A torch-type electric igniter integrated on the thrust chamber injector

Abstract

The present invention relates to a torch-type electric igniter integrated on a thrust chamber injector, comprising an ignition chamber, an electric nozzle, a sealing ring, and a nut. The present invention integrates the torch igniter and the injector into an integrated design, wherein the ignition medium is directly derived from the oxidizer chamber and the fuel chamber of the thrust chamber injector, eliminating the ignition valve and the ignition pipeline, simplifying the ignition system and reducing the weight. The igniter fuel of the present invention is divided into two paths, one path enters the center of the ignition chamber through the igniter fuel nozzle for combustion, and the other path enters the igniter exhaust cooling annular gap through the radial hole to cool the inner wall of the ignition chamber. The flow rates of the two paths are independently controlled by the nozzle size and the annular gap size, which is conducive to the precise control of the igniter operating parameters. The use of exhaust cooling improves the structural thermal protection capability of the igniter under ignition and main stage operating conditions. The indentation of the outlet area promotes the secondary combustion of oxygen-rich fuel gas and exhaust cooling fuel, thereby improving the ignition energy.

Description

Technical Field

[0001] The invention relates to a torch-type electric igniter integrated on a thrust chamber injector, which is suitable for torch ignition of a hydrogen-oxygen rocket engine and can be used in the field of aerospace. Background Art

[0002] Reusable liquid rocket engines and high-performance upper stage engines both require a higher number of engine ignitions. Currently, a widely adopted solution is to use a torch-type electric igniter to replace the traditional solid powder igniter. The ignition medium for a torch igniter is generally drawn from the engine pump pipeline or high-pressure ignition gas cylinder, entering the igniter through the ignition pipeline and ignition valve. The igniter is installed as a separate component in the thrust chamber head. Some liquid-liquid igniters generally require a dedicated pre-cooling discharge valve and purge valve. The entire ignition system is relatively complex, with many components and heavy weight. Summary of the Invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the existing technology, to provide a torch-type electric igniter integrated on the thrust chamber injector of a hydrogen-oxygen rocket engine, to eliminate the ignition valve and ignition pipeline, to simplify the ignition system and to reduce the weight.

[0004] The technical solution of the present invention is:

[0005] A torch type electric igniter integrated on a thrust chamber injector, comprising: an ignition chamber 3, an electric nozzle 1, a sealing ring 2 and a nut 15;

[0006] The nozzle 1 is screwed onto the center of the upper end of the ignition chamber 3 and sealed with a sealing ring 2. The ignition chamber 3 is fixed to the first bottom 14 of the thrust chamber injector with a nut 15. The ignition chamber 3 is welded to the second bottom 10 and the third bottom 4 of the thrust chamber injector.

[0007] The injector fuel chamber 12 is located between the first bottom 14 and the second bottom 10, and the injector oxidant chamber 8 is located between the second bottom 10 and the third bottom 4;

[0008] The ignition chamber 3 is provided with an ignition chamber fuel nozzle 5, an ignition chamber fuel nozzle flow channel 7, an ignition chamber fuel nozzle inlet 9, an ignition chamber exhaust cooling inlet 11, an ignition chamber exhaust cooling annular gap 13 and an ignition chamber oxidant nozzle 17. An ignition chamber central combustion chamber 6 is axially provided at the center of the ignition chamber 3;

[0009] The fuel is injected from the injector fuel chamber 12 through the ignition chamber fuel nozzle inlet 9, the ignition chamber fuel nozzle flow channel 7, and the ignition chamber fuel nozzle 5 into the ignition chamber central combustion chamber 6. The oxidizer is injected along the injector oxidizer chamber 8 and the ignition chamber oxidizer nozzle 17 into the ignition chamber central combustion chamber 6. The oxidizer and fuel are atomized and mixed in the ignition chamber central combustion chamber 6 and ignited by the upper nozzle 1 to form a high-temperature oxygen-rich combustion gas that is discharged downstream of the ignition chamber.

[0010] The fuel flows from the injector fuel cavity 12, passes through the radially arranged ignition chamber discharge cooling inlet 11 and enters the ignition chamber discharge cooling annular gap 13 to cool the inner wall of the ignition chamber. This part of the fuel meets the high-temperature oxygen-rich combustion gas in the center of the ignition chamber in the indented area 16 of the ignition chamber outlet, and is supplementally burned to increase the ignition energy.

