CN113932250A - Combustion chamber capable of suppressing oscillatory combustion and control method thereof - Google Patents

Combustion chamber capable of suppressing oscillatory combustion and control method thereof Download PDF

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CN113932250A
CN113932250A CN202010608632.1A CN202010608632A CN113932250A CN 113932250 A CN113932250 A CN 113932250A CN 202010608632 A CN202010608632 A CN 202010608632A CN 113932250 A CN113932250 A CN 113932250A
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fuel
swirler
outlet channel
combustion
air flow
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CN113932250B (en
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秦皓
汤冠琼
王雄辉
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AECC Commercial Aircraft Engine Co Ltd
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AECC Commercial Aircraft Engine Co Ltd
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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
    • F23R3/286—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply having fuel-air premixing devices
    • 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
    • F23R3/26—Controlling the air flow
    • 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
    • F23R3/38—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply comprising rotary fuel injection means

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Nozzles For Spraying Of Liquid Fuel (AREA)

Abstract

The invention provides a combustion chamber capable of inhibiting oscillatory combustion and a control method thereof. The combustion chamber comprises a main combustion stage, the main combustion stage comprises an axial swirler outlet channel, a radial swirler outlet channel and a downstream channel, the axial swirler outlet channel is provided with a multi-point transverse injection nozzle, and a pre-filming structure is formed at the intersection of the axial swirler outlet channel and the radial swirler outlet channel; the fuel is injected to the first air flow from the multi-point transverse injection nozzle, impacts on the pre-film structure and is spread into film-shaped fuel in advance, the fuel is sheared with the second air flow at the tail edge of the pre-film structure to form atomized fuel, and the atomized fuel is further mixed with the first air flow and the second air flow in a downstream channel to form a partially premixed oil-gas mixture; frequency of unstable flow of film-like fuel fpThe convection frequency of oil-gas mixing in the downstream channel is fmAcoustic characteristic frequency of combustion chamber is faBy adjusting fpOr/and fmLet fp≠faOr/and fm≠faTo suppress the oscillatory combustion.

Description

Combustion chamber capable of suppressing oscillatory combustion and control method thereof
Technical Field
The invention relates to the technical field of low-emission engine combustion chambers, in particular to a combustion chamber capable of inhibiting oscillatory combustion and a control method for inhibiting the oscillatory combustion of the combustion chamber.
Background
In order to meet the increasingly strict pollution emission standard of the aircraft engine, the low-emission combustion chamber technology is one of the main technical characteristics of the modern civil aircraft engine. The pneumatic design key of the low-emission combustion chamber lies in oil-gas tissue matching, namely an air rotational flow combination mode and a fuel injection atomization combination mode, and the oil-gas tissue matching has great influence on combustion efficiency, outlet temperature distribution, pollution emission, combustion stability and the like.
In order to adapt to a wide working range (the inlet temperature of a combustion chamber is between normal temperature and 900K, and the inlet pressure is between 1 and 40atm), the combustion chambers of international evidence-taking models all adopt lean oil premixing and staged combustion technology, and the technology is characterized in that a pre-combustion stage diffusion combustion mode is adopted only under low thrust, so that the combustion efficiency is ensured; the pre-combustion stage and main combustion stage partial pre-mixing combustion mode is adopted under the condition of medium and high thrust to reduce NOxDischarge and improve the outlet temperature distribution quality.
For example, patent document No. CN206281002U, entitled "middle aviation commercial aircraft engines llc" and "beijing aerospace university," describes a low-pollution combustion chamber with a single-layer pre-film radial two-stage reverse swirl flow in the main combustion stage, wherein the pre-combustion stage is at the center and the main combustion stage is at the periphery of the pre-combustion stage; the main combustion stage fuel oil from the fuel nozzle enters a main combustion stage fuel oil delivery hole and is sprayed into a main combustion stage pre-membrane plate inner channel through a main combustion stage fuel oil spray hole, part of the fuel oil forms main combustion stage direct-spray oil mist, part of the fuel oil strikes the main combustion stage pre-membrane plate to form a uniform oil film, external and internal reverse rotational flows formed by the main combustion stage pre-membrane plate outer channel and the main combustion stage pre-membrane plate inner channel can break and atomize the uniform oil film through shearing action to form main combustion stage pneumatic atomized oil mist, the main combustion stage pneumatic atomized oil mist and the direct-spray oil mist are further mixed with air to form uniform oil-gas mixture, and the uniform oil-gas mixture enters a combustion area to be premixed and combusted.
