Liquid oxygen and kerosene pintle injection equipment based on impact mixed flow and its starting method

Abstract

The present invention belongs to the technical field of liquid oxygen rocket engines, and specifically discloses a liquid oxygen-kerosene pintle injection device based on impact mixed flow and a starting method thereof, so as to solve the problems of complex structural design, complex processing technology and high cost of existing direct current or centrifugal injection generators; the present invention comprises a pintle injector, a generator, an igniter channel, a kerosene circulation channel and a liquid oxygen circulation channel; the pintle injector comprises a center tube, a center rod and a shell; a kerosene circulation channel is formed between the center tube and the center rod; a liquid oxygen circulation channel is formed between the center tube and the shell; the generator comprises a head and a combustion chamber; the igniter channel comprises a gunpowder igniter gas channel; the present invention proposes a gunpowder ignition scheme suitable for the pintle injector based on the unique structural characteristics and combustion flow field characteristics of the pintle injector, which has a simple structure and reliable ignition.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid oxygen rocket engines, and in particular relates to liquid oxygen-kerosene pintle injection equipment based on impact mixed flow and a starting method thereof. Background Art

[0002] Pintle injectors originated in the mid-1950s at the Jet Propulsion Laboratory in the United States, where they conducted experimental studies on the mixing and combustion reaction times of liquid hypergolic propellants. They are now widely used in variable-thrust and fixed-thrust liquid rocket engines. Liquid oxygen / kerosene propellants have high density and specific impulse, making them an optimal choice for the first stage of launch vehicles. Pintle injector thrust chambers using liquid oxygen / kerosene propellants have broad application prospects, particularly in the recovery and reuse of first-stage launch vehicles, significantly reducing launch costs.

[0003] Liquid oxygen-kerosene is a non-hypergolic propellant, and reliable ignition is essential for the reliable operation of LOX-kerosene-based pintle injectors. Common ignition methods for LOX-kerosene propellants include ignition agent ignition, torch ignition, and gunpowder ignition. Ignition agent ignition solutions have complex supply systems and require a portable ignition agent cartridge and supply system, while gunpowder ignition solutions offer a simpler installation structure and reliable ignition. Gunpowder ignition solutions are widely used in centrifugal and DC injector thrust chambers. However, the pintle injector's centrally mounted, single-nozzle design significantly differs from DC and centrifugal nozzles in its combustion flow field structure. While centrifugal and DC injectors offer uniform flow intensity distribution, this is less common in pintle injectors. Furthermore, pintle injectors exhibit significant flow gradients, making ignition more challenging. Summary of the Invention

[0004] In order to solve the problems of complex structural design, complex processing technology and high cost of existing direct current or centrifugal injection generators, the present invention provides a liquid oxygen and kerosene pintle injection device based on impact mixed flow and a starting method thereof.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The liquid oxygen and kerosene pintle injection device based on impact mixed flow includes a pintle injector, which includes a center tube, a center rod and a shell; a liquid oxygen flow channel is formed between the center tube and the shell; a kerosene flow channel is formed between the center tube and the center rod; and main and auxiliary kerosene nozzles are evenly arranged around the side surface of the rear end of the center tube.

[0007] The generator includes an upper cover, a shell, and a combustion chamber connected in sequence from front to back. The shell is connected to the end of the combustion chamber, and an upper cover is provided at the other end of the combustion chamber.

[0008] The igniter channel includes a powder igniter gas channel provided on the outer side of the upper cover, and a connecting flange is provided at the outer end of the powder igniter gas channel;

[0009] The kerosene flow channel and the liquid oxygen flow channel have an outlet corresponding to each other, forming a collision mixing flow area.

[0010] On the basis of the above technical solutions, the present invention also provides the following optional technical solutions:

[0011] In an optional scheme: the kerosene circulation channel includes a collector for introducing kerosene on the combustion chamber, a regenerative cooling interlayer arranged in the combustion chamber and the shell, and a kerosene channel arranged between the upper cover and the center tube; the kerosene jets from the kerosene main and auxiliary nozzles collide with the liquid oxygen in the axial jet of the liquid oxygen injection annular seam to form a spray fan, one end of the regenerative cooling interlayer is connected to the collector, and the other end thereof is connected to the shell.

[0012] In an optional solution, the outer diameter of the central tube located at one end close to the liquid oxygen injection annular gap is the same as the outer diameter of the central tube at one end of the kerosene main and auxiliary nozzles.

[0013] In an optional solution: the two layers of staggered spray fans impact the inner wall of the combustion chamber to form two staggered cooling rings.