[0011] Furthermore, the ignition chamber discharge cooling inlets 11 are arranged in n1 layers, the number of the ignition chamber discharge cooling inlets 11 in each layer is n2, and the ignition chamber discharge cooling inlets 11 between layers form an angle of 360 / n1 / n2 degrees.

[0012] Furthermore, the total area of ​​the ignition chamber discharge cooling inlet 11 is not less than twice the area of ​​the cooling annular gap;

[0013] The total area of ​​the ignition chamber exhaust cooling inlet 11 refers to the sum of the cross-sectional areas of all the ignition chamber exhaust cooling inlets 11; the cooling annular gap area refers to the cross-sectional area of ​​the cooling annular gap.

[0014] Further,

[0015] The ignition chamber fuel nozzle 5 and the ignition chamber oxidant nozzle 17 are both direct current nozzles. There are two ignition chamber fuel nozzles 5 and two oxidant nozzles 17. The plane formed by the ignition chamber fuel nozzle 5 and the plane formed by the ignition chamber oxidant nozzle 17 are perpendicular to each other. The angle between the two ignition chamber fuel nozzles 5 is A, and the distance between the intersection of the fuel nozzle and the end face of the nozzle is d1; the angle between the two oxidant nozzles 17 is B, and the distance between the intersection of the oxidant nozzle and the end face of the nozzle is d2.

[0016] Furthermore, the angle A ranges from 90° to 150°, the angle B ranges from 90° to 150°, and A≤B≤A+20°, 0.3D≤d1=d2≤D, where D is the diameter of the fuel cavity 6 in the center of the ignition chamber.

[0017] Furthermore, after the oxidant and fuel are injected into the central fuel cavity 6 of the ignition chamber, they collide with each other and form a point in space.

[0018] Furthermore, the length L of the ignition chamber outlet retracted area 16 is in the range of 0.5D≤L≤1.5D.

[0019] Furthermore, the ignition chamber 3 is integrally formed by 3D printing to achieve the distribution of the ignition medium and the combustion of the torch.

[0020] Furthermore, after the ignition chamber 3 is processed, an independent gas-liquid flow screening inspection is carried out, and then it is welded to the second and third bottoms of the injector, and connected to the first bottom with a nut, becoming a part of the injector, which is used for ignition of the igniter and as a fire guide tube in the center of the injector.

[0021] Furthermore, the ignition chamber fuel nozzle flow rate is controlled by the ignition chamber fuel nozzle (5) hole size, and the ignition chamber exhaust cooling flow rate is controlled by the cooling ring gap size.

[0022] Furthermore, when the thrust chamber is ignited and started,

[0023] The thrust chamber oxidizer valve opens first, and the oxidizer flows into the injector oxidizer chamber and into the central combustion chamber of the ignition chamber through the ignition chamber oxygen nozzle;

[0024] The ignition nozzle starts to energize and ignite;

[0025] The thrust chamber fuel valve opens, and the fuel enters the injector fuel chamber and the ignition chamber fuel nozzle into the ignition chamber central combustion chamber, and mixes with the oxidant in the ignition chamber central combustion chamber to form a combustible mixture;

[0026] The combustible mixture is ignited by the spark emitted by the nozzle to form an oxygen-rich flame, which is supplemented by the discharged cooled fuel at the outlet of the ignition chamber to increase the ignition energy of the torch. The torch is sprayed into the inner cavity of the thrust chamber to ignite the thrust chamber.

[0027] The beneficial effects of the present invention compared with the prior art are:

[0028] (1) The torch-type electric igniter structure of the present invention is integrated into the injector. The ignition medium is directly derived from the fuel chamber and oxidizer chamber of the injector. No ignition pipeline and ignition valve are required, which greatly simplifies the ignition system and reduces the system weight.

[0029] (2) The ignition chamber of the present invention is produced by 3D printing, and the ignition chamber nozzle, ignition chamber fuel flow channel and exhaust cooling structure are directly printed in an integrated manner, with only one part. Compared with the multi-part welding scheme in the traditional torch-type electric igniter scheme, the ignition chamber structure is simplified; after the ignition chamber is produced, a gas-liquid flow test is carried out separately for inspection and screening, which is conducive to ensuring the mass production of igniter products and controlling the production quality of igniters.

