High-temperature-rise center-fired combustion chamber design method

Abstract

The application discloses a high-temperature-rise center staged combustion chamber, which comprises a flame tube, a casing, a diffuser, a cap, a main combustion hole, a mixing hole, a swirler, a cooling hole and the like; the convergent section of the flame tube is designed by using the Vitoshinsky rule; the upper and lower wall surfaces of the convergent section area of the flame tube are respectively replaced by two arc segments. The high-temperature-rise center staged combustion chamber model designed in the application meets the design indexes required by the project under the condition that only two-stage swirler is required, and the total pressure loss coefficient is low, the combustion efficiency is high, and the outlet temperature distribution quality is high under the design working condition. The designed high-temperature-rise center staged combustion chamber has a higher temperature rise capacity and a more uniform outlet temperature distribution, i.e. a lower outlet temperature distribution coefficient OTDF and a lower average radial temperature distribution coefficient RTDF, thereby providing a benchmark model scheme for the dynamic characteristic research and test of the high-temperature-rise center staged combustion chamber.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature-rise central staged combustion chambers, and more particularly to a design method for high-temperature-rise central staged combustion chambers. Background Art

[0002] Due to the high temperature rise in the combustion chamber and the need for a high fuel-gas ratio combustion mechanism, more air is involved in combustion, which inevitably reduces the air available for cooling and mixing. However, the quality of the cooling air decreases, and the temperature of the air to be cooled actually increases. In other words, the amount of cooling air cannot be reduced, and the only options are to eliminate the mixing holes or reduce the amount of mixed air, while the turbine's temperature tolerance remains unchanged. Therefore, the requirement is to achieve a more uniform outlet temperature distribution and minimize temperature fluctuations while increasing the combustion chamber outlet temperature.

[0003] The high temperature rise combustion chamber requires a more uniform outlet temperature distribution and smaller temperature pulsation on the basis of increasing the outlet temperature of the combustion chamber. Therefore, OTDF, temperature pulsation amplitude and flame length are defined as the dynamic characteristic indicators of the high temperature rise combustion chamber.

[0004] Carry out preliminary scheme design of high temperature rise benchmark model combustion chamber, screen schemes under given high temperature rise combustion chamber constraint boundary conditions, combine numerical simulation technology to propose high temperature rise benchmark model combustion chamber scheme required for this project research, conduct performance survey of benchmark combustion chamber, and preliminarily obtain performance indicators of high temperature rise benchmark model combustion chamber.

[0005] Therefore, we proposed a high temperature rise central staged combustion chamber design method to solve the above problems. Summary of the Invention

[0006] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a design method for a high-temperature-rise central staged combustion chamber to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a high-temperature rise central staged combustion chamber, including a flame tube, a casing, a diffuser, a cap, a main combustion hole, a mixing hole, a swirler, a cooling hole, etc.; the flame tube convergence section is designed using the Witoshinsky law; the upper and lower walls of the flame tube convergence section area are respectively replaced by two circular arcs, and the upper and lower walls of the casing convergence section area are replaced by circular arcs and straight line segments; the outlet height of the lower wall of the casing convergence section area is adjusted to be slightly lower than the lowest height of the lower wall of the flame tube; the main combustion holes on the upper wall of the flame tube are cross-arranged with the main combustion holes on the lower wall, the mixing holes on the upper wall of the flame tube are cross-arranged with the mixing holes on the lower wall, and the main combustion holes and the mixing holes are cross-arranged on the same wall of the flame tube.

[0008] In a preferred embodiment, a high-temperature rise central staged combustion chamber design method includes the following design methods: calculation of combustion chamber related data; fuel design; central staged combustion chamber gas volume distribution; swirler structure design; main combustion hole and mixing hole design; diffuser design; inner and outer annular cavity channel design and flame tube convergence section design; cooling hole design.

[0009] In a preferred embodiment, the calculation of the combustion chamber includes the following methods: calculating the inclination angle of the combustion chamber; setting the head in the middle of the combustion chamber, and then calculating the head area, and at the same time calculating the air density at the flame tube inlet under the design working conditions; and then calculating the head reference speed, head width and head aspect ratio.

[0010] In a preferred embodiment, the fuel design includes the following methods: determining the pre-combustion stage fuel ratio; determining the main combustion stage fuel ratio; and then calculating the main combustion zone equivalence ratio.

[0011] In a preferred embodiment, the gas distribution of the central staged combustion chamber includes the following methods: determining the head air intake ratio; determining the main combustion hole air intake ratio; determining the mixed combustion hole air intake ratio; and determining the flame tube cooling air ratio.

[0012] In a preferred embodiment, the swirler structure design includes the following method: first calculating the effective area of ​​the flame tube; then determining the swirler frontal area and flow coefficient; and finally determining the inner and outer diameters and swirl number of the swirler.

[0013] In a preferred embodiment, in the design of the main combustion hole and the mixing hole, the main combustion hole and the mixing hole structure both adopt an "inverted right-angled trapezoidal cylinder" structure; first calculate the limiting hole structure parameters; calculate the main combustion hole area; calculate the main combustion zone length; calculate the main combustion zone residence time; calculate the main combustion zone equivalence ratio; calculate the mixing hole area; and determine the mixing hole position.

[0014] In a preferred embodiment, in the diffuser design, the diffuser inlet airflow density and inlet airflow velocity are first calculated; then the area ratio and the pre-diffuser length Lpred are determined; then key performance parameters such as the static pressure recovery coefficient and the total pressure loss are calculated; and finally, the diffuser structure is optimized.

[0015] In a preferred embodiment, in the design of the inner and outer annular channels, the reference cross-sectional area of ​​the combustion chamber and the areas of the inner and outer annular channels are first calculated;

[0016] Then calculate the inner and outer annular channel heights, the inner and outer annular cavity inlet flow velocities and the gas residence time in the flame tube; then calculate the flame tube convergence section: calculate the middle section length; calculate the flame tube contraction section length; calculate the convergence section inlet and outlet cross-sectional areas; design the flame tube center streamline - the double arc line; obtain the upper and lower wall fitting curves of the flame tube convergence section.

[0017] In a preferred embodiment, the cooling hole design includes the following: designing the head cooling holes; and designing the flame tube cooling holes.

