Fuel oil combined atomization device applied to small-size high-temperature-rise combustion chamber

Abstract

The invention discloses a fuel oil combined atomization device applied to a small-size high-temperature-rise combustion chamber, and relates to the technical field of aero-engines, the device comprises a first-stage axial swirler, a second-stage axial swirler and a centrifugal nozzle, the first-stage axial swirler and the second-stage axial swirler are coaxially installed on the head portion of a flame tube, and the centrifugal nozzle is coaxially installed on the head portion of the flame tube. The centrifugal nozzle is located in the first-stage axial cyclone, a venturi tube is further arranged between the second-stage axial cyclone and the first-stage axial cyclone, and a plurality of first oil spraying holes and second oil spraying holes are formed in the circumferential outer wall of the venturi tube. Fuel oil sprayed out of the first oil spraying hole and the second oil spraying hole can be atomized through air passing through the second-stage axial swirler. According to the invention, a partitioned and pressure-divided oil supply mode is adopted, the requirements of small oil supply flow under the working conditions of slow running and the like and large oil supply flow under the maximum design working conditions of climbing and the like are considered, and meanwhile, the requirements of efficient combustion on fuel oil atomization quality under different working conditions are met.

Description

Technical Field

[0001] The invention relates to the technical field of aviation engines, and in particular to a fuel combination atomization device applied to a small-sized high-temperature rise combustion chamber. Background Art

[0002] With the development of aircraft technology, in order to meet the demand for higher thrust-to-weight ratio of engines, the cycle parameters of turbine engines are gradually improved. The thrust-to-weight ratio target of traditional large engines has gradually increased from 8 to 10 to 16 to 20, or even higher. According to relevant research, for every 100K increase in turbine inlet temperature, the engine thrust will increase by 20%. For a typical fourth-generation aircraft (F119) to a fifth-generation aircraft (F135), the turbine inlet temperature increases from 1850K to 2000K, the combustion chamber temperature rise increases from 1200K to 1350K, and the thrust-to-weight ratio increases from 10 to 12. It can be seen that the development of advanced combustion chamber technology with high temperature rise is an effective way to increase thrust. Compared with traditional large engines, small turbine engines for small missiles / unmanned aerial vehicles have small structural dimensions and light weight. It is difficult to achieve fuel atomization and combustion organization under high oil-gas ratio conditions in a limited space. The design conclusions of fuel atomization and combustion organization of large engines cannot be simply and directly extrapolated to small turbine engines.

[0003] The high temperature rise combustion chamber technology aims to achieve efficient and stable combustion under higher oil-gas ratio conditions and maximize the heat release function of the combustion chamber. For the combustion organization of large engine combustion chambers under high oil-gas ratio conditions, a multi-stage swirler solution is usually adopted to increase the intake volume by increasing the head windward area, and at the same time, a reasonable heat return structure is constructed by using the interaction of multi-stage swirl air to strengthen the fuel atomization. Considering that the engine structure size of small missiles / unmanned aerial vehicles is small, the fuel supply pressure is low, the fuel flow is wide, and the cost is low, the traditional single oil / dual oil circuit centrifugal nozzle + two-stage swirler fuel atomization technology solution is no longer suitable for small turbine power for small missiles / unmanned aerial vehicles due to high fuel supply pressure and high cost. With the improvement of the thrust-to-weight ratio of small turbine power, it is urgent to solve the contradiction between reliable ignition under small working conditions and efficient and stable combustion under large working conditions. It is necessary to propose a new fuel atomization method suitable for small-sized high temperature rise combustion chambers to reduce the risk of flame instability, combustion oscillation and reduced combustion efficiency in high temperature rise combustion chambers.