[0030] (3) The igniter fuel of the present invention is divided into two paths. One path enters the center of the ignition chamber through the igniter fuel nozzle for combustion, and the other path enters the igniter discharge cooling annular gap through the radial hole to cool the inner wall of the ignition chamber. The flow rates of the two paths are independently controlled by the nozzle size and the annular gap size, which is conducive to the precise control of the igniter operating parameters.

[0031] (4) The igniter of the present invention adopts central oxygen-rich combustion. Since the flammable boundary of the fuel in the oxygen-rich range is wider than that in the rich combustion range, the igniter adopts central oxygen-rich combustion to improve the adaptability of the igniter to changes in ignition conditions, allowing the igniter inlet conditions to change within a certain range, thereby ensuring the ignition reliability of the igniter.

[0032] (5) The igniter of the present invention adopts a DC mutual impact nozzle, which is beneficial to the atomization and mixing of the oxidant and fuel.

[0033] (6) The igniter of the present invention adopts exhaust cooling, which improves the structural thermal protection capability of the igniter under ignition and main stage conditions. The indentation of the outlet area promotes the secondary combustion of oxygen-rich gas and exhaust cooling fuel, thereby improving the ignition energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a cross-sectional view of the igniter structure of the present invention Figure 1 ;

[0035] Figure 2 This is a cross-sectional view of the igniter structure of the present invention Figure 2

[0036] Figure 3 for Figure 1 Cross-section along BB and CC.

[0037] Among them: 1. Nozzle; 2. Sealing ring; 3. Ignition chamber; 4. Three bottoms; 5. Ignition chamber fuel nozzle; 6. Ignition chamber central combustion chamber; 7. Ignition chamber fuel nozzle flow channel; 8. Injector fuel chamber; 9. Ignition chamber fuel nozzle inlet; 10. Second bottom; 11. Ignition chamber discharge cooling inlet; 12. Injector fuel chamber; 13. Ignition chamber discharge cooling ring gap; 14. First bottom; 15. Nut; 16. Indentation area; 17. Ignition chamber oxygen nozzle. DETAILED DESCRIPTION

[0038] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0039] The present invention aims to simplify the ignition system and reduce its weight. Based on the above background, the present invention designs a torch-type electric igniter structure integrated with the thrust chamber injector. Specifically, the torch igniter and injector are designed as an integrated whole. The ignition medium is directly derived from the oxidizer and fuel chambers of the thrust chamber injector, eliminating the ignition valve and ignition piping, simplifying the ignition system and reducing its weight.

[0040] like Figure 1 and Figure 2 As shown, the torch igniter integrated in the injector designed by the present invention includes an ignition chamber 3, an electric nozzle 1, a sealing ring 2 and a nut 15.

[0041] The nozzle 1 is screwed onto the center of the upper end of the ignition chamber 3 and sealed with a sealing ring 2. The ignition chamber 3 is fixed to the first bottom 14 of the thrust chamber injector with a nut 15. The ignition chamber 3 is welded to the second bottom 10 and the third bottom 4 of the thrust chamber injector.

[0042] The injector fuel chamber 12 is located between the first bottom 14 and the second bottom 10, and the injector oxidant chamber 8 is located between the second bottom 10 and the third bottom 4;

[0043] The ignition chamber 3 is provided with an ignition chamber fuel nozzle 5, an ignition chamber fuel nozzle flow channel 7, an ignition chamber fuel nozzle inlet 9, an ignition chamber exhaust cooling inlet 11, an ignition chamber exhaust cooling annular gap 13 and an ignition chamber oxidant nozzle 17. An ignition chamber central combustion chamber 6 is axially provided at the center of the ignition chamber 3;

[0044] The fuel is injected from the injector fuel chamber 12 through the ignition chamber fuel nozzle inlet 9, the ignition chamber fuel nozzle flow channel 7, and the ignition chamber fuel nozzle 5 into the ignition chamber central combustion chamber 6; the oxidant is injected along the injector oxidant chamber 8 and the ignition chamber oxidant nozzle 17 into the ignition chamber central combustion chamber 6, as shown in FIG. Figure 2 As shown; the oxidant and fuel are atomized and mixed in the combustion chamber 6 at the center of the ignition chamber, and are ignited by the electric nozzle 1 above to form a high-temperature oxygen-rich combustion gas that is discharged downstream of the ignition chamber;