However, in the large state (climb and above), NOxThe discharge amount of the fuel has a great relationship with the fuel supply ratio of the main combustion stage, and NO is given when the fuel supply ratio of the main combustion stage is highxThe less discharge, the outlet temperatureThe higher the degree distribution quality is; however, the premixed combustion mode is prone to initiate the oscillatory combustion, and more oil generally needs to be distributed to the precombustion stage in order to suppress the oscillatory combustion. Therefore, in practical engine applications, the main stage fuel supply ratio is set mainly by oscillating combustion and NOxThe result of the trade-off between the exhaust, outlet temperature profiles.
Disclosure of Invention
The invention aims to provide a combustion chamber capable of inhibiting oscillatory combustion and a control method for inhibiting the oscillatory combustion of the combustion chamber, so as to improve the fuel supply proportion of a main combustion stage of an engine under a large-state condition and reduce NOxThe quality of the temperature distribution at the outlet of the combustion chamber is improved.
In order to achieve the purpose, the combustion chamber comprises a combustion chamber head, the combustion chamber head comprises a main combustion stage, the main combustion stage comprises an axial swirler, a radial swirler, an axial swirler outlet channel, a radial swirler outlet channel and a downstream channel, the axial swirler outlet channel is provided with a multi-point transverse injection nozzle, and a pre-film structure is formed at the intersection of the axial swirler outlet channel and the radial swirler outlet channel; the fuel is transversely injected to the first air flow of the axial swirler outlet channel from the multi-point transverse injection nozzle and impacts on the pre-film structure and is pre-spread into film-shaped fuel, the film-shaped fuel moves towards the downstream channel under the action of the aerodynamic force of the first air flow and is subjected to shearing action with the second air flow of the radial swirler outlet channel at the tail edge of the pre-film structure to form atomized fuel, and the atomized fuel is further mixed with the first air flow and the second air flow in the downstream channel of the main combustion stage to form a partially premixed oil-gas mixture; the frequency of unstable flow of the film-shaped fuel is fpThe oil-gas mixing convection frequency in the downstream channel is fmThe acoustic characteristic frequency of the combustion chamber is faThe control method is realized by adjusting fpOr/and fmSo that fp≠faOr/and fm≠faThereby suppressing the oscillatory combustion.
In one or more embodiments of the control method, f is adjusted by adjusting at least one of the swirl number, the swirl direction and the effective flow area of the axial swirler, or adjusting at least one of the swirl number, the swirl direction and the effective flow area of the radial swirler, or adjusting the thickness of the pre-filming structure, or adjusting the diameter and the number of the spray holes of the multi-point transverse injection nozzlep。
In one or more embodiments of the control method, f is adjusted by adjusting a length dimension of the blend in the downstream channelm。
The combustor comprises a combustor head, wherein the combustor head comprises a main combustion stage, the main combustion stage comprises an axial swirler, a radial swirler, an axial swirler outlet channel, a radial swirler outlet channel and a downstream channel, the axial swirler outlet channel is provided with a multi-point transverse injection nozzle, and a pre-membrane structure is formed at the intersection of the axial swirler outlet channel and the radial swirler outlet channel; the fuel is transversely injected to the first air flow of the axial swirler outlet channel from the multi-point transverse injection nozzle and impacts on the pre-film structure and is pre-spread into film-shaped fuel, the film-shaped fuel moves towards the downstream channel under the action of the aerodynamic force of the first air flow and is subjected to shearing action with the second air flow of the radial swirler outlet channel at the tail edge of the pre-film structure to form atomized fuel, and the atomized fuel is further mixed with the first air flow and the second air flow in the downstream channel of the main combustion stage to form a partially premixed oil-gas mixture; the frequency of unstable flow of the film-shaped fuel is fpThe oil-gas mixing convection frequency in the downstream channel is fmThe acoustic characteristic frequency of the combustion chamber is faBy adjusting fpOr/and fmSo that fp≠faOr/and fm≠faThereby suppressing the oscillatory combustion.