[0018] Technical effects and advantages of the present invention:

[0019] The designed high-temperature-rise centrally staged combustor model meets the project's design specifications, requiring only two swirler stages. Under design conditions, it demonstrates a low total pressure loss coefficient, high combustion efficiency, and a high-quality outlet temperature distribution. While maintaining a higher temperature rise capability, the designed high-temperature-rise centrally staged combustor exhibits a more uniform outlet temperature distribution, with a lower outlet temperature distribution coefficient (OTDF) and a lower average radial temperature distribution coefficient (RTDF). This provides a benchmark model for future research and testing of the dynamic characteristics of high-temperature-rise centrally staged combustors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the relationship between the total oil-gas ratio of the conventional combustion chamber and the gas-liquid ratio of the head swirl cup;

[0021] Figure 2 This is the design diagram of the diffuser aspect ratio;

[0022] Figure 3 This is a simplified diagram of the numerical model of the sudden expansion diffuser;

[0023] Figure 4 Velocity distribution vector diagram of the pre-diffuser;

[0024] Figure 5 Design optimization diagram for pre-diffuser;

[0025] Figure 6 This is the arrangement diagram of cooling holes on the flame tube wall;

[0026] Figure 7 This is the design diagram of the combustion chamber theoretical structure;

[0027] Figure 8 Processing structural design drawings for the combustion chamber;

[0028] Figure 9 Processing structure design drawings for flame tube;

[0029] Figure 10 This is the structural design drawing of the central classification cyclone;

[0030] Figure 11 This is the structural partition diagram of the high temperature rise center staged combustion chamber;

[0031] Figure 12 This is the grid division diagram of the high temperature rise center staged combustion chamber;

[0032] Figure 13Velocity distribution cloud diagram of the central section of the design working condition;

[0033] Figure 14 It is the velocity distribution vector diagram of the central section of the design working condition;

[0034] Figure 15 It is the temperature distribution cloud diagram of the central section under the design working condition;

[0035] Figure 16 The temperature distribution cloud diagram of the outlet section under the design working condition;

[0036] Figure 17 It is the velocity distribution cloud diagram of the central section of the slow train condition;

[0037] Figure 18 It is the velocity distribution vector diagram of the central section under slow train condition;

[0038] Figure 19 This is the temperature distribution cloud diagram of the central section under slow running condition;

[0039] Figure 20 This is the temperature distribution cloud diagram of the outlet section under slow running condition;

[0040] Figure 21 This is a comparison chart of the outlet cross-section RTDF under different working conditions of the central staged combustion chamber;

[0041] Figure 22 This is a comparison chart of the recirculation zone size under different working conditions of the central staged combustion chamber;

[0042] Figure 23 This is a trend chart of the change of the equivalence ratio of the pre-combustion stage to the main combustion stage with the total oil-gas ratio;

[0043] Figure 24 Take a screenshot of the Excel table "ε=f(AR)";

[0044] Figure 25 This is a screenshot of the Excel table "Inner and outer diameter values ​​of the flame tube convergence section".

[0045] The reference numerals in the drawings are: 1 pre-diffuser, 2 sudden expansion zone, 3 flame tube, 4 outer ring, 5 inner ring. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0047] The present invention focuses on the design research of the high-temperature rise central staged combustion chamber, including the structural design of the flame tube, swirler, main combustion hole, mixing hole, diffuser, nozzle, casing, etc. and the overall layout gas volume and fuel distribution design.

[0048] At the same time, the designed model was divided into grid zones, the benchmark simulation calculation was completed, and the design indicators were achieved.

[0049] This engine uses an annular combustion chamber.

[0050] The main advantages of the annular combustion chamber are that the aerodynamic layout and outlet airflow are easy to match, the loss pressure is small, the combustion chamber is compact, the length is short and light, and it can meet the requirements of a large bypass ratio.

[0051] The number of the annular combustion chamber heads of the present invention is 20.

[0052] Table 1 Aerodynamic parameters of the overall performance scheme

[0053]

[0054] Table 2 Structural limit dimensions of the overall performance scheme

[0055]

[0056] Reference Figure 1-25 , the design method of high temperature rise central staged combustion chamber includes the following design methods:

[0057] Calculate the combustion chamber inclination:

[0058] Combustion chamber inlet midpoint radius: (579.2 / 2+525.4 / 2) / 2=276.15mm

[0059] Combustion chamber outlet midpoint radius: (761 / 2+616 / 2) / 2=344.25mm

[0060]

[0061] Assuming the head is in the middle of the combustion chamber, the radius of the head position Rd = 310.7894 mm, and the area of ​​the head is

[0062] Assuming the total pressure loss of the flame tube in the design combustion chamber is 3.5%, the air density at the flame tube inlet under the design working condition is calculated as follows:

[0063]

[0064] In the formula, the total temperature of the flame tube inlet is usually T t3.1 =Total temperature at combustion chamber inlet T t3.0 =845K.

[0065] Head reference speed:

[0066] Head width B:

[0067] Head aspect ratio θ:

[0068] For large engines, the parameter θ is between 0.7 and 1.0.

[0069] Fuel design:

[0070] The pre-combustion stage is used from start-up to the transition point, and then the main combustion stage and pre-combustion stage work together to achieve the maximum fuel-air ratio. Given an idle fuel-air ratio of 0.0106, the fuel distribution ratio is as follows:

[0071] Pre-combustion fuel ratio = 0.0106 / 0.037 = 28.65%,

[0072] Main fuel level fuel ratio = 1-28.65% = 71.35%,

[0073] Therefore, the fuel ratios for the pre-combustion stage and the main combustion stage are taken as 30% and 70% respectively.

[0074] Main combustion zone equivalence ratio Φ P (Not considering the cooling air volume of the flame tube in front of the main combustion hole section):

[0075] visible

[0076] Visible Φ P The value is less than the main combustion zone smoke limit equivalent ratio of 1.4.

[0077] Central staged combustion chamber gas distribution

[0078] According to the project requirements, the central stage cyclone designed in this paper is a two-stage cyclone, and the head air intake is given to be 45.05%. Referring to the previous experience in the design of high-temperature three-cyclone combustion chambers, it is assumed that the head cooling air volume is 3.05%, the pre-combustion stage air intake is 18%, and the main combustion stage air intake is 24%.

[0079] Based on design experience with a swirl cup flow distribution of ≤16%, assuming 85% of the swirl flow is used to create the traditional swirl cup recirculation zone, thereby stabilizing the flame, the virtual swirl cup equivalent ratio at idle = (0.0106 × 14.7) / (18% × 85%) = 1.0. If the flameout fuel-air ratio is estimated to be 50% of the idle fuel-air ratio, this virtual swirl cup equivalent ratio at flameout is 0.5. The flameout fuel-air ratio can be estimated to be 0.005, which meets the current flameout fuel-air ratio requirements for military aircraft.

[0080] Secondly, if it is assumed that 85% of the swirl gas volume is used to atomize the fuel, the gas-liquid ratio of the head swirl cup is (3.91×18%×85%) / 0.1445=4.14, which is greater than 3-4, which satisfies the requirement. Figure 1 The swirl cup atomization test results shown above require a swirl cup gas-liquid ratio, so good atomization can be achieved at the design point.

[0081] The gas volume ratio of the main combustion hole is: 2×(53.50%-45.05%)=16.9%.

