Firebox of civilian aircraft engine designs characteristic and crucial technology

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Our country already project approving proper motion develops large and civil aircraft. Academician of Liu Daxiang of expert of famous aviation engine points out: "Big airlines project whether one of successful keys are dynamical problem, must want base oneself upon at home, own development. At present Chinese aviation industry still is put in the problem such as heavy-duty name small base. Motivation is the heart of equipment, final plane must have ' Chinese heart ' " . Accordingly, the aviation engine of the big thrust that the large airlines of the civil aircraft that our country proper motion develops or martial utility must use our country proper motion develop in future, low pollution, macrobian life. Civil engine must have good environmental protection sex, namely of engine discharge must satisfy international Civil Aviation Organization (ICAO) release discharge a standard (basically be the index such as CO, UHC, NOx and fume) , satisfy civilian machine to be since abroad at the same time when falling of relevant country discharge standard requirement, achieve comfortable boat to ask and obtain ability of comfortable boat card to enter market of world civil engine. And the firebox that regards the important key of engine as one of components is contaminant is exclusive " maker " , it is civil engine deny development to succeed and can obtain the key that enters market qualification. From 20 centuries 70 time ICAO begins to make since discharging a standard strictly, company of world-famous aviation engine discharges a requirement to satisfy, occupational civilian machine market, the development that began low pollution firebox works, fetched significant gain. Low discharge firebox development to must use a lot of new designs, production technology and new material, new technology to wait. Low discharge, the key that the development of macrobian life firebox is development of civil engine success, because this should be aimed at abroad active service / ongoing and large-scale for military use and current situation of firebox of civil aviation engine, analyse its to design characteristic and development technology, understand and master long life life, low the crucial technology that discharges firebox design and about discharge a standard, to begin civil engine firebox development lays next foundations. Abroad is active service / firebox of ongoing and civil engine basically designs a characteristic at present, the company that produces large-scale for military use and civil aviation engine can be being developed on international basically is the minority such as R of · of CFMI, GE, PW, R, IAE a few companies, the engine that a few afore-mentioned companies produce is main forestall plaza of world civil engine, and Russia produces civil aviation engine to be in the world share of civilian machine market is relatively minor. Since ICAO begin to make discharge a standard, discharge in castigatory discharge to engine in the standard since raising stricter and stricter requirement, the advanced engine that these companies develop is not had is not will be satisfied or the significant demand that excel discharges a standard to regard firebox as the design. Firebox developed a technology to also obtain significant progress, produced a large number of contented pollution to discharge the advanced firebox that the standard asks, these firebox used advanced improvement to organize the new technology of combustion and cooling structure mostly. Watch 1 gave out the engine firebox that contemporary and main large and civil aircraft uses designs a characteristic. These firebox are the demand development according to environmental protection standard, represented basically low pollution is at present civil the top level of firebox, the key burns from the organization below and the cooling technology respect of firebox introduces the design characteristic of these firebox. 1 organization of Nextpage 　 　 burns the only link accent that firebox of contemporary and civil engine basically has a tradition, double-loop antrum and current and newest double-loop are mixed beforehand come back stream implement firebox 3 kinds of structures. No matter advanced civil motor is to use double-loop antrum to return be only link antrum to classification combustion technology discharges those who reduce NOx as firebox constituent flaming key considers a target, mix what head oil gas basically considers in the design to burn in order to reduce beforehand temperature, use divisional combustion to decrease respectively start, accommodation train, those who take off to fall with cruise operating mode discharge index. 1.

