High-combustion and high-velocity oxygen-fuel spray gun device and working method therefor

Abstract

A high-combustion and high-velocity oxygen-fuel spray gun device, comprising a coaxial stabilizer (1), a combustion chamber (2), a coupler (4) and a gun barrel (8), wherein the front end of the combustion chamber (2) is of a Laval nozzle structure; the coaxial stabilizer (1) is hermetically connected to the rear end of the combustion chamber (2) and is provided with a bore pressure-measuring tube (9), an ignition needle (10), a fuel needle (11), a first oxygen input tube (12) and a second oxygen input tube (13); the coupler (4) is axially provided with a central through hole and an outer water-cooled through hole, one end of the coupler (4) is hermetically connected to an outlet of the Laval nozzle structure of the combustion chamber (2), and the other end of the coupler (4) is hermetically connected to the gun barrel (8) to integrally form a spray gun body; an inner axial through hole of the gun barrel (8) widens from the rear end to the front end; the interior of the combustion chamber (2), the central through hole of the coupler (4) and the interior of the gun barrel (8) jointly form a flame channel; a spray gun housing (3) is sleeved outside the combustion chamber (2); a gun barrel housing (7) is sleeved outside the gun barrel (8); two ends of the spray gun housing (3) are hermetically fixed to the coaxial stabilizer (1) and the coupler (4); two ends of the gun barrel housing (7) are hermetically fixed to ends of the coupler (4) and the gun barrel (8); a water-cooled channel is formed between the spray gun housing (3), the gun barrel housing (7) and the spray gun body; and the coupler (4) is radially provided with a powder feeding needle (6) to feed a carrier gas, which carries a spray powder, and hydrogen into the flame channel of the central through hole. Further disclosed is a working method for the high-combustion and high-velocity oxygen-fuel spray gun device. By introducing hydrogen and oxygen to carry out high-velocity combustion at the coupler (4), a bor

Description

A hypersonic flame spray gun device and its working method Technical Field

[0001] This invention relates to the field of supersonic flame spraying, specifically to a hypersonic flame spray gun device and method that further increases the pressure difference and temperature inside and outside the spray gun through supercombustion (supersonic combustion), thereby increasing the flame velocity. Background Technology

[0002] High-velocity oxygen fuel (HVOF) spraying is a thermal spraying method that uses the continuous combustion of oxygen and fuel as a heat source and kinetic energy, and employs a special spray gun structure to achieve a flame velocity exceeding the speed of sound. Due to its high particle velocity, short heating time, and effective suppression of oxidation, phase transformation, and decomposition processes in powder materials, HVOF produces coatings with high bonding strength, high density, and stable physicochemical properties. Furthermore, its high spraying efficiency and wide applicability to various spray materials have led to its rapid development and widespread application in the field of surface protection.

[0003] However, after decades of development, the flame jet speed of supersonic flame guns in industrial production has reached a bottleneck. Due to limitations such as combustion efficiency, pressure, and temperature, the flame speed is generally between Mach 6 and 8. The quality and performance of the coating are highly correlated with the flame jet speed, which seriously restricts the further development of surface coating protection in ultra-harsh environments such as aerospace and deep-sea exploration. It also seriously restricts the further breakthrough of coating protection in industrial applications in terms of extending the service life of parts.

[0004] Therefore, there is an urgent need for a device and method that can further improve the combustion efficiency, pressure and temperature of the spray gun, thereby further increasing the flame velocity of the high-velocity oxygen fuel spraying (HVOF) technology. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a hypersonic flame spray gun device and method, which can further increase the flame velocity through supersonic combustion, reaching Mach 10 or higher.