[0082] The project requires that the gas volume ratio of the main combustion hole and the mixing hole is about 17%. Therefore, the gas volume of the mixing hole is allocated 17%, and the remaining gas volume is used for flame tube cooling, that is, the flame tube cooling gas volume ratio is: 1-45.05%-16.9%-17%=21.05%.

[0083] Therefore, the final combustion chamber flow distribution scheme is shown in Table 3.

[0084] Table 3 Overall layout of combustion chamber and air intake distribution

[0085]

[0086] Cyclone structural parameter design

[0087] The swirl number of the swirler directly affects the size and flow pattern of the recirculation zone at the head of the flame tube, and directly affects the combustion performance.

[0088] The swirl number of the axial blade cyclone is as follows:

[0089]

[0090] The swirl intensity is characterized by the swirl number. When the swirl number exceeds 0.6, it is considered strong swirl, and a recirculation zone will appear. The existence of the recirculation zone is important for flame stability and oil-gas mixing. It should be noted that based on design experience and literature research, a swirl number between 0.5 and 0.6 will also form a stable recirculation zone. Because the swirl volume of the class is mainly used to generate the recirculation zone of the traditional swirl cup, and a swirl number greater than 0.6 will result in insufficient head design space, the design swirl number range is between 0.5 and 0.6.

[0091] When the swirl number exceeds 1.2, it is considered very strong swirl. Since the main combustion stage is lean-burn at idle speed, combustion oscillation is easily caused by such strong swirl. Based on existing design experience, the range of the main combustion stage swirl number is preliminarily determined to be between 0.8 and 1.2.

[0092] One of the basic principles of cyclone design is that it cannot be light-transmitting, that is, no light can be seen when viewed from the front to the back. This principle is:

[0093] Where: n is the number of blades; L is the axial length of the cyclone; θ is the blade outlet angle; θ is the outer diameter of the cyclone flow path.

[0094] Blade chord length Ratio of cyclone blade height h to chord length c Determines the maximum diameter of the head air swirler. In addition, the length L affects the fuel injection and the length of the fuel and air mixing.

[0095] Calculate the effective area of ​​the flame tube:

[0096] Among them, q m3.1 =3.91kg / s, ΔP L --Pressure drop of flame tube, ΔP L =3141000Pa×3.5%=109935Pa,

[0097] According to PM=ρRT, we get ρ a3.1 =12.6409kg / m 3 .

[0098] therefore:

[0099] Blade inlet area formula: A sw =π(R O 2 -R i 2 )-nt(R O -R i ) / cosθ

[0100] When the cyclone outlet is not extended, the geometric flow area of ​​its outlet is:

[0101] A s =A sw .cosθ

[0102] After calculating the geometric flow area, the remaining step is to select the flow coefficient C d For axial flow cyclones, it is roughly 0.84-0.88. For curved blades, polished blades, a higher value can be taken; for straight blades (because of airflow separation), unpolished blades can take a lower value. Therefore, C d The initial value is 0.84.

[0103] According to the flow formula:

[0104] The total pressure loss of the flame tube in the designed combustion chamber is 3.5%

[0105] ΔP=3141000Pa×3.5%=109935Pa, AL=Sdome=12048.4514mm 2 ,

[0106]

[0107] A three-dimensional combustion chamber model is established based on the opening area of ​​each row of holes initially calculated using the above method. The flow rate of each row of holes is calculated and compared with the three-dimensional flow distribution results in Table 1. If the results do not match, the initial flow coefficient is corrected based on the three-dimensional calculation results, and the area of ​​each row of holes is recalculated. The above steps are repeated until the three-dimensional flow distribution result is the same as the one-dimensional flow distribution result.

[0108] After multiple iterative calculations, the structural parameters of the centrally graded two-stage cyclone are shown in Table 4.

[0109] Table 4 Structural parameters of the central graded two-stage cyclone

[0110]

[0111] Pre-combustion stage cyclone swirl number:

[0112]

[0113] Main combustion stage cyclone swirl number:

[0114]

[0115] It can be seen that the swirl number of the pre-combustion stage is in the range of 0.5-0.6, and the swirl number of the main combustion stage is in the range of 0.8-1.2.

[0116] In combustion chamber applications, there is often an extension section at the swirler outlet. In this case, the effective flow path area of ​​the component with the extension section needs to be calculated. The following conditions must be considered: whether the outlet of the extension section has the minimum flow path area (if the outlet area of ​​the extension section ≥ the effective flow path area, the effect is negligible); the length of the extension section (this effect is generally not significant and is mainly due to friction); and whether the outlet of the extension section is convergent (it should be).

[0117] If the outlet area of ​​the extension section is less than the effective flow path area, and (effective flow path area - outlet area of ​​the extension section) is larger, then use:

[0118]

[0119] Where A 总 --Total flow area of ​​cyclone; A 有效 --The effective area of ​​the cyclone; A o --The minimum area of ​​the convergent segment.

[0120] There is an extension section at the outlet of the main combustion stage cyclone, and the outlet of the extension section is convergent. Therefore, it is necessary to calculate whether the outlet of the extension section has the minimum flow path area. That is, if the outlet area of ​​the extension section is ≥ the effective flow path area, the impact can be ignored.

[0121] From Table 4, we can see that the effective area of ​​the main combustion stage cyclone is 562.8803 mm 2 ; and the inner diameter of the minimum outlet area of ​​the extended convergent section of the main combustion stage cyclone is 23.3782mm, and the outer diameter is 28.3565mm, then the minimum outlet area of ​​the extended convergent section is:

[0122] π×(28.3565 2 -23.3782 2 )=809.1199mm 2 >562.8803mm 2 , so the impact is ignored.

[0123] The function of the cap cover is to guide the compressor flow into the flame tube and the two-stream channel with a smaller pressure loss, to produce a smaller pressure loss in the cap cover to increase the head pressure drop, and to be insensitive to the inlet airflow distortion. Therefore, the average radius of the intake cap cover inlet generally falls on the extension line of the center streamline of the pre-diffuser to ensure smooth air intake.

[0124] If the opening area of ​​the cap is too large, overflow is likely to occur; if the area is too small, the flow will contract, the static pressure recovery of the airflow will be reduced, and separation will occur at the cap lip. Both situations will increase losses.

[0125] Generally, Acoin:Aain:Aaou≈Aoh:Aoin:Aoou where:

[0126] Acoin--cap inlet area;

[0127] Aain - the area of ​​the inner ring two-branch channel;

[0128] Aaou - the area of ​​the outer ring two-branch channel;

[0129] Aoh--head aperture area;

[0130] Aoin - area of ​​inner ring air inlet;

[0131] Aoou--Outer ring air inlet area.

