3D printing integrated injector

Abstract

The invention discloses a 3D printing integrated injector. An ignition channel penetrates through a head cavity A and a head cavity B and is located between the head cavity A and the head cavity B; the nozzles A and the nozzles B are of an integrated coaxial structure and are evenly distributed on the periphery of the ignition channel in the circumferential direction. Wherein the nozzle A comprises inlet holes and a straight channel, the inlet holes are located in the head cavity A, and at least four inlet holes are evenly distributed in the circumferential direction and communicate with the straight channel in the center; the nozzle B is located in the head cavity B and comprises a flow equalizing ring cavity, a contraction channel and an outlet ring seam; the overall appearance section of the flow equalizing ring cavity and the contraction channel is in a circular truncated cone shape, the front end of the contraction channel is an outlet circular seam formed between the side wall of the outlet end of the straight channel of the nozzle A and the bottom B, and a mixing area is formed between the outlet end of the straight channel of the nozzle A and the bottom B; an annular cavity is formed between the outer walls of the head cavity A and the head cavity B, namely the annular wall with the flow equalizing hole and the outer wall of the cavity, an inlet is formed in the outer wall of the cavity, and the ignition channel, the head cavity A, the head cavity B, the chamber pressure measuring channel, the nozzle A and the nozzle B are integrally printed and formed in a 3D mode.

Description

Technical Field

[0001] The invention relates to a 3D printing integrated injector, which can be used in the fields of aerospace, thermal energy engineering and combustion technology. Background Art

[0002] The injector is a key component of a liquid rocket engine. Its function is to spray fuel and oxidizer into the combustion chamber for atomization, evaporation, mixing, and combustion. The high-temperature, high-pressure combustion gas generated enters the nozzle and is accelerated to eject to generate thrust. Liquid rocket engine injectors are usually connected to multiple base plates by brazing with hundreds of nozzles. There are many parts and welds, and the internal quality and mechanical properties of the brazed seams cannot be directly tested and can only be guaranteed through the process. If the brazed seams crack, there is a risk of cross-cavity explosion between the fuel chamber and the oxidizer chamber. At the same time, the processing and assembly accuracy of the matching dimensions of each part and the welding deformation are also prone to deviations in the nozzle gap and indentation depth, which affect the consistency of the injection state. The deviation of the nozzle gap is prone to cause a high local mixing ratio, which leads to the risk of nozzle and panel ablation.

[0003] In addition, in order to obtain the working characteristics of the thrust chamber, it is necessary to measure the thrust chamber pressure, etc. The pressure lead-out pipe connects the combustion chamber and the measuring device. Currently, due to the limitation of structural space, the pressure lead-out pipe usually needs to pass through the fuel chamber and the oxidizer chamber. If the brazing seam of the lead-out pipe cracks, there will be a risk of explosion in the fuel chamber and the oxidizer chamber. If the weld between the lead-out pipe and the oxidizer collector cracks, there is a risk of explosion caused by contact between the combustion chamber gas and the oxidizer.

[0004] In order to minimize the number of parts and welds and improve product reliability, 3D printing laser selective melting (SLM) technology can be used to integrally process hundreds of nozzles, base plates, etc. In order to improve the internal quality, molding accuracy and product performance requirements of the integrated injector molding, it is extremely important to adopt support-free structure design and strengthen the internal quality design of the printed product. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and provide a 3D printing integrated injector with a small number of part welds, a support-free structure design, a high internal quality design and high-precision throttling controllable.

[0006] The technical solution of the present invention is: a 3D printed integrated injector, comprising an ignition channel, a head cavity A, a head cavity B, a chamber pressure measurement channel, a nozzle A, and a nozzle B;

[0007] The ignition channel runs through the head cavity A and the head cavity B and is located in the middle; the nozzle A and the nozzle B are integrated into a coaxial structure and are evenly distributed in the circumferential direction outside the ignition channel; wherein the nozzle A includes an inlet hole and a straight channel, the inlet hole is located inside the head cavity A, and at least four inlet holes are evenly distributed in the circumferential direction and connected to the straight channel in the center;