[0045] The fuel flows from the injector fuel cavity 12, passes through the radially arranged ignition chamber discharge cooling inlet 11 and enters the ignition chamber discharge cooling annular gap 13 to cool the inner wall of the ignition chamber. This part of the fuel meets the high-temperature oxygen-rich combustion gas in the center of the ignition chamber in the indented area 16 of the ignition chamber outlet, and is supplementally burned to increase the ignition energy.

[0046] like Figure 3 As shown, the ignition chamber discharge cooling inlet 11 is provided with n1 layers (generally 1 to 3), and the number of radial holes (i.e., the ignition chamber discharge cooling inlet 11) in each layer is n2 (generally 4 to 8), and the radial holes between layers form an angle of 360 / n1 / n2 degrees. The total area of ​​the radial holes is required to be no less than twice the area of ​​the cooling ring gap.

[0047] The total area of ​​the ignition chamber exhaust cooling inlet 11 refers to the sum of the cross-sectional areas of all the ignition chamber exhaust cooling inlets 11; the cooling annular gap area refers to the cross-sectional area of ​​the cooling annular gap.

[0048] The ignition chamber fuel nozzle 5 and the ignition chamber oxidant nozzle 17 are both straight-flow nozzles.

[0049] There are two ignition chamber fuel nozzles 5 and two oxidant nozzles 17, and the number of nozzles can be increased as needed. The plane formed by the ignition chamber fuel nozzles 5 and the plane formed by the ignition chamber oxidant nozzles 17 are perpendicular to each other. The angle between the two fuel nozzles is A, and the distance between the intersection of the fuel nozzles and the end face of the nozzle is d1; the angle between the two oxidant nozzles is B, and the distance between the intersection of the oxidant nozzles and the end face of the nozzle is d2.

[0050] The value range of angle A is 90°~150°.

[0051] The value range of angle B is 90°~150°.

[0052] And: A≤B≤A+20°, 0.3D≤d1=d2≤D.

[0053] The length L of the ignition chamber indentation area will affect the afterburning and thermal protection effects, and the value range of L is 0.5D≤L≤1.5D.

[0054] Due to the above design, after the oxidant and fuel are injected into the central fuel cavity 6 of the ignition chamber, they collide with each other at a point in space and can be mixed more evenly.

[0055] The nut 15 adopts a thin nut and a fine thread scheme, and is prevented from loosening by means of applying glue, adding a spring washer or an elastic retaining ring, etc.

[0056] After the ignition chamber 3 is produced using 3D printing, only machining of the assembly size is performed. Then, gas-liquid flow tests are carried out on the ignition chamber oxidizer path, fuel nozzle path, and fuel discharge cooling path respectively to check the flow characteristics of the ignition chamber product nozzle and cooling annular seam to ensure the consistency of the ignition chamber product.

[0057] Working process:

[0058] During thrust chamber ignition, the thrust chamber oxidizer valve opens, allowing oxidizer to flow into the injector oxidizer chamber and into the central combustion chamber through the ignition chamber oxygen nozzle. The ignition nozzle then energizes and ignites. The thrust chamber fuel valve opens, allowing fuel to enter the injector fuel chamber and into the central combustion chamber through the ignition chamber fuel nozzle. This fuel mixes with the oxidizer in the central combustion chamber to form a combustible mixture. This mixture is ignited by the spark from the nozzle, forming an oxygen-rich flame. This flame then combusts with the discharged, cooled fuel at the ignition chamber outlet, increasing the flare's ignition energy. The flare then sprays into the thrust chamber interior, igniting the thrust chamber.

[0059] Example:

[0060] The torch-type electric igniter provided in this embodiment consists of an ignition chamber, an ignition nozzle, and a sealing ring. The ignition chamber mainly includes fuel and oxidant nozzles and a combustion chamber, which are integrally formed using 3D printing to achieve functions such as ignition medium distribution and torch combustion. After the ignition chamber is processed, an independent gas-liquid flow screening inspection is carried out, and then it is welded to the second and third bottoms of the injector, and connected to the first bottom with a nut, becoming a part of the injector. It not only assumes the ignition function of the igniter, but also assumes the function of the spark plug in the center of the traditional injector. This igniter solution has the characteristics of a simple system and light weight, and can adapt to unlimited starting and ignition of the thrust chamber of a liquid rocket engine.