[0132] Effective area of ​​the head: 422.1602 + 562.8803 + 84.1561 × 0.85 = 1056.5732 mm 2

[0133] From the design data in the following chapters, we can see that:

[0134] Effective area of ​​inner ring cavity: 599.0168mm 2 ;

[0135] Effective area of ​​outer ring cavity: 693.5732mm 2 ;

[0136] Inner ring channel area: 1987.9179mm 2 ;

[0137] Outer ring cavity channel area: 1878.1436mm 2 ;

[0138] Acoin: 1987.9179: 1878.1436 = 1056.5732: 599.0168: 693.5732

[0139] Then: 1987.9179 / 599.0168=3.3186,

[0140] 1878.1436 / 693.5732=2.7079(3.3186+2.7079) / 2=3.0133

[0141] Acoin=1056.5732×3.0133=3183.7720mm 2

[0142] Acoin=π[(R+x) 2 -(Rx) 2 ] / 20=4πRx / 20,

[0143] Where R is the average radius of the cap inlet, and x is the distance in the y direction between the (inner) outer diameter of the cap inlet and the average radius.

[0144] R=303.5822mm, calculated x=16.6911mm. Since the cap can reduce the pressure loss, Acoin can be appropriately enlarged.

[0145] In addition, considering the main stage fuel injection assembly problem, that is, x ≥ the main stage fuel injection outer radius (24.0233 mm), the value of x is 30 mm during design.

[0146] Design of main combustion hole and mixing hole

[0147] In the main combustion zone, the role of the main combustion hole transverse jet is to jointly form and cut off the recirculation zone, thereby strengthening the combustion process; in the mixing zone, the role of the mixing hole transverse jet is to adjust the outlet temperature distribution of the combustion chamber. The main combustion hole and mixing hole structure of the high temperature rise center staged combustion chamber designed in this paper both adopt the "inverted right-angled trapezoidal cylinder" structure, such as Figure 9As shown in the figure, the shorter design on one side of the incoming flow direction makes it easier for the main combustion hole jet to cut off the reflow zone, and for the mixing hole jet to effectively mix with the incoming flow, thereby adjusting the outlet temperature distribution.

[0148] Define the pore structure parameters:

[0149] The hole front edge depth a=0.3-0.5mm, the hole rear edge depth b=10-11mm, the hole wall thickness c=1mm, and the hole diameter d=12.3-13.5mm.

[0150] Therefore, the values ​​are: a=0.4mm, b=10mm, c=1mm, d=13.0mm.

[0151] According to experience, the number of main combustion holes n p =4n a , that is, n in a single-head combustion chamber p =4;

[0152] Main combustion hole diameter d p With H d Related, d p =aH d , where a is the coefficient, and a value of about 0.114 is appropriate.

[0153] Main combustion hole area:

[0154]

[0155] In summary: the number of main combustion holes in a single-head combustion chamber is 4. The main combustion holes on the upper and lower walls of the flame tube are arranged crosswise as shown in the figure. There are 2 on the upper wall and 2 on the lower wall respectively. The diameter of the main combustion hole is d p =13.00mm, total area of ​​main combustion hole A p,h =530.9292mm 2 , flow coefficient C d =0.75.

[0156] Main combustion zone length L p :

[0157] L p Refers to the distance from the first-stage swirler outlet to the center of the main combustion hole in the x-axis direction.

[0158] Main combustion zone residence time, V pz The volume of the main combustion zone is defined as the volume from the head swirler outlet section to the center of the main combustion hole, G paThe air volume flow rate in the main combustion zone is defined as all flows in the main combustion zone, including the swirler, head cooling, half of the main combustion hole, and the multi-slant hole flow from the head swirler outlet section to the center of the main combustion hole.

[0159] Then: V pz =L p ·A L =78.792×12048.4514=949321.5827mm 3 .

[0160] Given the air ratio of the main combustion zone is 53.50%, the total cooling air volume of the flame tube Wc = mc × Wt3 = 21.05% × 3.91 kg / s = 0.823055 kg / s. Assuming that the cooling air volume in front of the main combustion hole section Wp,c ≈ 0.30Wc = 0.3 × 0.823055 kg / s = 0.2469165 kg / s, then:

[0161]

[0162] The reference is that the residence time of the main combustion zone of the existing single-annular combustion chamber is about 5ms.

[0163] Air flow in the main combustion zone: 45.05% + 0.5 × 16.9% + 0.3 × 21.05% = 59.815%

[0164] Equivalence ratio of the main combustion zone (taking into account the cooling air volume of the flame tube in front of the main combustion hole section):

[0165]

[0166] The equivalence ratio of the main combustion zone is around 1.00, which is smaller than the main combustion zone smoke limit equivalence ratio of 1.4, meeting the requirements for suppressing smoke in the main combustion zone.

[0167] Mixing hole area:

[0168] That is, 3.91 kg / s × 17% = 0.75 × 1667.1397 A d,h , A d,h =531.6091mm 2 ,

[0169] Single mixing hole area

[0170] Number of mixing holes n d (usually 4-8 times the nozzle) ≈ 4,

[0171] Mixing hole position:

[0172] Set the projected distance from the center of the main combustion hole to the center of the flame tube outlet section in the x-axis direction, that is, the mixing section length, to L d The projected distance L from the center of the cyclone outlet section to the center of the main combustion hole in the x-axis direction is measured. ps is 66.0352mm, because L d +L ps =L f -L sw =230-33.9437×cos9.662°=196.5378mm, so L d =196.5378-66.0352=130.5026mm.

[0173] make The initial value of the axial distance of the mixing hole (ie, the projection distance from the center of the cyclone outlet cross section to the center of the mixing hole in the x-axis direction) is 2D=123.4 mm.

[0174] Diffuser design

[0175] Calculate the airflow density at the diffuser inlet under design conditions:

[0176]

[0177] That is, the high-pressure compressor outlet velocity is 129.2281m / s, making the expansion ratio about 7, and slowing the airflow to about 20m / s. The expansion ratio is large, so a sudden expansion diffuser is selected.

[0178] Existing research shows that every 1% increase in the total pressure loss coefficient increases specific fuel consumption by 0.5%. If the combustion chamber's total pressure loss coefficient is 6%, the diffuser's total pressure loss accounts for approximately 30% of the total loss. If the gas flow in the pre-diffuser does not separate, the diffuser's total pressure loss coefficient is 6% x 30% = 2%.

[0179] The diffuser's function is to reduce speed and expand pressure, minimizing total pressure loss while increasing static pressure. This loss is generally required to be within 2%. A longer pre-diffuser increases frictional losses, while a shorter pre-diffuser results in a larger opening angle, increasing separation losses.

[0180] Figure 2 In the equation, the horizontal axis is the dimensionless length LW and the vertical axis is the area ratio AR. The empirical formula (corresponding to the dotted line in the left figure) is:

[0181]

[0182] Aspect ratio

[0183] h is the height of the pre-diffuser inlet, L pred is the length of the pre-diffuser in the x direction.