[0006] The technical solution adopted in this invention is as follows:

[0007] A hypersonic flame spray gun device includes: a coaxial stabilizer, a combustion chamber, a connector, and a barrel. The front end of the combustion chamber is a Laval nozzle structure. The coaxial stabilizer is sealed to the rear end of the combustion chamber and is equipped with a barrel pressure measuring tube, an ignition needle, a fuel needle, a No. 1 oxygen input pipe, and a No. 2 oxygen input pipe. The connector has a central through hole and an outer water-cooling through hole along the axial direction. One end of the connector is sealed to the outlet of the Laval nozzle structure of the combustion chamber, and the other end is sealed to the barrel. The whole device constitutes the spray gun body. The barrel is axially... The through-hole diffuses from the rear end to the front end. The interior of the combustion chamber, the central through-hole, and the interior of the gun barrel together form a flame channel. A spray gun shell is fitted outside the combustion chamber, and a gun barrel shell is fitted outside the gun barrel. The two ends of the spray gun shell are sealed and fixed to the coaxial stabilizer and coupling. The two ends of the gun barrel shell are sealed and fixed to the coupling and the end of the gun barrel. A water-cooling channel is formed between the spray gun shell, the gun barrel shell, and the spray gun body. A powder feeding needle is provided radially on the connector to feed carrier gas carrying spray powder and hydrogen into the flame channel of the central through-hole.

[0008] In the above technical solution, the coaxial stabilizer has multiple through holes inside, which are respectively sealed and connected to the barrel pressure measuring tube, ignition needle, fuel needle, oxygen input tube No. 1, and oxygen input tube No. 2. The two through holes for installing the fuel needle and oxygen input tube No. 1 intersect and converge inside the coaxial stabilizer, and merge into one through hole at the end near the combustion chamber.

[0009] Furthermore, the combustion chamber includes a large combustion space at the rear end and a Laval nozzle structure, which consists of a large space section, a contraction section, a throat, and an expansion section, enabling the flame ejected from the combustion chamber outlet to exceed the speed of sound.

[0010] Furthermore, the connector is also equipped with a three-way adapter, one end of which is sealed to the carrier gas pipe and serves as the carrier gas inlet, the other end of which is connected to the hydrogen pipe and serves as the hydrogen inlet, and the other end of which is connected to the powder feeding needle and serves as the outlet of the mixture of carrier gas and hydrogen, wherein the carrier gas contains spray powder.

[0011] Furthermore, the carrier gas supply pressure is required to be 1.2-1.6 MPa, and the hydrogen supply pressure is required to be 1.2-1.6 MPa.

[0012] Furthermore, the through hole along the axial direction of the barrel axis is in a diffused diameter-maintaining state along the flame jet direction. The diffuser section includes two diffuser sections with different diffuser angles. The barrel section near the connector has a larger diffuser angle, while the barrel section near the muzzle has a smaller diffuser angle.

[0013] Furthermore, the fuel output pressure in the fuel needle is required to be 1.5-2 MPa, the oxygen supply pressure in oxygen input pipe No. 1 is required to be 1.2-2 MPa, and the oxygen supply pressure in oxygen input pipe No. 2 is required to be 1.2-2 MPa.

[0014] The working method of the above-mentioned device includes the following steps:

[0015] 1) Start the cooling water circulation, start the fuel supply, start the carrier gas supply, and supply the oxygen flow rate of the oxygen input pipe No. 1 to the ignition gun parameters.

[0016] 2) Execute the ignition procedure, ignite the ignition needle, and simultaneously increase the fuel supply and oxygen supply of oxygen input pipe No. 1 according to the set fuel-oxygen ratio, so that the flame velocity of the spray gun reaches Mach 8.

[0017] 3) Turn on the oxygen supply of oxygen input pipe No. 2 and turn on the hydrogen supply. The hydrogen and carrier gas will converge and mix together and enter the flame channel of the connector. The flame speed in this section exceeds the speed of sound and is a supersonic flame. The hydrogen and oxygen will undergo ultra-high efficiency combustion in the supersonic flame, which will further increase the barrel pressure and flame temperature, thereby further increasing the speed of the flame jet from the spray gun, making the flame speed exceed Mach 10.

[0018] 4) Once the flame has stabilized, begin feeding powder and begin the spraying operation;

[0019] 5) After the spraying operation is completed, execute the gun stop procedure. First, stop the powder feeding, then stop the hydrogen supply and the oxygen supply of oxygen input pipe No. 2, then stop the fuel supply and the oxygen supply of oxygen input pipe No. 1. After the flame is extinguished, turn on the oxygen supply of oxygen input pipe No. 1 for a period of time and then turn it off. Finally, turn off the carrier gas.