[0014] In an optional solution, the axis of the pyrotechnic igniter gas channel forms an angle α° with the axis of the combustion chamber, α°=10°-30°, and the distance D between the inner extension line of the pyrotechnic igniter gas channel and the outer edge of the center tube is D=10mm-30mm;

[0015] The angle between the spray fan and the axis of the combustion chamber is β°, β°=60°~80°.

[0016] In an optional solution: the kerosene passage further includes a kerosene pre-injection pressure-controlled pipe nozzle for pressure measurement and a kerosene pre-injection pulse pressure-measurement pipe nozzle for pulsating pressure measurement, which are arranged on the upper cover;

[0017] The liquid oxygen channel further comprises a liquid oxygen pre-spray pulsation pressure measuring nozzle and a liquid oxygen pre-spray pressure measuring nozzle arranged on the shell for pulsation pressure measurement.

[0018] In the optional solution: three evenly distributed reinforcing ribs are provided on the center tube, which are used for locking and supporting the center tube and the center rod with self-locking nuts; the upper cover, center tube and shell are fixed by standard bolts; a graphite sealing ring is provided between the upper cover and the center tube for sealing; a rubber ring is provided between the upper cover and the shell for sealing; a pan-seal sealing ring is provided between the center tube and the shell for low-temperature sealing, and an opening adjustment gasket is crimped between the center tube and the shell to adjust the throttling area of ​​the liquid oxygen flow channel.

[0019] In the optional solution: the combustion chamber, the shell, the center tube, and the upper cover are all based on additive manufacturing + fine processing; the combustion chamber is welded to the inner wall surface of the shell, and the outer wall surface is welded into a whole through a connecting ring.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention designs a gunpowder ignition scheme suitable for the pintle injector based on its unique structural characteristics and combustion flow field characteristics, which has a simple structure and reliable ignition.

[0022] 2. The liquid oxygen-kerosene pintle injection equipment based on impact mixed flow proposed in the present invention has a simpler structure, lower processing cost, higher structural reliability and can be reused multiple times compared to direct current chamber injectors and centrifugal injectors.

[0023] 3. The liquid oxygen-kerosene pintle injection equipment based on impact mixed flow proposed in the present invention is provided with a cavity reversal hole between the oxygen pre-spray chamber and the liquid oxygen collecting ring. This can ensure that the pre-spray chamber is as small as possible while simultaneously meeting the requirements of shortening the startup process of the gas-liquid injection process and injection uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1-1 A schematic diagram of the structure of one side of the liquid oxygen-kerosene pintle injection equipment based on impingement mixed flow of the present invention;

[0025] Figure 1-2 The other side structural diagram of the liquid oxygen-kerosene pintle injection equipment based on impingement mixed flow of the present invention;

[0026] Figure 1-3 A schematic diagram of the end structure of the liquid oxygen-kerosene pintle injection device based on impingement mixed flow according to the present invention;

[0027] Figure 2 Schematic diagram of the combustion chamber structure of the liquid oxygen-kerosene pintle injection equipment based on impingement mixed flow of the present invention;

[0028] Figure 3 Schematic diagram of the connecting ring structure in the liquid oxygen-kerosene pintle injection equipment based on impingement mixed flow of the present invention;

[0029] Figure 4-1 A schematic structural diagram of one side of the shell of the liquid oxygen-kerosene pintle injection device based on impingement mixed flow according to the present invention;

[0030] Figure 4-2 A schematic diagram of the structure of the other side of the shell in the liquid oxygen-kerosene pintle injection device based on impingement mixed flow of the present invention;

[0031] Figure 4-3 Axonometric drawing of the housing of the liquid oxygen-kerosene pintle injection device based on impact mixed flow of the present invention;

[0032] Figure 5 Schematic diagram of the structure of the opening adjustment gasket in the liquid oxygen-kerosene needle injection equipment based on impact mixed flow of the present invention;

[0033] Figure 6 Schematic diagram of the central tube structure of the liquid oxygen-kerosene pintle injection equipment based on impact mixed flow of the present invention;

[0034] Figure 7-1 A schematic structural diagram of the upper side of the upper cover of the liquid oxygen-kerosene pintle injection device based on impact mixed flow according to the present invention;

[0035] Figure 7-2 A schematic structural diagram of the bottom of the upper cover in the liquid oxygen-kerosene pintle injection device based on impact mixed flow according to the present invention;