In one or more embodiments of the combustion chamber, the axial swirlerAt least one of the swirl number, the swirl direction and the effective flow area of the multi-point transverse jet nozzle, or at least one of the swirl number, the swirl direction and the effective flow area of the radial swirler, or the thickness of the pre-film structure, or the orifice diameter and the orifice number of the multi-point transverse jet nozzle are set to be equal to fpIs associated so that fp≠fa。
In one or more embodiments of the combustor, the blended length in the downstream channel is sized to be equal to fmIs associated so that fm≠fa。
In one or more embodiments of the combustor, the axial swirler is a vaned swirler.
In one or more embodiments of the combustor, the radial swirler is a chamfered radial swirler.
The control method for inhibiting the oscillatory combustion of the combustion chamber and the combustion chamber capable of inhibiting the oscillatory combustion adjust the unstable flow frequency of the fuel oil or/and the oil-gas mixing convection frequency by the structural dimension design of the main combustion stage and the pneumatic parameter design of the swirler so as to enable the unstable flow frequency or/and the oil-gas mixing convection frequency to be in error frequency with the acoustic characteristic frequency of the combustion chamber, and the two error frequency methods are combined to realize the error frequency with the acoustic characteristic frequency of the combustion chamber in a wide rotating speed range, so that the oscillatory combustion can be inhibited, more fuel oil can be supplied to the main combustion stage, the fuel supply proportion of the main combustion stage of an engine under the large-state condition is improved, and NO is reducedxThe quality of the temperature distribution at the outlet of the combustion chamber is improved.
Drawings
The above and other features, properties and advantages of the present invention will become more apparent from the following description of the embodiments with reference to the accompanying drawings, in which:
fig. 1 is a schematic structural view of a core engine of an aircraft engine according to the prior art.
FIG. 2 is a schematic view of a combustion head according to the present invention.
FIG. 3 is a schematic illustration of a primary combustion stage of a combustor according to the present invention.
FIG. 4 is a schematic illustration of the fuel average motion profile of the primary combustion stage according to the present invention.
FIG. 5 is a schematic illustration of a prefilming unsteady flow process of a primary firing stage according to the present invention.
FIG. 6 is a graphical representation of combustion oscillation frequency as a function of engine speed according to an example engine.
Detailed Description
The following discloses many different embodiments or examples for implementing the subject technology described. Specific examples of components and arrangements are described below to simplify the present disclosure, but these are merely examples and do not limit the scope of the invention. For example, if a first feature is formed over or on a second feature described later in the specification, this may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact. Additionally, reference numerals and/or letters may be repeated in various examples throughout this disclosure. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Further, when a first element is described as being coupled or coupled to a second element, the description includes embodiments in which the first and second elements are directly coupled or coupled to each other, as well as embodiments in which one or more additional intervening elements are added to indirectly couple or couple the first and second elements to each other. It is to be noted that the drawings are designed solely as examples and are not to scale and should not be construed as limiting the scope of the invention as it may be practiced otherwise than as specifically claimed. Furthermore, the terms "first," "second," and the like, as used herein, are used interchangeably to distinguish one element from another and are not intended to denote position or importance of the respective element. The terms "upstream" and "downstream" refer to relative directions with respect to fluid flow in a fluid channel, e.g., "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction to which the fluid flows.
As shown in fig. 1, the core engine of the aircraft engine of the prior art comprises a high-pressure compressor 1, a combustor 2 and a high-pressure turbine 3, wherein the combustor 2 comprises a nozzle 4, a combustor head 5 and a liner 6.