[0008] Nozzle B is located inside the head cavity B, and includes a flow-equalizing annular cavity, a contraction channel, and an outlet annular seam; the overall cross-section of the flow-equalizing annular cavity and the contraction channel is a truncated cone, and the front end of the contraction channel is an outlet annular seam formed between the side wall of the outlet end of the straight channel of nozzle A and the bottom B, and a mixing zone is formed between the outlet end of the straight channel of nozzle A and the bottom B; the outer wall of the head cavity A and the head cavity B, that is, an annular cavity is formed between the annular wall with the flow-equalizing hole and the outer wall of the cavity, and an inlet is arranged on the outer wall of the cavity, and the fuel enters the head cavity B through the flow-equalizing hole from the inlet, and then flows through the flow-equalizing annular cavity, the contraction channel, and the outlet annular seam through the inlet hole arranged on the flow-equalizing annular cavity to enter the mixing zone; the oxidizer enters the mixing zone from the head cavity A through the inlet hole and the straight channel of nozzle A, mixes with the fuel, and then enters the combustion chamber; the chamber pressure measurement channel connects to the combustion chamber from the bottom B and passes through the head cavity B, avoiding the head cavity A; the above-mentioned ignition channel, head cavity A, head cavity B, chamber pressure measurement channel, nozzle A, and nozzle B are formed by 3D integrated printing.

[0009] Preferably, a multi-layer annular nozzle structure is arranged outside the ignition channel, and a plurality of coaxial structures integrated with nozzles A and nozzles B are evenly distributed on each layer of the annular nozzle structure.

[0010] Preferably, the inlet and the inlet hole are both hole structures with a round top and a pointed bottom, and the pointed angle ranges from 60° to 80°.

[0011] Preferably, the area of ​​the flow-averaging holes on the annular wall decreases linearly within the range of 0-180°, and the area ratio from the inlet near the outer wall of the cavity to the opposite side is 1:0.8.

[0012] Preferably, the width of the annular gap at the outlet of the nozzle B is not less than 0.35 mm, and the ratio of its throttling area to the throttling area of ​​the flow-averaging annular cavity is 10% to 20%.

[0013] Preferably, the included angle of the contraction channel is 60° to 80°, and there is a smooth transition between the contraction channel and the outlet annular gap and the flow-averaging annular cavity.

[0014] Preferably, the throttling area of ​​the straight channel of nozzle A is 2 to 3 times the cross-sectional area of ​​the inlet hole.

[0015] Preferably, the bottom B is a microporous structure panel, which ensures structural strength while achieving effective cooling of the panel through air film cooling.

[0016] Preferably, the microporous structure is a straight through hole of 0.1 to 0.3 mm, or a randomly distributed mesh hole of 0.1 to 0.2 mm.

[0017] Preferably, the chamber pressure measurement channel is an internal channel, attached to or embedded in a ring wall with a flow-averaging hole, and its inner diameter is 2 to 3 mm.

[0018] The beneficial effects of the present invention compared with the prior art are:

[0019] 1) The 3D printed integrated injector is used to reduce the welds between the head cavity, nozzle, measuring device and each bottom, and prevent the nozzle ablation caused by uneven annular gap of the injector nozzle due to the influence of weld heat input;

[0020] 2) The one-piece injector is directly formed by 3D printing without support, which ensures that the internal structure does not collapse and the dimensional accuracy is controllable. At the same time, it improves the uniformity of the flow field distribution of each head cavity of the injector and the uniformity of the outflow of each nozzle, thereby improving the combustion efficiency and avoiding problems such as nozzle ablation caused by high local mixing ratio;

[0021] 3) Nozzle B adopts the design of uniform flow annular cavity and contraction channel, which can effectively reduce the ineffective local damage and flow resistance along the nozzle, improve the anti-disturbance margin of the nozzle, and at the same time increase the injection speed of the annular gap and improve the combustion stability margin of the thrust chamber;

[0022] 4) The integrated printing of bottom B can improve the connection strength with the nozzle, avoiding problems such as difficulty in later assembly. At the same time, the cooling amount can be adjusted by adjusting the size of the microporous structure to adapt to different products.

[0023] 5) The chamber pressure measurement channel is set based on the spatial trend and is directly led out from cavity B. The channel does not pass through cavity A to avoid ice blockage caused by ice formation due to heat exchange of the combustion chamber gas in the channel by the fluid in the low-temperature cavity A. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of a 3D printing integrated injector of the present invention;

[0025] Figure 2 It is a half-section view from another angle of the structure of the present invention.