[0061] The igniter and ignition chamber share the propellant supply main line, main valve, and blow-off valve. The igniter and ignition chamber ignite simultaneously, eliminating the need for separate ignition valves and ignition lines. The ignition system is greatly simplified and its weight is significantly reduced. Based on the engine's starting and main-stage operating conditions, the igniter nozzle size and cooling ring gap dimensions are reasonably adjusted to ensure the mixing ratio of the igniter under ignition and main-stage operating conditions.

[0062] The ignition chamber utilizes an oxygen-enriched combustion and exhaust cooling structure. The oxidant is supplied from the injector's oxidizer chamber, and the fuel is supplied from the injector's fuel chamber. The ignition chamber nozzle flow rate is controlled by the nozzle orifice size, while the ignition chamber exhaust cooling flow rate is controlled by the size of the cooling annular gap. Both the fuel and oxidizer nozzles in the ignition chamber are direct-flow nozzles. The oxidizer and fuel nozzles are perpendicular to each other, and the oxidizer and fuel nozzles collide at a single point in space, facilitating atomization and mixing. Oxygen-enriched combustion is employed in the center of the ignition chamber, improving ignition reliability and adaptability to operating conditions.

[0063] The ignition chamber exhaust cooling fuel enters the cooling ring through the radial hole (ignition chamber exhaust cooling inlet 11) on the igniter to exhaust and cool the inner wall of the ignition chamber, ensuring the thermal protection performance of the ignition chamber under ignition conditions and engine main stage conditions.

[0064] Oxygen-rich combustion gas in the center of the ignition chamber supplements combustion with the exhaust cooling fuel in the igniter's indented area and outlet, increasing ignition energy. The center mixture ratio of the ignition chamber is oxygen-rich (the center mixture ratio is generally 15-25), and the overall mixture ratio is fuel-rich (the overall mixture ratio is generally 1-2). When the engine main stage is operating, the igniter operates as an independent small combustion chamber.

[0065] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A torch type electric igniter integrated on the thrust chamber injector, characterized in that include: It comprises an ignition chamber (3), an electric nozzle (1), a sealing ring (2) and a nut (15); The nozzle (1) is installed at the center of the upper end of the ignition chamber (3) through a thread and is sealed by a sealing ring (2). The ignition chamber (3) and the first bottom (14) of the thrust chamber injector are fixed by a nut (15). The ignition chamber (3) and the second bottom (10) and the third bottom (4) of the thrust chamber injector are welded. The injector fuel chamber (12) is located between the first bottom (14) and the second bottom (10), and the injector oxidant chamber (8) is located between the second bottom (10) and the third bottom (4); An ignition chamber fuel nozzle (5), an ignition chamber fuel nozzle flow channel (7), an ignition chamber fuel nozzle inlet (9), an ignition chamber discharge cooling inlet (11), an ignition chamber discharge cooling annular gap (13) and an ignition chamber oxidant nozzle (17) are provided in the ignition chamber (3), and an ignition chamber central combustion chamber (6) is provided in the center of the ignition chamber (3) along the axial direction; The fuel is injected from the injector fuel chamber (12) through the ignition chamber fuel nozzle inlet (9), the ignition chamber fuel nozzle flow channel (7), and the ignition chamber fuel nozzle (5) into the ignition chamber central combustion chamber (6); the oxidant is injected along the injector oxidant chamber (8) and the ignition chamber oxidant nozzle (17) into the ignition chamber central combustion chamber (6); the oxidant and the fuel are atomized and mixed in the ignition chamber central combustion chamber (6), and are ignited by the upper electric nozzle (1) to form a high-temperature oxygen-rich combustion gas which is discharged downstream of the ignition chamber; The fuel flows from the injector fuel cavity (12) through the radially arranged ignition chamber discharge cooling inlet (11) into the ignition chamber discharge cooling annular gap (13) to cool the inner wall of the ignition chamber. This part of the fuel meets the high-temperature oxygen-rich gas in the center of the ignition chamber in the ignition chamber outlet indentation area (16) to perform supplementary combustion, thereby increasing the ignition energy.