Referring to fig. 2, 3 and 5, the combustor 2 of the present invention employs lean premixed staged combustion technology, and the combustor head 5 mainly includes a pre-combustion stage 7 and a main combustion stage 8. The main combustion stage 8 comprises an axial swirler 9, a radial swirler 10, an axial swirler exit channel 13, a radial swirler exit channel 14 and a downstream channel 12, wherein a multi-point transverse injection nozzle 15 is arranged at the axial swirler exit channel 13, and a pre-filming structure 16 is formed at the intersection of the axial swirler exit channel 13 and the radial swirler exit channel 14.
Referring to fig. 3 to 5, the fuel 17 is transversely injected from the multi-point transverse injection nozzle 15 to the first air flow 18 of the axial swirler exit passage 13 and impacts on the prefilming structure 16 and is pre-spread into a film-like fuel 19, the film-like fuel 19 moves in the direction of the downstream passage 12 under the aerodynamic force of the first air flow 18 and is sheared with the second air flow 21 of the radial swirler exit passage 14 at the trailing edge 20 of the prefilming structure 16 to form atomized fuel 22, the atomized fuel 22 is further mixed with the first air flow 18 and the second air flow 21 in the downstream passage 12 of the main combustion stage 8 to form a partially premixed fuel-air mixture 23, and the fuel-air mixture 23 flows out of the downstream passage 12 and enters the combustion zone of the flame tube 6 to be combusted.
Compared with a circumferential seam-shaped prefilming nozzle, the multipoint transverse injection nozzle 15 can keep high oil supply pressure drop when the fuel 17 is injected, ensures higher injection momentum ratio, enables the fuel 17 to impact the prefilming structure 16, reduces the influence of external disturbance on the oil supply, improves the stability of the oil supply, can inhibit oscillatory combustion, enables more fuel to be distributed to the main combustion stage 8, and reduces NO (NO) by adopting a fuel transverse injection scheme with prefilming atomization effect, and can inhibit oscillatory combustionxThe discharge and the improvement of the outlet temperature distribution quality are realized; the prefilming structure 16 can control the average movement locus 100 of fuel (including fuel 17, film-shaped fuel 19 and atomized fuel 22) or fuel-air mixture 23 in the axial swirler outlet passage 13 and the downstream passage 12 of the main combustion stage 8, thereby controlling the average movement locusAnd (4) making oil mist distribution of the combustion field.
The swirling flow organization scheme of the two-stage air intake combination of the axial swirler 9 and the radial swirler 10 can increase the air intake area of the main combustion stage 8 and improve the air flow of the main combustion stage 8; through the matching of the air inlet proportion and the rotational flow strength of the two-stage rotational flow of the axial cyclone 9 and the radial cyclone 10, the pre-film shearing atomization effect and the mixing efficiency in the downstream channel 12 can be enhanced, the premixing quality is improved, the oscillatory combustion can be inhibited, more fuel oil can be distributed to the main combustion stage 8, and the NO is further reducedxThe discharge and the improvement of the outlet temperature distribution quality.
In addition, the combined structure of the axial swirler 9 and the radial swirler 10 can ensure convenient processing and strong engineering realizability. For example, an integral casting process scheme can be adopted, the swirling flow channels of the axial swirler 9 and the radial swirler 10 can be realized in an electric machining or machining mode, and the pre-film structure 16 can be guaranteed to be thick and have surface roughness by adopting a fine machining method.
The axial swirler 9 can be a vane type swirler to increase the air inlet area and ensure the transverse jet trajectory of the fuel 17. The radial swirler 10 may be a chamfered radial swirler to further optimize the structure, facilitate the processing, and improve the mixing effect of the atomized fuel 22 with the first air flow 18 and the second air flow 21.
In order to better suppress the oscillatory combustion, the inventor has made extensive theoretical studies and simulation experiments to propose a control method for suppressing the oscillatory combustion in a combustion chamber, which starts from an oil-gas texture matching scheme of the combustion chamber by adjusting the frequency f of the unstable flow (fluctuation of the oil film surface under the aerodynamic action of air) of the film-like fuel oil 19pOr/and the frequency of oil-gas mixture convection in the downstream channel 12 (inverse of the transport time required for the oil-gas mixture 23 in the downstream channel 12) fmSo that fpOr/and fmAcoustic characteristic frequency f of combustion chamber 2aFrequency error, i.e. get fp≠faOr/and fm≠faTo suppress the oscillatory combustion, improve the main combustion stage fuel supply proportion of the engine under the condition of large state and reduce NOxThe quality of the temperature distribution at the outlet of the combustion chamber is improved.
