High-temperature-rise three-vortex combustor

Abstract

The present invention discloses a high-temperature-rise three-swirl combustor, which relates to the technical field of combustors. The key points of its technical solution are as follows: It includes a combustor, and the combustor is composed of a casing, a pre-diffuser, a cap, an inner and outer annular cavity, a flame tube, main combustion holes, mixing holes, a swirler, and a head. The characteristics are: The combustor adopts an annular combustor. A pre-diffuser is embedded on one side of the casing, a cap is embedded on one side of the flame tube, a swirler is embedded inside the cap, and the swirler adopts a three-stage swirler. There are 2 main combustion holes and 2 mixing holes on both the upper and lower wall surfaces of the flame tube. Cooling holes are provided inside the combustor, and the cooling holes include head cooling holes and flame tube cooling holes. The combustor of the present invention has high performance and meets the requirements of various design indicators; the combustion is stable, the ignition is rapid and reliable, and the combustion temperature is uniform; the combustion intensity in the main combustion zone is high; the temperature gradient on the wall surface of the flame tube is low, avoiding wall surface ablation and improving the service life of the flame tube.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion chambers, and more specifically, to a high-temperature-rise triple-swirl combustion chamber. Background Art

[0002] A combustion chamber is a device in which fuel or propellant burns to generate high-temperature gas, and is a combustion device made of high-temperature-resistant alloy materials. The fuel burns in this chamber. It is an important component of gas turbine engines, ramjet engines, and rocket engines.

[0003] A combustion chamber is an essential and important component of an aero gas turbine engine. Its function is to release the chemical energy in the fuel through combustion and convert it into heat energy, which is directly added to the air in the engine to improve its work capacity.

[0004] As is well known, aero engines are developing towards a higher thrust-to-weight ratio. In fact, increasing the specific thrust is to increase the outlet temperature of the combustion chamber and achieve a compact design. The increase in the outlet temperature of the combustion chamber will inevitably require a higher temperature-rise capacity than the current combustion chamber. As the temperature rise of the combustion chamber increases, the total fuel-air ratio of the combustion chamber will also increase accordingly.

[0005] Therefore, the purpose of the present invention is to research and manufacture a combustion chamber with a lower total pressure loss coefficient and higher combustion efficiency compared to the prior art, and under the design conditions, the ignition can be rapid and reliable, and the combustion temperature is more uniform. Summary of the Invention

[0006] The purpose of the present invention is to solve the above problems and provide a high-temperature-rise triple-swirl combustion chamber.

[0007] The above technical purpose of the present invention is achieved through the following technical solutions: A high-temperature-rise triple-swirl combustion chamber, including a combustion chamber, the combustion chamber is composed of a casing, a pre-diffuser, a cap, an inner and outer annular cavity, a flame tube, main combustion holes, mixing holes, a swirler, and a head. The characteristics are: The combustion chamber adopts an annular combustion chamber. One side of the casing is embedded with a pre-diffuser. One side of the flame tube is embedded with a cap. The cap internally is embedded with a swirler. The swirler adopts a three-stage swirler. Both the upper and lower wall surfaces of the flame tube are provided with 2 main combustion holes and 2 mixing holes. The combustion chamber internally is provided with cooling holes. The cooling holes include head cooling holes and flame tube cooling holes.

[0008] By adopting the above technical solutions, the function of the pre-diffuser is to reduce the speed and increase the pressure, while minimizing the total pressure loss while increasing the static pressure. The function of the cap is to guide the compressor inlet flow into the two-channel of the flame tube and the inner and outer annular cavities with a small pressure loss, generate a small pressure loss in the cap to increase the head pressure drop, and be insensitive to the inlet air flow distortion.

[0009] Compared with the sudden-expansion diffuser commonly used, the pre-diffuser designed in the present invention has the advantage that, on the basis of ensuring the area ratio and length Lpred, the outlet air flow direction of the pre-diffuser is consistent with the central axis of the combustion chamber, avoiding the occurrence of separation vortices near the diffuser outlet position, thereby reducing the separation loss.

[0010] The present invention is further configured such that: the inclination angle α of the combustion chamber is 9.6620°.

[0011] The present invention is further configured such that: the fuel design of the combustion chamber: the fuel design of the combustion chamber includes a pilot stage and a main combustion stage, and the fuel ratios of the pilot stage and the main combustion stage are respectively 30% and 70%.

[0012] The present invention is further configured such that: the gas volume distribution of each stage of the swirl in the combustion chamber: the air intake at the head is 45.05%, the cooling air volume at the head is 3.05%, the air intake ratio of the first-stage swirler in the duty class is 5.5%, the air intake ratio of the second-stage swirler in the duty class is 12.5%, and the air intake of the main combustion stage is 24%.

[0013] The present invention is further configured such that: the structural parameter design of the swirler is as follows:

[0014] The average radius of the inlet of the cap is 303.5822 mm, and the distance in the y direction between the outer diameter (inner) of the inlet of the cap and the average radius is 30.00 mm;

[0015] The initial value of the swirl number Cd of the main combustion stage swirler is 0.84;

[0016] The number of blades of the first-stage swirler is 8, the blade inlet area is 187.4665 mm 2 , the effective area is 128.9934 mm 2 , the blade thickness is 1.00 mm, the outer diameter is 11.30 mm, and the inner diameter is 7.50 mm;

[0017] The number of blades of the second-stage swirler is 10, the blade inlet area is 471.1369 mm 2 , the effective area is 293.1668 mm 2 , the blade thickness is 1.20 mm, the outer diameter is 18.90 mm, and the inner diameter is 13.30 mm;

[0018] The number of blades of the third-stage swirler is 15, the blade inlet area is 1306.9945 mm 2 , the effective area is 562.8803 mm 2 , the blade thickness is 1.10 mm, the outer diameter is 34.32 mm, and the inner diameter is 26.40 mm.

[0019] By adopting the above technical solutions, the cyclone used in the present invention is composed of two-stage fuel injection and three-stage axial cyclones. The first-stage fuel nozzle adopts a double-oil-circuit centrifugal nozzle, which is supplied with fuel from the auxiliary oil circuit under low operating conditions, and is supplied with fuel from the main oil circuit or both the main and auxiliary oil circuits simultaneously under high operating conditions. The second-stage fuel nozzle is a pre-film air atomizing nozzle. The swirl numbers of the three-stage axial cyclones increase sequentially from inside to outside, and the swirl directions are clockwise rotation, counterclockwise rotation, and counterclockwise rotation in sequence. The first-stage cyclone is used to provide air volume to assist the double-oil-circuit centrifugal nozzle to enhance the spray atomization quality and prevent carbon deposition on the lip of the fuel nozzle. All the air volume of the first-stage swirl and 80% of the air volume of the second-stage swirl are used to generate the central recirculation zone of the traditional swirl cup, and the swirl directions of the two are opposite. The strong shear force formed by the shearing action of the two airflows is conducive to breaking the oil film into fine droplets, resulting in better atomization effect; the remaining air volume of the second-stage swirl and all the air volume of the third-stage swirl jointly form a high-speed shear layer at the lip of the pre-film nozzle to shear and atomize the thin oil film, strengthening the atomization of the main combustion-stage fuel and the mixing of fuel and air. The third-stage cyclone plays a role in stabilizing combustion. When the second-stage cyclone and the third-stage cyclone rotate in the same direction, it will strengthen the flow field in the main combustion zone and improve the combustion stability. Under high operating conditions, the pre-combustion-stage flame ignites the main combustion stage, making the ignition of the main combustion stage rapid and reliable, and at the same time, a relatively uniform combustion temperature can be obtained.

