CN112066415B - Combustion chamber, gas turbine and method for suppressing oscillatory combustion - Google Patents
Combustion chamber, gas turbine and method for suppressing oscillatory combustion Download PDFInfo
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- CN112066415B CN112066415B CN201910496531.7A CN201910496531A CN112066415B CN 112066415 B CN112066415 B CN 112066415B CN 201910496531 A CN201910496531 A CN 201910496531A CN 112066415 B CN112066415 B CN 112066415B
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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
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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
- F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
- F23R3/26—Controlling the air flow
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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
- F23R3/38—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply comprising rotary fuel injection means
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Abstract
The invention relates to a combustion chamber, a gas turbine and a method for suppressing oscillatory combustion, wherein the combustion chamber comprises a flame tube head, the head comprises a main combustion stage and a pre-combustion stage, the main combustion stage is provided with a main combustion stage inner wall and a main combustion stage outer wall, and a main combustion stage upstream end wall radially protruding from the main combustion stage inner wall; a radial space between the inner wall of the main combustion stage and the outer wall of the main combustion stage provides a main combustion stage channel for mixing air and fuel oil, the inlet end of the main combustion stage channel receives air from the main combustion stage gas inlet part, and the outlet end of the main combustion stage channel is communicated with a flame tube accommodating cavity of the combustion chamber; the main combustion stage air inlet part comprises a first main combustion stage air inlet part and a second main combustion stage air inlet part; the primary stage first intake air portion includes an acoustically restrictive first port extending through an axial thickness of the primary stage upstream endwall.
Description
Technical Field
The invention relates in particular to a combustion chamber, a gas turbine and a method of suppressing oscillatory combustion.
Background
In order to meet the airworthiness requirement, the aero-engine adopts the lean oil combustion technology to reduce NOxWhile lean combustion tends to initiate oscillatory combustion, it can be severe enough to cause ablation of the hot end components of the combustion chamber. In addition, to reduce NOxTo exhaust, more air needs to be distributed to the head of the combustion chamber to lower the equivalence ratio of the combustion zone, while the liner cooling air is reduced, the acoustic impedance of the liner walls is increased, and the degree of oscillatory combustion is also exacerbated.
In order to suppress the oscillatory combustion, there are two embodiments of active control and passive control. For active control, dynamic signals of pulsating pressure or other pneumatic parameters in the combustion chamber need to be monitored in real time, and according to the oscillation frequency and waveform of the pulsating pressure, a control system supplies fuel or adds an opposite-phase excitation to a gas path through a high-speed actuating element so as to reduce the pulsating pressure in the combustion chamber. But this requires a more complex control system and the requirements on the sensor itself are high. For passive control, it is necessary to identify the conditions of the occurrence of the oscillatory combustion or the mechanism of the occurrence of the oscillatory combustion through experiments, and to improve the structure of the combustion chamber or change the fuel supply manner according to the actual conditions of the oscillatory combustion.
For the central staged combustion technique, as shown in fig. 1, by adjusting the staged proportion of fuel, more fuel can be fed into the precombustion stage, thereby achieving a reduction in the intensity of the oscillatory combustion. But the intensity of the oscillatory combustion is reduced and NO is increasedxAnd (4) discharging, so that the discharge margin is reduced. In order to ensure the emission characteristics, the boundary of stable combustion needs to be widened, i.e., the oscillation boundary (dotted line, i.e., position where the oscillation amplitude suddenly increases) in fig. 1 needs to be shifted to the left of the coordinate axis by a new design or a system control means.
For the central staged combustion mode, one of the main driving mechanisms of the oscillatory combustion known so far is the interaction of the flames of the main combustion stage and the pre-combustion stage and the response thereof under turbulence or acoustic wave disturbance, which is mainly related to the swirl number of the main combustion stage and the pre-combustion stage, through optical diagnostic techniques.