[0026] In the figure: 1 - head cavity A, 2 - head cavity B, 3 - ignition channel, 4 - chamber pressure measurement channel, 5 - nozzle A, 6 - bottom A, 7 - cavity outer wall, 8 - ring wall with equal flow hole, 9 - equal flow hole, 10 - nozzle B, 11 - cavity inner wall, 12 - bottom B, 13 - inlet. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the embodiments.

[0028] A 3D printing integrated injector, such as Figure 1As shown, it includes head cavity A1, head cavity B2, ignition channel 3, and chamber pressure measurement channel 4; the ignition channel runs through head cavity A and head cavity B and is located in the middle;

[0029] In the above-mentioned 3D printing integrated injector, the nozzle A5 and the nozzle B10 are integrated into a coaxial structure and are evenly distributed in the circumferential direction outside the ignition channel; wherein the nozzle A includes an inlet hole and a straight channel, the inlet hole is located inside the head cavity A1, and is a special-shaped hole with a round top and a pointed bottom, and the sharp angle is 70°, to ensure that 3D printing can be directly formed without support, and there are at least four inlet holes evenly distributed in the circumferential direction and connected to the straight channel in the center. The throttling area of ​​the straight channel of nozzle A is about 2.4 times the cross-sectional area of ​​the inlet hole. A mixing zone is formed between the outlet end of the straight channel of nozzle A5 and the bottom B12.

[0030] In the above-mentioned 3D printing integrated injector, the nozzle B10 is located inside the head cavity B2, including a flow-equalizing annular cavity, a contraction channel, and an outlet annular slit, replacing the traditional long annular slit, ensuring that the outlet injection speed is increased under the same pressure drop and the gas-liquid injection speed ratio is increased on the basis of support-free printing, and at the same time has a damping chamber function to reduce the occurrence of instability. The front end of the contraction channel is an outlet annular slit formed between the side wall of the outlet end of the nozzle A5 straight channel and the bottom B12, and its width is not less than 0.35mm, and its throttling area is 15% of the throttling area of ​​the flow-equalizing annular cavity. The contraction channel has an angle of 70°, and there is a smooth transition between the contraction channel and the outlet annular slit and the flow-equalizing annular cavity.

[0031] In the above-mentioned 3D printing integrated injector, the overall cross-section of the nozzle B10 is a truncated cone, which ensures direct molding without support by 3D printing and can improve the uniformity of flow field distribution in the gas head cavity;

[0032] In the above-mentioned 3D printing integrated injector, the outer wall of the head cavity A1 and the head cavity B2, that is, the annular wall with the equal flow hole and the outer wall of the cavity form an annular cavity, and an inlet is set on the outer wall of the cavity, and the fuel enters the head cavity B2 from the inlet through the equal flow hole 9, wherein the equal flow holes 9 are symmetrically and evenly distributed on the annular wall with the equal flow hole, and are special-shaped holes with a round top and a pointed bottom, and the area of ​​the equal flow hole decreases linearly within the range of 0-180°, and the area ratio from the vicinity of the inlet 13 to the opposite side is 1:0.8; the fuel then enters the equal flow annular cavity, the contraction channel, and the outlet annular seam through the inlet hole set on the equal flow annular cavity of the nozzle B10 to enter the mixing zone; the oxidant enters the mixing zone from the head cavity A1 through the inlet hole of the nozzle A5 and the straight channel, and is mixed with the fuel and then enters the combustion chamber;

[0033] The chamber pressure measurement channel is connected to the combustion chamber from the bottom B12 and only passes through the head cavity B2; the head cavity A1, head cavity B2, ignition channel 3, chamber pressure measurement channel 4, nozzle A5, and nozzle B10 are formed by 3D integrated printing.

[0034] In the above-mentioned 3D printing integrated injector, the bottom B12 is a microporous structure panel, which ensures structural strength while achieving effective cooling of the panel through air film cooling; the microporous structure can be a 0.2mm straight through hole or a randomly distributed 0.15mm mesh.