[0020] The beneficial effects of this invention are as follows:

[0021] This invention innovatively adopts a hydrogen-oxygen supersonic combustion method, in which hydrogen and oxygen undergo an ultra-high-efficiency combustion reaction in a supersonic flame stream. This increases the pressure difference between the barrel and atmospheric pressure to 9-11 Bar and raises the flame temperature to about 3300 degrees Celsius, thus breaking through the conventional supersonic flame gun's flame stream speed of 6-8 Mach and increasing the flame stream speed of the supersonic flame gun to over 10 Mach.

[0022] Traditional methods of increasing combustion chamber space and supplying more fuel and oxygen to raise barrel pressure and flame temperature, thereby increasing flame velocity, present the following problems: Firstly, as the combustion chamber space increases, fuel and oxygen struggle to burn completely within a short time, especially in areas far from the ignition point. This severely limits combustion efficiency, consequently restricting the flame velocity. Secondly, the slow flame velocity in the combustion zone means that if excess calorific value is released here, the large combustion chamber hinders heat transfer, significantly reducing water cooling effectiveness. This results in an extremely high heat load on the combustion chamber, potentially leading to dangerous situations such as torch explosions.

[0023] This invention introduces hydrogen and oxygen to induce supersonic combustion at the connector. The supersonic flame rapidly transfers heat to the muzzle, converting it into kinetic energy, while avoiding excessive heat concentration and excessive heat load in the combustion chamber. Simultaneously, hydrogen, as a reducing gas, effectively inhibits the formation of brittle phases, improving coating quality. Furthermore, the use of a double-diffusion barrel allows for a more rapid release of higher flame internal energy, converting it into kinetic energy and further increasing the flame velocity, while also preventing excessive pressure and temperature concentration. Attached Figure Description

[0024] Figure 1 is a schematic diagram of a supersonic flame spray gun device according to an embodiment of the present invention.

[0025] Wherein: 1-Coaxial stabilizer, 2-Combustion chamber, 3-Spray gun housing, 4-Connector, 5-T-connector, 6-Powder feeding needle, 7-Barrel housing, 8-Barrel, 9-Burning chamber pressure measuring tube, 10-Ignition needle, 11-Fuel needle, 12-Oxygen input pipe No. 1, 13-Oxygen input pipe No. 2, 14-First fastening sleeve, 15-Water cooling inlet channel, 16-Water cooling outlet channel, 17-Second fastening sleeve, 18-Return water pipe, 19-Third fastening sleeve. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that the purpose and effects of the present invention become clearer. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0027] According to a specific embodiment of the present invention, as shown in FIG1, a schematic diagram of a hypersonic flame spray gun device is provided, including: a coaxial stabilizer, a combustion chamber, a connector, and a gun barrel, which together constitute the spray gun body. A spray gun outer shell is also fitted outside the combustion chamber, and a gun barrel outer shell is also fitted outside the gun barrel to construct a water cooling channel.

[0028] The coaxial stabilizer 1 has multiple through holes inside, which are respectively sealed and connected to the barrel pressure measuring tube 9, ignition needle 10, fuel needle 11, oxygen input tube 12 (No. 1), and oxygen input tube 13 (No. 2). The main function of the coaxial stabilizer 1 is to ensure stable, safe, and efficient combustion in the combustion chamber.

[0029] Furthermore, the two through holes for installing the fuel needle 11 and the oxygen input pipe 12 intersect and converge inside the coaxial stabilizer, and merge into one through hole at one end near the combustion chamber.

[0030] Furthermore, the coaxial stabilizer 1 is sealed and fixed to the rear end of the combustion chamber 2 (with the flame jet direction as the front), and is in close contact with the spray gun housing 3 through the first fastening sleeve 14 and sealed with a high-temperature resistant sealing ring.

[0031] The front end of the combustion chamber 2 is connected to one end of the connector 4 and sealed with a high-temperature O-ring. Furthermore, the combustion chamber 2 integrates a fully combusted space and a Laval nozzle structure, which, as shown in Figure 1, consists of a large space section (i.e., a section with a constant diameter), a contraction section, a throat, and an expansion section. The section with a constant diameter is the fully combusted space, and the contraction section, throat, and expansion section constitute the Laval nozzle structure. The combustion chamber 2 enables the flame jet ejected from its outlet to exceed the speed of sound.