Referring to fig. 3 and 4, the key design dimension of the oil and gas matching scheme of the combustion chamber 2 has d1、d2、L1、L2And the thickness b of the pre-film structure 16.
Wherein, the dimension d1Influencing the average movement trajectory 100 of the fuel (including fuel 17, film-like fuel 19, atomized fuel 22) or the mixture of fuel and air 23 in the axial swirler exit passage 13 and the downstream passage 12 of the main combustion stage 8; dimension d2Influencing the exit flow velocity at the downstream channel 12 of the primary combustion stage 8; dimension L1Influencing the residence time (or transit time) of the atomized fuel 22 or mixture 23 in the downstream channel 12 of the main combustion stage 8, i.e. influencing the convective frequency f of the mixture of fuel and airmThe mixing uniformity and the oscillatory combustion of oil and gas are influenced; dimension L2The effect of fuel 17 injected to the prefilming structure 16 and spread into a film is influenced; the dimension b influences the effect of the pre-film atomization.
In addition to the above dimensions, the swirl number S of the axial swirler 911And its rotation direction and effective flow area A11The swirl number S of the radial swirler 1012And its rotation direction and effective flow area A12When the aerodynamic design parameters are equal, the unstable flow frequency f of the film-shaped fuel 19pThe effect of the pre-film atomization is also influenced.
The control method for inhibiting the oscillatory combustion of the combustion chamber of the invention designs the size and the parameters of the combustion chamber 2 so that fpOr/and fmAcoustic characteristic frequency f of combustion chamber 2aThe frequency is staggered, so that the oscillatory combustion is restrained, the fuel oil distribution proportion of the main combustion stage 8 is increased, and the NO is reducedxThe purpose of discharging and improving the quality of the temperature distribution at the outlet.
The principle and process of pneumatic design of the above dimensions and parameters using this control method are described in detail below:
1. as shown in fig. 3, dimension d2According to the design process of a conventional combustion chamber, the combustion chamber can be designed by determining one corresponding to the aerodynamic thermal parameters and the geometric dimensions of the engine and the components thereof at the design point state (when the engine is designed, the aerodynamic thermal parameters and the geometric dimensions of the engine and the components thereof are determinedSpecific flight conditions and engine operating conditions, referred to as design points), the outlet reference flow rate at the downstream passage 12 of the main combustion stage 8 is set to determine the dimension d2。
2. Dimension d1、L2And the orifice diameter d of the multipoint transverse jet nozzle 15injAnd the number of orifices NinjMatching design is required:
as shown in FIG. 4, for lateral injection, the portion of the aforementioned average trajectory 100 within the axial swirler exit passage 13 of the main combustion stage 8 (i.e., x ≦ L)2In range) and weber number
Figure BDA0002560080350000071
Liquid to gas momentum ratio
Figure BDA0002560080350000072
In connection with, where paIs air density, UaThe average axial flow velocity at the outlet of the axial swirler 9, i.e. the flow velocity of the first air flow 18, is related to the air flow distribution and the pressure drop distribution of the combustion chamber 2, at the design point condition, UaEffective flow area A through axial swirler 911Preliminary evaluation, pfAs the density of the fuel oil,
Figure BDA0002560080350000073
the fuel flow rate at the orifice of the multi-point transverse jet nozzle 15.