Most of the design results of the conventional combustion chamber aerodynamic heating power scheme only consider the steady-state working state or the steady combustion state, but cannot meet the transient state or the unsteady combustion state, such as the influence of oscillatory combustion on aerodynamic heating power. In order to inhibit the oscillatory combustion and ensure the safety, the performances such as emission and outlet temperature distribution have to be sacrificed, so that the conventional combustion chamber pneumatic-thermal design scheme has difficulty in ensuring that all indexes are met at the same time.
There is a need in the art for a combustor, a gas turbine, and a method of suppressing oscillatory combustion that suppresses the oscillatory combustion phenomenon of the combustor, widens the stable combustion boundary, improves combustion performance, and ensures the life of the combustor and the performance and life of the gas turbine.
Disclosure of Invention
It is an object of the present invention to provide a combustion chamber.
It is another object of the present invention to provide a gas turbine.
It is a further object of the present invention to provide a method of suppressing ringing combustion.
A combustion chamber according to one aspect of the invention includes a liner head comprising a main combustion stage and a pre-combustion stage, the main combustion stage having a main combustion stage inner wall and a main combustion stage outer wall, and a main combustion stage upstream end wall projecting radially from the main combustion stage inner wall; a radial space between the inner wall of the main combustion stage and the outer wall of the main combustion stage provides a main combustion stage channel for mixing air and fuel oil, the inlet end of the main combustion stage channel receives air from the main combustion stage gas inlet part, and the outlet end of the main combustion stage channel is communicated with a flame tube accommodating cavity of the combustion chamber; the main combustion stage air inlet part comprises a first main combustion stage air inlet part and a second main combustion stage air inlet part; the primary stage first intake air portion includes an acoustically restrictive first port extending through an axial thickness of the primary stage upstream endwall.
In an embodiment of the combustion chamber, the first port with acoustic throttling is structured such as to satisfy:
wherein, P'4Is the amplitude of the pulsating pressure in the flame tube, P4Is the mean pressure, Δ P, in the flame tubeoriThe constant beta is the energy conversion efficiency of converting the acoustic energy of the first duct into kinetic energy for the via hole pressure drop of the acoustic orifice.
In an embodiment of the combustion chamber, the second air intake has a second air intake passage provided by an axial space between the upstream end wall of the main combustion stage and a downstream end wall of the main combustion stage projecting radially from an outer wall of the main combustion stage, the second air intake passage having a swirler disposed therein.
In an embodiment of the combustion chamber, the first main combustion stage air intake portion and the second main combustion stage air intake portion respectively and independently supply air to the main combustion stage channel, and the air input from the two air intake portions is mixed in the main combustion stage channel.
In an embodiment of the combustion chamber, the first port axis is parallel to the axial direction.
In an embodiment of the combustion chamber, the axis of the first port is inclined to the axial direction in a positive or negative direction.
In an embodiment of the combustion chamber, a plurality of fuel injection holes are provided in a sidewall of the primary combustion stage passage to inject fuel to combine with air entering the primary combustion stage passage.
A combustion chamber according to another aspect of the present invention comprises a liner head, the head comprising a main combustion stage and a pre-combustion stage, air for mixing with fuel injected from the main combustion stage entering the main combustion stage through a main combustion stage air inlet, the combustion chamber comprising a steady state and an oscillatory combustion state, the main combustion stage air inlet comprising a main combustion stage first air inlet having a first aperture, in the steady state, air can enter the main combustion stage through the main combustion stage first air inlet and the main combustion stage second air inlet respectively, in the oscillatory combustion state, the throttling effect of the first aperture reduces a proportion of air entering the main combustion stage through the main combustion stage first air inlet in an oscillatory combustion pressure wave environment propagating through a liner cavity of the combustion chamber, the proportion of air entering the main combustion stage through the second air inlet of the main combustion stage is increased, so that the swirl number of the main combustion stage is adjusted.
A gas turbine according to a further aspect of the invention comprises a combustor as described in any one of the above.