[0032] Furthermore, because the temperature (up to about 3300°C) and pressure (9-11 Bar) of the combustion system of the spray gun of the present invention are higher than those of ordinary supersonic spray guns, the material of the combustion chamber 2 must be a material with a high melting point and high thermal conductivity. In this embodiment, pure copper material is used, and it is pure copper material that has undergone grain refinement and other related treatments to improve tensile strength.

[0033] The spray gun housing 3 is sealed to the connector 4 and then fastened by the second fastening sleeve 17.

[0034] The connector 4 has an axisymmetric structure. The axial through hole at the center of the axis is the flame channel. There are multiple axisymmetric axial through holes near the outside that are water cooling channels. There are two axisymmetric through holes in the radial direction that are carrier gas and hydrogen channels for inserting the powder feeding needle.

[0035] Furthermore, one end of the connector 4 is connected to the outlet of the combustion chamber 2 and sealed with a high-temperature O-ring, while the other end of the connector 4 is connected to the barrel 8 and sealed with a high-temperature O-ring. The interior of the combustion chamber, the axial through hole at the center of the connector shaft, and the interior of the barrel together form a flame channel. The main functions of the connector 4 are: firstly, to act as a transition system between the combustion chamber 2 and the barrel 8, sharing the combustion task of the combustion chamber 2, serving as the starting point for scramjet (supersonic combustion), further increasing the difference between the barrel pressure and atmospheric pressure, further increasing the flame temperature, and thus further increasing the flame velocity; secondly, to act as a clamp for fixing the input carrier gas and hydrogen device. Furthermore, the material of the connector 4 must also possess the same properties as the combustion chamber 2.

[0036] The powder feeding needle 6 is sealed and installed in the radial through hole of the connector 4. One end leads to the flame at the axis of the connector 4. The material of this section extending into the flame must have extremely high wear resistance and melting point, such as tungsten steel. The other end is securely and sealed to the outlet of the three-way adapter 5. One end of the three-way adapter 5 is sealed and connected to the carrier gas pipe, serving as the carrier gas inlet. The spray powder is carried in by the carrier gas. In this embodiment, nitrogen is used as the carrier gas at a pressure of 1.2-1.6 MPa. The second end is connected to the hydrogen pipe, serving as the hydrogen inlet at a pressure of 1.2-1.6 MPa. The third end is connected to the powder feeding needle 6, serving as the outlet for the nitrogen and hydrogen mixture.

[0037] The two ends of the barrel housing 7 are sealed to the connector 4 and the barrel 8 respectively, using high-temperature resistant O-rings for sealing. The connection between the barrel housing and the connector is secured by a third fastening sleeve 19. Furthermore, the space enclosed by the spray gun housing 3, coaxial stabilizer 1, combustion chamber 2, connector 4, barrel 8, and barrel housing 7 forms the water-cooling channel for the spray gun. In this embodiment, a return water pipe 18 is also provided. The flow direction of the cooling water in the spray gun's water-cooling channel is as follows: water-cooling inlet channel 15, the space enclosed by the combustion chamber 2, coaxial stabilizer 1, and spray gun housing 3, the cooling water channel of the connector 4, the space enclosed by the barrel 8 and barrel housing 7, return water pipe 18, and water-cooling outlet channel 16.

[0038] In this example, the barrel 8 is an axisymmetric hollow structure, with its rear end sealed to the connector 4. The through-hole along the axial direction of the barrel 8 diffuses outwards along the flame jet direction, with the diameter of the through-hole increasing progressively until it reaches the designed value and remains constant. In this embodiment, as shown in Figure 1, the two sections of the barrel 8 from left to right employ two different diffusion angles. The left section has a larger diffusion angle, which rapidly releases the internal energy of the flame stream into kinetic energy, preventing excessive concentration and high pressure and temperature in the superburning section. The right section has a smaller diffusion angle, which releases the internal energy of the flame stream more smoothly, continuously increasing the flame stream velocity. Compared to existing supersonic spray gun barrels, the diffuser structure of the barrel 8 can release higher levels of internal flame energy more rapidly, converting it into kinetic energy and further increasing the flame stream velocity.