[0020] The present invention is further arranged as follows: The main combustion holes and mixing holes of the combustion chamber are designed as follows: The number of main combustion holes n p = 4n a , that is, in a single-head combustion chamber, n p = 4, the main combustion holes on the upper and lower walls of the flame tube are arranged in a staggered manner, the diameter d of the main combustion holes p = 13.00 mm, the total area A of the main combustion holes p,h = 530.9292 mm 2 , the flow coefficient C d = 0.75; the length of the main combustion zone of the flame tube is 78.792 mm, and the equivalence ratio of the main combustion zone of the flame tube is 0.9082; the number of mixing holes is 4, the area of a single mixing hole is 132.7323 mm 2 , the mixing holes on the upper and lower walls of the flame tube are arranged in a staggered manner, and the structures of the main combustion holes and the mixing holes both adopt an inverted right-angled trapezoidal cylinder structure.

[0021] By adopting the above technical solutions, the main combustion holes and mixing holes introduce airflows from the annular cavity to form transverse jets, and the transverse jets are mixed with the mainstream in the combustion chamber. In the main combustion zone, the function of the transverse jets from the main combustion holes is to jointly form and truncate the recirculation zone, thereby strengthening the combustion process; in the mixing zone, the function of the transverse jets from the mixing holes is to adjust the outlet temperature distribution of the combustion chamber. The jets from the main combustion holes cooperate with the swirl of the swirler to form the flow state in the main combustion zone. The penetration depth of the jets from the opposed main combustion holes is generally half of the height of the combustion chamber head, greatly shortening the recirculation zone and increasing the combustion intensity in the main combustion zone. At the same time, due to the low-pressure zone generated by the swirler, a part of the jets (usually considered that half of the jets from the main combustion holes enter the recirculation zone) flows back, strengthening the combustion function in the recirculation zone.

[0022] The structures of the main combustion holes and mixing holes designed in the present invention both adopt the "inverted right-angled trapezoidal cylinder" structure as shown in the figure. The side on the incoming flow direction is designed to be shorter, which is convenient for the jets from the main combustion holes to truncate the recirculation zone and for the jets from the mixing holes to effectively mix with the incoming flow, thereby adjusting the outlet temperature distribution.

[0023] The present invention is further configured such that: the pre-stage diffuser adopts an annular curved wall expansion angle facing the flow design.

[0024] By adopting the above technical solutions, in addition to achieving the effect of avoiding the generation of separated vortices, the total pressure loss coefficient of the pre-stage diffuser is also greatly reduced, far lower than the design standard of 2% during design. Thus, under the condition that the total pressure loss index of the combustion chamber design remains unchanged, sufficient space is left for the total pressure loss of the combustion chamber liner design.

[0025] The present invention is further configured such that: the cooling holes of the combustion chamber are designed as follows: the head cooling holes adopt the straight hole impingement cooling method, and the combustion chamber liner wall cooling holes adopt the form of dense multi-inclined holes.

[0026] By adopting the above technical solutions, the combustion chamber liner wall cooling holes adopt the multi-inclined hole cooling method. The cooling airflows enter numerous inclined small holes from the cold side, conduct internal convective heat transfer with the inner surface of the wall inside the inclined holes, take away the heat of the combustion chamber liner wall, and after the cooling airflows exit the combustion chamber liner wall, a full-coverage film cooling is formed on the hot side of the wall. The heat transfer characteristics of the multi-inclined hole cooling are as follows: first, the heat transfer on the back is enhanced because the small holes suck the gas boundary layer on the cold side of the combustion chamber liner; second, the heat transfer in the hole inlet area of the small holes is enhanced; third, a large number of inclined small holes greatly increase the cooling area; fourth, on the hot side of the combustion chamber liner, a full film protection is formed.

[0027] In summary, the present invention has the following beneficial effects:

[0028] The high-temperature-rise three-swirling-flow combustor of the present invention improves the high fuel-air ratio of the combustor while still ensuring the high-performance requirements of the combustor, meeting the requirements of various design indicators; the combustion is stable, the ignition is rapid and reliable, and the combustion temperature is uniform; the combustion intensity in the main combustion zone is high; the temperature gradient of the flame tube wall surface is reduced, avoiding excessive temperature gradient and ablation of the wall surface, and improving the service life of the flame tube. Brief Description of the Drawings

[0029] Figure 1 is a schematic structural diagram of the high-temperature-rise three-swirling-flow combustor in an embodiment of the present invention;

[0030] Figure 2 is a left view of the casing in an embodiment of the present invention;

[0031] Figure 3 is a schematic structural diagram of the head in an embodiment of the present invention;

[0032] Figure 4 is a bottom view of the flame tube in an embodiment of the present invention;

[0033] Figure 5 is a schematic structural diagram of the cap in an embodiment of the present invention;

[0034] Figure 6 is a design drawing of the length-width ratio of the diffuser in an embodiment of the present invention;

[0035] Figure 7 is a simplified diagram of the numerical model of the combustor in an embodiment of the present invention;

[0036] Figure 8 is a velocity distribution vector diagram of the pre-diffuser in an embodiment of the present invention;

[0037] Figure 9 is a design drawing of the pre-diffuser in an embodiment of the present invention;

[0038] Figure 10 is a design drawing of the cooling holes on the flame tube wall surface in an embodiment of the present invention;

[0039] Figure 11 is a theoretical structural design drawing of the combustor in an embodiment of the present invention;

[0040] Figure 12 is a design drawing of the processing structure of the flame tube in an embodiment of the present invention;

[0041] Figure 13 is a design drawing of the swirler structure in an embodiment of the present invention;

[0042] Figure 14 is a structural partition diagram of the high-temperature-rise combustor in an embodiment of the present invention;

[0043] Figure 15 is a grid diagram of the high-temperature-rise combustor in an embodiment of the present invention;

[0044] Figure 16 is the contour map of the velocity distribution of the central section under the design condition in the embodiment of the present invention;

[0045] Figure 17 is the vector diagram of the velocity distribution of the central section under the design condition in the embodiment of the present invention;

[0046] Figure 18 is the contour map of the temperature distribution of the central section under the design condition in the embodiment of the present invention;

[0047] Figure 19 is the contour map of the temperature distribution of the outlet section under the design condition in the embodiment of the present invention;

[0048] Figure 20 is the contour map of the velocity distribution of the central section under the idle condition in the embodiment of the present invention;

[0049] Figure 21 is the vector diagram of the velocity distribution of the central section under the idle condition in the embodiment of the present invention;

[0050] Figure 22 is the contour map of the temperature distribution of the central section under the idle condition in the embodiment of the present invention;

[0051] Figure 23 is the contour map of the temperature distribution of the outlet section under the idle condition in the embodiment of the present invention;

[0052] Figure 24 is the RTDF diagram of the outlet section under different conditions in the embodiment of the present invention;

[0053] Figure 25 is the diagram of the size of the recirculation zone under different conditions of the three - swirl combustor in the embodiment of the present invention;

[0054] Figure 26 is the diagram of the change of the equivalence ratio of the pilot stage and the main combustion stage with the total fuel - air ratio in the embodiment of the present invention;

[0055] Figure 27 is the Excel table "ε=f(AR)" in the embodiment of the present invention;

[0056] Figure 28 is the Excel table "inner and outer diameter values of the flame tube converging section" in the embodiment of the present invention;

[0057] Figure 29 is the simplified side sectional view of the swirler in the embodiment of the present invention

[0058] Figure 30 is the Brayton cycle diagram.