The traditional civil engine firebox before GE90 basically uses firebox of antrum of 1 only link the texture of only link antrum that centrifugal nozzle adds head pulverization unit. Its masterpiece is series of CFM56 engine firebox. Its firebox is short annular structure, constituent combustion uses centrifugal nozzle to add dual class to come back stream implement fuel pulverization system, the pulverization that ensured fuel is good and constituent flaming stability are characteristic. The engine of company of R · R uses firebox of only link antrum mostly, the head uses pneumatic pulverization nozzle and come back stream implement structure. RB211-524/535 engine firebox is firebox of the 2nd phase, the structure of firebox of only link antrum that uses fuel atomizer of 18 air pulverization. Newest B787 is motivation with Trent 1000 engine, its firebox is the firebox of the 5th phase that develop by Trent700 and comes, through improving the design of geometrical structure with controlling NOx generate, it uses fuel atomizer of 24 air pulverization, advocate those who light an area to compare the RB211-524/535 firebox that uses firebox of only link antrum likewise advocate cubage burning an area increases 24% , improved rekindle performance; Total volume decreased however 30% , controlled contaminant discharge. The V2500 engine of IAE also uses design of only link antrum. Its discharge index to satisfy CAEP/2 and CAEP/4 to discharge limitation to discharge a standard. PW and company of R · R are on foundation of firebox of only link antrum, developed the combustion technology that axial classifications, this type firebox also is a kind of firebox of only link antrum. The principle of firebox is not to change air allocation to compare, adjust however the fuel of each area allocates, thereby enkindle temperature is maintained go up relative to constant level in, part accommodation train with takeoff condition, in order to realize engine low discharge. When firebox begins the work, go to gush of one part fuel above all the area of the 1st combustion of firebox, other fuel mix with air first, again gush enters downstream the 2nd combustion area or advocate combustion area, in order to make lowest of NOx discharge capacity. Area of the 1st combustion starts to work to accommodation train condition in engine, area of the 2nd combustion works below high-power condition. Axial classifications the advantage of firebox is ignition fast and reliable, advocate section plane of temperature of radial of exit of tall, firebox can develop area combustion efficiency a satisfactory level, and once develop,change no longer to satisfactory level. The combustion system that the lean oil that PW company develops mixes axial to classification beforehand has 3 different combustion areas, the geometrical appearance of every area is in distinct engine power range and fuel / air is optimized than falling. Accordingly, this firebox appears impossibly lean oil burns. The job that its control a system is the working status according to engine allocates fuel accurately to 3 areas, in order to obtain accurate fuel / air comparing, make NOx and CO discharge capacity are achieved least. Company of R · R also developed axial to classification firebox, already applied its to BR715 engine. TALON firebox is the plan of chance of associated technology test and verify that PW and MTU implement (JTDP) the firebox of only link antrum of development, its go out the RQL(rich oil of PW lean oil to burn quickly) the technology applies in civil firebox, special rich oil is designed in forehead of firebox of all job status, outclass chemistry is appropriate compare combustion than oil gas, also ensure at the same time stability of low power position. First TALON firebox is used in PW4098, engine of series of PW4000, PW6000 uses the TALON Ⅱ firebox after improving, PW8000 uses structure of firebox of TALON Ⅲ . TALON Ⅲ and TALON X firebox increased further advocate cubage burning an area, ensured of maximize quench mix, combustion time is short, the NOx when land and taking off is discharged decreased than ICAO96 standard 70% . 1.

Firebox of 2 double-loop antrum is mixed for performance of position of contented low power discharge a requirement, GE engine company was designed above all contented low the double-loop antrum firebox that discharges standard demand. Double-loop antrum firebox uses radial to classification commonly structure, those who have a platoon to put low, flame tube is long / compare reasonable, length weak point, weight high kinetic problem mixes light, rotor less prevent the characteristic such as carbon deposit. The CFM56-5B that GE company designs is A320 familial in the motor that uses technology of advanced double-loop antrum firebox exclusively, the DAC of CFM56 reduced NOx of 45% . Firebox of GE90 double-loop antrum starts in engine / accommodation train condition, antrum of only outward annulus offers oil, right now oil gas of outer shroud antrum compares velocity of flow of tall, air to spend time of low, combustion to grow, reduced CO/CH to discharge a level not only, still increased startability and capacity of empty midpoint fire, expanded flameout is attrib border; In other job status, offer oil to 2 annulus antrum at the same time, core antrum optimizes a design by big operating mode, high rate, the oil gas of reason head spends time of tall, combustion than velocity of flow of low, air short, can reduce the platoon of NOx to put a standard, and diameter of enkindle room exit distributings to temperature evener. 1.