[0039] The barrel pressure measuring tube 9 is sealed and installed in a through hole of the coaxial stabilizer 1. It is made of pure copper and its main function is to monitor the internal pressure of the spray gun.

[0040] The ignition needle 10 is sealed and installed in a through hole of the coaxial stabilizer 1. Its main function is to release the electric arc for ignition. Commonly used ignition needles on the market can be used.

[0041] The fuel needle 11 is sealed in the through hole at the shaft center of the coaxial stabilizer 1, and its outlet is also located in the through hole at the shaft center of the coaxial stabilizer 1. The fuel used in this embodiment is aviation kerosene, and the kerosene pressure is 1.5-2 MPa.

[0042] The oxygen input pipe 12 is installed in the through hole that intersects with the axial through hole of the coaxial stabilizer 1. It is a conventional combustion oxygen supply pipe with an oxygen input pressure of 1.2-2 MPa, preferably 1.5-1.8 MPa.

[0043] Furthermore, oxygen input pipe 12 supplies oxygen throughout the entire ignition and spraying process, maintaining a constant oxygen-fuel ratio to ensure complete combustion of the fuel.

[0044] Furthermore, the oxygen input through oxygen input pipe 12 also has the function of atomizing aviation kerosene.

[0045] The oxygen input pipe 13 is sealed and installed in a through hole of the coaxial stabilizer 1. Its main function is to further input oxygen and increase the oxygen content around the flame core. The oxygen input pressure is in the range of 1.2-2 MPa, preferably 1.5-1.8 MPa.

[0046] In the above scheme, the fastening sleeve is tightened by threading to press the contact between the coaxial stabilizer, combustion chamber, spray gun housing, connector or barrel housing, ensuring that they are not moved by the pressure inside the gun.

[0047] According to a specific embodiment of the present invention, the working method of the above-mentioned hypersonic flame spray gun device includes the following:

[0048] 1. Start the cooling water circulation, start the aviation kerosene supply, start the nitrogen supply, and supply oxygen flow rate to the ignition gun parameters via oxygen pipe input pipe 12 of oxygen pipe 1.

[0049] 2. Execute the ignition procedure. Ignition needle 10 is energized for ignition. The supply of aviation kerosene and the supply of oxygen in oxygen input pipe 12 are increased simultaneously according to a certain fuel-oxygen ratio, so that the flame velocity of the spray gun reaches the conventional Mach 8.

[0050] 3. Turn on the oxygen supply through oxygen input pipe 13 (No. 2) and the hydrogen supply, allowing the hydrogen and carrier gas to mix and enter the flame space of connector 4. The flame velocity in this section exceeds the speed of sound, constituting a supersonic flame. The hydrogen and oxygen undergo highly efficient combustion in the supersonic flame, further increasing the barrel pressure and flame temperature. This increases the pressure difference between the barrel and atmospheric pressure from the conventional 6-8 Bar to 9-11 Bar, and the flame temperature from the conventional 3000℃ to approximately 3300℃, thereby further increasing the velocity of the flame ejected from the spray gun to over Mach 10.

[0051] 4. Once the flame has stabilized, begin feeding powder and begin the spraying operation.

[0052] 5. After the spraying operation is completed, execute the gun shutdown procedure. First, stop the powder feeding, then stop the hydrogen supply and the oxygen supply of oxygen input pipe 13 (No. 2), then stop the aviation kerosene supply and the oxygen supply of oxygen input pipe 12 (No. 1). After the flame is extinguished, turn on the oxygen supply of oxygen input pipe 12 (No. 1) for a period of time and then turn it off. Finally, turn off the nitrogen supply.

Claims

1. A hypersonic flame spray gun device, characterized in that, include: The spray gun consists of a coaxial stabilizer, a combustion chamber, a connector, and a barrel. The combustion chamber has a Laval nozzle structure at its front end. The coaxial stabilizer is sealed to the rear end of the combustion chamber and includes a barrel pressure gauge, an ignition needle, a fuel needle, oxygen input pipe No. 1, and oxygen input pipe No.

