Porous medium sweating cooling combustion chamber based on ceramic matrix composite material

Abstract

The invention discloses a porous medium sweating and cooling combustion chamber based on a ceramic matrix composite material, and relates to the technical fields of gas turbines, new energy and the like. In order to solve the problem of combustion instability such as combustion oscillation of a traditional gas turbine combustion chamber, a ceramic-based porous medium combustion chamber structure is adopted, liquid fuel infiltrates from the outer wall face of a porous medium and is evaporated and gasified on the inner wall, and then combustion occurs. The gasification reaction of the liquid fuel in the porous medium and on the wall surface can take away a large amount of heat, so that the effects of heat insulation, heat protection and wall surface cooling are achieved, and the combustion chamber can be protected from thermal damage. On the other hand, traditional jet flow or rotational flow combustion is replaced by wall face evaporation combustion, and combustion oscillation caused by uneven mixing or jet flow is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power devices such as gas turbines, aeroengines, rocket engines, etc., and in particular to a porous media transpiration cooling combustion chamber based on ceramic matrix composites, which is also applicable to new energy fields such as hydrogen energy, synthetic fuel burners, etc. that require high thermal intensity and high stability combustion equipment. BACKGROUND

[0002] Traditional gas turbine combustion chambers usually use gaseous or atomized liquid fuel to be injected into the combustion zone through nozzles (jet or swirl nozzles) and mixed with air for combustion. This approach has the following main problems:

[0003] 1. Combustion instability (oscillation): uneven fuel / air mixing, unstable jet shear layer, or acoustic coupling can easily cause strong combustion oscillation, leading to increased pressure pulsation, reduced thermal efficiency, deteriorated emissions, and even damage to combustion chamber components.

[0004] 2. Thermal protection challenge: the combustion chamber operates in an extremely high temperature environment (often exceeding the melting point of metal materials), requiring complex cooling systems (such as film cooling, impingement cooling) to protect the wall surface. The efficiency of traditional cooling methods is limited, and the cooling gas flow will dilute the combustion zone, affecting combustion efficiency and emissions, and the cooling gas consumption is large.

[0005] 3. High-temperature material limitations: even with advanced high-temperature alloys and cooling techniques, some areas of the combustion chamber (especially the flame tube) still face severe thermal stress, oxidation, and creep problems, limiting the further increase of combustion chamber temperature and service life.

[0006] 4. Fuel adaptability: for some difficult-to-atomize or easy-to-coking liquid fuels (such as heavy oil, bio-oil), the traditional injection method has poor mixing effect, low combustion efficiency, and is prone to carbon deposition.

[0007] Ceramic matrix composites (CMC) are considered as the ideal structural material for the next generation of high-temperature combustion chambers (such as flame tubes, nozzles) due to their excellent high-temperature mechanical properties (high strength, high modulus), excellent oxidation / corrosion resistance, low density, good thermal shock resistance, and potential long service life, which can break through the temperature limit of traditional high-temperature alloys. However, CMC materials themselves also have a maximum use temperature limit (such as SiC / SiC about 1400-1500℃), and effective thermal management strategies are still needed in higher temperature combustion environments.

[0008] Porous media combustion technology has been widely concerned due to its high combustion efficiency, low pollutant emission, stable combustion (uniform combustion and oscillation suppression), wide load regulation range and other advantages. Combining porous media with the wall structure of the combustion chamber, especially using the transpiration and evaporation of liquid fuel in the porous media for "transpiration cooling", provides a new idea for solving the above two challenges. Transpiration cooling is one of the highest efficiency active cooling methods known. When the cooling medium (here, the fuel) flows through the porous wall, especially on the hot side of the wall, it can absorb a large amount of latent heat and significantly reduce the wall temperature. However, how to efficiently and reliably integrate the high-temperature-resistant CMC material, the porous medium with a specific structure, the liquid fuel supply, and the evaporation combustion mechanism into the actual combustion chamber structure and effectively solve the combustion stability problem is still a technical difficulty that needs to be broken through. SUMMARY

[0009] The present application aims to overcome the above-mentioned defects of the prior art and provide a porous media transpiration cooling combustion chamber based on ceramic matrix composites. The combustion chamber combines the high-temperature structural performance of ceramic matrix composites, the uniform evaporation / combustion characteristics of porous media, and the transpiration cooling mechanism to achieve efficient wall cooling and highly stable combustion.