3TAPS technology firebox 　 GEnx is the thrust stage that GE company is B787 of 250 class plane and A350 to develop for 236.

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The double rotor of 23kN, exceed big contain path to compare engine of fan of large environmental protection clean and civil eddy, its structure results from the GE90 engine that exceeds big thrust. The double-loop antrum that its geometry structure is different from GE90 and CFM56-5 completely (DAC) structure, used double-loop to be mixed beforehand come back shed firebox (TAPS) combustion technology. This engine reduced fuel wastage and contaminant discharge capacity greatly, it is current coequal thrust stage is the cleanest on the world, most the engine of environmental protection. The working principle of TAPS technology is to use nozzle of pulverization of fuel of two annular and homocentric Parker Hannifin to come back to the center respectively stream implement exit offers oil and outer shroud to come back stream implement in fuel injection, even oil gas is formed to mix in firebox head. In general firebox, mix into of the rich oil before igniting is mixed, after igniting, turn for lean oil, in flowed backward once upon a time in oil gas mixture and burning to be changed to lean oil by rich oil, because combustion temperature is high,will produce NOx. And in TAPS, combustion begins initial stage, puissant double-loop is mixed beforehand come back stream implement make oil gas is mixed very well with respect to mix into at the beginning, oil gas mixture is in the combustion process that flowed backward once upon a time, rich oil to lean oil transition short, not only NOx decreased 50% and firebox job temperature reduced 200 ℃ . The test of TAPS firebox model that GE company has makes clear, this technology realized low NOx to discharge level and low turbine inlet temperature inhomogenous spend 2 ends. 2 flame tube of Nextpage 　 　 are cooling and contemporary head of civilian machine firebox is designed for lean oil commonly, the empty tolerance that is used at refrigeration compares traditional firebox to be reduced greatly; Engine total pressure ratio is high at the same time, firebox inlet temperature is higher than traditional firebox a lot of, firebox work environment should compare traditional firebox to be gotten badly much, grow the need of life to get used to firebox, must use more advanced firebox refrigeration structure. The refrigeration of existing and large civil engine basically uses concussion to enrage film to add float wall or wall of much inclined hole to wait for advanced compound and cooling structure. 2.

Flame tube of wall of float of flame tube of 1 float wall is general by a lot of annular paragraph join with adiabatic annulus and become. Annular paragraph the back has convection to come loose to the one side of blaze hot protruding annulus, have the crack that can form cooling heat insolation to enrage film. Adiabatic annulus by " float tile " composition, join with bolt outer annulus paragraph on. "Float tile " use nicety to cast, can change. In the coating of local spray heat barrier of cooling and adiabatic annulus, can drop component surface temperature. Float wall flame tube has improvement requirement of work of flame tube wall, lengthen flame tube life, improvement firebox temperature distributings wait for a characteristic. 20 centuries at the beginning of 90 time, PW company uses float wall flame tube to V2500 engine, apply to the civil engine such as series of engine of F119 for military use and PW4000, PW6000, PW8000 again later. In recent years, in IHPTET the plan falls, PW company experiments in complete annular combustor again on test and verify besmear has SiC/SiC pottery and porcelain base of composite material coating " float tile " enrage velar refrigeration technology with concussion. SiC/SiC pottery and porcelain base composite material coating is technology of a kind of aggrandizement, can avoid " float tile " suffer corrode, raise its high temperature resistant ability, prolong its life. And technology of refrigeration of concussion gas film can make float wall firebox compares next works in high temperature, expensive oil gas, obtain even temperature field to distributing. The structure of float tile fragment that typical float tile fragment writtens guarantee compose is like V2500 engine firebox, its head uses float to block splash board structure of refrigeration of much inclined hole. Float tile fragment chooses what block heats up alloy and likelihood to be able to bear or endure the material of higher temperature and enhance pottery and porcelain / ODS material undertakes machining, it structure and radiation thermal current are kept apart outside flame tube. Add heat barrier coating through film of concussion, convection, gas compound and cooling means can satisfy tile fragment refrigeration to need. The TALON series firebox of PW also uses concussion to enrage film to add the cooling program of float wall, enhanced cool performance further, improved the working life of firebox significantly. 2.