A method of suppressing ringing combustion in accordance with yet another aspect of the present invention includes:
a plurality of air flow paths are arranged to provide air for the main combustion stage of the combustion chamber;
in a steady state, the plurality of air flow paths provide air to the primary combustion stage;
in an oscillatory combustion state, the air flow of one air flow path of the plurality of air flow paths is reduced under the condition of an oscillatory pressure wave transmitted by the flame tube cavity, the proportion of the air flow of other air flow paths in the plurality of air flow paths is correspondingly increased, and the number of the main combustion stage outlet swirls is adjusted by the change of the air inlet flow path.
In summary, the invention has the advantages that the air inlet duct with the acoustic throttling function is arranged, so that the air inlet duct with the acoustic throttling function is ensuredThe combustion performance under a stable state is proved, the oscillation combustion boundary is widened, more fuel oil can be distributed to the main combustion level, the potential of further reducing emission is realized, and the outlet temperature distribution quality is improved; even if oscillatory combustion occurs, the first air inlet part is closed by the acoustic throttling action of pressure waves, the shearing action of the main combustion stage outlet jet flow and the pre-combustion stage outlet jet flow is changed, and the velocity gradient of a shearing area is changed
The response characteristic of the flame (interaction of the flame of the main combustion stage and the flame of the pre-combustion stage) in the shearing area to turbulence or sound waves is changed, so that the heat release driving force of the combustion area is weakened, the pressure amplitude of oscillatory combustion is restrained, the combustion stability is ensured, and the performance and the service life of a combustion chamber and a gas turbine are 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 in conjunction with the accompanying drawings, it being noted that the drawings are given by way of example only and are not drawn to scale, and should not be taken as limiting the scope of the invention which is actually claimed, wherein:
FIG. 1 is a schematic illustration of the effect of fuel staging ratio on pulsating pressure and emissions.
FIG. 2 is a graph of pulsating pressure and combustor via pressure drop as a function of acoustic throttling effect.
FIG. 3 is a schematic illustration of an air flow path of a combustor for one or more embodiments.
FIG. 4 is a schematic view of an air flow path of a combustor head at steady state in one or more embodiments.
FIG. 5 is a schematic air flow path of a combustor head in an oscillatory combustion regime according to one or more embodiments.
FIG. 6 is a schematic illustration of a primary combustion stage configuration of a combustor head according to one or more embodiments.
FIG. 7 is a schematic structural diagram of a first air intake portion of one or more embodiments.
FIG. 8 is a schematic illustration of a main combustion stage structured gas quantity analysis according to FIG. 6.
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 among the 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.
Further, it is to be understood that the positional or orientational relationships indicated by the terms "front, rear, upper, lower, left, right", "transverse, vertical, horizontal" and "top, bottom" and the like are generally based on the positional or orientational relationships illustrated in the drawings and are provided for convenience in describing the invention and for simplicity in description, and that these terms are not intended to indicate and imply that the referenced devices or elements must be in a particular orientation or be constructed and operated in a particular orientation without departing from the scope of the invention. Also, this application uses specific language to describe embodiments of the application. The terms "inside" and "outside" refer to the inner and outer parts relative to the outline of each part itself, and the terms "first", "second", "third", and the like are used to define the parts, and are used only for the convenience of distinguishing the corresponding parts, and unless otherwise stated, the terms have no special meaning, and therefore, the scope of the present invention should not be construed as being limited. Reference throughout this specification to "one embodiment," "an embodiment," and/or "some embodiments" means that a particular feature, structure, or characteristic described in connection with at least one embodiment of the present application is included in at least one embodiment of the present application. Therefore, it is emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, some features, structures, or characteristics of one or more embodiments of the present application may be combined as appropriate.