[0010] The technical solution of the present application is as follows:

[0011] A porous media transpiration cooling combustion chamber based on ceramic matrix composites, characterized in that it comprises:

[0012] A combustion chamber body, the wall surface of which is composed of a porous media structure of ceramic matrix composites, the porous media structure having interconnected inner and outer wall surfaces, the inner wall surface facing the combustion area inside the combustion chamber, and the outer wall surface facing the outside of the combustion chamber;

[0013] A liquid fuel supply for delivering liquid fuel to the outer wall surface of the porous media structure and allowing the liquid fuel to penetrate to the inner wall surface by capillary action or pressure driving;

[0014] An igniter arranged on the end cover of the combustion chamber body for igniting the mixture of fuel and oxidant;

[0015] An air channel arranged on the end cover and / or side wall of the combustion chamber body for supplying oxidant to the inside of the combustion chamber;

[0016] Wherein, the liquid fuel is delivered to the outer wall surface of the porous media structure by the fuel supply system, penetrates from the outer wall surface to the inner wall surface under the action of capillary force or pressure driving, and after being heated and vaporized on the inner wall surface, mixes with the oxidant input by the air channel and burns, while realizing transpiration cooling of the wall surface of the combustion chamber by evaporation heat absorption.

[0017] Further, the ceramic matrix composite material is at least one of silicon carbide ceramic matrix composite material, carbon fiber reinforced silicon carbide ceramic matrix composite material, and oxide ceramic matrix composite material. The porous medium structure is integrally formed with the combustion chamber body by a sintering process.

[0018] Further, the average pore size of the porous medium structure ranges from 10 microns to 10 millimeters, and the porosity ranges from 30% to 70%.

[0019] Further, the liquid fuel supply system includes a fuel tank, a pump, and a fuel distribution cavity or fuel distributor arranged on the outer wall surface of the porous medium structure, to ensure uniform wetting of the liquid fuel on the outer wall surface.

[0020] Further, the combustion chamber body is cylindrical, annular, or has a complex curved surface structure, and the porous medium structure forms the flame tube wall surface or the combustion chamber head wall surface.

[0021] Further, the air passage includes:

[0022] The primary air inlet is arranged on the combustion chamber end cover and is provided with a swirler.

[0023] The secondary air inlet is arranged on the combustion chamber side wall.

[0024] Further, the porosity of the porous medium structure is gradiently distributed along the wall thickness direction, and the porosity of the inner wall surface region is greater than that of the outer wall surface region.

[0025] Further, the oil supply pressure of the liquid fuel supply system is 0.05-5.0 MPa, which is adjusted according to the working pressure of the combustion chamber and the permeation characteristics of the porous medium structure.

[0026] Further, the igniter is an electric spark plug arranged at the center of the combustion chamber end cover or at a predetermined position on the side wall.

[0027] Further, the inner wall surface temperature of the porous medium structure is controlled to be lower than the temperature of the combustion area by sweating cooling, and the sweating cooling mechanism effectively reduces the wall surface temperature of the combustion chamber to below the safe use temperature threshold of the ceramic matrix composite material.

[0028] The working principle of the present application is:

[0029] 1. Fuel wetting and permeation: The liquid fuel is uniformly applied to the outer wall surface of the porous medium structure by the supply system. Under the driving of capillary force or externally applied pressure, the liquid fuel gradually wets the entire porous medium wall thickness and permeates from the outer wall surface to the inner wall surface.

[0030] 2. Evaporation and vaporization: When fuel penetrates to the inner wall surface close to the high-temperature combustion zone, it is rapidly heated by the high-temperature combustion gas (usually > 1000℃) inside the combustion chamber, and undergoes evaporation and vaporization.

[0031] 3. Mixing and combustion: The vaporized fuel vapor is released from the pores of the porous medium inner wall surface and rapidly diffuses to the combustion zone adjacent to the wall surface. At this time, the oxidizer (air) entering through the air inlet mixes with the released fuel vapor in this area. The mixed combustible gas is initially ignited by the igniter or is ignited by the stable flame, and the combustion reaction occurs in the area adjacent to the inner wall surface (forming one or more layers of premixed / partially premixed flame) or in the main combustion zone expanding to the center of the combustion chamber, releasing heat.