[0004] Previous studies on fuel atomization in high-temperature rise combustion chambers of large engines have mostly focused on designing nozzles and swirlers separately, and the two need to be matched and designed separately. Currently, most aircraft engines use center-mounted nozzles for fuel supply. As the fuel supply flow rate increases, the nozzle diameter gradually increases. Therefore, the frontal area can only be increased by increasing the outer diameter of the swirler. However, the combustion chamber of a small turbine engine is small in size, and the outer diameter of the swirler cannot be significantly increased. Since the high-temperature rise combustion chamber carries out high oil-to-gas ratio combustion near the head of the flame tube, even close to chemically appropriate combustion, the head of the flame tube will be subject to a high heat load. In order to prevent coking, ablation and carbon deposition of the venturi tube caused by high temperature, a reasonable active cooling solution must also be considered when designing the fuel atomization device. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art, and the purpose is to provide a combined fuel atomization device for use in a small-sized high-temperature rise combustion chamber, which adopts a zoned and pressure-controlled fuel supply method, taking into account the needs of small fuel supply flow under conditions such as slow speed and large fuel supply flow under maximum design conditions such as climbing, while meeting the requirements of fuel atomization quality for efficient combustion under different conditions.

[0006] The present invention is achieved through the following technical solutions:

[0007] A fuel combined atomization device applied to a small-sized high-temperature rise combustion chamber comprises a primary axial swirler, a secondary axial swirler and a centrifugal nozzle, wherein the primary axial swirler and the secondary axial swirler are coaxially mounted on a flame tube head, the centrifugal nozzle is located in the primary axial swirler, a venturi is further provided between the secondary axial swirler and the primary axial swirler, a plurality of first fuel injection holes and second fuel injection holes are provided on the circumferential outer wall of the venturi, and the airflow passing through the secondary axial swirler can atomize the fuel sprayed from the first fuel injection holes and the second fuel injection holes.

[0008] Furthermore, a first main oil supply channel and a first main oil supply ring are provided in the Venturi tube, the first main oil supply channel is distributed axially along the Venturi tube, and the first main oil supply channel is connected with the first main oil supply ring, the first main oil supply ring is circumferentially distributed in the Venturi tube, and the first oil injection holes are all connected with the first main oil supply ring.

[0009] Furthermore, a second main oil supply channel and a second main oil supply ring are provided in the Venturi tube, the second main oil supply channel is distributed axially along the Venturi tube, and the second main oil supply channel is connected with the second main oil supply ring, the second main oil supply ring is circumferentially distributed in the Venturi tube, and the second oil injection holes are all connected with the second main oil supply ring.

[0010] Furthermore, a first main oil circuit and a second main oil circuit are provided between the first-stage axial swirler and the second-stage axial swirler, the first main oil circuit is connected to the first main oil circuit oil supply channel, and the second main oil circuit is connected to the second main oil circuit oil supply channel.

[0011] Furthermore, the first oil injection holes and the second oil injection holes are distributed on the outer wall of the venturi in two rows that are staggered circumferentially and evenly spaced.

[0012] Further, the number of the first fuel injection holes and the second fuel injection holes are both 10-20, and the diameters of the first fuel injection holes and the second fuel injection holes are 0.3 mm-0.6 mm.

[0013] Furthermore, the first-stage axial swirler and the second-stage axial swirler are both blade-type swirlers, and the first-stage axial swirler and the second-stage axial swirler have the same or opposite rotation directions.

[0014] Furthermore, it also includes a casing, a diffuser is provided at one end of the casing, and the flame tube is located in the casing.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0016] 1. The present invention adopts a zoned and pressure-controlled fuel supply method, and the fuel nozzle and the air swirler are integrated in the design, which simplifies the geometric structure and realizes a wide range of fuel flow regulation to meet the fuel flow requirements of different working conditions;

[0017] 2. The present invention utilizes the first main oil supply ring and the second main oil supply ring disposed in the venturi tube to play a rectifying role, and by arranging the first injection holes and the second injection holes in front and rear rows in a staggered manner with equal spacing in the circumferential direction, it can ensure that the fuel in the combustion chamber is evenly distributed and the combustion is stable;

[0018] 3. The present invention can reasonably adapt the number and diameter of the first fuel injection holes and the second fuel injection holes on the outer wall of the venturi tube to meet the demand for higher fuel flow under low oil pressure regulation, and has stronger versatility;

[0019] 4. The reasonable arrangement of the oil injection holes on the wall of the venturi tube of the present invention can provide oil supply while cooling the venturi tube to a certain extent, thereby reducing the risk of coking, ablation and carbon deposition of the venturi tube, and improving safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0021] Figure 1 It is a schematic diagram of the structure of the high temperature rise combustion chamber of the present invention;