[0184] Combustion chamber inlet outer diameter R3.0-combustion chamber inlet inner diameter r3.0=h=26.9mm,

[0185] The front diffuser is selected to be annular straight wall with symmetrical expansion angle. The total length L of the combustion chamber is 400mm, and the length of the flame tube Lf is 230mm. Then the length of the front diffuser + the sudden expansion gap is less than 170mm.

[0186] During the combustion chamber design process, excluding the cap design space, it was finally determined that the x-direction projection distance left for the pre-diffuser and the sudden expansion gap was 161.1288 mm.

[0187] Inner ring expansion angle β i , outer ring expansion angle β0 expansion gap ratio: Among them, the sudden expansion gap D is the distance between the front diffuser outlet and the head air inlet, and h is the front diffuser inlet height, such as Figure 3 shown.

[0188] There is an optimal value for the sudden-expansion gap ratio, which maximizes the diffuser static pressure recovery coefficient and minimizes the total pressure loss coefficient.

[0189] Therefore, an Excel table ε=f(AR) is developed for comparative analysis based on the key performance parameters of the diffuser, such as Figure 24 Based on design experience and research literature, the sudden expansion gap generally ranges from 51 to 56 mm. After comprehensive analysis, the AR value was finally determined to be 1.83.

[0190] Therefore, if AR=1.83, then

[0191]

[0192] n is the expansion ratio, and n = AR, R 3.0 =289.6mm, r 3.0 =262.7mm, R 3.0 -r 3.0 =h=26.9mm, A 3.0 =2333.7117mm 2 , then A 3.1 =4270.6924mm 2 .

[0193] In summary: the pre-diffuser inlet height h = 26.9 mm, the ratio of the pre-diffuser outlet area to the inlet area is AR = 1.83, and the pre-diffuser length L pred =107.0367mm, expansion angle of the front diffuser Check based on existing geometric conditions It should be within the range of 4° to 8° to meet the requirements.

[0194] The ideal static pressure recovery coefficient is

[0195] The actual static pressure recovery coefficient is

[0196]

[0197] Diffuser efficiency

[0198] Under the conditions of 845K and 31atm, the specific heat ratio γ is calculated by table interpolation to be 1.3527.

[0199] Total pressure loss of pre-diffuser:

[0200]

[0201] Pre-diffuser outlet Mach number:

[0202]

[0203] Total pressure loss in the sudden expansion section: A3.0 = 2333.7117 mm 2 , Aref=16297.6445mm 2

[0204]

[0205] Total pressure loss of the entire diffuser section: ε t =1-(1-ε pd )(1-ε dd )=1-(1-0.005295)×(1-0.01243)=0.01766

[0206] Generally speaking, the loss of the diffuser is less than 2% of the total pressure at the compressor outlet.

[0207] Due to the symmetrical design of the front diffuser with an annular straight wall expansion angle, the following will occur Figure 4 The separation phenomenon shown is that a separation vortex appears on the upper wall of the pre-diffuser near the outer ring expansion angle, which leads to a significant increase in the air intake volume of the inner ring cavity.

[0208] The reason is believed to be that the airflow direction at the combustion chamber inlet section is not parallel to the center line of the pre-diffuser, that is, the pre-diffuser with a symmetrical design of annular straight wall expansion angle is not compliant with the combustion chamber inlet flow. Therefore, the following design is made on the basis of ensuring the area ratio and the length Lpred of the pre-diffuser in the x direction: Figure 5The front diffuser shown, i.e. adopting the "annular curved wall expansion angle impingement" design, makes the front diffuser outlet airflow direction consistent with the combustion chamber central axis, i.e. the flame tube head center streamline is on the extension line of the front diffuser outlet airflow center streamline, thereby ensuring smooth intake of the flame tube head. The "annular curved wall expansion angle impingement" design makes the front diffuser not only avoid generating separation vortex, but also greatly reduce the total pressure loss coefficient to 0.24%, which is much lower than the design standard of 2% in design, thereby giving enough space for the flame tube design total pressure loss under the condition that the combustion chamber design total pressure loss index is unchanged.

[0209] Inner and outer ring cavity passage design

[0210] Set the combustion chamber (casing) reference section area A ref , the flame tube reference section area AL, assuming the inner and outer ring cavity airflow passage average airflow velocity A passage is 40 m / s.

[0211] Given AL = 12048.4514 mm 2 , the inner and outer ring cavity airflow passage air ratio m passage is 54.95%, then W t3 ·m passage = ρ·V passage A passage , i.e. 3.91 kg / s × 54.95% = 12.6409 kg / m 3 × 40 m / s × A passage , A passage = 4249.1931 mm 2 .

[0212] The maximum cross section (i.e. reference section) area of the combustion chamber:

[0213] A ref = A L +A passage = 12048.4514 mm 2 + 4249.1931 mm 2 = 16297.6445 mm 2 , then

[0214] Assuming the flame tube middle section size is designed according to the middle diameter constant m k = 1 (i.e. the areas of the upper and lower two ring cavities divided by the center streamline are equal).

[0215]

[0216] Where R d = 310.7894 mm, H d=123.4mm, α=9.962°, and the outer ring cavity channel height H is obtained by substituting po =17.5963mm, inner ring channel height H pi =29.2324mm.

[0217] Considering that the area of ​​the inner and outer annular channels is much larger than the sum of the areas of the flame tube cooling holes and the main combustion holes and the mixing holes, the determining factors affecting the gas volume distribution of the inner and outer annular channels are the areas of the flame tube cooling holes and the main combustion holes and the mixing holes in the inner and outer annular channels.

[0218] Inner ring channel area: 4249.1931 / 2 = 2124.5966 mm 2 , which is much larger than the opening area of ​​the inner ring cavity 132.7323×4+669×π×0.35 2 =788.3906mm 2 ;

[0219] Outer ring cavity channel area: 4249.1931 / 2=2124.5966mm 2 , which is much larger than the opening area of ​​the outer ring cavity 132.7323×4+984×π×0.35 2 =909.6168mm 2 .

[0220] Furthermore, considering the size limitation of the casing, it is necessary to fine-tune the calculated inner and outer annular channel heights. Here, the flame tube wall thickness is fine-tuned by 2 mm, that is, Hpo = 15.5963 mm, Hpi = 27.2324 mm, and then calculated:

[0221] Outer ring cavity channel area: 1878.1436mm 2 ; Inner ring cavity channel area: 1987.9179mm 2 .