2 much inclined hole are cooling flame tube of refrigeration of much inclined hole of flame tube 　 is cast by nicety of high temperature alloy, the link of the refrigeration that enrage film that did not introduce convention, use two air current that had shed a large number of inclined hole that angle differs on flame tube to undertake cooling however. Efficient refrigeration undertakes to its when two air current flow into flame tube (be equivalent to disperse the internal heat with sudorifics cooling) , cooling efficiency is as high as 90% , but refrigerative air dosage decreases 40% , the length that field of firebox outlet temperature compares even, firebox is shorter. The F414 engine of GE90 and for military use all used this kind of flame tube that machines by GTD222 alloy. In the engine that comparatives in thrust stage, the length of GE90 engine firebox is the shortest. Firebox develops crucial technology 　 　 of 1 design technology (1) firebox designs a technology. Our country will begin the development of civilian machine firebox first, the design system of military plan firebox cannot get used to civilian machine firebox to go after the design of low pollution, macrobian life to ask, because this answers to begin civilian machine to design crucial technology research as soon as possible, build firebox of machine of our country civilian to design a system. Firebox key designs a technology to include low pollution firebox structure moves heating power function to design a technology to wait compatibly. (2) technology of firebox fuel eject. Discharge to achieve low pollution, fuel flow wants cent to be much passageway supply, partial fuel is mixed beforehand evaporate beforehand, need to master corresponding fuel eject consequently technology and corresponding treatment and debug a technology. (3) firebox organization combustion and pollution discharge control technology. Firebox of civilian machine low pollution advocate equivalent burning an area is compared differ with groovy firebox, constituent combustion means also has major distinction, need to consider to organize combustion and pollution to discharge pilot technology. (4) refrigeration of firebox flame tube designs a technology. Should master firebox refrigeration structure to design technology, cooling component to conduct heat design technology and flame tube optimize design technology. (5) the intensity of firebox component designs a technology. The life of the place in basically including the local stress part of cast, weldment is forecasted, the technology such as vibration of macrobian life flame tube and life analysis, the intensity that consider and forms part of civilian machine firebox designs criterion. 2 material and 　 of craft key technology (1) processing technique of component of flame tube refrigeration. Flame tube of civilian machine firebox uses float wall, poriferous wall and poriferous layer more board wait for advanced and cooling structure, must solve bore of accurate CNC Machining, fast laser and high accuracy fusible pattern to cast wait for crucial technology. (2) adiabatic coating and its spray technology. To prolong engine life, face of cliff of flame tube hot end asks spray is adiabatic normally coating. But level of adiabatic coating development and existing material function and craft level remain to rise. 3 measure and experiment technology 　 (1) measure a technology. How to get flame tube wall effectively lukewarm distributing and the stress below high temperature is to raise firebox and engine dependability, contented intensity to design the vital technology of the requirement, should begin advanced wall gentle stress measures technical research. (2) experiment technology. The dependability experiment technology of technology of experiment of character of pulverization of the fuel below condition of technology of test and verify of experiment of wear of flame tube of the model below condition of high temperature high pressure and technology of experiment of full measure firebox, macrobian life, pressurization and fuel atomizer will be become restrict civilian. (3) fume and pollution discharge test technology. Of development starting function to deny contented ICAO to discharge the standard, key that get attestation and obtains evidence of motor comfortable boat is engine the fume that the experiment offers and pollution discharge index whether pass authoritative orgnaization examine, the analysis that because this must master engine and firebox fume and pollution,discharges and test technology, build the engine exhaust pollution that gets used to international standard and fumy test plant. We must master the last word design of civilian machine firebox, material and craft, measure and the crucial technology such as the experiment, grind beforehand and obtain a breakthrough what develop the crucial technology such as constituent firebox and cooling structure mainly. The risk issue that the organization that avoid answers to may arise in firebox development at the same time burns and intellectual property is encroached in cooling structure design and brings. CNC Milling CNC Machining