[0059] In the figure: 1. Combustion chamber; 101. Pre - diffuser; 102. Casing; 2. Flame tube; 201. Main combustion holes; 202. Mixing holes; 203. Flame tube wall cooling holes; 204. Head cooling holes; 205. Cap; 206. Head; 3. Swirler; 301. Third - stage swirler blades; 302. Second - stage swirler blades; 303. First - stage swirler blades; 4. Inner annulus cavity; 5. Outer annulus cavity; 6. Sudden expansion area. Detailed implementation mode

[0060] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the embodiments and drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0061] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0062] Embodiment:

[0063] As Figures 1 - 30 shown, the high - temperature - rise three - swirler combustion chamber 1 includes a combustion chamber 1, which is composed of a casing 102, a pre - diffuser 101, a cap 205, inner and outer annulus cavities, a flame tube 2, main combustion holes 201, mixing holes 202, a swirler 3 and a head 206. Its characteristics are: the combustion chamber 1 adopts an annular combustion chamber 1, the pre - diffuser 101 is embedded on one side of the casing 102, the cap 205 is embedded on one side of the flame tube 2, the swirler 3 is embedded inside the cap 205, the swirler 3 adopts a three - stage swirler 3, 2 main combustion holes and 2 mixing holes 202 are provided on both the upper and lower walls of the flame tube 2, cooling holes are provided inside the combustion chamber 1, and the cooling holes include head cooling holes 204 and flame tube 2 cooling holes.

[0064] Design indicators and requirements

[0065] Design requirements for the overall performance scheme

[0066]

[0067] The present invention has mainly carried out the design research on the high - temperature - rise three - swirler combustion chamber 1, including the structural design of the flame tube 2, the swirler 3, the main combustion holes 201, the mixing holes 202, the pre - diffuser, the nozzle, the casing 102, etc. and the overall layout of the gas - fuel distribution design. The grid partition of the designed model has been carried out, and the simulation calculation of the benchmark model has been completed, meeting the design indicators.

[0068] This engine selects the annular combustor 1. The main advantages of the annular combustor 1 are that the aerodynamic layout and the outlet air flow are easy to match, the pressure loss is small, the combustor 1 is compact, the length is short and it is light, and it can meet the requirements of a large bypass ratio. The number of heads 206 of the annular combustor 1 of the present invention is 20.

[0069] Design indicators of the overall performance scheme

[0070]

[0071] Structural limit dimensions of the overall performance scheme

[0072]

[0073] Fuel design:

[0074] The pilot stage is used from start-up to the transition point, and then the main combustion stage and the pilot stage work together to the maximum fuel-air ratio. Given the idle fuel-air ratio of 0.0106, the fuel distribution ratio is as follows:

[0075] Pilot stage fuel ratio = 0.0106 / 0.037 = 28.65%,

[0076] Main combustion stage fuel ratio = 1 - 28.65% = 71.35%,

[0077] Therefore, the fuel ratios of the pilot stage and the main combustion stage are taken as 30% and 70% respectively.

[0078] Equivalence ratio Φ in the main combustion zone p :

[0079]

[0080] Φ p The value is less than the smoke limit equivalence ratio of 1.4 in the main combustion zone.

[0081] Gas volume distribution of each swirl stage:

[0082] Given the head intake of 45.05%, assume: the cooling air volume of the head 206 is 3.05%, the pilot stage intake is 18%, and the main combustion stage intake is 24%. The pilot stage intake of 18% means setting the intake ratio of the first-stage swirl cup 3 in the class as x and the intake ratio of the second-stage swirl cup 3 in the class as y. y > x, the idle fuel-air ratio is 0.0106, and the virtual swirl cup equivalence ratio at idle is 0.0106 × 14.7 ÷ (x + 0.8y) = 1.0, then x + 0.8y = 0.155, meeting the requirement of the swirl cup flow distribution x + 0.8y ≤ 16%.

[0083] Then from x + 0.8y = 0.155 and x + y = 18%, we get x = 5.5% and y = 12.5%.

[0084] In summary: the air intake of the head 206 is 45.05%, and the cooling air volume of the head is m dc 3.05%. The air intake ratio of the first-stage swirler 3 in the duty class is 5.5%, the air intake ratio of the second-stage swirler 3 in the duty class is 12.5%, and the air intake of the main combustion stage is 24%.

[0085] Table 4 Air intake distribution of the overall layout of the combustion chamber

[0086]

[0087]

[0088] Design of the structural parameters of swirler 3

[0089] Let the total pressure loss of the flame tube of the designed combustion chamber be 3.5%

[0090] △P = 3141000Pa × 3.5% = 109935Pa, AL = Sdome = 12048.4514mm 2 ,

[0091]

[0092] The function of the hood 205 is to guide the flow from the compressor to flow into the flame tube 2 and the secondary air passage with a small pressure loss, generate a small pressure loss in the hood 205 to increase the pressure drop of the head 206, and is not sensitive to the inlet air flow distortion. Therefore, the average radius of the inlet of the air intake hood 205 generally falls on the extended center streamline of the pre-stage diffuser 101 to ensure smooth air intake.

[0093] If the opening area of the hood 205 is too large, overflow is likely to occur; if the area is too small, the flow contracts, the static pressure recovery of the air flow decreases, and separation occurs at the lip of the hood 205. Both situations will increase the loss.

[0094] Generally, Acoin:Aain:Aaou≈Aoh:Aoin:Aoou

[0095] Wherein:

[0096] Acoin - the inlet area of the hood;

[0097] Aain - the area of the inner-ring secondary air passage;

[0098] Aaou - the area of the outer-ring secondary air passage;

[0099] Aoh - the area of the head holes;

[0100] Aoin - the area of the inner-ring air inlet holes;

[0101] Aoou - the area of the outer-ring air inlet holes.

[0102] Effective area of the head 206:

[0103] 84.1561×0.85 + 128.9934 + 293.1668 + 562.8803 = 1056.5732 mm 2

[0104] Effective area of the inner cavity: 599.0168 mm 2

[0105] Effective area of the outer cavity: 693.5732 mm 2

[0106] Channel area of the inner cavity: 1987.9179 mm 2

[0107] Channel area of the outer cavity: 1878.1436 mm 2

[0108] Acoin: 1987.9179 : 1878.1436 = 1056.5732 : 599.0168 : 693.5732

[0109] Then: 1987.9179 / 599.0168 = 3.3186, 1878.1436 / 693.5732 = 2.7079

[0110] (3.3186 + 2.7079) / 2 = 3.0133

[0111] Acoin = 1056.5732 × 3.0133 = 3183.7720 mm 2

[0112] Acoin = π[(R + x) 2 - (R - x) 2 / 20 = 4πRx / 20, where R is the average radius of the inlet of the cap, and x is the distance in the y - direction between the inner and outer diameters and the average radius of the inlet of the cap. R = 303.5822 mm, and by calculation x = 16.6911 mm. Since the cap has the effect of reducing pressure loss, Acoin can be appropriately enlarged. In addition, considering the problem of the main combustion stage fuel injection assembly, that is, x ≥ the outer radius of the main combustion stage fuel injection (24.0233 mm), so x is taken as 30 mm during design.

[0113] The swirl number of the swirler 3 directly affects the size and flow pattern of the recirculation zone at the head 206 of the flame tube, and directly affects the combustion performance.

[0114] The swirl number of the axial - vane swirler 3 is as follows:

[0115]

[0116] The swirl intensity is characterized by the swirl number. When the swirl number is greater than 0.6, it is called strong swirl, and a recirculation zone will appear. The existence of the recirculation zone plays an important role in flame stabilization and fuel mixing. When the swirl number is greater than 1.2, it is very strong swirl.