[0222] Flame tube effective area: 2345.3344mm 2

[0223] Effective area of ​​inner ring cavity:

[0224] 132.7323×4×0.75+669×π×0.35 2 ×0.78=599.0168mm 2

[0225] The gas volume distribution ratio of the inner ring cavity is: 599.0168mm 2 / 2345.3344mm 2 =25.54%

[0226] Effective area of ​​outer ring cavity:

[0227] 132.7323×4×0.75+984×π×0.35 2 ×0.78=693.5732mm 2

[0228] The gas volume distribution ratio of the outer ring cavity is: 693.5732mm 2 / 2345.3344mm 2 =29.57%

[0229] Flow rate in the inner annular cavity:

[0230] 3.91kg / s×25.54%=12.6409kg / m 3 ×1987.9179×10 -6 m 2 ×V passage,in V passage,in =39.7394m / s

[0231] Flow rate in the outer ring cavity:

[0232] 3.91kg / s×29.57%=12.6409kg / m3×1878.1436×10 -6 m 2 ×V passage，ou

[0233] V passage,ou =48.6991m / s

[0234] It is known that the flame tube length Lf = 230mm and the area of ​​the flame tube reference cross section AL = 12048.4514mm 2 Flame tube volume:

[0235] V=L f .A L =(230-33.9437×cos9.662°)×12048.4514=2367976.028mm 3 Flame tube volume flow rate:

[0236]

[0237] Gas residence time:

[0238]

[0239] Flow resistance coefficient:

[0240]

[0241] Flame tube length L f check:

[0242]

[0243] =56.3395

[0244] From the above formula, we know that OTDF and L f Inversely proportional, then given by L f =230mm, so the designed OTDF value will be less than 0.286, which will meet the OTDF requirement.

[0245] Flame tube convergence section design

[0246] Middle section length L R The experience value is:

[0247] L R =(0.6-0.7)H d =(74.04~86.38)mm=80mm

[0248] Flame tube contraction section length:

[0249] L L =L f -L sw -L R =230MM-33.9437×cos9.662°-80mm=116.5378mmConverging section inlet cross-sectional area:

[0250]

[0251] Cross-sectional area of ​​convergent section outlet:

[0252]

[0253] Design the center streamline of the flame tube - double arc line:

[0254] H=0.5(D2-D1)=R2-R1=344.25-324.4094=19.8406mm,

[0255]

[0256] Witoshinsky's law (empirical formula):

[0257]

[0258] When X=116.5378,

[0259]

[0260]

[0261] mk =1.11, therefore, take the median diameter constant m k =1.11, that is

[0262] A 1x =0.5263A x , A 2x =0.4737A x ,

[0263]

[0264] Create an Excel table "Inner and outer diameter values ​​of the flame tube convergence section", such as Figure 25 As shown, the flame tube shape is then designed.

[0265] Cooling hole design

[0266] Head cooling hole design

[0267] Known head cooling air volume ratio m dc is 3.05%, according to the flow formula Calculate, where the flow coefficient C d The value ranges from 0.65 to 0.85, and the value of 0.7 is generally used in most designs. d The initial value is 0.7. After multiple iterative calculations, the flow coefficient C is finally determined. d =0.85. That is, 3.91kg / s×3.05%=0.85×1667.1397×Adome, and we can calculate A dome =84.1561mm 2 The number of head cooling holes is designed to be 144 = 72 / row × 2 rows, with two rows of concentric circles cross-distributed circumferentially. The diameter of the cooling holes (limited to between 0.8-1.0mm) is 0.8626mm, and a straight hole impact cooling method is used.

[0268] Flame tube cooling hole design

[0269] The flame tube wall adopts a dense multi-slant hole cooling form. Flow coefficient C d The value is between 0.7 and 0.8, and the initial value is 0.75; the diameter of the flame tube cooling hole is limited to between 0.6 and 0.7 mm, and the value is 0.7 mm; the inclination angle is selected as 22° according to the shape of the flame tube (the value is between 20° and 30°).

[0270] The cooling air volume ratio of the flame tube is known to be m c is 21.05%, according to the flow formula Calculation, after multiple iterative calculations, the flow coefficient C is finally determined d is 0.78, that is:

[0271] 3.91kg / s×21.05%=0.78×1667.1397×Acool, Acool=636.1490mm 2 , the number of cooling holes in the flame tube is 636.1490÷(π×0.35 2 ) = 1653

[0272] Measured:

[0273] The upper wall area of ​​the flame tube is 26937.1192mm 2 ,

[0274] The area of ​​the lower wall of the flame tube is 18286.5999mm 2 ,

[0275] Then: 26937.1192mm 2 / 18286.5999mm 2 =1.47.

[0276] Since the ratio of the upper and lower wall areas of the flame tube = the ratio of the number of cooling holes on the upper and lower walls of the flame tube, let the number of cooling holes on the lower wall be x, then x + 1.47x = 1653, and x = 669. Therefore, there are 669 cooling holes on the lower wall and 984 cooling holes on the upper wall.

[0277] This project adopted a rhombus-shaped opening pattern for the first round of design, where the flow-direction hole spacing s equals the transverse hole spacing p. This design principle aims to achieve a more regular arrangement of the cylinder's openings. Compared to a regular rhombus, at the same per-unit-area opening ratio, the rhombus-shaped arrangement exhibits greater interference between rows. This results in greater uniformity in air film coverage and enhanced heat transfer from the cooling airflow to the wall surface.

[0278] After multiple iterative calculations, it was finally determined that:

[0279] 44 rows of holes on the upper wall, 24 cooling holes per row, s = 4.70 mm, p = 4.89 mm;

[0280] There are 47 rows of holes on the lower wall, with 16 cooling holes in each row, s = 4.10 mm, p = 4.87 mm.

[0281] Opening rate per unit area of ​​upper wall A p :

[0282] Opening rate per unit area of ​​lower wall A p :

[0283] 3D model design completed

[0284] The design of high temperature rise center staged baseline combustor, including flame tube, casing, diffuser, cap, primary hole, mixing hole, swirler, cooling hole, etc., the initial combustor designed according to the Excel table "flame tube convergent section inner and outer diameter value" is shown in Figure 7 The flame tube convergent section is fitted by each point of the upper and lower wall surfaces in the Excel table.

[0285] Considering the processing difficulty, the upper and lower wall surfaces of the flame tube convergent section are replaced by two circular arcs respectively, and the upper and lower wall surfaces of the casing convergent section are replaced by a circular arc and a straight line. At the same time, considering the installation and assembly of the test piece during the test, the height of the lower wall surface of the casing convergent section is slightly lower than the lowest height of the lower wall surface of the flame tube, as shown in Figure 8 In addition, the primary holes of the upper wall surface of the flame tube and the primary holes of the lower wall surface are arranged in cross, the mixing holes of the upper wall surface of the flame tube and the mixing holes of the lower wall surface are arranged in cross, and the primary holes and the mixing holes are arranged in cross on the same wall surface of the flame tube, as shown in Figure 9 .