[0035] In the above-mentioned 3D printed integrated injector, the chamber pressure measurement channel 3 is set based on the spatial trend, is an internal channel, can be attached or embedded in the ring wall with equal flow holes, and is directly led out from cavity B. The inner diameter of the chamber pressure measurement channel is usually 2 mm.

[0036] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the protection scope of the technical solution of the present invention.

[0037] Parts of the present invention that are not described in detail belong to common knowledge among those skilled in the art.

Claims

1. A 3D printing integrated injector, characterized in that: It includes an ignition channel, a head cavity A, a head cavity B, a chamber pressure measurement channel, a nozzle A, and a nozzle B; The ignition channel runs through the head cavity A and the head cavity B and is located in the middle; the nozzle A and the nozzle B are integrated into a coaxial structure and are evenly distributed in the circumferential direction outside the ignition channel; The nozzle A includes an inlet hole and a straight channel, the inlet hole is located inside the head cavity A, and at least four inlet holes are evenly distributed along the circumferential direction and connected to the straight channel in the center; Nozzle B is located inside the head cavity B, and includes a flow-equalizing annular cavity, a contraction channel, and an outlet annular seam; the overall cross-section of the flow-equalizing annular cavity and the contraction channel is a truncated cone, and the front end of the contraction channel is an outlet annular seam formed between the side wall of the outlet end of the straight channel of nozzle A and the bottom B, and a mixing zone is formed between the outlet end of the straight channel of nozzle A and the bottom B; the outer wall of the head cavity A and the head cavity B, that is, an annular cavity is formed between the annular wall with the flow-equalizing hole and the outer wall of the cavity, and an inlet is arranged on the outer wall of the cavity, and the fuel enters the head cavity B through the flow-equalizing hole from the inlet, and then flows through the flow-equalizing annular cavity, the contraction channel, and the outlet annular seam through the inlet hole arranged on the flow-equalizing annular cavity to enter the mixing zone; the oxidizer enters the mixing zone from the head cavity A through the inlet hole and the straight channel of nozzle A, mixes with the fuel, and then enters the combustion chamber; the chamber pressure measurement channel connects to the combustion chamber from the bottom B and passes through the head cavity B, avoiding the head cavity A; the above-mentioned ignition channel, head cavity A, head cavity B, chamber pressure measurement channel, nozzle A, and nozzle B are formed by 3D integrated printing.

2. A 3D printing integrated injector according to claim 1, characterized in that: A multi-layer annular nozzle structure is arranged outside the ignition channel, and a plurality of coaxial structures integrated with nozzles A and nozzles B are evenly distributed on each layer of the annular nozzle structure.

3. The 3D printing integrated injector according to claim 1, characterized in that: The inlet and the inlet hole are both hole structures with a round top and a pointed bottom, and the pointed angle range is 60° to 80°.

4. The 3D printing integrated injector according to claim 1, characterized in that: The area of ​​the flow-averaging holes on the annular wall decreases linearly within the range of 0-180°, and the area ratio from the inlet near the outer wall of the cavity to the opposite side is 1:0.

8.

5. The 3D printing integrated injector according to claim 1, characterized in that: The width of the annular gap at the outlet of nozzle B is not less than 0.35 mm, and its throttling area is 10% to 20% of the throttling area of ​​the uniform flow annular cavity.

6. A 3D printing integrated injector according to claim 5, characterized in that: The included angle of the contraction channel is 60° to 80°, and there is a smooth transition between the contraction channel and the outlet annular gap and the flow-averaging annular cavity.

7. The 3D printing integrated injector according to claim 1, characterized in that: The throttling area of ​​the straight channel of nozzle A is 2 to 3 times the cross-sectional area of ​​the inlet hole.

8. The 3D printing integrated injector according to claim 1, characterized in that: Bottom B is a microporous structure panel, which ensures structural strength while achieving effective panel cooling through air film cooling.

9. The 3D printing integrated injector according to claim 7, characterized in that: The microporous structure is a straight through hole of 0.1 to 0.3 mm, or a randomly distributed mesh hole of 0.1 to 0.2 mm.

10. The 3D printing integrated injector according to claim 1, characterized in that: The chamber pressure measurement channel is an internal channel, attached to or embedded in a ring wall with a flow-averaging hole, and its inner diameter is 2 to 3 mm.

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