[0032] 4. Sweating cooling: Liquid fuel is preheated by absorbing heat from the porous medium skeleton during penetration from the outer wall surface to the inner wall surface; most importantly, when the fuel undergoes phase transition (evaporation) from liquid to gas in the inner wall surface area, it needs to absorb a large amount of latent heat (much larger than sensible heat). This phase transition endothermic process continuously and efficiently removes heat from the porous medium skeleton that constitutes the wall surface, especially in the inner wall surface area adjacent to the high-temperature combustion gas, significantly reducing the actual working temperature of the porous medium skeleton and the entire wall surface. This way of using the working medium (here, the fuel itself) to absorb latent heat during the flow through the porous wall, especially on the hot side, to achieve cooling, is called "sweating cooling".

[0033] Compared with the prior art, the beneficial effects of the present application are as follows:

[0034] The present application discards the traditional centralized fuel injection (jet / swirl nozzle). Fuel is evaporated and released in large areas, continuously and uniformly throughout the inner wall surface through the porous wall surface. This distributed, planar fuel supply method has the following advantages:

[0035] Greatly improved mixing uniformity: Fuel vapor is released from the entire wall surface, and can achieve more complete and uniform microscopic mixing with air entering from the head or side wall in a large area, avoiding local over-concentration or under-concentration areas.

[0036] Eliminate jet / swirl-related instability: The root causes of heat release pulsation induced by jet shear layer instability, swirl vortex breakage and other fluid dynamics phenomena are fundamentally eliminated, which in turn triggers combustion oscillation.

[0037] Acoustic coupling is weakened: Distributed combustion sources and more uniform temperature fields reduce the coupling strength between combustion heat release pulsation and combustion chamber acoustic modes. Therefore, the combustion process of the present application exhibits significantly enhanced stability, effectively suppressing or eliminating combustion oscillation.

[0038] 1. Excellent cooling performance: The sweat cooling mechanism that utilizes fuel evaporation phase change to absorb large amount of latent heat has much higher cooling efficiency than traditional film cooling (relying on film insulation) and convective cooling (relying on sensible heat exchange). It can more effectively control the combustion chamber wall temperature (especially the critical inner wall temperature) below the safe working temperature threshold of the selected ceramic matrix composite, greatly extending the service life of the combustion chamber, and providing the material and cooling basis for increasing the combustion chamber inlet temperature (and thus the thermal efficiency).

[0039] 2. Excellent combustion stability: The wall evaporation fuel supply method completely replaces the jet / swirl injection, fundamentally eliminating the combustion oscillation problem caused by hydrodynamic instability. The combustion process is more stable and quiet, with significantly reduced pressure pulsation, improving the operation safety and reliability, and widening the stable working range.

[0040] 3. Improve combustion efficiency and reduce emissions: The uniform evaporation and gasification of fuel on the wall and the full mixing with air are conducive to achieving a more complete combustion reaction closer to the stoichiometric ratio, improving the combustion efficiency. More uniform mixing and combustion also help reduce the emissions of incomplete combustion products such as unburned hydrocarbons (UHC), nitrogen oxides (NOx), and carbon monoxide (CO).

[0041] 4. Improve structural reliability and thermal efficiency potential:

[0042] The ceramic matrix composite itself has excellent high-temperature performance, combined with efficient sweat cooling, allowing the combustion chamber to operate safely and reliably at higher working temperatures, creating conditions for improving the thermal efficiency of the entire engine.

[0043] Avoids the dilution of cooling air in the main combustion zone in traditional cooling methods, allowing the main combustion zone to maintain a more ideal ratio for combustion, which is conducive to improving combustion efficiency and flame temperature.

[0044] 5. Improve fuel adaptability: The structure greatly reduces the requirements for liquid fuel atomization. The fuel does not need to be finely atomized, but only needs to be able to effectively infiltrate and penetrate the porous medium. This is particularly beneficial for the clean and efficient combustion of difficult-to-atomize and coking heavy fuels (such as heavy oil, residual oil, and some biofuels), and broadens the fuel sources.