[0036] Figure 8 Schematic diagram of the guide cone structure in the liquid oxygen-kerosene pintle injection equipment based on impact mixed flow of the present invention;

[0037] Figure 9-1 Schematic diagram of the central rod structure in the liquid oxygen-kerosene pintle injection equipment based on impact mixed flow of the present invention;

[0038] Figure 9-2 A schematic structural diagram of the arrangement of the self-impact cooling nozzles in the liquid oxygen-kerosene pintle injection equipment based on impingement mixed flow according to the present invention;

[0039] Figure 10 Schematic diagram of the vibration measuring support structure in the liquid oxygen-kerosene pintle injection equipment based on impact mixed flow of the present invention;

[0040] Figure 11 A schematic diagram of the positioning key structure in the liquid oxygen-kerosene needle injection equipment based on impact mixed flow of the present invention.

[0041] Reference numerals: 01-combustion chamber; 02-connecting ring; 03-housing; 04-opening adjustment gasket; 05-center tube; 06-upper cover; 07-guide cone; 08-center rod; 09-vibration test support; 10-positioning key; 11-panel seal; 12-graphite seal; 13-self-locking nut; 14-rubber ring; 15-standard bolt; 011-gas outlet; 012-collector pressure measuring nozzle; 013-kerosene inlet; 014-collector; 015-combustion chamber regenerative cooling interlayer; 031-liquid oxygen collector pulsation pressure measuring nozzle; 032-propellant igniter gas channel; 0 33-shell drainage pipe; 034-liquid oxygen inlet; 035-shell regenerative cooling interlayer; 036-liquid oxygen collecting ring; 037-liquid oxygen pre-spray pressure measuring nozzle; 038-chamber pressure measuring nozzle; 039-liquid oxygen discharge trough; 051-kerosene main and auxiliary nozzles; 052-reinforcement ribs; 053-kerosene discharge trough; 054-liquid oxygen injection annular seam; 061-kerosene pre-spray pressure measuring nozzle; 062-kerosene pre-spray pulsating pressure measuring nozzle; 063-U-shaped reflux chamber on the upper cover; 064-flow equalization network; 081-self-impact cooling nozzle; 082-positioning groove; 083-locking thread; 084-spray fan. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0043] Figure 1- Figure 11 As shown, an embodiment of the present invention provides a liquid oxygen-kerosene pintle injection device based on impact mixed flow, including a pintle injector, a thrust chamber, a powder igniter gas channel, a liquid oxygen flow channel, and a kerosene flow channel;

[0044] The pintle injector includes a center tube 05, a center rod 08, and a self-locking nut 13, all of which are rotating bodies. The center tube 05 is fixed to the center rod 08 via a positioning key 10 and a self-locking nut 13. Three evenly distributed reinforcing ribs 052 are provided on the center tube 05 to provide support for the self-locking nut 13 to lock the center tube 05 and the center rod 08. The rear end of the center tube 05 is machined with main and auxiliary kerosene nozzles 051. Kerosene enters through the center tube 05, and the center tube 05 and the center rod 08 are assembled to form a kerosene circulation channel. The locking thread 083 at the upper end of the center rod and the self-locking nut 13 are coated with glue to prevent loosening. The material of the center rod 08 is a high-temperature alloy. The pintle head is equipped with two circles of self-striking cooling nozzles 081 to effectively cool the end of the center rod 08.

[0045] The generator consists of a top cover (06), a center tube (05), a shell (03), and a combustion chamber (01), all connected from front to back. All are manufactured using additive manufacturing and precision machining. The combustion chamber (01) is welded to the inner wall of the shell (03), and the outer wall is welded to form a single unit via a connecting ring (02).

[0046] The upper cover 06, the center tube 05 and the shell 03 are fixed by standard bolts 15. A graphite sealing ring 12 is provided between the upper cover 06 and the center tube 05 for sealing. A rubber ring 14 is provided between the upper cover 06 and the shell 03 for sealing. A wide-seal sealing ring 11 is provided between the center tube 05 and the shell 03 for low-temperature sealing. An opening adjustment gasket 04 is crimped between the center tube 05 and the shell 03 to adjust the throttling area of ​​the liquid oxygen flow channel.

[0047] As shown in Figure 1, multiple main and auxiliary nozzles 051 are evenly distributed between the center rod 08 and the rear end surface of the center tube 05. The outer diameter of the center tube 05 located near the liquid oxygen injection annular gap 054 is the same as the outer diameter of the center tube 05 near the kerosene main and auxiliary nozzles 051.