[0022] Figure 2 It is a structural schematic diagram of the fuel combination atomization device of the present invention;

[0023] Figure 3 It is a structural schematic diagram of the fuel combination atomization device of the present invention from another perspective;

[0024] Figure 4 It is a structural schematic diagram of the fuel combination atomization device of the present invention from another perspective;

[0025] Figure 5 For the present invention Figure 4 Cross-sectional view of the middle BB;

[0026] Figure 6 For the present invention Figure 4 Cross-sectional view of CC.

[0027] Marks and corresponding parts names in the attached drawings:

[0028] 1. Diffuser; 3. Casing; 4. Flame tube; 21. Centrifugal nozzle; 22. Primary axial swirler; 23. First main oil circuit; 2301. First oil injection hole; 2302. Oil supply channel of first main oil circuit; 2303. Oil supply ring of first main oil circuit; 24. Second main oil circuit; 2401. Second oil injection hole; 2402. Oil supply channel of second main oil circuit; 2403. Oil supply ring of second main oil circuit; 25. Venturi tube; 26. Secondary axial swirler. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0030] Example

[0031] like Figures 1 to 6 As shown, the present invention includes a primary axial swirler 22, a secondary axial swirler 26 and a centrifugal nozzle 21. The primary axial swirler 22 and the secondary axial swirler 26 are coaxially installed at the head of the flame tube 4. The centrifugal nozzle 21 is located in the primary axial swirler 22. A venturi 25 is also provided between the secondary axial swirler 26 and the primary axial swirler 22. A plurality of first fuel injection holes 2301 and second fuel injection holes 2401 are provided on the circumferential outer wall of the venturi 25. The airflow passing through the secondary axial swirler 26 can shear and carry the fuel sprayed from the first fuel injection holes 2301 and the second fuel injection holes 2401 to achieve atomization.

[0032] Most of the aircraft engines in the prior art use a centrally mounted nozzle for fuel supply. As the fuel supply flow rate increases, the nozzle diameter gradually increases. Therefore, the frontal area can only be increased by increasing the outer diameter of the engine's swirler. However, the combustion chamber of a small turbine engine is relatively small, so the outer diameter of the swirler cannot be significantly increased. At the same time, since the high-temperature rise combustion chamber performs high oil-to-gas ratio combustion near the flame tube head, even close to chemically appropriate combustion, the flame tube head will be subject to a high heat load, making the venturi in the engine prone to coking, ablation and carbon deposition. For this reason, the technical solution is provided with a plurality of first injection holes 2301 and second injection holes 2401 on the outer wall of the venturi tube 25 between the first-stage axial swirler 22 and the second-stage axial swirler 26, respectively. The first injection holes 2301 and the second injection holes 2401 are respectively provided. 01 and the second fuel injection hole 2401 are supplied with oil independently of each other, so that the atomization device adopts a zoned and differential pressure fuel supply method, taking into account the needs of small fuel supply flow under slow conditions and the fuel supply flow under maximum design conditions such as climbing, while meeting the requirements of fuel atomization quality for efficient combustion under different conditions. The technical scheme adopts an overall layout scheme integrating a centrifugal nozzle 21 and an air swirler, wherein the duty area adopts a centrally installed single-oil-circuit centrifugal nozzle 21 for fuel supply, and the main oil area adopts the first fuel injection hole 2301 and the second fuel injection hole 2401 for fuel supply, so that when the air passes through the first fuel injection hole 2301 and the second fuel injection hole 2401, the fuel sprayed from the first fuel injection hole 2301 and the second fuel injection hole 2401 relies on the lateral aerodynamic force of the air to achieve good atomization, thereby reducing the demand for fuel supply pressure for fuel atomization.

