the afterburner duct and form a stabilized flame front, without any necessity for recourse to any other film stabilizing means.
  • said afterburner duct comprises a section having a divergent configuration relative to said exhaust gas flow direction, and said fourth portion of the tubular structure is located in an upstream region of said divergent section.
  • tubular structure comprises at least two tubular portions supplied in parallel by the same intake orifice.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Incineration Of Waste (AREA)
  • Combustion Of Fluid Fuel (AREA)
US365402A 1972-06-01 1973-05-31 After burner Expired - Lifetime US3899883A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7219731A FR2188060B1 (enrdf_load_stackoverflow) 1972-06-01 1972-06-01

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US3899883A true US3899883A (en) 1975-08-19

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US365402A Expired - Lifetime US3899883A (en) 1972-06-01 1973-05-31 After burner

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US (1) US3899883A (enrdf_load_stackoverflow)
DE (1) DE2327187C3 (enrdf_load_stackoverflow)
FR (1) FR2188060B1 (enrdf_load_stackoverflow)
GB (1) GB1427197A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4005572A (en) * 1975-04-18 1977-02-01 Giffhorn William A Gas turbine engine control system
US4751815A (en) * 1986-08-29 1988-06-21 United Technologies Corporation Liquid fuel spraybar
US5076062A (en) * 1987-11-05 1991-12-31 General Electric Company Gas-cooled flameholder assembly
US5245934A (en) * 1988-06-08 1993-09-21 Mortimer Technology Holdings Ltd. Heating matter

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3931707A (en) * 1975-01-08 1976-01-13 General Electric Company Augmentor flameholding apparatus
RU2472027C1 (ru) * 2011-07-12 2013-01-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования Уфимский государственный авиационный технический университет Фронтовое устройство форсажной камеры со стабилизатором пламени изменяемой геометрии
CN116025924B (zh) * 2023-01-13 2024-09-20 南京航空航天大学 一种加力燃烧室外凹腔火焰稳定器后壁面强制冷却装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2944388A (en) * 1955-02-24 1960-07-12 Thompson Ramo Wooldridge Inc Air atomizing spray bar
US2959006A (en) * 1957-02-01 1960-11-08 Snecma Semi-vaporisation burner
US3043101A (en) * 1959-03-13 1962-07-10 Roils Royce Ltd By-pass gas turbine engine employing reheat combustion
US3786632A (en) * 1971-08-21 1974-01-22 Rolls Royce Reheat system for a gas turbine engine

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2711070A (en) * 1952-07-31 1955-06-21 Westinghouse Electric Corp Gas turbine apparatus
DE1123163B (de) * 1958-05-23 1962-02-01 Gen Electric Rueckstosstriebwerk mit Nachverbrennungseinrichtungen
FR1588974A (enrdf_load_stackoverflow) * 1968-10-02 1970-03-16

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2944388A (en) * 1955-02-24 1960-07-12 Thompson Ramo Wooldridge Inc Air atomizing spray bar
US2959006A (en) * 1957-02-01 1960-11-08 Snecma Semi-vaporisation burner
US3043101A (en) * 1959-03-13 1962-07-10 Roils Royce Ltd By-pass gas turbine engine employing reheat combustion
US3786632A (en) * 1971-08-21 1974-01-22 Rolls Royce Reheat system for a gas turbine engine

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4005572A (en) * 1975-04-18 1977-02-01 Giffhorn William A Gas turbine engine control system
US4751815A (en) * 1986-08-29 1988-06-21 United Technologies Corporation Liquid fuel spraybar
US5076062A (en) * 1987-11-05 1991-12-31 General Electric Company Gas-cooled flameholder assembly
US5245934A (en) * 1988-06-08 1993-09-21 Mortimer Technology Holdings Ltd. Heating matter

Also Published As

Publication number Publication date
DE2327187A1 (de) 1973-12-20
GB1427197A (en) 1976-03-10
DE2327187C3 (de) 1981-07-09
FR2188060B1 (enrdf_load_stackoverflow) 1976-06-11
DE2327187B2 (de) 1980-11-27
FR2188060A1 (enrdf_load_stackoverflow) 1974-01-18

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