Combustion system, gas engine and method of designing a combustion system

Abstract

The present application relates to the technical field of engine, and discloses a combustion system, a gas engine and a combustion system design method, a second fuel injection hole sprays an oil jet to ignite a part of natural gas jets on the same side of the second fuel injection hole, and under the action of a vortex in a combustion chamber, with the second fuel injection hole continuously spraying the oil jet, a flame formed by the oil jet igniting the natural gas jets gradually becomes longer along the vortex direction, so that the oil jet sprayed by the second fuel injection hole ignites the natural gas jets on the side of the natural gas injector opposite to the fuel injector; the oil jet sprayed by the first fuel injection hole ignites the remaining natural gas jets, so that the oil jets sprayed by the fuel injector on both sides of a reference line can achieve the maximum ignition effect, all the natural gas jets are ignited by using the least oil jet, the ignition effect of igniting the natural gas by using the fuel is improved, the thermal efficiency is higher, and the emission is lower.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to a combustion system, a gas engine, and a combustion system design method. Background Technology

[0002] High-pressure direct injection compression ignition (HPDI) natural gas engines use 5% diesel fuel injected into the cylinder before the compression reaches top dead center for ignition, while 95% natural gas is injected into the flame at a pressure of 300 bar to become the primary fuel for combustion and power generation. HPDI engines maintain the same power and torque as traditional diesel engines, offering identical performance, but with 20% higher power and torque compared to spark-ignition natural gas engines.

[0003] In existing technologies, some HPDI engines use coupled injectors, meaning that diesel injection and natural gas injection are performed by the same injector, and their arrangement is as follows: Figure 1 and Figure 2 As shown, the injector adopts a dual-row orifice design, in which the lower layer of injection orifices is for diesel fuel and the upper layer is for natural gas fuel. Multiple natural gas injection orifices and multiple diesel injection orifices are arranged at intervals along the circumference of the injector. The multiple natural gas injection orifices and multiple diesel injection orifices are distributed in a one-to-one correspondence. The central axis of the natural gas injection orifice and the central axis of the corresponding diesel injection orifice are located on the same plane and are parallel. The diesel fuel jet injected by the diesel injection orifice is shorter than the natural gas jet injected by the natural gas injection orifice.

[0004] In the HPDI engine using coupled injectors, the natural gas passage in the injector needs to be sealed with diesel fuel, and the pressure of the gas rail determines the injection pressure of both diesel and natural gas. Due to the difficulty in manufacturing the gas rail, the current gas rail pressure is relatively low. Although the diesel fuel consumption is lower, the overall injection duration is longer, and diesel atomization is poor.

[0005] To address this, existing technologies have proposed a dual-injector combustion system, such as... Figure 3 As shown, a natural gas injector 1000' is arranged in the center of the combustion chamber, and a fuel injector 2000' is arranged at the edge. This separates diesel injection and natural gas injection to solve the problem of diesel injection pressure being affected by natural gas rail pressure, thereby increasing diesel injection pressure, shortening injection duration, and improving fuel atomization effect.

[0006] The aforementioned combustion system employing dual injectors has limitations. Because the fuel injectors are positioned at the edge, diesel injection holes can only be installed on the side facing the natural gas. Installing diesel injection holes on the side away from the natural gas would not only fail to ignite the gas but would also cause diesel to be sprayed onto the cylinder liners. If a smaller diesel jet ignites a larger natural gas jet, the natural gas jet on the side away from the fuel injectors will inevitably be difficult to ignite, resulting in lower heat exchange efficiency and poor emissions performance.

[0007] Therefore, a combustion system is urgently needed to solve the above-mentioned technical problems. Summary of the Invention

[0008] The purpose of this invention is to propose a combustion system, a gas engine, and a combustion system design method that can achieve the effect of better igniting multiple natural gas mists with the least amount of fuel mist, shorten the combustion duration, and improve the combustion efficiency of the gas engine.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] A combustion system includes a piston, a cylinder head, a natural gas injector, and a fuel injector. A combustion chamber is formed between the piston and the cylinder head. An air intake passage is provided on the cylinder head, and the air intake passage is configured to cause the airflow in the combustion chamber to flow in the form of a vortex along the circumference of the combustion chamber. The natural gas injector is arranged coaxially with the piston, and the natural gas injector is provided with a plurality of natural gas injection holes arranged circumferentially at intervals.

[0011] The intersection point of the central axis of the fuel injector and the first preset plane is the first intersection point, and the intersection point of the central axis of the natural gas injector and the first preset plane is the second intersection point. The first preset plane is perpendicular to the central axis of the piston, and the line connecting the first intersection point and the second intersection point is the baseline.

[0012] The fuel injector is provided with a first fuel injection hole and a second fuel injection hole, which are located on both sides of the reference line. The angle between the central axis of the first fuel injection hole and the reference line is α, and the angle between the central axis of the second fuel injection hole and the reference line is β, where α > β.