[0033] At the same time, the oil supply channels of the first oil injection hole 2301 and the second oil injection hole 2401 provided in the present technical solution are integrated in the interior of the venturi 25. In this way, when the fuel passes through the oil supply channel located in the venturi 25, the fuel can exchange heat with the venturi 25, thereby achieving the purpose of cooling the venturi 25 to a certain extent, thereby reducing the risks of coking, ablation and carbon deposition of the venturi 25. Therefore, the present technical solution solves the problems of low oil supply pressure, wide fuel flow adjustment range and limited structural size of small and medium-sized turbojet engines in the prior art, and at the same time utilizes the outflow characteristics of the first oil injection hole 2301 and the second oil injection hole 2401 distributed on the venturi 25 to achieve effective cooling of the venturi.

[0034] The working principle of the present invention is: when a small missile or unmanned aerial vehicle is started, the controller sends an ignition command to start the motor. Driven by the compressor, compressed air enters the swirler from the head of the flame tube. At the same time, the centrifugal nozzle 21 in the central duty area supplies oil, and the oil mist cone flows to the outlet of the venturi 25 under the air of the first-stage axial swirler 22, and then strengthens the atomization under the action of the reverse swirling air of the second-stage axial swirler 26, and constructs a recirculation zone in the main combustion zone. The recirculation zone draws the main combustion hole intake air to participate in further mixing. The igniter is powered to ignite and ignites the oil and gas mixture near the nozzle outlet. Under the action of the recirculation zone, a stable duty flame is formed through flame transmission.

[0035] When a small missile or a UAV is cruising, the controller issues a refueling command. At this time, the first main oil circuit 23 gradually supplies oil, and the compressor speed is increased through the oil-rich combustion in the main combustion zone, thereby increasing the air intake at the flame tube head. The increase in the air intake at the flame tube head not only strengthens the atomization of the fuel sprayed from the first fuel injection hole 2301, but also increases the size of the reflow zone of the main combustion zone, thereby enhancing the air intake suction effect of the main combustion hole, enhancing the oil-gas mixing, further increasing the combustion efficiency, and increasing the temperature of the combustion chamber, further improving the temperature rise of the combustion chamber.

[0036] When a small missile or a drone is in a large working condition such as patrolling and climbing, the controller issues an oil replenishment command, and the first main oil circuit 23 and the second main oil circuit 24 supply oil at the same time, the air intake of the flame tube head is further increased, the fuel atomization effect is further enhanced, and the improvement of combustion efficiency leads to an increase in the temperature and temperature rise of the combustion chamber. At the same time, the oil supply of the second main oil circuit 24 realizes active thermal protection of the venturi tube 25 to a certain extent, so that as the oil-gas ratio and combustion efficiency of the combustion chamber increase, the venturi tube 25 will not be burned by high temperature, and the risk of coking and carbon deposition of the venturi tube is reduced to a certain extent.

[0037] The venturi 25 is provided with a first main oil supply channel 2302 and a first main oil supply ring 2303. The first main oil supply channel 2302 is distributed axially along the venturi 25, and the first main oil supply channel 2302 is connected to the first main oil supply ring 2303. The first main oil supply ring 2303 is circumferentially distributed in the venturi 25, and the first oil injection holes 2301 are all connected to the first main oil supply ring 2303.

[0038] In this embodiment, in order to ensure that independent fuel is sprayed out from the first fuel injection hole 2301 on the venturi tube 25, a first main oil circuit oil supply channel 2302 and a first main oil circuit oil supply ring 2303 are provided in the venturi tube 25. The first main oil circuit oil supply ring 2303 is circumferentially distributed in the venturi tube 25. Such a design not only enables multiple first fuel injection holes 2301 on the circumference of the venturi tube 25 to be connected with the first main oil circuit oil supply ring 2303, but also utilizes the annular structure of the first main oil circuit oil supply ring 2303 to increase the contact area between the fuel and the venturi tube 25, thereby improving the cooling effect of the fuel on the venturi tube 25.

[0039] The venturi 25 is provided with a second main oil supply channel 2402 and a second main oil supply ring 2403. The second main oil supply channel 2402 is distributed axially along the venturi 25, and the second main oil supply channel 2402 is connected to the second main oil supply ring 2403. The second main oil supply ring 2403 is circumferentially distributed in the venturi 25, and the second oil injection holes 2401 are all connected to the second main oil supply ring 2403.