[0117] For the pre-combustion stage two-stage swirler 3, the inner swirler 3 air flow is mainly responsible for atomization, and the outer swirler 3 air flow is mainly responsible for generating the recirculation zone. Therefore, it is determined that the swirl number of the outer swirler 3 should be greater than that of the inner swirler 3. For the main combustion stage swirler 3, since the main combustion stage air flow needs to mix a large amount of fuel to achieve the purpose of premixing and pre-evaporation, a relatively large swirl intensity is required. When the swirl number is greater than 1.2, it belongs to very strong swirl. Since the main combustion stage is lean combustion under idle conditions, combustion oscillation is likely to occur in this very strong swirl. At the same time, referring to the existing design experience, the selection range of the swirl number of the main combustion stage is preliminarily determined to be between 0.8 and 1.2.

[0118] Swirl number of the inner swirler 3 in the pre-combustion stage:

[0119]

[0120] Swirl number of the outer swirler 3 in the pre-combustion stage:

[0121]

[0122] Swirl number of the main combustion stage swirler 3:

[0123]

[0124] Equivalence ratio of the main combustion stage under design conditions: The main combustion stage is rich combustion.

[0125] Equivalence ratio of the main combustion stage under idle conditions: The main combustion stage is lean combustion.

[0126] One of the basic design principles of the swirler 3 is that there should be no light transmission, that is, when viewed from front to back, no light can be seen. This criterion is:

[0127] In the formula:

[0128] n--Number of blades;

[0129] L--Axial length of the swirler 3;

[0130] θ--Outlet angle of the blade;

[0131] -Outer diameter of the flow path of the swirler 3.

[0132] Chord length c of the blade:

[0133]

[0134] The ratio of the vane height h to the chord length c of the swirler 3 Determines the maximum diameter of the air swirler 3 at the head 206. In addition, the length L affects the fuel injection and the length of fuel-air mixing.

[0135] Calculate the effective area of the flame tube:

[0136]

[0137] Where, q m3.1 = 3.91 kg / s, ΔΡ L -- The pressure drop of the flame tube.

[0138] ΔΡ L = 3141000 Pa × 3.5% = 109935 Pa,

[0139] According to PM = ρRT, ρ a3.1 = 12.6409 kg / m 3 .

[0140] Therefore:

[0141]

[0142] Vane inlet area formula:

[0143] A sw = π(R o 2 - R i 2 ) - nt(R o - R i ) / cosθ

[0144] In the case where the outlet of the swirler 3 has no extension, its outlet geometric flow path area is:

[0145] A s = A sw · cosθ

[0146] After calculating the geometric flow path area, the remaining is to select the discharge coefficient Cd. For the axial-flow swirler 3, it is approximately 0.84 - 0.88. For the curved vanes and polished vanes, a higher value can be taken; for the straight vanes (due to air flow separation) and unpolished vanes, a lower value can be taken. Therefore, the initial value of Cd is 0.84.

[0147] Establish a three-dimensional combustion chamber model based on the opening areas of the holes in each row calculated initially according to the above method, calculate the flow rates of the holes in each row, and compare them with the one-dimensional flow rate distribution results in Table 4. If the results do not match, correct the initial flow coefficient according to the three-dimensional calculation results and recalculate the areas of the holes in each row; repeat the above steps until the three-dimensional flow rate distribution results are the same as the one-dimensional flow rate distribution results.

[0148] After multiple iterative calculations, the windward areas of each swirler 3 are shown in Table 5.

[0149] Table 5 Structural parameters of swirlers at all levels

[0150]

[0151] In the application of the combustion chamber, there is often an extension section at the outlet of the swirler 3. At this time, it is necessary to calculate the effective flow path area of the component with the extension section, depending on the following situation: whether the outlet of the extension section is the minimum flow path area (if the outlet area of the extension section ≥ the effective flow path area, the influence is ignored).

[0152] If the outlet area of the extension section < the effective flow path area and (the effective flow path area - the outlet area of the extension section) is large, then adopt:

[0153]

[0154] A 总 -- The total flow area of the swirler;

[0155] A 有效 -- The effective area of the swirler;

[0156] A o -- The minimum area of the converging section.

[0157] There is an extension section at the outlet of the third-stage swirler 3, and the outlet of the extension section is converging. Therefore, it is necessary to calculate whether the outlet of the extension section is the minimum flow path area, that is, if the outlet area of the extension section ≥ the effective flow path area, the influence is ignored. It can be seen from Table 5 that the effective area of the third-stage swirler 3 is 562.8803 mm 2 ; and the inner diameter at the minimum outlet area of the extended converging section of the third-stage swirler 3 is 25.4722 mm, and the outer diameter is 29.9741 mm. Then the minimum outlet area of the extended converging section is π×(29.9741 2 - 25.4722 2 ) = 784.1846 mm 2 > 562.8803 mm 2 , so the influence is ignored.

[0158] Design of main combustion holes and mixing holes

[0159] Limit the hole structure parameters: the depth a of the hole leading edge is 0.3 - 0.5 mm, the depth b of the hole trailing edge is 10 - 11 mm, the hole wall thickness c is 1 mm, and the hole diameter d is 12.3 - 13.5 mm. Therefore, the values are taken as: a = 0.4 mm, b = 10 mm, c = 1 mm, d = 13.0 mm.

[0160] According to experience, the number of main combustion holes n p = 4n a , that is, in the single-head 206 combustion chamber, n p = 4

[0161] The diameter d of the main combustion hole p is related to H d , d p = aH d , where a is a coefficient, and about 0.114 is appropriate.

[0162] The area of the main combustion hole:

[0163]

[0164]

[0165] In summary: in the single-head 206 combustion chamber, the number of main combustion holes is 4. The main combustion holes on the upper and lower walls of the flame tube are arranged crosswise as shown in the figure, with 2 on each of the upper and lower walls. The diameter d of the main combustion hole p = 13.00 mm, the total area A of the main combustion holes p,h = 530.9292 mm 2 , and the flow coefficient C d = 0.75.

[0166] The length L of the main combustion zone P

[0167]

[0168] L p refers to the distance in the x-axis direction from the outlet of the first-stage swirler 3 to the center of the main combustion hole.

[0169] The residence time in the main combustion zone Vpz is the volume of the main combustion zone, defined as from the outlet section of the swirler 3 at the head 206 to the center of the main combustion hole. Gpa is the volumetric air flow rate in the main combustion zone, defined as all the flows in the main combustion zone, including the outlet flow of the swirler 3, the head cooling air volume, half of the main combustion hole flow, and the cooling air volume of the multi-oblique holes from the head 260 to the center of the main combustion hole.

[0170] Then: V pz = L p ·A L= 78.792 × 12048.4514 = 949321.5827 mm 3 。

[0171] Given the air ratio in the main combustion zone of 53.50%, the total cooling air flow rate of the combustion chamber liner Wc = mc × Wt3 = 21.05% × 3.91 kg / s = 0.823055 kg / s. Assuming the cooling air flow rate in front of the main combustion holes Wp,c ≈ 0.30Wc = 0.3 × 0.823055 kg / s = 0.2469165 kg / s, then:

[0172]

[0173]

[0174] Referring to the existing single - annular - cavity combustor, the residence time in the main combustion zone is about 5 ms.

[0175] Air flow rate in the main combustion zone: 45.05% + 0.5 × 16.9% + 0.3 × 21.05% = 59.815%

[0176] Equivalence ratio in the main combustion zone:

[0177]

[0178] The equivalence ratio in the main combustion zone is about 1.00, which is less than the smoke - limit equivalence ratio of 1.4 in the main combustion zone, meeting the requirement of suppressing smoke in the main combustion zone.