Referring to fig. 3, the combustion chamber structure of the gas turbine includes a front diffuser 1, an outer casing 2, an inner casing 9, a head 8, a fuel nozzle 3, an ignition burner 5, an outer ring liner 6 and an inner ring liner 11; the head part 8 can adopt an air inlet structure comprising a swirler, and both the outer ring flame tube 6 and the inner ring flame tube 11 can adopt an air film cooling mode. Under the stable combustion state, air flows out from the outlet of the preposed diffuser 1 and is divided into three flows to enter the flame tube cavity 12: air 7 enters the flame tube chamber 12 through the swirler passages of the head 8; air 4 enters the flame tube cavity 12 through the cooling holes of the outer ring flame tube 6; air 10 enters the combustor basket cavity 12 through the inner ring combustor basket 11 cooling holes.
It should be noted that the axial and radial directions of the following embodiments refer to the axial and radial directions of the combustion chamber head 8, and the combustion chamber head 8 may be arranged obliquely to the axial direction of the engine as shown in fig. 3, so that the axial and radial directions of the following embodiments may not necessarily be the same as the axial and radial directions of the engine.
Referring to FIG. 4, in one embodiment, for air entering the combustor basket cavity 12 through the head 8, the air flow paths associated with the interaction of the main stage and precombustion stage flames of one of the primary active mechanisms of oscillatory combustion include, independently from each other, air flow paths 22, 23 entering the main stage through the main stage inlet 100, and air flow path 21 entering through the precombustion stage swirler 20, the air flow path 22 entering the main stage passage 300 through the main stage first inlet 100, the air flow path 23 entering the main stage passage 300 through the main stage second inlet 200, the air flow paths 22, 22,23 are combined with fuel injected from the main stage fuel orifices 18 in the main stage passage 300 and exit the outlet end of the main stage passage 300 where they meet the air flow path 21 at a junction 24. Referring to fig. 5, when the combustion chamber is in the oscillation combustion state, the first intake portion 100 is closed, and air cannot enter through the air flow path 22, but only enters the main combustion stage passage 300 from the air flow path 23 to reach the intersection region 24, so that the effect of suppressing the oscillation combustion is achieved on the principle that unsteady disturbance (such as turbulence or sound wave) in the combustion chamber causes heat release fluctuation of the flame in the shear region at the intersection region 24 (in the shear region, the main combustion stage flame and the precombustion stage flame interact with each other), which is one of the main causes for driving the oscillation combustion. The amplitude of the oscillatory combustion is determined by two components: the heat release in the combustion zone drives and the damping of the flow boundary, the stronger the drive the greater the amplitude, generally speaking, the damping conditions of the combustion chamber under certain conditions may be considered constant. In the oscillatory combustion state, the first air inlet part 100 is closed through the acoustic throttling effect, the main combustion stage outlet jet flow which is mixed and output from the air flow paths 21 and 22 to the main combustion stage outlet jet flow which is output from the main combustion stage passage 300 only through the air flow path 22 is changed, at the moment, the swirl number of the main combustion stage outlet is changed, and the velocity gradient in the shearing area of the main combustion stage outlet jet flow and the pre-combustion stage outlet jet flow is changed
Therefore, the response characteristic of the flame in the shear zone to disturbance is changed, and the heat release driving force of the combustion zone is weakened so as to reduce the amplitude of oscillation.
Referring to fig. 4-6, in one or more embodiments, the specific structure of head 8 may be that head 8 includes a main combustion stage and a pre-combustion stage. The precombustion stage may include a precombustion stage fuel nozzle 19 and a precombustion stage swirler 20; the main combustion stage may include a main combustion stage inner annular wall 14 and a main combustion stage outer annular wall 13, a main combustion stage upstream end wall 17 projecting radially from the main combustion stage inner annular wall 14, and a main combustion stage downstream end wall 171 projecting radially from the main combustion stage outer annular wall 13. The radial space between the inner ring wall 14 and the outer ring wall 13 of the main combustion stage provides a main combustion stage channel 300, and air entering from the air inlet part of the main combustion stage enters the main combustion stage channel 300 through the inlet end of the main combustion stage channel 300, mixes with fuel sprayed from the main combustion stage fuel spray holes 18 arranged on the side wall of the main combustion stage channel 300, and rotates and sprays from the outlet end of the main combustion stage channel 300 communicated with the flame tube accommodating cavity 12. Preferably, the main stage fuel injection orifices 18 are multi-point fuel injection orifices to enhance the atomized blending of fuel and air.