2. The connector has an axially oriented central through-hole and an outer water-cooling through-hole. One end of the connector is sealed to the outlet of the Laval nozzle structure in the combustion chamber, and the other end is sealed to the barrel, forming the spray gun body. The axial through-hole inside the barrel diffuses from the rear end to the front end. The interior of the combustion chamber, the central through-hole, and the interior of the barrel together form a flame channel. A spray gun shell is fitted outside the combustion chamber, and a barrel shell is fitted outside the barrel. The two ends of the spray gun shell are sealed to the coaxial stabilizer and the connector, and the two ends of the barrel shell are sealed to the connector and the end of the barrel. A water-cooling channel is formed between the spray gun shell, the barrel shell, and the spray gun body. A powder feeding needle is radially provided on the connector to feed carrier gas carrying spray powder and hydrogen into the flame channel of the central through-hole.

2. The hypersonic flame spray gun device according to claim 1, characterized in that, The coaxial stabilizer has multiple through holes inside, which are respectively sealed and connected to the barrel pressure measuring tube, ignition needle, fuel needle, oxygen input tube No. 1, and oxygen input tube No.

2. Among them, the two through holes for installing the fuel needle and oxygen input tube No. 1 intersect and converge inside the coaxial stabilizer, and merge into one through hole at the end near the combustion chamber.

3. The hypersonic flame spray gun device according to claim 1, characterized in that, The combustion chamber includes a large combustion space at the rear end and a Laval nozzle structure, which consists of a large space section, a contraction section, a throat, and an expansion section, enabling the flame ejected from the combustion chamber outlet to exceed the speed of sound.

4. The hypersonic flame spray gun device according to claim 1, characterized in that, The connector is also equipped with a three-way adapter, one end of which is sealed to the carrier gas pipe and serves as the carrier gas inlet, the other end of which is connected to the hydrogen pipe and serves as the hydrogen inlet, and the other end of which is connected to the powder feeding needle and serves as the outlet of the mixture of carrier gas and hydrogen. The carrier gas contains spray powder.

5. The hypersonic flame spray gun device according to claim 4, characterized in that, The carrier gas supply pressure is required to be 1.2-1.6 MPa, and the hydrogen supply pressure is required to be 1.2-1.6 MPa.

6. The hypersonic flame spray gun device according to claim 1, characterized in that, The through hole along the axial direction of the barrel axis is in a diffused diameter-maintaining state along the flame jet direction. The diffuser section includes two diffuser sections with different diffuser angles. The barrel section near the connector has a larger diffuser angle, while the barrel section near the muzzle has a smaller diffuser angle.

7. The hypersonic flame spray gun device according to claim 1, characterized in that, The fuel output pressure in the fuel needle is required to be 1.5-2 MPa, the oxygen supply pressure in oxygen input pipe No. 1 is required to be 1.2-2 MPa, and the oxygen supply pressure in oxygen input pipe No. 2 is required to be 1.2-2 MPa.

8. The method of operating the apparatus according to any one of claims 1-7, characterized in that, Including the following: 1) Start the cooling water circulation, start the fuel supply, start the carrier gas supply, and supply the oxygen flow rate of the oxygen input pipe No. 1 to the ignition gun parameters. 2) Execute the ignition procedure, ignite the ignition needle, and simultaneously increase the fuel supply and oxygen supply of oxygen input pipe No. 1 according to the set fuel-oxygen ratio, so that the flame velocity of the spray gun reaches Mach 8. 3) Turn on the oxygen supply of oxygen input pipe No. 2 and turn on the hydrogen supply. The hydrogen and carrier gas will converge and mix together and enter the flame channel of the connector. The flame speed in this section exceeds the speed of sound and is a supersonic flame. The hydrogen and oxygen will undergo ultra-high efficiency combustion in the supersonic flame, which will further increase the barrel pressure and flame temperature, thereby further increasing the speed of the flame jet from the spray gun, making the flame speed exceed Mach 10. 4) Once the flame has stabilized, begin feeding powder and begin the spraying operation; 5) After the spraying operation is completed, execute the gun stop procedure. First, stop the powder feeding, then stop the hydrogen supply and the oxygen supply of oxygen input pipe No. 2, then stop the fuel supply and the oxygen supply of oxygen input pipe No.

1. After the flame is extinguished, turn on the oxygen supply of oxygen input pipe No. 1 for a period of time and then turn it off. Finally, turn off the carrier gas.

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