[0286] The center staged swirler structure composed of two-stage fuel injection and two-stage axial swirler is shown in Figure 10 The primary fuel nozzle adopts a double oil path centrifugal nozzle, and the main fuel stage fuel nozzle adopts a direct jet nozzle; the two-stage swirler has an increasing number of swirls from inside to outside, and the rotation directions are clockwise and counterclockwise respectively.

[0287] The grid partition is completed

[0288] The high temperature rise center staged combustor is designed as 20 heads. In order to calculate simply, this paper selects a single head sector area as the calculation domain, which includes the pre-diffuser, the inner and outer two cavity channels, the flame tube, the swirler, etc. Since the flame tube cooling hole in the project is designed in the form of dense multi-inclined hole, if structured grid is used, it will be too time-consuming, therefore, this project uses unstructured grid division, and the total number of grids is about 1177 million. Considering the large number of grids, the complexity of the combustor structure and the performance of the working computer, the overall structure of the combustor is divided into zones during grid division, which is convenient for finding and correcting errors, as shown in Figure 11 .

[0289] This project compares the axial velocity distribution along the radial direction at the center of the backflow zone under different grid numbers. When the velocity distribution no longer changes significantly with the number of grids, it is considered that the grid is irrelevant, and the total number of grids is finally determined to be 1177 million.

[0290] The inlet section adopts a flow inlet boundary condition, while the flame liner outlet is set to an outflow boundary condition. Both turbine cooling bleed air outlets are designed as adiabatic walls, similar to the casing. The swirling air volume of the two-stage swirler and the inlet air flow rate of each opening on the flame liner wall (including the main combustion orifice, mixing orifice, and flame liner film cooling hole) are calculated through flow coupling. Rotational periodic boundary conditions are set on the sidewalls of the entire fluid domain of the single-head annular combustor.

[0291] A hollow conical spray model is set at the two-stage fuel nozzle, and the structure and aerodynamic parameters of the conical spray are set.

[0292] Research Results and Analysis

[0293] pass Figure 13 、 Figure 14 、 Figure 17 and Figure 18 It can be seen that a relatively stable central recirculation zone is formed in the main combustion zone, regardless of the design operating conditions or the slow-run operating conditions. The special geometric structure of the high-temperature rise central staged combustion chamber causes combustion stratification under the design operating conditions, in which the outer layer of the flame is the main combustion stage flame, and the inner layer is the duty stage flame. It should be noted that the outer layer of the main combustion stage flame and the inner layer of the duty stage flame do not cross-propagate with each other, and the boundaries between the layers can be clearly seen. Therefore, when designing the air flow and fuel flow distribution scheme of the combustion chamber, it is necessary to take into account the characteristics of the combustion chamber flow field structure zoning, that is, it is necessary to comprehensively consider the low pollution and stable combustion oil-gas ratio requirements of each sub-combustion zone under different operating conditions.

[0294] from Figure 16 and Figure 20 It can be seen that the high temperature area of ​​the flame tube outlet cross section is mostly distributed in the radially upper position of the outlet cross section. This situation is consistent with Figure 21 The RTDF shape fits well.

[0295] The simulated values ​​of the flame tube outlet cross-section temperature of the designed high-temperature rise central staged combustion chamber under different working conditions are shown in Table 5.

[0296] Table 5 Simulated values ​​of outlet section temperature under different working conditions of central staged combustion chamber

[0297]

[0298] It can be seen from Table 5 that under the design conditions, the outlet temperature distribution coefficient OTDF is calculated as

[0299] Meet the design requirement of OTDF value < 0.286; under slow running condition, Meet the design requirement of OTDF value < 0.350.

[0300] The average radial temperature distribution coefficient (RTDF) calculated under the design condition was 0.0997, meeting the design requirement of an RTDF range of 0.08-0.12. The RTDF calculated under the slow-run condition was 0.133, meeting the design requirement of an RTDF range of 0.08-0.14.

[0301] from Figure 21 It can be seen that the average radial temperature distribution of the flame tube outlet cross section shows a "double peak" under the design working condition. Figure 16 and Figure 20 By comparison, it can be found that the average radial temperature distribution of the flame tube outlet section under the design working condition is more uniform than that under the slow working condition. Figure 21 This can be confirmed. Figure 15 It can be seen that after the main combustion zone, the upper half of the flame tube burns more fully than the lower half, and the high-temperature combustion extends to the area behind the mixing hole. The reason is that the upper wall of the flame tube is dense and has more inclined holes than the lower wall, so the mixing is more sufficient than that in the lower half of the flame tube.

[0302] from Figure 21 It can be seen that the average radial temperature distribution of the flame tube outlet cross section shows a "single peak" under slow running conditions, which appears roughly at a height of 60%-90%. Under slow running conditions, local high temperature areas appear on both sides of the upper half of the outlet cross section, and the average radial temperature in the upper half of the outlet cross section is higher, resulting in a "single peak" phenomenon. Under slow running conditions, only the auxiliary oil circuit of the class is supplied with oil, and the main combustion stage is not supplied with oil. Figure 19 It can be seen that under slow running conditions, combustion is basically completed in the main combustion zone, showing a "wing" shape.

[0303] from Figure 22 It can be seen that a stable recirculation area is formed under both the design and slow running conditions. This is because the velocity distribution under different working conditions of the same combustion chamber structure is roughly similar, so the shape and size of the recirculation area under the design and slow running conditions are similar. Figure 22 It can be seen that the recirculation area is fuller under the design condition.

[0304] Under design conditions, the total pressure loss coefficient of the combustion chamber Meet the requirements of total pressure loss; under slow running conditions, the total pressure loss coefficient Meet the requirements of total pressure loss.

[0305] Under design conditions, the combustion chamber achieved a combustion efficiency of 99.85%, meeting the design requirement of a combustion efficiency greater than 99%. Under slow-run conditions, the combustion efficiency reached 99.99%, meeting the slow-run requirement of a combustion efficiency greater than 98%. In summary, the simulation results for the various performance characteristics of the designed high-temperature-rise centrally staged combustor are shown in Table 6.

[0306] Table 6 Performance simulation results of central staged combustion chamber under different working conditions

[0307]

[0308] The stage transition of staged combustion, that is, when the total oil-gas ratio in the combustion chamber reaches a certain level, the pre-combustion stage and the main combustion stage work together.

[0309] Before the transition, only the primary stage is fueled, and after the transition, both stages are fueled simultaneously; therefore, to achieve stable combustion, the equivalence ratio of the two stages after the transition must be greater than the minimum stable combustion equivalence ratio. For high temperature rise combustion chambers and low pollution combustion chambers, the flameout equivalence ratio is 0.5. According to the gas distribution of the main combustion stage and the pre-combustion stage and the oil distribution of the main and pre-combustion stages, the transition is as follows: Figure 23 As shown, if the transfer point is set at 0.01532, the impact of the grading point set at a larger working condition on the acceleration of the military aircraft can be avoided.