The second air intake portion 200 may be embodied as a second air intake passage provided by the axial space between the upstream end wall 17 of the main stage and the downstream end wall 171 of the main stage, and the second air intake passage may be provided with a swirler 16. The specific configuration of the first intake section 100 may be an acoustically restrictive first port 25 having an axial thickness through the upstream endwall 17 of the main stage as shown in FIGS. 6-8. As shown in fig. 4, the main combustion stage first air intake portion 100 and the main combustion stage second air intake portion 200 may independently supply air to the main combustion stage channel 300, and the air flow paths 21 and 22 may interact with each other after entering the main combustion stage channel 300. It is understood that the acoustic throttling of the first port 25 shown in fig. 5 is closed in the oscillatory combustion state so that gas cannot pass through the first port 25 to close the first intake portion 100, which is an example of an ideal throttling state, but should not be limited thereto. An embodiment that reduces the intake air flow rate of the first intake portion 100 may also be employed. The principle of the acoustic throttling effect of the first duct 25 is that when the combustion chamber is in the oscillatory combustion state, the pressure wave of the oscillatory combustion can generate the acoustic throttling effect on the gas passing through the duct with a specific structure, and the actual pressure drop of the gas passing through the duct with the specific structure is increased. Specific phenomena can be referred to fig. 2.
FIG. 2 is the inventors' discovery of the acoustic throttling effect of the cooling holes of the combustor basket assembly, plotted on the ordinate as the actual through hole pressure drop Δ P versus the mean pressure P of the basket receptacle 124To the power of 3/2, i.e. of
The abscissa is the pulsating pressure amplitude | P 'of the liner cavity 12'4(amplitude corresponding to main frequency after Fourier transform) and average pressure P4Is a percentage of
Since the flow mach number in the combustion chamber is generally 0.2 or less, the pressure drop in the intake passage at each point in the combustion chamber is normal (for example, in the case of non-oscillatory combustion)
Determined by its flow resistance characteristics, i.e. only with the effective area ACdAnd intake air composition parameter
In connection with, if
Without change, the voltage drop is controlled by ACdAnd (6) determining. FIG. 2 shows that
Under the condition of no change, the fuel-air ratio is increased, so that the combustion chamber generates oscillation combustion, and the oscillation amplitude is increased along with the increase of the fuel-air ratio, so that the combustion chamber pressure drop observed in the test is changed along with the oscillation amplitude. Test data analysis results show that the cooling pore passage of the flame tube is throttled under the condition of the sound field of oscillatory combustion, so that the AC of the cooling gas of the flame tubedReduced, total combustion chamber flow ACdDecreasing, resulting in an increase in combustion chamber pressure drop. The oblique line (y ═ x in the figure) in the figure represents the pulsating pressure amplitude corresponding to the trigger throttling effect; in the range of the upper left side of the oblique line, the pulsating pressure cannot change the pressure drop of the combustion chamber, in the range of the lower right side of the oblique line, the pulsating pressure can cause the pressure drop of the combustion chamber to increase, when the pulsating pressure increases to a certain degree, the air inlet of the flame tube is completely blocked, and all the air inlet can only enter the flame tube from the head. By theoretical derivation, the triggering conditions for acoustic throttling can be derived as follows:
wherein, P'4Is the amplitude of the pulsating pressure in the flame tube, P4Is the mean pressure, Δ P, in the flame tubeoriThe constant beta is the energy conversion efficiency of converting the acoustic energy of the first hole channel with the acoustic throttling function into the kinetic energy for designing the hole pressure drop of the acoustic throttling hole. The constant β is related to the pore diameter d, the pore length l, with β being greater the smaller d or the larger l. As can be seen for example from figure 2,
1) designing a pore passage with pressure drop of 3 percent (oil-gas ratio is low, and oscillation combustion is not generated), wherein the pulsating pressure is less than 0.5 percent, and at the moment, acoustic throttling does not occur, so that the actual pressure drop in the combustion chamber is basically the same as the designed pressure drop; when the pulsating pressure is between 0.5 and 3 percent, a small part of the flame tube assembly (such as an inner ring or an outer ring of the flame tube) generates throttling action first, and the pressure drop of the combustion chamber is slightly increased; when the pulsating pressure is more than 3%, most of the flame tube assemblies are throttled, and the pressure drop of a combustion chamber is obviously increased;