[0048] As shown in Figure 1, the axis of the powder igniter gas channel 032 forms an angle α° with the axis of the combustion chamber 01, α° = 10° ~ 30°, and the distance D between the inner extension line of the powder igniter gas channel 032 and the outer edge of the center tube 05 is D = 10mm ~ 30mm, which ensures that the ignition agent is sprayed into the area of ​​the spray fan with relatively good atomization and appropriate mixing ratio during ignition, which is conducive to reliable ignition.

[0049] When the generator is started, the oxygen-rich gas from the powder igniter is injected into the combustion chamber 01 along the axis through the powder igniter gas channel 032, and contacts the small amount of kerosene in the radial kerosene nozzle jet and the liquid oxygen in the axial jet. The kerosene starts to burn with the liquid oxygen under the heating of the high-temperature flame, and the generator completes the ignition.

[0050] As shown in Figure 1, the kerosene circulation channel includes a kerosene inlet 013 entering the collector 014, a combustion chamber regenerative cooling interlayer 015, a shell regenerative cooling interlayer 035, a shell drainage pipe 033, and an upper cover U-shaped reflux cavity 063. It enters from the upper end of the central tube 05, and the main and auxiliary kerosene nozzles 051 jets are evenly arranged in a circle between the central tube 05 and the central rod 08, forming a complete kerosene channel.

[0051] After liquid oxygen and kerosene enter the generator, they collide to form spray fan 084, which has an angle α with the thrust chamber axis. α is obtained by calculating the injection parameters. The impact point between spray fan 084 and the inner wall of combustion chamber 01 forms two staggered cooling rings.

[0052] The regenerative cooling interlayer arranged in the combustion chamber 01 and the shell 03 is connected to the collector 014 at one end and to the kerosene main and auxiliary nozzles 051 formed by the central tube 05 and the central rod 08 at the other end.

[0053] The pre-injection cavity should be as small as possible to shorten the gas-liquid injection process during the startup process and improve the thermal protection of the combustion chamber. A small pre-injection cavity will lead to poor uniformity, and the injection uniformity is ensured by the liquid oxygen cavity hole.

[0054] As shown in Figures 4 and 7, a liquid oxygen collector pressure measuring nozzle 037 is provided on the shell 03, a room pressure measuring nozzle 038 is provided on the shell 03, a collector pressure measuring nozzle 012 is provided on the collector 014, and a liquid oxygen pre-spray pressure measuring nozzle 061 is provided on the upper cover 06, which are respectively used to measure the pressure at various locations, detect the flow resistance, and ensure the operation of the generator.

[0055] The method for starting the liquid oxygen-kerosene pintle injection device based on impingement mixed flow comprises the following steps:

[0056] Step 1: The kerosene in the kerosene flow channel passes through the collector 014, the combustion chamber regenerative cooling interlayer 015, the shell regenerative cooling interlayer 035, the shell drainage pipe 033, and the upper cover U-shaped reflux cavity 063, and enters from the upper end of the central tube 05. The main and auxiliary kerosene nozzle jets are evenly arranged in a circle between the central tube 05 and the central rod 08;

[0057] Step 2: Liquid oxygen enters the liquid oxygen collector 036 from the liquid oxygen inlet 034, enters the liquid oxygen injection annular gap 054 through the liquid oxygen collecting annular cavity, and the axial jet of liquid oxygen collides with the kerosene jets from the kerosene main and auxiliary nozzles to form a spray fan 084, wherein the impact point of the spray fan and the inner wall of the combustion chamber is offset to form two cooling rings;

[0058] Step 3: The oxygen-rich gas from the powder igniter is injected into the combustion chamber 01 along the axis through the powder igniter gas channel 032, and contacts with a small amount of kerosene in the radial kerosene nozzle jet and liquid oxygen in the axial jet to achieve ignition.