[0045] 6. Structural simplification potential: It may reduce or simplify the design of complex fuel nozzle systems (such as atomizing nozzles and swirlers) and cooling air delivery channels (such as film holes and cooling flow channels) in traditional combustion chambers, reducing manufacturing complexity and cost. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1The overall structure profile schematic diagram of the ceramic matrix composite-based porous medium sweating cooling combustion chamber of the present application.

[0047] Figure 2 The 3D structure schematic diagram of the local enlargement of the porous medium wall surface.

[0048] Figure 3 The principle schematic diagram of the fuel infiltration, permeation, evaporation and combustion inside the porous medium wall surface. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application is further described in detail below in combination with the drawings and examples. The specific examples described herein are only used to explain the present application and do not limit the present application.

[0050] Please refer to Figure 1 As shown in the figure, a ceramic matrix composite-based porous medium sweating cooling combustion chamber mainly comprises: a combustion chamber body 1 made of a high-temperature-resistant ceramic matrix composite material, forming a combustion reaction space.

[0051] A porous medium wall surface 2 as the core part of the combustion chamber body constitutes the main heated wall surface (such as the flame tube wall surface and the head wall surface) of the combustion chamber. The wall surface has an inner wall surface 21 and an outer wall surface 22 which are interconnected. The porous medium needs to have a specific pore size (preferably 10 μm-10 mm) and porosity (preferably 30%-70%) to ensure that: a) the liquid fuel can be effectively permeated; b) sufficient mechanical strength and thermal shock resistance; c) the gasified fuel can be smoothly released and mixed with the oxidant.

[0052] A liquid fuel supply system 3 including a fuel pump, a pipeline and a fuel distribution chamber or distributor arranged outside the combustion chamber, for delivering liquid fuel (such as aviation kerosene, diesel, biofuel, liquid hydrogen carrier, etc.) to the outer wall surface 22 of the porous medium at a controllable pressure and flow rate.

[0053] An igniter 4 is usually arranged at a suitable position of the combustion chamber head or side wall, for igniting the mixture at start-up, establishing the initial flame and forming stable combustion.

[0054] An air (oxidant) inlet 6 for supplying the oxidant (usually air, but also possibly oxygen-enriched air or pure oxygen) required for combustion to the inside of the combustion chamber. The inlet can be located at the combustion chamber head (main combustion zone air supply) and / or the side wall (mixing or secondary air supply).

[0055] The combustion chamber further comprises a combustion tail gas outlet 8 arranged at the end of the combustion chamber body 1 and in communication with the combustion zone 7. The pore size and porosity of the porous medium structure 2 are non-uniformly distributed along the axial direction of the combustion chamber, and larger pore size and higher porosity are adopted in the high-temperature zone. The liquid fuel is at least one of aviation kerosene, diesel, liquid hydrogen, RP-1 rocket kerosene, or heavy oil.

[0056] The combination of the ceramic matrix composite and the porous medium structure 2 enables the combustion chamber to work for a long time at a gas temperature of 1400-1600℃.

[0057] Example 1: Small gas turbine flame tube

[0058] Application scenario: Combustion chamber flame tube suitable for small industrial gas turbines.

[0059] Combustion chamber body 1: designed as a cylindrical structure with a diameter of 200mm and a length of 300mm. The whole is composed of a porous medium wall (2).

[0060] Porous medium wall 2:

[0061] Material: silicon carbide fiber reinforced silicon carbide ceramic matrix composite (SiC / SiC CMC). The material has good long-term strength retention and oxidation resistance at 1400℃.

[0062] Structure: wall thickness 50mm.

[0063] Porous parameters: average pore size: 50μm (controlled by pore former content and sintering process). Porosity: 45% (volume fraction). The pore size and porosity are designed to ensure good permeability of the fuel (mainly capillary action, supplemented by low pressure driving) and sufficient wall strength.

[0064] Liquid fuel supply system 3:

[0065] o Fuel: liquid hydrogen.

[0066] o Fuel supply mode: an annular fuel distribution cavity is coaxially sleeved on the outer wall 22 of the flame tube. The distribution cavity is closely attached to the outer porous medium wall 22, and the inner wall is provided with uniformly distributed micropores or uses a porous metal plate to ensure that the fuel is uniformly applied to the entire outer wall.