[0179] Area of the mixing holes:

[0180] That is, 3.91 kg / s × 17% = 0.75 × 1667.1397A d，h , A d，h = 531.6091 mm 2 ,

[0181] Area of a single mixing hole

[0182] Number of mixing holes n d (Generally 4 - 8 times that of the nozzle) ≈ 4

[0183] Location of the mixing holes:

[0184] Set the length from the center of the main combustion holes to the center of the mixing holes as Lpd, and the length of the mixing section as L d 。

[0185] Here, L d Refers to the distance from the center of the main combustion holes to the outlet of the combustion chamber liner in the x - axis direction.

[0186] Because Ld +L P =L f -L sw = 230 - 33.9437×cos9.662° = 196.5378 mm,

[0187] The measured distance from the center of the outlet section of the cyclone 3 to the center of the main combustion hole is 66.0352 mm,

[0188] So L d = 196.5378 - 66.0352 = 130.5026 mm.

[0189] Let The axial distance of the mixing hole (i.e., the distance from the outlet section of the cyclone 3 in the x - direction) is tentatively set as 2D

[0190] Diffuser design:

[0191]

[0192] That is, the outlet velocity of the high - pressure compressor is 132.5414 m / s, making the pressure ratio about 7, and reducing the air flow speed to about 20 m / s. Since the pressure ratio is relatively large, a sudden - expansion diffuser is selected.

[0193] From existing research, it is known that for every 1% increase in the total - pressure loss coefficient, the specific fuel consumption rate will increase by 0.5%. The overall total - pressure loss coefficient of the combustor is 6%, and the total - pressure loss of the diffuser is about 30% of the total loss. If the flow of the gas in the pre - diffuser does not separate, then the total - pressure loss coefficient of the diffuser is 6%×30% = 2%.

[0194] The function of the diffuser is to reduce the speed and increase the pressure, while minimizing the total - pressure loss as much as possible. Generally, the loss is required to be within 2%. A longer pre - diffuser 101 will lead to an increase in the loss caused by friction, while a shorter pre - diffuser 101 with a larger divergence angle will lead to an increase in the separation loss.

[0195] Figure 6 Among them, the abscissa is the dimensionless length LW, and the ordinate is the area ratio AR.

[0196] Empirical formula (corresponding to the dotted line in the left figure):

[0197]

[0198]

[0199] Aspect ratio

[0200] Figure 7 Among them, h is the inlet height of the pre - diffuser 101, and Lpred is the length of the pre - diffuser 101 in the x - direction.

[0201] The outer diameter R3.0 of the inlet of Combustor 1 - the inner diameter r3.0 of the inlet of Combustor 1 = h = 26.9 mm

[0202] The pre - diffuser 101 is selected with a symmetric annular straight - wall expansion angle. The total length L of Combustor 1 is taken as 400 mm, and the length Lf of the flame tube 2 is 230 mm. Then, the length of the pre - diffuser 101+the sudden - expansion gap < 170 mm

[0203] When AR = 2, substituting into Equation (2) gives Substituting into Equation (1) gives Form an Excel table ε = f(AR), where the value range of AR < 2

[0204] Inner - ring sudden - expansion angle β i , outer - ring sudden - expansion angle β o

[0205] Sudden - expansion gap ratio: Among them, the sudden - expansion gap D is the distance between the outlet of the pre - diffuser 101 and the inlet of the head 206, and h is the inlet height of the pre - diffuser 101

[0206] Analyzing from the Excel table ε = f(AR), the value of AR is finally determined to be 1.83

[0207] Therefore, set AR = 1.83, then

[0208]

[0209] n is the pressure - ratio, and n = AR R3.0 = 289.6 mm, r3.0 = 262.7 mm, R3.0 - r3.0 = h = 26.9 mm, A3.0 = 2333.7117 mm 2 , then A3.1 = 4270.6924 mm 2 .

[0210] In summary: The inlet height h of the pre - diffuser 101 is 26.9 mm, the ratio of the outlet area to the inlet area of the pre - diffuser 101, i.e., AR = 1.83, the length Lpred of the pre - diffuser 101 is 107.0367 mm, and the expansion angle of the pre - diffuser 101 Checking according to the existing geometric conditions should be in the range of 4° to 8°, meeting the requirements

[0211] Since using a symmetric annular straight - wall expansion angle design for the pre - diffuser 101 will result in such as Figure 8The separation phenomenon shown, that is, separation vortices appear near the outer ring abrupt expansion angle on the upper wall of the pre-stage diffuser 101, which in turn leads to a significant increase in the intake air volume of the inner ring cavity 4. The reason is considered to be that the air flow direction at the inlet section of the combustion chamber 1 is not parallel to the center line of the pre-stage diffuser 101, that is, the pre-stage diffuser 101 with a symmetric design of the annular straight wall expansion angle is not compliant with the oncoming flow of the combustion chamber 1 inlet. Therefore, an annular curved wall expansion angle oncoming flow design is adopted. On the basis of ensuring the area ratio and the length Lpred of the pre-stage diffuser 101 in the x direction, the pre-stage diffuser 101 shown in Figure 9 is designed. At the same time, the outlet air flow direction of the pre-stage diffuser 101 is made consistent with the central axis of the combustion chamber 1, that is, the center streamline of the head 206 of the flame tube 2 is on the extension line of the center streamline of the outlet air flow of the pre-stage diffuser 101, thereby ensuring smooth intake of air at the head 206 of the flame tube 2. It has been verified that adopting the annular curved wall expansion angle oncoming flow design will not only achieve the effect of avoiding the generation of separation vortices, but also greatly reduce the total pressure loss coefficient of the pre-stage diffuser, far lower than the design standard of 2% during design. Therefore, under the condition that the total pressure loss index of the combustion chamber design remains unchanged, sufficient space is left for the total pressure loss of the flame tube design.

[0212] The ideal static pressure recovery coefficient is

[0213] The actual static pressure recovery coefficient is

[0214]

[0215] Diffuser efficiency

[0216] At 845K and 31atm, γ = 1.3527.

[0217] Total pressure loss of the pre-stage diffuser 101:

[0218]

[0219] Outlet velocity of the pre-stage diffuser 101

[0220] Sound speed

[0221]

[0222] Total pressure loss of the abrupt expansion section: A 3.0 = 2333.7117mm 2 , A ref = 16297.6445mm 2

[0223]

[0224] Total pressure loss of the entire diffuser section:

[0225] ε t = 1 - (1 - ε pd )(1 - ε dd ) = 1 - (1 - 0.005295)×(1 - 0.01243) = 0.01766

[0226] Generally, the loss of the diffuser should be less than 2% of the total pressure at the compressor outlet.

[0227] Inner and outer annular cavity channel design

[0228] Set the area A at the reference section of Combustor 1 ref , the area AL at the reference section of the flame tube, and assume the average gas flow velocity V passage in the inner and outer annular cavity gas flow channels is 40 m / s.

[0229] Given AL = 12048.4514 mm 2 , the air ratio m passage in the inner and outer annular cavity gas flow channels is 54.95%, then from W t3 ·m passage = ρ·V passage A passage That is, 3.91 kg / s×54.95% = 12.6409 kg / m 3 ×40 m / s×A passage , we get A passage = 4249.1931 mm 2 .

[0230] The area A of the maximum section (i.e., the reference section) of Combustor 1 ref = A L + A passage = 12048.4514 mm 2 + 4249.1931 mm 2 = 16297.6445 mm 2 , then

[0231] Assume the middle section size of Flame Tube 2 is designed according to the scheme with the median diameter constant m k = 1 (i.e., the areas of the upper and lower two annular cavities divided by the central streamline are equal).