[0059] Furthermore, in step 2, after the generator is turned off, the residual liquid oxygen in the liquid oxygen injection annular gap 054 is blown away by nitrogen. At intervals of 0.2 to 0.5 seconds, the residual kerosene in the central barrel is statically blown away by nitrogen, providing conditions for the secondary start-up of the generator.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit 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. Liquid oxygen and kerosene pintle injection equipment based on impingement mixed flow, characterized by: The invention comprises a pintle injector, which comprises a central tube (05), a central rod (08) and a shell (03); a liquid oxygen flow channel is formed between the central tube (05) and the shell (03); a kerosene flow channel is formed between the central tube (05) and the central rod (08); and main and auxiliary kerosene nozzles (051) are evenly arranged around the rear end side of the central tube (05); The generator comprises an upper cover (06), a shell (03), and a combustion chamber (01) connected in sequence from front to back, the shell (03) being connected to the end of the combustion chamber (01), and an upper cover (06) being provided at the other end of the combustion chamber (01); An igniter channel includes a powder igniter gas channel (032) arranged outside the upper cover (06), and a connecting flange is provided at the outer end of the powder igniter gas channel (032); The kerosene flow channel and the liquid oxygen flow channel have an outlet corresponding to each other to form a collision mixing flow area; The kerosene circulation channel includes a collector (014) for introducing kerosene on the combustion chamber (01), a regenerative cooling interlayer arranged in the combustion chamber (01) and the shell (03), and a kerosene channel arranged between the upper cover (06) and the central tube (05); the kerosene jets from the kerosene main and auxiliary nozzles (051) collide with the liquid oxygen jets from the axial line of the liquid oxygen injection annular gap (054) to form a spray fan (084); one end of the regenerative cooling interlayer is connected to the collector (014), and the other end thereof is connected to the shell (03).

2. The liquid oxygen-kerosene pintle injection equipment based on impinging mixed flow according to claim 1, characterized in that: The outer diameter of the center tube (05) located at one end close to the liquid oxygen injection annular gap (054) is the same as the outer diameter of the center tube (5) located at one end close to the kerosene main and auxiliary nozzles (051).

3. The liquid oxygen-kerosene pintle injection equipment based on impinging mixed flow according to claim 2, characterized in that: The two-layer offset spray fan (084) impacts the inner wall of the combustion chamber (01) to form two offset cooling rings.

4. The liquid oxygen-kerosene pintle injection equipment based on impinging mixed flow according to claim 3 is characterized in that: The axis of the powder igniter gas channel (032) forms an angle α° with the axis of the combustion chamber (01), α°=10°~30°, and the distance D between the inner extension line of the powder igniter gas channel (032) and the outer edge of the center tube (05) is D=10mm~30mm; The angle between the spray fan (084) and the axis of the combustion chamber (01) is β°, where β°=60°~80°.

5. The liquid oxygen-kerosene pintle injection equipment based on impingement mixed flow according to claim 4, characterized in that: The kerosene passage further comprises a kerosene pre-spray pressure-connecting nozzle (061) for pressure measurement and a kerosene pre-spray pulse pressure-measuring nozzle (062) for pulse pressure measurement, which are arranged on the upper cover (06).

6. The liquid oxygen-kerosene pintle injection equipment based on impinging mixed flow according to claim 5, characterized in that: The central tube (05) is fixedly assembled with the central rod (08) via a positioning key (10) and a self-locking nut (13); The central tube (05) is provided with three evenly distributed reinforcing ribs (052) for the self-locking nut (13) to lock and support the central tube (05) and the central rod (08); The upper cover (06), the central tube (05) and the shell (03) are fixed by standard bolts (15); a graphite sealing ring (12) is provided between the upper cover (06) and the central tube (05) for sealing; a rubber ring (14) is provided between the upper cover (06) and the shell (03) for sealing; a universal sealing ring (11) is provided between the central tube (05) and the shell (03) for low-temperature sealing, and an opening adjustment gasket (04) is press-fitted between the central tube (05) and the shell (03) for continuously adjusting the throttling area of ​​the liquid oxygen flow channel.

7. A method for starting a liquid oxygen-kerosene pintle injection device based on impingement mixed flow according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: The kerosene in the kerosene flow channel enters the collector (014), the combustion chamber regeneration cooling interlayer (015), the shell regeneration cooling interlayer (035), the shell drainage pipe (033), the upper cover U-shaped reflux cavity (063), and enters from the upper end of the central tube (05). The main and auxiliary kerosene nozzles (051) are evenly arranged in a circle between the central tube (05) and the central rod (08); Step 2: Liquid oxygen enters the liquid oxygen collector (036) from the liquid oxygen inlet (034), enters the liquid oxygen injection ring gap (054) through the liquid oxygen collecting ring cavity, and collides with the kerosene radially jetted from the kerosene main and auxiliary nozzles (051) along the axial jet, forming a spray fan (084), wherein the impact point of the spray fan (084) and the inner wall of the combustion chamber (01) is offset to form two cooling rings; Step 3: The oxygen-rich gas from the powder igniter is injected into the combustion chamber (01) along the axis through the powder igniter gas channel (032), and contacts a small amount of kerosene from the radial kerosene nozzle to achieve ignition.

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