[0067] o Fuel supply pressure: 0.1-0.3MPa (gauge pressure). The pressure setting needs to be adjusted according to the permeability of the porous medium, the viscosity of the fuel, and the required fuel flow to ensure that the fuel can uniformly penetrate the entire wall thickness and form a stable evaporation and gasification layer on the inner wall, avoiding direct injection of liquid fuel into the combustion zone or insufficient fuel supply.

[0068] · Igniter 4: spark plug installed at the center of the combustion chamber head end cover 5.

[0069] • Air (oxidizer) inlet 6: Located at the head end cover 5 of the combustion chamber, supplied with primary combustion air through a swirler (or simple orifice plate). Mixing air holes (not shown separately in the figure) can be provided as needed.

[0070] • Operating parameters and effects:

[0071] o Wall temperature: The temperature of the porous medium wall at different depths was measured by thermocouples under the condition that the gas temperature at the outlet of the combustion chamber was about 1350°C. The measured results showed that the inner wall 21 had a stable temperature of about 1100°C (lower than the safe use temperature threshold of SiC / SiC CMC of 1250°C), which was significantly lower and more uniform than the wall temperature of a metal flame tube without cooling or traditional gas film cooling under the same working conditions (usually needs to be cooled to 900°C

[0072] below, and there are hot spots).

[0073] o Combustion stability: Dynamic pressure tests were conducted within a wide load range (50%-100%). The pressure fluctuation RMS value (reflecting the intensity of combustion oscillation) was reduced by more than 70% compared with the baseline combustion chamber using traditional pressure atomizing nozzles, and the combustion was extremely stable.

[0074] o Emissions: Thanks to uniform mixing, NOx emissions were significantly lower than those of the baseline combustion chamber.

[0075] Example 2: Rocket engine thrust chamber body

[0076] • Application scenario: Suitable for the convergent section of the nozzle of a liquid rocket engine thrust chamber to withstand extremely high heat flux density. • Combustion chamber body 1: The structure is a complex curved surface (convergent cone). The porous medium wall 2 is applied to the convergent section of the nozzle

[0077] .

[0078] • Porous medium wall 2:

[0079] o Material: Carbon fiber reinforced silicon carbide ceramic matrix composite (C / SiC CMC). This material has excellent high-temperature performance and thermal shock resistance, suitable for extreme environments of rocket engines.

[0080] o Structure: According to the heat flux distribution, the wall thickness is designed to be gradient (thickest at the throat, e.g. 8mm; thinner at the inlet, e.g. 4mm).

[0081] o Porous parameters: Average pore size: 200μm (considering the surface tension of RP-1 kerosene and the requirement of high permeation rate). Porosity: 60% (volume fraction). High air permeability is required to adapt to high fuel flow and high heat flux.

[0082] • Liquid fuel supply system 3:

[0083] o Fuel: RP-1 rocket kerosene (as coolant and fuel). Note: oxidizer (e.g. liquid oxygen) is usually injected separately from the injector head.

[0084] o Fuel supply: Separate fuel reservoirs are set between the thrust chamber body shell and the porous wall 22. Each reservoir corresponds to a part of the porous wall. By adjusting the supply pressure or flow rate of each reservoir, targeted cooling (active thermal management) can be achieved for different heat flux regions.

[0085] o Fuel supply pressure: Higher than the combustion chamber pressure (Pc). The pressure difference ΔP is calculated according to the permeation resistance and the required cooling flow rate. The typical range may be 1.0-5.0 MPa (gauge pressure). Ensure that the fuel can overcome the combustion chamber pressure to permeate the wall and fully vaporize on the inner wall.

[0086] • Igniter 4: Usually head torch ignition or chemical ignition (not directly acting on the porous wall region).

[0087] • Working characteristics and effects:

[0088] o Cooling effect: In the extremely high heat flux region of the nozzle throat (>10 MW / m 2 ), sweating cooling can effectively control the wall temperature below the safe working temperature of C / SiC CMC (e.g. <1500℃). The heat absorbed by fuel vaporization protects the structural material.

[0089] o Fuel utilization: The fuel vapor that permeates the wall and absorbs heat vaporizes as a coolant, and after being released into the combustion chamber (thrust chamber cavity), it mixes with the oxidizer (e.g. liquid oxygen) injected from the head and participates in combustion, generating thrust. The coolant (fuel) is fully utilized.