[0232]

[0233]

[0234] Among them, Rd = 310.7894 mm, Hd = 123.4 mm, α = 9.662°. Substituting these values, the height of the 5 channels in the outer ring cavity Hpo = 17.5963 mm, and the height of the 4 channels in the inner ring cavity Hpi = 29.2324 mm.

[0235] Considering that the channel areas of the inner and outer ring cavities are much larger than the sum of the areas of the flame tube cooling holes, main combustion holes, and mixing holes, the determining factors affecting the gas volume distribution in the inner and outer ring cavities are the areas of the flame tube cooling holes, main combustion holes, and mixing holes in the inner and outer ring cavities.

[0236] Inner ring cavity channel area: 4249.1931 / 2 = 2124.5966 mm 2

[0237] 132.7323 × 4 + 669 × π × 0.35 2 = 788.3906 mm 2

[0238] Outer ring cavity channel area: 4249.1931 / 2 = 2124.5966 mm 2

[0239] 132.7323 × 4 + 984 × π × 0.35 2 = 909.6168 mm 2

[0240] Furthermore, considering the limitation of the casing size, it is necessary to finely adjust the heights of the inner and outer ring cavity channels obtained by calculation. Here, referring to the wall thickness of the flame tube, a fine adjustment of 2 mm is made, that is, H po = 15.5963 mm, H pi = 27.2324 mm. Then, the calculated results are as follows: Outer ring cavity channel area: 1878.1436 mm 2 ;

[0241] Inner ring cavity channel area: 1987.9179 mm 2 .

[0242] Effective area of the flame tube: 2345.3344 mm 2

[0243] Effective area of the inner ring cavity: 132.7323 × 4 × 0.75 + 669 × π × 0.35 2 × 0.78 = 599.0168 mm 2 , 599.0168 mm 2 / 2345.3344 mm 2 = 25.54%

[0244] Effective area of the outer ring cavity: 132.7323 × 4 × 0.75 + 984 × π × 0.352 × 0.78 = 693.5732 mm 2 , 693.5732 mm 2 / 2345.3344 mm 2 = 29.57%

[0245] Flow rate of the inner cavity:

[0246] 3.91 kg / s × 25.54% = 12.6409 kg / m³ × 1987.9179 × 10 -6 m 2 × V passage，in

[0247] V passage，in = 39.7394 m / s

[0248] Flow rate of the outer cavity: 29.40%

[0249] 3.91 kg / s × 29.57% = 12.6409 kg / m³ × 1878.1436 × 10 -6 m 2 × V passage，ou

[0250] V passage，ou = 48.6991 m / s

[0251] It is known that the length of the flame tube 2, Lf = 230 mm, and the area at the reference cross-section of the flame tube, AL = 12048.4514 mm 2 .

[0252] Volume of the flame tube 2:

[0253] V = L f '· A L = (230 - 33.9437 × cos9.662°) × 12048.4514 = 2367976.028 mm 3

[0254] Volume flow rate of the flame tube 2:

[0255]

[0256] Residence time of the fuel gas:

[0257]

[0258] Flow resistance coefficient:

[0259]

[0260] Length L of the flame tube 2 f Verification:

[0261]

[0262] As can be seen from the above formula, OTDF is inversely proportional to L f So, given L f = 230 mm, the designed OTDF value will be less than 0.286, that is, it will meet the OTDF requirement.

[0263] Design of the converging section of the flame tube 2

[0264] Length of the middle section L R Take the empirical value as:

[0265] L R =(0.6 - 0.7)H d =(74.04 - 86.38) mm = 80 mm.

[0266] Length of the converging section of the flame tube 2:

[0267] L L = L f - L sw - L R = 230 mm - 33.9437×cos9.662° - 80 mm = 116.5378 mm

[0268] Cross-sectional area at the inlet of the converging section:

[0269]

[0270] Cross-sectional area at the outlet of the converging section:

[0271]

[0272]

[0273] Design the center streamline of the flame tube 2 - double arc line:

[0274] H = 0.5(D2 - D1) = R2 - R1 = 344.25 - 324.4094 = 19.8406 mm,

[0275]

[0276] Vitosinski's law (empirical formula):

[0277]

[0278] When X = 116.5378,

[0279]

[0280]

[0281]

[0282] m k = 1.11. Therefore, the mean diameter constant m is taken as k = 1.11, that is

[0283] A1x = 0.5263Ax, A2x = 0.4737Ax,

[0284]

[0285] Formulate the Excel table "Inner and Outer Diameter Values of the Converging Section of the Combustion Chamber 2", and then design the shape of the combustion chamber.

[0286] Cooling Hole Design

[0287] Design of the Head Cooling Holes 204

[0288] Given that the cooling air volume ratio m of the head 206 is dc 3.05%, according to the flow rate formula Calculate, where the flow coefficient C d is taken between 0.65 - 0.85, and generally 0.7 is mostly used for design. Therefore, the flow coefficient C d is initially taken as 0.7. After multiple iterative calculations, the final determined flow coefficient C d is 0.85. That is, 3.91 kg / s × 3.05% = 0.85 × 1667.1397 × A dome Calculate to get A dome = 84.1561 mm 2 Design the number of head cooling holes to be 144 = 72 / row × 2 rows. The two rows are concentric and cross-distributed circumferentially. The diameter of the cooling holes (limited between 0.8 - 1.0 mm) is 0.8626 mm, and the straight hole impingement cooling method is used for design.

[0289] Design of the Cooling Holes of the Combustion Chamber 2

[0290] The wall surface of the combustion chamber 2 adopts a dense multi-inclined hole cooling form. The flow coefficient Cd is taken between 0.7 - 0.8, and the initial value is 0.75; the diameter of the cooling holes 203 of the combustion chamber is limited between 0.6 - 0.7 mm, and the value is 0.7 mm; the inclination angle is selected as 22° (taken between 20° - 30°) according to the shape of the combustion chamber.

[0291] Given that the cooling air volume ratio m of the combustion chamber 2 is c 21.05%, according to the flow rate formula Calculate. After multiple iterative calculations, the final determined flow coefficient Cd is 0.78, that is:[[]] ​

[0292] 3.91 kg / s × 21.05% = 0.78 × 1667.1397 × Acool, Acool = 636.1490 mm 2 ,

[0293] The number of cooling holes in the flame tube 2 is 636.1490 ÷ (π × 0.35 2 ) = 1653 holes

[0294] Measured:

[0295] The upper wall area of the flame tube 2 is 26937.1192 mm 2 ,

[0296] The lower wall area of the flame tube 2 is 18286.5999 mm 2 ,

[0297] Then:

[0298] 26937.1192 mm 2 / 18286.5999 mm 2 = 1.47

[0299] Since the ratio of the upper and lower wall areas of the flame tube 2 = the ratio of the number of cooling holes in the upper and lower walls of the flame tube 2, let the number of cooling holes in the lower wall be x, then x + 1.47x = 1653, and by calculation, x = 669 holes. Therefore, there are 669 cooling holes in the lower wall and 984 cooling holes in the upper wall.

[0300] In the first round of design for this project, the long diamond-shaped hole-opening rule is adopted, that is, the flow direction hole pitch s = the transverse hole row pitch p. This design idea is to make the collective arrangement of the holes on the cylinder body more regular. Compared with the regular diamond shape, under the same hole-opening rate per unit area, the interference between columns in the long diamond-shaped arrangement is stronger, the air film coverage uniformity is better, and the heat transfer of the cooling air flow to the wall surface is stronger.