2) the design pressure drop of 5% is similar to the 3% case, but due to the design pressure drop increase, it is required that the pulsating pressure exceeds 1%, and a small part of the flame tube assembly is throttled. The staged throttling mode (a small part of the flame tube assembly and then a large part of the flame tube assembly) is related to the opening mode of the cooling holes; additional experimental results designed for 3% and 5% pressure drop also demonstrate that throttling is related to pressure drop.
Based on the principle, the inventor creatively changes the adverse phenomenon of the acoustic throttling of the flame tube cooling hole, which is found in the process of carrying out the combustion chamber test, into the 'waste' state (the acoustic throttling of the flame tube cooling hole can reduce the cold effect of the flame tube and is not beneficial to the cooling of the flame tube), and applies the adverse phenomenon to the head main combustion stage design, namely, the main combustion stage air hole with the acoustic throttling characteristic is designed to inhibit the oscillatory combustion.
Referring to fig. 7, in one or more embodiments, the structural parameters of the first orifice 25 having an acoustic throttling effect include the total number of orifices N, the orifice diameter d, and the orifice length l. In order to have an acoustic throttling effect, it is necessary to design a pressure drop according to the through hole of the first porthole 25
SelectingAppropriate hole diameter d and hole length l. According to actual requirements, the shape of the first duct 25 may be a straight-hole duct 251 whose axis is parallel to the axial direction, or an inclined-hole duct 252 having a positive inclination angle α with the axial direction, or an inclined-hole duct 253 having a negative inclination angle- α with the axial direction, so as to ensure the number of main combustion stage outlet swirls in a stable state, which may be specifically evaluated by a Computational Fluid Dynamics (CFD) method. In the oscillatory combustion state, the number of main stage outlet swirls after closing the first port 25 by the acoustic throttling effect is only related to the configuration of the swirl blades of the swirler 20 of the second intake section, and can be evaluated by a Computational Fluid Dynamics (CFD) method. Referring to fig. 8, the air flow rate for the first air intake portion 100 is W1And the air flow rate W of the second air intake portion 2002Thus, the amount of air passing through the cross-section 26 of the main stage fuel injection holes 18 is W1+W2(ii) a The flow of air through the jet at the outlet cross-section 27 of the main combustion stage channel 300 is W1+W2. When the combustion chamber is in a stable combustion state, W1＝a，W2B; in the case of the oscillatory combustion, W is now present due to the acoustic throttling of the first port 251＝0，W2A + b; because the total intake air flow can be combined with a CFD method, and the head intake local optimization is adopted, the intake air flow of the main combustion stage is ensured to be not changed remarkably or the variable quantity is small as much as possible, so that the air flow passing through the fuel injection hole section 26 of the main combustion stage is always W1+W2A + b, therefore, the axial flow speed in the main combustion stage channel 300 is basically kept unchanged under the condition of stable combustion or oscillatory combustion, the pneumatic atomization effect of the fuel injected to the main combustion stage fuel injection holes 18 is basically unchanged, and the premixing time t of the injected main combustion stage fuel in the main combustion stage channelpremixIs also substantially unchanged. The direction (decrease or increase) and degree of change from the swirl number at the outlet cross-section 27 of the main combustion stage channel 300 in the steady state of the combustion chamber to the swirl number at the outlet cross-section 27 of the main combustion stage channel 300 in the oscillatory combustion state can be realized by designing the total number N of the structural dimensions of the first duct, the diameter d of the hole, the positive and negative directions of the inclination, the angle of inclination α, and the ratio a/(a + b) of the air intake amount of the first duct as shown in fig. 7, and can be preliminarily measured by the CFD methodAnd (4) calculating. The actual effect can be obtained by optical test or by referring to published test data at home and abroad, the Rayleigh Index (Rayleigh Index) and the flow field of the intersection region 24 under the oscillating combustion condition with different intensities (which can be realized by adjusting the fuel grading ratio)
The distribution of (2); according to Rayleigh index distribution and flow field
And (3) distribution, so that the adjustment direction and the adjustment degree of the swirl number of the main combustion stage are selected, and the design size of the first hole passage and the main combustion stage aerodynamic design parameters such as a/(a + b), the positive and negative inclination directions, the inclination angle alpha and the like are determined.