[0090] o Potential advantages: Compared with traditional regenerative cooling (fuel flowing in channels for heat exchange), sweating cooling can theoretically achieve higher cooling efficiency (latent heat of phase change) and more uniform wall temperature distribution, reducing thermal stress. The structure may be more compact (no need for complex internal cooling channels).

[0091] The above description is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation based on the content of the specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A ceramic matrix composite based porous media transpiration cooled combustion chamber, characterized in that, The application relates to a combustion chamber, comprising: a combustion chamber body (1) with a wall surface formed by a porous medium structure (2) of a ceramic matrix composite, the porous medium structure (2) having inner wall surfaces (21) and outer wall surfaces (22) that are interconnected, the inner wall surfaces (21) facing a combustion area (7) inside the combustion chamber, and the outer wall surfaces (22) facing the outside of the combustion chamber; a liquid fuel supply (3) for delivering liquid fuel to the outer wall surfaces (22) of the porous medium structure (2) and allowing the liquid fuel to permeate to the inner wall surfaces (21) by capillary action or pressure driving; an igniter (4) arranged on an end cover (5) of the combustion chamber body (1) for igniting the mixture of fuel and oxidant; and an air channel (6) arranged on the end cover (5) and / or the side wall of the combustion chamber body (1) for supplying oxidant to the inside of the combustion chamber. The liquid fuel is delivered to the outer wall surfaces (22) of the porous medium structure (2) by the fuel supply system (3), and permeates from the outer wall surfaces (22) to the inner wall surfaces (21) by capillary action or pressure driving, and is mixed with the oxidant input by the air channel (6) after being gasified by heat, and is combusted, and the evaporation heat absorption realizes the sweating cooling of the wall surface of the combustion chamber. The ceramic matrix composite is at least one of a silicon carbide ceramic matrix composite, a carbon fiber reinforced silicon carbide ceramic matrix composite and an oxide ceramic matrix composite. The porous medium structure (2) is integrally formed with the combustion chamber body (1) by a sintering process. The average pore size of the porous medium structure (2) ranges from 10 microns to 10 millimeters, and the porosity ranges from 30% to 70%. The liquid fuel supply system (3) comprises a fuel tank, a pump and a fuel distribution cavity or a fuel distributor arranged on the outer wall surfaces (22) of the porous medium structure (2), and ensures that the liquid fuel uniformly infiltrates the outer wall surfaces (22).

2. The combustion chamber of claim 1, wherein The combustion chamber body (1) is in a cylindrical, annular or complex curved surface structure, and the porous medium structure (2) forms a flame tube wall surface or a combustion chamber head wall surface of the combustion chamber.

3. The combustion chamber according to claim 1 or 2, characterized in that The air channel (6) comprises a main combustion air inlet arranged on the end cover (5) of the combustion chamber and provided with a swirler, and a secondary air inlet arranged on the side wall of the combustion chamber.

4. The combustion chamber according to any one of claims 1 to 3, characterized in that The porosity of the porous medium structure (2) is gradient-distributed along the wall thickness direction, and the porosity of the inner wall surfaces (21) is greater than that of the outer wall surfaces (22).

5. The combustion chamber according to any one of claims 1 to 3, characterized in that The oil supply pressure of the liquid fuel supply system (3) is 0.05-5.0 MPa, which is adjusted according to the working pressure of the combustion chamber and the permeation characteristics of the porous medium structure (2).

6. The combustion chamber according to any one of claims 1 to 3, characterized in that The igniter (4) is an electric spark plug arranged at the center of the end cover (5) of the combustion chamber or at a predetermined position of the side wall. The temperature of the inner wall surfaces (21) of the porous medium structure (2) is controlled to be lower than that of the combustion area (7) by sweating cooling, and the sweating cooling mechanism effectively reduces the wall surface temperature of the combustion chamber and makes it lower than the safe use temperature threshold of the ceramic matrix composite.

7. The combustion chamber according to any one of claims 1 to 3, characterized in that ​ 8. The combustion chamber according to any one of claims 1 to 3, characterized in that ​ 9. The combustion chamber according to any one of claims 1 to 3, characterized in that ​ 10. The combustion chamber according to any one of claims 1 to 3, characterized in that ​

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