[0301] After multiple iterative calculations, it is finally determined that:

[0302] There are 44 rows of holes on the upper wall, with 24 cooling holes in each row, s = 4.70 mm, p = 4.89 mm;

[0303] 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.

[0304] The hole-opening rate Ap per unit area of the upper wall:

[0305]

[0306] The hole-opening rate Ap per unit area of the lower wall:

[0307]

[0308] Completion status of research content

[0309] Three-dimensional model design completed

[0310] The design of the reference combustion chamber 1, including the flame tube 2, the casing 102, the diffuser, the cap 205, the main combustion holes 201, the mixing holes 202, the swirler 3, etc. The initial combustion chamber 1 designed according to the Excel table "Inner and outer diameter values of the converging section of the flame tube 2" is as Figure 10 shown. The converging section of the flame tube 2 is fitted by the points on the upper and lower walls in the Excel table.

[0311] Considering the processing difficulty, the upper and lower walls of the converging section of the flame tube 2 are approximately replaced by arcs at both ends, and the upper and lower walls of the converging section of the casing 102 are replaced by arcs and straight segments. At the same time, considering the installation and assembly problems of the test piece during the test, the outlet height of the lower wall of the converging section of the casing 102 is adjusted to be slightly lower than the lowest height of the lower wall of the flame tube 2, as Figure 7 shown. In addition, the main combustion holes 201 on the upper wall of the flame tube 2 and the main combustion holes 201 on the lower wall are arranged in a cross pattern, the mixing holes 202 on the upper wall of the flame tube 2 and the mixing holes 202 on the lower wall are arranged in a cross pattern, and the main combustion holes 201 and the mixing holes 202 are arranged in a cross pattern on the same wall of the flame tube 2, as Figure 11 shown.

[0312] The head structure of the three-stage swirl swirler 3 composed of two-stage fuel injection and three-stage swirler 3 is as Figure 12 shown. The two-stage fuel nozzle adopts a double-oil-way centrifugal nozzle and a pre-film air atomizing nozzle from the inside to the outside; the swirl numbers of the three-stage swirler 3 increase sequentially from the inside to the outside, and the swirl directions are clockwise rotation, counterclockwise rotation, and counterclockwise rotation in sequence. The generation of the central recirculation zone in the traditional swirl cup is borne by all the gas volumes of the first-stage swirl and 80% of the second-stage swirl; the remaining gas volumes of the second-stage swirl and all the gas volumes of the third-stage swirl jointly strengthen the atomization and fuel-air mixing of the main combustion stage fuel.

[0313] Mesh partition completed

[0314] The high-temperature-rise three-stage swirl combustion chamber 1 is designed with 20 heads. For the sake of simplicity in calculation, a single-head fan-shaped area is selected as the calculation domain in this paper. The calculation domain of this single-head combustion chamber 1 includes the swirler 3, the pre-diffuser 101, the inner and outer secondary air channels, the flame tube 2, etc. Since the cooling holes of the flame tube 2 in the project are designed in the way of dense multi-inclined holes, if structured grids are used, it will be too time-consuming and laborious. Therefore, unstructured grids are used in this project, and the number of grids is about 22.8 million. Among them, considering the large number of grids, the complex structure of the combustion chamber 1, and the performance of the working computer, when the grids are divided, the overall structure of the combustion chamber 1 is partitioned for easy searching and error correction, as Figure 13 shown.

[0315] In this project, by comparing the axial velocity distribution along the radial direction at the center of the recirculation zone for different numbers of grids, when the velocity distribution no longer changes significantly with the number of grids, the grids are considered irrelevant, and the total number of grids is finally determined to be 22.8 million.

[0316] The flow inlet boundary condition is adopted for the inlet section, the outflow boundary condition is set for the outlet of the flame tube 2, and the adiabatic wall surfaces are set for the two turbine cooling air outlets, the same as the casing 102. The swirling air volume of each stage of the swirler 3 and the intake air flow rate of the wall surface of the flame tube 2 (including the main combustion holes 201, the mixing holes 202, and the film cooling holes of the flame tube 2) are obtained through the flow coupling calculation. The side walls of the entire fluid domain of the single-head annular combustor 1 are all set as the rotating periodic boundary condition.

[0317] A hollow conical spray model is set at the two-stage fuel injection nozzles, and the structure and aerodynamic parameters of the conical spray are set.

[0318] Research Results and Analysis

[0319] Through Figure 15 , Figure 16 , Figure 20 and Figure 21 It can be seen that whether it is under the design condition or the idle condition, a relatively stable central recirculation zone is formed in the main combustion zone, and small recirculation zones with similar degrees are also formed on both radial sides of the central recirculation zone. The special geometric structure of the three-swirler combustor 1 causes combustion stratification under the design condition. Among them, the outer layer of the flame is the main combustion stage flame, and the inner layer is the value class flame. It should be noted that the main combustion stage flame in the outer layer and the value class flame in the inner layer do not cross and spread with each other, and the boundary between layers can be clearly seen. Therefore, when designing the air flow and fuel flow distribution scheme of the combustor 1, it is necessary to consider the characteristics of the flow field structure partition of the combustor 1, that is, it is necessary to comprehensively consider the low-pollution and stable combustion fuel-air ratio requirements of each sub-combustion zone under different conditions.

[0320] From Figure 19 and Figure 23 it can be seen that the high-temperature region of the outlet section of the flame tube 2 is basically distributed at the center position of the outlet section in the radial direction. This situation is consistent with the RTDF in Figure 23 and Figure 25 .

[0321] Implementation of Technical Indicators

[0322] Outlet Temperature Distribution Factor OTDF:

[0323] Design Condition:

[0324] Meet the design requirement that the OTDF value < 0.286;

[0325] Idle condition:

[0326] Meet the design requirement that the OTDF value < 0.300.

[0327] Average radial temperature distribution factor RTDF

[0328] The RTDF value obtained from the simulation calculation under the design condition is 0.094, meeting the design requirement that the RTDF value range is 0.08 - 0.12. The RTDF value obtained from the simulation calculation under the idle condition is 0.073.

[0329] From Figure 24 it can be seen that at the design condition, the average radial temperature distribution at the outlet section of the flame tube 2 shows a "single peak", which appears roughly at the height of 50% - 90%. From Figure 19 it can be seen that local high-temperature regions appear on both sides of the upper half of the outlet section, and then the average radial temperature in the upper half of the outlet section is relatively large, showing a "single peak" phenomenon. It can also be verified in Figure 18 and from Figure 18 it can be seen that after the main combustion zone, the combustion in the upper half region of the flame tube 2 is more complete than that in the lower half region, and the high-temperature combustion extends to the region behind the mixing holes 202. The reason is that the number of dense multi-oblique holes on the upper wall of the flame tube 2 is more than that on the upper wall, and thus the mixing is relatively more sufficient compared to the lower half region of the flame tube 2.

[0330] From Figure 24 it can be seen that at the idle condition, the average radial temperature distribution at the outlet section of the flame tube 2 shows a "double peak", and compared with the design condition, the average radial temperature distribution at the outlet section of the flame tube 2 under the idle condition is more uniform, which can be verified in Figure 23 . At the idle condition, only the sub - fuel supply line of the value class supplies fuel, and the main combustion stage does not supply fuel. From Figure 22 it can be seen that the combustion under the idle condition is basically completed in the main combustion zone, showing a "wing" - shaped combustion.

[0331] Total pressure loss coefficient

[0332] Design condition:

[0333] Total pressure loss coefficient of the combustion chamber Meet the requirement of total pressure loss;

[0334] Idle condition:

[0335] Total pressure loss coefficient Meet the requirement of total pressure loss.