From the above description, it is known that a method of suppressing oscillatory combustion in a combustion chamber of a gas turbine may include the steps of:
providing a plurality of air flow paths to provide air to the primary combustion stage of the combustor, e.g., air flow paths 22, 23 to provide air to the primary combustion stage;
under a stable state, the plurality of air flow paths provide air for the main combustion stage; for example, in steady state, the air flow paths 22, 23 provide air to the main combustion stage;
in an oscillatory combustion state, one of the air flow paths is subjected to the throttling action of an oscillatory pressure wave propagated from the flame tube cavity, so that the air flow of the air flow path is reduced, and the air flow of other air flow paths is correspondingly increased; for example, in the oscillatory combustion regime, the air flow path 22 is closed by acoustic throttling of oscillatory pressure waves propagating through the liner chamber, the total air flow is substantially constant, air enters the main combustion stage from the air flow path 23, and the air flow in the air flow path 23 is increased, thereby changing the velocity gradient in the shear region between the main combustion stage exit jet and the precombustion stage exit jet
Therefore, the response characteristic of the flame in the shear zone to disturbance is changed, and the heat release driving force of the combustion zone is weakened so as to reduce the amplitude of oscillation.
In summary, the combustion chamber, the gas turbine and the method for suppressing the oscillatory combustion in the embodiment have the advantages that the combustion performance in a stable state is guaranteed, the oscillatory combustion boundary is widened, more fuel oil can be distributed to the main combustion stage, the potential of further reducing emission is realized, and the outlet temperature distribution quality is improved by arranging the air inlet duct with the acoustic throttling function; even if the oscillation combustion occurs, the air inlet is throttled under the action of pressure waves, so that the air inflow proportion of the first air inlet part is reduced (even completely throttled), the air inflow proportion of the second air inlet part is improved, the swirl number of the main combustion stage is changed, and the shearing action of the jet flow at the outlet of the main combustion stage and the jet flow at the outlet of the pre-combustion stage (namely the speed gradient at the shearing layer) is influenced
) The response of the shear layer flame (flame in the interaction area of the main combustion level flame and the pre-combustion level flame) to turbulence or sound field disturbance is changed, so that the response of flame heat release to the disturbance is weakened, the heat release drive of the combustion area is weakened, the pressure amplitude of oscillatory combustion is restrained, the oscillatory combustion boundary is further widened, the combustion stability is ensured, and the performance and the service life of a combustion chamber and a gas turbine are improved.