2. The torch-type electric igniter integrated on the thrust chamber injector according to claim 1, characterized in that: The ignition chamber discharge cooling inlets (11) are arranged in n1 layers, the number of the ignition chamber discharge cooling inlets (11) in each layer is n2, and the ignition chamber discharge cooling inlets (11) between layers form an angle of 360 / n1 / n2 degrees.

3. The torch-type electric igniter integrated on the thrust chamber injector according to claim 2, characterized in that: The total area of ​​the ignition chamber discharge cooling inlet (11) is not less than twice the area of ​​the cooling annular gap; The total area of ​​the ignition chamber discharge cooling inlet (11) refers to the sum of the cross-sectional areas of all the ignition chamber discharge cooling inlets (11); and the cooling annular gap area refers to the cross-sectional area of ​​the cooling annular gap.

4. The torch-type electric igniter integrated on the thrust chamber injector according to claim 2, characterized in that: The ignition chamber fuel nozzle (5) and the ignition chamber oxidant nozzle (17) are both direct current nozzles. There are two ignition chamber fuel nozzles (5) and two oxidant nozzles (17). The plane formed by the ignition chamber fuel nozzles (5) and the plane formed by the ignition chamber oxidant nozzles (17) are perpendicular to each other. The angle between the two ignition chamber fuel nozzles (5) is A, and the distance between the intersection of the fuel nozzles and the end face of the nozzle is d1; the angle between the two oxidant nozzles (17) is B, and the distance between the intersection of the oxidant nozzles and the end face of the nozzle is d2.

5. The torch-type electric igniter integrated on the thrust chamber injector according to claim 4, characterized in that: The angle A has a value range of 90° to 150°, the angle B has a value range of 90° to 150°, and A≤B≤A+20°, 0.3D≤d1=d2≤D, and D is the diameter of the fuel cavity (6) in the center of the ignition chamber.

6. The torch-type electric igniter integrated on the thrust chamber injector according to claim 5, characterized in that: After the oxidant and fuel are injected into the central fuel cavity (6) of the ignition chamber, they collide with each other at a point in space.

7. The torch-type electric igniter integrated on the thrust chamber injector according to claim 1, characterized in that: The length L of the ignition chamber outlet indentation area (16) has a value range of: 0.5D≤L≤1.5D.

8. The torch-type electric igniter integrated on the thrust chamber injector according to claim 1, characterized in that: The ignition chamber (3) is integrally formed by 3D printing to achieve the distribution of ignition medium and torch combustion.

9. The torch-type electric igniter integrated on the thrust chamber injector according to claim 1, characterized in that: After the ignition chamber (3) is processed, an independent gas-liquid flow screening inspection is carried out, and then it is welded to the second and third bottoms of the injector, and connected to the first bottom with a nut to become a part of the injector. It is used for ignition of the igniter and serves as a spark pipe in the center of the injector.

10. The torch-type electric igniter integrated on the thrust chamber injector according to claim 1, characterized in that: The ignition chamber fuel nozzle flow rate is controlled by the ignition chamber fuel nozzle (5) hole size, and the ignition chamber exhaust cooling flow rate is controlled by the cooling ring gap size.

11. The torch-type electric igniter integrated on the thrust chamber injector according to claim 1, characterized in that: When the thrust chamber is ignited and started, The thrust chamber oxidizer valve opens first, and the oxidizer flows into the injector oxidizer chamber and into the central combustion chamber of the ignition chamber through the ignition chamber oxygen nozzle; The ignition nozzle starts to energize and ignite; The thrust chamber fuel valve opens, and the fuel enters the injector fuel chamber and the ignition chamber fuel nozzle into the ignition chamber central combustion chamber, and mixes with the oxidant in the ignition chamber central combustion chamber to form a combustible mixture; The combustible mixture is ignited by the spark emitted by the nozzle to form an oxygen-rich flame, which is supplemented by the discharged cooled fuel at the outlet of the ignition chamber to increase the ignition energy of the torch. The torch is sprayed into the inner cavity of the thrust chamber to ignite the thrust chamber.

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