With continued reference to FIG. 4, for main stage cross-injection, the portion of the aforementioned average trajectory 100 within the axial swirler exit passage 13 of the main stage 8 (i.e., x ≦ L)2In range) there is an empirical relationship:
Figure BDA0002560080350000081
the trial range of the formula is q inj5 to 100 and Weinj400-1600, can basically cover the operating range of multiple spot transverse jet nozzle 15. Determining the dimension d according to design requirements1And L2. L is less than or equal to x2Within the range that the fuel 17 is to be sprayed onto the surface of the prefilming structure 16, i.e. z ≧ zd1According to this formula, the desired liquid-to-air momentum ratio q can be determinedinj。
In the determination of qinjThen, the diameter d of the nozzle hole is determinedinjAnd the number of orifices Ninj。
The flow characteristics of the multi-point direct injection nozzle are satisfied
Figure BDA0002560080350000082
Wherein FN is the nozzle flow rate, WfFor the fuel supply flow, a design point is selected according to the requirements, for example, the long-term engine operating state-cruise state, and the fuel flow W of the main combustion stage 8 is obtained given the fuel distribution ratiof，ΔPinjThe difference in the oil supply pressure at the inlet and outlet of the multi-point transverse jet nozzle 15 can be obtained by sensor measurements. Nozzle flow number FN and orifice diameter dinjAnd the number of orifices NinjThe general relationship of (a) is FN ^ Ninj·inj 2. Thus, the diameter d of the nozzle hole can be obtainedinjAnd the number of orifices NinjFuel flow W to main combustion stagefAnd the fuel supply pressure difference Δ PinjThe relationship between
Figure BDA0002560080350000083
Generally requires Δ PinjThe sum of the pressure of the combustion chamber 2 and the inner cavity pressure is not more than the upper limit of the oil supply pressure of the engine oil pump.
From the foregoing, it can be seen that for a given fuel flow WfAnd the fuel supply pressure difference Δ PinjDiameter d of orificeinjSquare sum of the number of orifices NinjAre numerically inversely proportional. Diameter d of the orificeinjThe minimum value of (a) is limited by the processing technology capability, generally the larger the better the processing; number of spray holes NinjThe pre-filming effect and the circumferential uniformity of oil-gas mixing in the downstream channel 12 of the main combustion stage 8 are affected, and the larger the oil-gas mixing is, the better the oil-gas mixing is; thus, the diameter d of the nozzle holeinjAnd the number of orifices NinjThe design of (c) is finally determined based on process level and experimental results or CFD (Computational Fluid Dynamics) numerical simulation results.
3. Unsteady flowDynamic frequency fpThe regulation of (2):
as shown in fig. 5, the fuel 17 is injected laterally to the first air flow 18 from the orifice array of the multi-point lateral jet nozzle 15, and impinges on the lower surface of the pre-filming structure 16 and spreads in advance into a film-like fuel 19, the film-like fuel 19 having an initial average thickness tf. The film-shaped fuel 19 generates an unstable flow under the action of the first air flow 18, the frequency f of which flow is unstablepWith the flow rate U of the first air stream 18aFuel density ρfThe initial average thickness t of the film-like fuel 19fAnd length L of broken liquid filmfThere is a relation between
Figure BDA0002560080350000091
Wherein, UaAs previously mentioned, at design point conditions, the effective flow area A through the axial swirler 911Preliminary evaluation, initial average thickness t of film-like fuel 19fAnd length L of broken liquid filmfAll can be obtained by optical model test.
The aerodynamic design and the dimensioning shown in fig. 3 and 4 indicate the swirl number S of the axial swirler 911And its rotation direction and effective flow area A11The swirl number S of the radial swirler 1012And its rotation direction and effective flow area A12The thickness b of the pre-film structure 16 is equal to the liquid film breaking length LfWith an effect. While the outlet average axial flow velocity of the axial swirler 9, i.e. the flow velocity U of the first air flow 18aAnd the fuel flow rate U at the orifice of the multipoint transverse jet nozzle 15fThe initial average thickness t of the film-like fuel 19fHaving an influence, as described above, in the design point state, UaEffective flow area A through axial swirler 911Preliminary evaluation, fuel flow rate
Figure BDA0002560080350000092
Diameter d of the nozzle orifice of the multi-point transverse jet nozzle 15injAnd the number of orifices NinjIt is related.