Although the present invention has been disclosed in the above-mentioned embodiments, it is not intended to limit the present invention, and those skilled in the art may make variations and modifications without departing from the spirit and scope of the present 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 (9)
1. A combustor of a gas turbine, the combustor comprising a liner head, the head comprising a main combustion stage and a pre-combustion stage, the main combustion stage having a main combustion stage inner wall and a main combustion stage outer wall, and a main combustion stage upstream end wall projecting radially from the main combustion stage inner wall; it is characterized in that the preparation method is characterized in that,
the radial space between the inner wall of the main combustion stage and the outer wall of the main combustion stage provides a main combustion stage channel for mixing air and fuel oil, the inlet end of the main combustion stage channel receives air from the main combustion stage gas inlet part, and the outlet end of the main combustion stage channel is communicated with a flame tube accommodating cavity of the combustion chamber;
the main combustion stage air inlet part comprises a first main combustion stage air inlet part and a second main combustion stage air inlet part; the primary stage first air intake includes an acoustically restrictive first port extending through an axial thickness of the primary stage upstream endwall; wherein the structure of the first hole passage with the acoustic throttling function satisfies the following conditions:
wherein, P’ 4Is the amplitude of the pulsating pressure in the flame tube, P4Is the mean pressure, Δ P, in the flame tubeoriThe constant beta is the energy conversion efficiency of converting the acoustic energy of the first duct into kinetic energy for the via hole pressure drop of the acoustic orifice.
2. The combustion chamber of claim 1 wherein the secondary intake section of the primary combustion stage has a secondary intake passage provided by an axial space between the upstream end wall of the primary combustion stage and a downstream end wall of the primary combustion stage projecting radially from an outer wall of the primary combustion stage, the secondary intake passage having a swirler disposed therein.
3. The combustor of claim 1, wherein the first and second main stage air induction portions each independently deliver air to the main stage channel, and wherein the air input from the two air induction portions is mixed within the main stage channel.
4. The combustor of claim 3, wherein said first port axis is parallel to the axial direction.
5. A combustion chamber according to claim 3 wherein the axis of the first port is inclined to the axial direction in either a positive or negative direction.
6. The combustion chamber of claim 1 wherein the side wall of the primary stage channel is provided with a plurality of fuel injection orifices for injecting fuel to combine with air entering the primary stage channel.
7. A combustion chamber of a gas turbine, the combustion chamber comprises a flame tube head, the head comprises a main combustion stage and a pre-combustion stage, air for mixing with fuel oil injected by the main combustion stage enters the main combustion stage through a main combustion stage air inlet, the combustion chamber comprises a stable state and an oscillation combustion state, the combustion chamber is characterized in that the main combustion stage air inlet comprises a main combustion stage first air inlet and a main combustion stage second air inlet, the main combustion stage first air inlet is provided with a first pore passage, in the stable state, air can respectively enter the main combustion stage through the main combustion stage first air inlet and the main combustion stage second air inlet, in the oscillation combustion state, the first air inlet of the main combustion stage has an acoustic throttling effect generated by the first pore passage under an oscillation combustion environment propagated by a flame tube cavity of the combustion chamber, the throttling effect is related to a pressure drop of a through hole of the first pore passage and a pulsating pressure amplitude in the flame tube, the proportion of the air entering the main combustion stage through the first air inlet of the main combustion stage is reduced, and the proportion of the air entering the main combustion stage through the second air inlet of the main combustion stage is increased, so that the swirl number of the outlet of the main combustion stage is adjusted.
8. A gas turbine comprising a combustor according to any one of claims 1 to 7.
9. A method of suppressing a screech combustion of a gas turbine, comprising:
a plurality of air flow paths are arranged to provide air for the main combustion stage of the combustion chamber;
in a steady state, the plurality of air flow paths provide air to the primary combustion stage;
in an oscillatory combustion state, the air flow of one air flow path of the multiple air flow paths is reduced under the environment of oscillatory pressure waves propagated by the flame tube cavity through an acoustic throttling effect, the acoustic throttling effect is related to the pressure drop of the through holes of the air flow path and the amplitude of pulsating pressure in the flame tube, and the air flow of other air flow paths in the multiple air flow paths is correspondingly increased to adjust the outlet swirl number of the main combustion stage.
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