[0040] Similarly, in order to ensure that independent fuel can be sprayed out from the first fuel injection hole 2301 on the venturi tube 25 in the present embodiment, a second main oil circuit oil supply channel 2402 and a second main oil circuit oil supply ring 2403 are also provided in the venturi tube 25. The second main oil circuit oil supply channel 2402 and the second main oil circuit oil supply ring 2403 are not connected to the first main oil circuit oil supply channel 2302 and the first main oil circuit oil supply ring 2303, thereby ensuring the mutual independence between the first fuel injection hole 2301 and the second fuel injection hole 2401.

[0041] Preferably, the second main oil supply channel 2402 and the first main oil supply channel 2302 are respectively located on both sides of the axial direction of the Venturi tube 25, so that the fuel in the second main oil supply channel 2402 and the first main oil supply channel 2302 can respectively perform heat exchange with different positions of the Venturi tube 25, thereby achieving the purpose of uniform heat dissipation of the Venturi tube 25.

[0042] Among them, the inner diameter of the first main oil circuit oil supply ring 2303 is set smaller than the inner diameter of the second main oil circuit oil supply ring 2403, ensuring that the first main oil circuit oil supply ring 2303 and the second main oil circuit oil supply ring 2403 are located in different radial directions of the Venturi tube 25, avoiding the intersection of the first main oil circuit oil supply ring 2303 and the second main oil circuit oil supply ring 2403.

[0043] A first main oil circuit 23 and a second main oil circuit 24 are also provided between the first-stage axial swirler 22 and the second-stage axial swirler 26 . The first main oil circuit 23 is connected to the first main oil circuit oil supply channel 2302 , and the second main oil circuit 24 is connected to the second main oil circuit oil supply channel 2402 .

[0044] The first main oil circuit 23 and the second main oil circuit 24 provided in the present embodiment are respectively connected to the fuel pump of the engine. The fuel pump can independently transport fuel to the first main oil circuit 23 and the second main oil circuit 24, so that the fuel can be sprayed out from the first injection hole 2301 and the second injection hole 2401.

[0045] The first oil injection holes 2301 and the second oil injection holes 2401 are arranged in two rows, staggered and evenly spaced in the circumferential direction on the outer wall of the venturi tube 25 .

[0046] In order to reduce the mutual influence between the first fuel injection hole 2301 and the second fuel injection hole 2401 and improve the atomization effect of the fuel in this embodiment, the first fuel injection hole 2301 and the second fuel injection hole 2401 are arranged in a circumferentially staggered distribution; the first fuel injection hole 2301 and the second fuel injection hole 2401 are arranged in different axial directions of the venturi 25, so that the first fuel injection hole 2301 and the second fuel injection hole 2401 are in a front-to-back distribution state, ensuring that the fuel can be evenly sprayed from the surface of the venturi 25, and at the same time, the swirling air generated by the secondary axial swirler 26 is used to shear the sprayed fuel and carry it to the combustion area to achieve sufficient atomization of the fuel.

[0047] The first fuel injection hole 2301 and the second fuel injection hole 2401 are arranged in a front-to-rear circumferential staggered manner to effectively reduce the interaction between the front and rear rows of fuel injection holes, so that the fuel sprayed from the second fuel injection hole 2401 can still be subjected to sufficient aerodynamic force, thereby enhancing the atomization effect.

[0048] The number of the first fuel injection holes 2301 and the second fuel injection holes 2401 are both 10-20, and the diameter of the first fuel injection holes 2301 and the second fuel injection holes 2401 are 0.3 mm-0.6 mm.

[0049] Preferably, the diameters and numbers of the first fuel injection holes 2301 and the second fuel injection holes 2401 on the surface of the venturi tube 25 can be reasonably adapted to meet the demand for higher fuel flow under low oil pressure conditions.

[0050] The primary axial swirler 22 and the secondary axial swirler 26 are both blade-type swirlers, and the primary axial swirler 22 and the secondary axial swirler 26 have the same or opposite rotation directions.

[0051] The primary axial swirler 22 and the secondary axial swirler 26 provided in the present embodiment are both prior art and are blade-type swirlers.