[0310] Summary and Recommendations

[0311] From the analysis of the above research results, it can be concluded that the designed high-temperature rise central staged combustion chamber model meets the design indicators required by the project when only two stages of swirlers are required. Under the design operating conditions, it has a low total pressure loss coefficient, high combustion efficiency, and high outlet temperature distribution quality.

[0312] The designed high-temperature-rise central staged combustor not only has a higher temperature-rise capability, but also has a more uniform outlet temperature distribution, i.e., a lower outlet temperature distribution coefficient OTDF and a lower average radial temperature distribution coefficient RTDF, providing a benchmark model scheme for the next step of dynamic characteristics research and testing of high-temperature-rise central staged combustor.

Claims

1. Design method of high temperature rise central staged combustion chamber, characterized by ； Step S1: Calculate the combustion chamber inclination angle: The inclination angle α is calculated based on the radius difference and length of the combustion chamber inlet / outlet midpoints; Set the head position, calculate the head area, flame tube inlet air density, head reference speed and aspect ratio; Step S2: Fuel distribution design: Pre-combustion fuel oil accounts for 28.65%, and main combustion fuel oil accounts for 71.35%; The equivalence ratio of the main combustion zone is calculated to be 1.01; Step S3: Gas distribution in the central staged combustion chamber: The head air intake ratio is 45.05%, the main combustion port air intake ratio is 16.9%, the mixing port air intake ratio is 17%, and the flame tube cooling air ratio is 21.05%; Step S4: Design of cyclone structural parameters: Calculate the effective area of ​​the flame tube; Determine the flow coefficient and ultimately determine the inner and outer diameters of the cyclone and the swirl number; Step S5: Design of main combustion holes and mixing holes: Adopting an inverted right-angle trapezoidal cylindrical structure, the hole front edge depth is limited to 0.3-0.5mm, the rear edge depth is 10-11mm, and the wall thickness is 1mm; Calculate the main combustion zone length, residence time and equivalence ratio; Step S6: Diffuser design: Calculate the diffuser inlet airflow density and high-pressure compressor outlet velocity under design conditions, and determine the ratio of the pre-diffuser outlet area to the inlet area, i.e., AR = 1.83; The optimized structure is annular curved wall expansion angle flow structure, which controls the total pressure loss coefficient to 0.24%; Step S7: Flame tube convergence section design: Based on the Witoshinsky law, the central streamlines of the double arcs are fitted to generate the wall curve of the convergent section. Step S8: Cooling hole design: The head cooling holes adopt straight hole impact cooling with a hole diameter of 0.8mm-1.0mm; The cooling holes on the flame tube wall are arranged in a rhombus shape, with the opening rate per unit area of ​​the upper wall being 0.01674, and the opening rate per unit area of ​​the lower wall being 0.01927; The high temperature rise center staged combustion chamber includes the following parts: flame tube, casing, diffuser, cap, main combustion hole, mixing hole, swirler and cooling hole; The upper and lower walls of the flame tube convergence area are replaced by two arc segments respectively, and the upper and lower walls of the casing convergence area are replaced by arc segments and straight line segments; Adjust the outlet height of the lower wall of the convergent section of the casing to be slightly lower than the lowest height of the lower wall of the flame tube; The main combustion holes on the upper wall of the flame tube are cross-arranged with the main combustion holes on the lower wall, the mixing holes on the upper wall of the flame tube are cross-arranged with the mixing holes on the lower wall, and the main combustion holes and the mixing holes on the same wall of the flame tube are cross-arranged.

2. The method for designing a high-temperature-rise centrally staged combustion chamber according to claim 1, characterized in that: In step S1 , the radius of the midpoint of the combustion chamber inlet is 276.15 mm, the radius of the midpoint of the combustion chamber outlet is 344.25 mm, and the inclination angle α is 9.6620°.

3. The method for designing a high temperature rise central staged combustion chamber according to claim 1, characterized in that: In step S1: the radius of the head position is 310.7894 mm, the head area is 12048.4514 mm², the air density of the flame tube inlet is 12.6409 kg / m³, the head reference speed is 11.5654 m / s, the head width B is 97.6374 mm, and the head aspect ratio θ is 0.7912.

4. The method for designing a high temperature rise central staged combustion chamber according to claim 1, characterized in that: In step S4: the effective area of ​​the flame tube is 2345.3344 mm², and the flow coefficient is 0.

84.

5. The method for designing a high temperature rise central staged combustion chamber according to claim 1, characterized in that: In step S4: the inner diameter of the pre-combustion stage cyclone is 7.5000, the outer diameter of the pre-combustion stage cyclone is 16.8060, the inner diameter of the main combustion stage cyclone is 24.306, the outer diameter of the main combustion stage cyclone is 32.6998, the swirl number of the pre-combustion stage cyclone is 0.5311, and the swirl number of the main combustion stage cyclone is 1.0463.

6. The method for designing a high temperature rise central staged combustion chamber according to claim 1, characterized in that ； In step S5: the length of the main combustion zone is 78.792, the residence time of the main combustion zone is 5.1310 ms, and the equivalence ratio of the main combustion zone is 0.9082.

7. The method for designing a high temperature rise central staged combustion chamber according to claim 1, characterized in that: There is also an inner and outer annular channel design between the diffuser design and the flame tube convergence section design: The design of the inner and outer annular channels includes the following: the maximum cross-sectional area of ​​the combustion chamber is 16297.6445 mm², the outer annular channel area is 1878.1436 mm², the inner annular channel area is 1987.9179 mm², the flame tube effective area is 2345.3344 mm², the inner annular channel effective area is 599.0168 mm², the inner annular gas distribution ratio is 25.54%, the outer annular channel effective area is 693.5732 mm², the outer annular gas distribution ratio is 29.57%, the inner annular flow rate is 39.7394 m / s, and the outer annular flow rate is 48.6991 m / s. When the flame tube length is 230mm and the area of ​​the flame tube reference cross-section is 12048.4514mm², the flame tube volume is 2367976.028mm³, the flame tube volume flow rate is 139345695mm³ / s, the gas residence time is 16.9935ms, and the flow resistance coefficient is 222.9204.

8. The method for designing a high temperature rise central staged combustion chamber according to claim 1, characterized in that ； Step S7 also Includes the following: Middle section length The empirical value is 80mm, the length of the flame tube contraction section is 116.5378mm, the inlet cross-sectional area of ​​the convergent section is 12757.4238mm², and the outlet cross-sectional area of ​​the convergent section is 7840.8262mm².

9. The method for designing a high temperature rise central staged combustion chamber according to claim 1, characterized in that: The cooling hole design in step S8 also includes the following: The cooling holes on the flame tube upper wall are arranged in 24 holes / row × 44 rows; The cooling holes on the lower wall of the flame tube are arranged in 16 holes / row × 47 rows.

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