[0336] Combustion efficiency:

[0337] Design condition: 99.65%, meeting the requirement that the combustion efficiency under the design condition is greater than 99%;

[0338] Idle condition: 99.9999%, meeting the requirement that the combustion efficiency under the idle condition is greater than 98%.

[0339] Size of the recirculation zone:

[0340] From Figure 25 it can be seen that stable recirculation zones are formed under both the design condition and the idle condition. This is because the velocity distributions under different operating conditions in the same combustor 1 structure are roughly similar, so the shapes and sizes of the recirculation zones under the design and idle conditions are similar. And from Figure 25 it can be seen that the recirculation zone is more plump under the design condition.

[0341] Transition point

[0342] The transition of staged combustion, that is, when the total fuel-air ratio in combustor 1 reaches what value, the pilot burner and the main burner work together.

[0343] Before the transition, only the pilot burner supplies fuel. After the transition, both stages supply fuel 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 the high-temperature rise combustor 1 and the low-pollution combustor 1, the extinction equivalence ratio is 0.5.

[0344] According to the gas volume distribution between the main burner and the pilot burner and the fuel volume distribution between the main and pilot burners, the transition is as Figure 26 shown. The transition point is taken at 0.01532, which can avoid the influence on the acceleration performance of military aircraft due to setting the staging point at a relatively large operating condition.

[0345] From the analysis of the above research results, it can be obtained that the designed high-temperature rise three-swirling combustor 1 model meets the design indicators, has a low total pressure loss coefficient and a high combustion efficiency. Under the design condition, the flame of the pilot burner ignites the main burner, making the ignition of the main burner rapid and reliable, and at the same time, a relatively uniform combustion temperature can be obtained.

[0346] Working principle: The high-pressure air flow compressed by the compression system enters the combustor 1, and fuel is injected into the high-pressure air flow by the fuel injection system, and then sufficient and effective combustion occurs in the combustor 1; the high-temperature and high-pressure gas formed after combustion drives the turbine to provide the work required by the compression system.

[0347] In addition to the work consumed by driving the compressor, the energy conversion of the remaining high-temperature and high-pressure gas has the following ways:

[0348] (1) Discharged through the nozzle to generate thrust and push the aircraft forward;

[0349] (2) Through the power turbine for mechanical transmission to drive the propeller or fan to generate thrust and lift.

[0350] In terms of the thermodynamic cycle, an aero gas turbine engine belongs to the Brayton Cycle. In the Brayton Cycle, the constant pressure heating process is completed by the main combustion chamber 1 system. As Figure 30 shown in the ideal Brayton cycle diagram, 1-2 is the adiabatic compression process, 2-3 is the constant pressure heating process, 3-4 is the adiabatic expansion process, and 4-1 is the constant pressure heat release process.

[0351] As can be seen from the above, the combustion chamber 1 is an important and essential component of an aero gas turbine engine. Its function is to release the chemical energy in the fuel through combustion, convert it into heat energy, and directly add it to the air in the engine to improve its work capacity. From the perspective of engineering thermodynamics, the combustion chamber 1 belongs to an energy conversion device.

[0352] This specific embodiment is only an explanation of the present invention and does not limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively as needed, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. High-temperature-rising triple-swirl combustor, comprising a combustor (1), wherein the combustor (1) is composed of a casing (102), a pre-diffuser (101), a cap (205), an inner and outer annular cavity (5), a flame tube (2), main combustion holes (201), mixing holes (202), a swirler (3) and a head (206), and is characterized in that: The combustion chamber (1) adopts an annular combustion chamber (1). One side of the casing (102) is embedded with a pre - diffuser (101). One side of the flame tube (2) is embedded with a cap (205). Inside the cap (205) is embedded a swirler (3). The swirler (3) adopts a three - stage swirler (3). On the upper and lower wall surfaces of the flame tube (2), there are 2 main combustion holes (201) and 2 mixing holes (202) respectively. Inside the combustion chamber (1), there are cooling holes, and the cooling holes include head cooling holes (204) and flame tube wall cooling holes (203). The pre - diffuser (101) adopts a design with an annular curved - wall expansion angle facing the flow. The inlet height h of the pre - diffuser (101) is 26.9 mm. The ratio of the outlet area to the inlet area of the pre - diffuser (101), i.e., AR = 1.

83. The length Lpred of the pre - diffuser (101) is 107.0367 mm. The expansion angle θ of the pre - diffuser (101) is 11.9084°. The main combustion holes (201) and mixing holes (202) of the combustion chamber (1) are designed as follows: In the single-head combustion chamber (1), the number n of the main combustion holes (201) p = 4. The main combustion holes (201) on the upper and lower wall surfaces of the flame tube (2) are arranged in a staggered manner. The diameter d of the main combustion holes (201) p = 13.00 mm. The total area A of the main combustion holes (201) p,h = 530.9292 mm 2 , and the flow coefficient C d = 0.

75. The length of the main combustion zone of the flame tube (2) is 78.792 mm, and the equivalence ratio of the main combustion zone of the flame tube (2) is 0.9082. The number of the mixing holes (202) is 4, and the area of a single mixing hole (202) is 132.7323 mm 2 . The mixing holes (202) on the upper and lower wall surfaces of the flame tube (2) are arranged in a staggered manner. The structures of both the main combustion holes (201) and the mixing holes (202) adopt an inverted right-angled trapezoidal cylinder structure.

2. The high-temperature-rise triple swirl combustor according to claim 1, wherein: The inclination angle α of the combustion chamber (1) is 9.6620°.

3. The high-temperature-rise triple-swirl combustor according to claim 1, characterized in that: The fuel design of the combustion chamber (1) includes the fuel ratios of the pilot stage and the main combustion stage. The fuel ratios of the pilot stage and the main combustion stage are taken as 30% and 70% respectively.

4. The high-temperature-rise three-swirling-flow combustion chamber according to claim 1, wherein: The gas volume distribution of each stage of the swirler in the combustion chamber (1) is as follows: the inlet air at the head is 45.05%, the cooling air volume at the head is 3.05%, the inlet air ratio of the first - stage swirler (3) of the duty class is 5.5%, the inlet air ratio of the second - stage swirler (3) of the duty class is 12.5%, and the inlet air of the main combustion stage is 24%.

5. The high-temperature-rise triple swirl combustor according to claim 1, characterized in that: The structural parameter design of the swirler (3) is as follows: The average inlet radius of the cap (205) is 303.5822 mm; The initial value of the swirl number Cd of the main combustion stage swirler (3) is 0.84; The number of blades (303) of the first-stage cyclone is 8, the blade inlet area is 187.4665 mm 2 , the effective area is 128.9934 mm 2 , the blade thickness is 1.00 mm, the outer diameter is 11.30 mm, and the inner diameter is 7.50 mm; The number of blades (302) of the second-stage cyclone is 10, the blade inlet area is 471.1369 mm 2 , the effective area is 293.1668 mm 2 , the blade thickness is 1.20 mm, the outer diameter is 18.90 mm, and the inner diameter is 13.30 mm; The number of blades (301) of the third-stage cyclone is 15, the blade inlet area is 1306.9945 mm 2 , the effective area is 562.8803 mm 2 , the blade thickness is 1.10 mm, the outer diameter is 34.32 mm, and the inner diameter is 26.40 mm.

6. The high-temperature-rise triple-swirl combustor according to claim 1, characterized in that: The head cooling holes (204) adopt the straight - hole impingement cooling method, and the flame tube wall cooling holes (203) adopt the form of dense multi - inclined holes.

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