Thereby, the rotational flow number S of the axial swirler 9 is adjusted11Rotational, effective flowThrough area A11Or adjusting the swirl number S of the radial swirler 1012Effective flow area A12Or adjusting the thickness b of the pre-film structure 16, or adjusting the orifice diameter d of the multi-point transverse jet nozzle 15injAnd the number of orifices NinjCan realize the unstable flow frequency fpIs adjusted to the acoustic characteristic frequency f of the combustion chamber 2aFrequency error, i.e. fp≠faThereby suppressing the oscillatory combustion.
4. Oil-gas mixing convection frequency fmThe regulation of (2):
convection frequency of oil-gas mixture
Figure BDA0002560080350000093
Wherein U is1Is the axial flow velocity of the mixture 23 in the downstream channel 12 of the main combustion stage 8. Therefore, by adjusting the dilution length dimension L in the downstream channel 12 of the main stage 81Can make fmAcoustic characteristic frequency f of combustion chamber 2aFrequency error, i.e. fm≠faThereby suppressing the oscillatory combustion.
5. Frequency f of unsteady flowpFrequency of convection mixing with oil and gas fmAnd (3) combination and adjustment:
as shown in FIG. 6, an example of the combustion oscillation frequency of a certain type of engine varying with the engine speed is given, where the abscissa is the dimensionless speed and the ordinate is the oscillation frequency f of the combustion chamberc. The dashed box designated 200 in fig. 6 shows that in the case of simultaneous operation of the main combustion stage and the precombustion stage, in the vicinity of a dimensionless speed of 1, oscillatory combustion occurs in the combustion chamber 2 at an oscillation frequency fc750-800, the oscillation frequency fcAcoustic characteristic frequency f of combustion chamber 2 of the engineaThe same belongs to a thermoacoustic oscillation mode.
Oscillation frequency f occurring at the rotational speedcFor example, according to the above relation
Figure BDA0002560080350000101
Can be designed and screened out through an optical model test pieceSatisfying an unstable flow frequency fpThe design of the combustion chamber 2 shown in FIG. 3, not equal to 750-800, achieves an unstable flow frequency f of the film-shaped fuel 19pWith the acoustic characteristic frequency f of the combustion chamber 2 at the current speedaStaggered, thereby suppressing the oscillatory combustion.
If the aerodynamic design of the axial swirler 9 and the radial swirler 10 and the dimensioning of the prefilming structure 16 and the multipoint transverse jet nozzle 15 are present, which are optimally adapted to the design of the combustion chamber 2 shown in fig. 3, f is difficult to achievepNot equal to 750-800, the blending length L of the downstream channel 12 of the main combustion stage 8 shown in FIG. 3 can be adjusted1To achieve an error frequency.
The dimensionless speed and frequency of oscillation of the combustion chamber 2 at f are determined by the engine type and/or other fuel supply conditionscPossibly unlike the example in fig. 6, by the unstable flow frequency fpFrequency offset and oil-gas mixing convection frequency fmThe combination of the cross frequencies makes it possible to achieve acoustic frequencies f of the combustion chamber 2 in a wide rotational speed rangeaThe frequency of the fault may be varied, for example, at moderate rotational speeds by means of an unstable flow frequency fpFrequency mismatch, convection frequency f through oil-gas mixing at high rotational speedsmMistaking, or reversing the order of the two.
The control method for inhibiting the oscillatory combustion of the combustion chamber and the combustion chamber capable of inhibiting the oscillatory combustion adjust the unstable flow frequency of the fuel oil or/and the oil-gas mixing convection frequency by the structural dimension design of the main combustion stage and the pneumatic parameter design of the swirler so as to enable the unstable flow frequency or/and the oil-gas mixing convection frequency to be in error frequency with the acoustic characteristic frequency of the combustion chamber, and the two error frequency methods are combined to realize the error frequency with the acoustic characteristic frequency of the combustion chamber in a wide rotating speed range, so that the oscillatory combustion can be inhibited, more fuel oil can be supplied to the main combustion stage, the fuel supply proportion of the main combustion stage of an engine under the large-state condition is improved, and NO is reducedxThe quality of the temperature distribution at the outlet of the combustion chamber is improved.