[0052] It also includes a casing 3 , one end of which is provided with a diffuser 1 , and the flame tube 4 is located inside the casing 3 .

[0053] The centrifugal nozzle 21 provided in the present technical solution adopts a low-pressure fuel atomizing nozzle. When the engine is started, the controller issues an ignition command, and the air from the diffuser 1 enters the first-stage axial swirler 22 through the head of the flame tube 4. At the same time, the centrifugal nozzle 21 in the central duty area supplies oil, and the oil mist cone flows to the outlet of the venturi 25 under the influence of the swirling air of the first-stage axial swirler 22, and then the air flowing out of the second-stage axial swirler 26 impacts the first-stage swirling air, thereby strengthening the atomization and constructing a reasonable heat recirculation zone. Then, the oil-gas mixture near the nozzle outlet is ignited, and a stable duty flame is formed under the action of the recirculation zone.

[0054] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fuel atomization device for a small-sized high-temperature combustion chamber, characterized in that: The invention comprises a primary axial swirler (22), a secondary axial swirler (26) and a centrifugal nozzle (21), wherein the primary axial swirler (22) and the secondary axial swirler (26) are coaxially mounted on the head of a flame tube (4), the centrifugal nozzle (21) is located inside the primary axial swirler (22), a venturi (25) is further arranged between the secondary axial swirler (26) and the primary axial swirler (22), a plurality of first fuel injection holes (2301) and second fuel injection holes (2401) are arranged on the circumferential outer wall of the venturi (25), and the airflow passing through the secondary axial swirler (26) can atomize the fuel sprayed from the first fuel injection holes (2301) and the second fuel injection holes (2401).

2. A fuel atomization device for a small-sized high-temperature combustion chamber according to claim 1, characterized in that: The venturi (25) is provided with a first main oil supply channel (2302) and a first main oil supply ring (2303); the first main oil supply channel (2302) is distributed axially along the venturi (25), and the first main oil supply channel (2302) is connected to the first main oil supply ring (2303); the first main oil supply ring (2303) is circumferentially distributed in the venturi (25), and the first oil injection holes (2301) are all connected to the first main oil supply ring (2303).

3. A fuel atomization device for a small-sized high-temperature combustion chamber according to claim 2, characterized in that: The venturi (25) is provided with a second main oil supply channel (2402) and a second main oil supply ring (2403); the second main oil supply channel (2402) is distributed axially along the venturi (25), and the second main oil supply channel (2402) is connected to the second main oil supply ring (2403); the second main oil supply ring (2403) is circumferentially distributed in the venturi (25), and the second oil injection holes (2401) are all connected to the second main oil supply ring (2403).

4. The fuel combination atomization device for a small-sized high-temperature rise combustion chamber according to claim 3, characterized in that: A first main oil circuit (23) and a second main oil circuit (24) are also provided between the first-stage axial swirler (22) and the second-stage axial swirler (26); the first main oil circuit (23) is connected to the first main oil circuit oil supply channel (2302), and the second main oil circuit (24) is connected to the second main oil circuit oil supply channel (2402).

5. The fuel combination atomization device for a small-sized high-temperature rise combustion chamber according to claim 1, characterized in that: The first oil injection holes (2301) and the second oil injection holes (2401) are distributed in two rows circumferentially and staggered at equal intervals on the outer wall of the venturi tube (25).

6. The fuel combination atomization device for a small-sized high-temperature rise combustion chamber according to claim 1, characterized in that: The number of the first fuel injection holes (2301) and the second fuel injection holes (2401) are both 10-20, and the diameters of the first fuel injection holes (2301) and the second fuel injection holes (2401) are 0.3 mm-0.6 mm.

7. The fuel combination atomization device for a small-sized high-temperature rise combustion chamber according to claim 1, characterized in that: The first-stage axial swirler (22) and the second-stage axial swirler (26) are both blade-type swirlers, and the first-stage axial swirler (22) and the second-stage axial swirler (26) have the same or opposite rotation directions.

8. The fuel combination atomization device for a small-sized high-temperature rise combustion chamber according to claim 1, characterized in that: It also comprises a casing (3), one end of which is provided with a diffuser (1), and the flame tube (4) is located inside the casing (3).

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