Although the present invention has been disclosed in terms of the preferred embodiment, it is not intended to limit the invention, and variations and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention. Therefore, any modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope defined by the claims of the present invention, unless the technical essence of the present invention departs from the content of the present invention.

Claims (8)

1. The control method for inhibiting the oscillatory combustion of the combustion chamber comprises a combustion chamber head, wherein the combustion chamber head comprises a main combustion stage, the main combustion stage comprises an axial swirler, a radial swirler, an axial swirler outlet channel, a radial swirler outlet channel and a downstream channel, the axial swirler outlet channel is provided with a multi-point transverse injection nozzle, and a pre-film structure is formed at the intersection of the axial swirler outlet channel and the radial swirler outlet channel; the fuel is transversely injected to the first air flow of the axial swirler outlet channel from the multi-point transverse injection nozzle and impacts on the pre-film structure and is pre-spread into film-shaped fuel, the film-shaped fuel moves towards the downstream channel under the action of the aerodynamic force of the first air flow and is subjected to shearing action with the second air flow of the radial swirler outlet channel at the tail edge of the pre-film structure to form atomized fuel, and the atomized fuel is further mixed with the first air flow and the second air flow in the downstream channel of the main combustion stage to form a partially premixed oil-gas mixture;
characterized in that the frequency of unstable flow of the film-shaped fuel is fpThe oil-gas mixing convection frequency in the downstream channel is fmThe acoustic characteristic frequency of the combustion chamber is faThe control method is realized by adjusting fpOr/and fmSo that fp≠faOr/and fm≠faThereby suppressing the oscillatory combustion.
2. The method of claim 1, wherein the axial swirler is controlled by adjusting at least one of a swirl number, a swirl direction, and an effective flow area of the axial swirler or the radial swirler is controlled by adjusting a swirl number, a swirl direction, and an effective flow area of the radial swirlerAt least one of the areas, or adjusting the thickness of the pre-film structure, or adjusting the diameter and number of orifices of the multi-point lateral spray nozzle to adjust fp。
3. The control method of claim 1, wherein f is adjusted by adjusting a length dimension of the intermixing in the downstream channelm。
4. The combustor capable of inhibiting oscillatory combustion comprises a combustor head, wherein the combustor head comprises a main combustion stage, the main combustion stage comprises an axial swirler, a radial swirler, an axial swirler outlet channel, a radial swirler outlet channel and a downstream channel, the axial swirler outlet channel is provided with a multi-point transverse injection nozzle, and a pre-membrane structure is formed at the intersection of the axial swirler outlet channel and the radial swirler outlet channel; the fuel is transversely injected to the first air flow of the axial swirler outlet channel from the multi-point transverse injection nozzle and impacts on the pre-film structure and is pre-spread into film-shaped fuel, the film-shaped fuel moves towards the downstream channel under the action of the aerodynamic force of the first air flow and is subjected to shearing action with the second air flow of the radial swirler outlet channel at the tail edge of the pre-film structure to form atomized fuel, and the atomized fuel is further mixed with the first air flow and the second air flow in the downstream channel of the main combustion stage to form a partially premixed oil-gas mixture;
characterized in that the frequency of unstable flow of the film-shaped fuel is fpThe oil-gas mixing convection frequency in the downstream channel is fmThe acoustic characteristic frequency of the combustion chamber is faBy adjusting fpOr/and fmSo that fp≠faOr/and fm≠faThereby suppressing the oscillatory combustion.
5. The combustor of claim 4, wherein the axial swirler has a swirl number, a swirl direction, and an effective flow areaAt least one of the volumes, or at least one of the swirl number, the swirl direction and the effective flow area of the radial swirler, or the thickness of the pre-filming structure, or the orifice diameter and the orifice number of the multi-point transverse injection nozzle are set to be equal to fpIs associated so that fp≠fa。
6. The combustor of claim 4, wherein the length of said blending in said downstream channel is sized to be equal to fmIs associated so that fm≠fa。
7. The combustor of claim 4, wherein the axial swirler is a vaned swirler.
8. The combustor of claim 4, wherein the radial swirler is a chamfered radial swirler.
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