[0013] The plane perpendicular to the baseline and containing the central axis of the fuel injector is the second preset plane. The first fuel injection hole is located on the side of the second preset plane closer to the natural gas injector. The angle between the fuel jet injection direction of the second fuel injection hole and the tangential direction of the airflow flowing in the form of a vortex through the fuel injector is an acute angle.

[0014] As a preferred embodiment of the above-mentioned combustion system, the diameter of the first fuel injection hole is D1, and the diameter of the second fuel injection hole is D2, where D1 > D2.

[0015] As a preferred embodiment of the above-mentioned combustion system, the central axis of the first fuel injection hole and the central axis of the second fuel injection hole are coplanar.

[0016] As a preferred technical solution of the above-mentioned combustion system, the angle between the central axis of the first fuel injection hole and the central axis of the fuel injector is the first injection cone angle, and the angle between the central axis of the second fuel injection hole and the central axis of the fuel injector is the second injection cone angle. The first injection cone angle is equal to the second injection cone angle and both are θ, where θ≤90°.

[0017] As a preferred technical solution for the above-mentioned combustion system, 5°≤α≤60°, 5°≤β≤60°.

[0018] As a preferred technical solution of the above-mentioned combustion system, the angle between the central axis of the natural gas injection hole and the central axis of the natural gas injector is γ, where 60°≤γ≤85°.

[0019] As a preferred technical solution of the above-mentioned combustion system, the natural gas injection holes are provided with eight holes, which are evenly distributed circumferentially along the central axis of the natural gas injector.

[0020] As a preferred technical solution of the above-mentioned combustion system, the central axis of each of the natural gas injection holes and the central axis of the natural gas injector are both located on a third preset plane, and the fuel injector is located in the area enclosed by two adjacent third preset planes.

[0021] To achieve the above objectives, the present invention also provides a gas engine, including a cylinder block and a combustion system as described in any of the above embodiments, wherein the cylinder block is connected to the cylinder head, the cylinder block is provided with a piston hole, and the piston is slidably disposed in the piston hole.

[0022] To achieve the above objectives, the present invention also provides a combustion system design method, applicable to the combustion system described in any of the above embodiments, the combustion system design method comprising the following steps:

[0023] Construct a three-dimensional model of the combustion system and perform three-dimensional combustion simulation based on the three-dimensional model of the combustion system;

[0024] If the fuel jet injected from the first fuel injection orifice can reach the bottom surface of the natural gas injector and / or the top surface of the piston, then reduce the angle between the central axis of the first fuel injection orifice and the central axis of the fuel injector.

[0025] If the fuel jet injected from the second fuel injection orifice can reach the bottom surface of the natural gas injector and / or the top surface of the piston, then reduce the angle between the central axis of the second fuel injection orifice and the central axis of the fuel injector.

[0026] If the fuel jet injected from the second fuel injection hole can reach the side of the natural gas injector, then increase the angle between the central axis of the second fuel injection hole and the central axis of the fuel injector.

[0027] If the fuel jet injected by the second fuel injection orifice cannot ignite the natural gas jet located on the same side of the baseline as the second fuel injection orifice, and the natural gas jet on the side of the natural gas injector opposite to the fuel injector, then the diameter of the second fuel injection orifice shall be increased.

[0028] If the fuel jet injected from the first fuel injection orifice cannot ignite and the first fuel injection orifice is located on the same side of the baseline and there are no other natural gas jets besides the natural gas jet on the side of the natural gas injector facing away from the fuel injector, then the diameter of the first fuel injection orifice is increased.

[0029] The beneficial effects of this invention are as follows: The combustion system and gas engine provided by this invention have a natural gas injector coaxial with the piston, and a fuel injector located on one side of the natural gas injector. The first fuel injection hole and the second fuel injection hole are located on opposite sides of the baseline, with α > β. The angle between the fuel jet injection direction of the second fuel injection hole and the tangential direction of the airflow flowing in a vortex form through the fuel injector is an acute angle. The fuel jet injected by the second fuel injection hole ignites a portion of the natural gas jet on the same side as the second fuel injection hole. Under the action of the vortex in the combustion chamber, as the second fuel injection hole continues to inject fuel jet, the flame formed by the fuel jet igniting the natural gas jet gradually lengthens along the vortex direction. Thus, the fuel jet injected by the second fuel injection hole ignites the natural gas jet on the side of the natural gas injector opposite to the fuel injector. The fuel jet injected by the first fuel injection hole ignites the remaining natural gas jet, thereby enabling the fuel jets injected by the fuel injector on both sides of the baseline to achieve the maximum ignition effect. This achieves the goal of igniting all the natural gas jets with the least amount of fuel jet, improving the ignition effect of using fuel to ignite natural gas, resulting in higher thermal efficiency and lower emissions.

[0030] The combustion system design method provided by this invention enables rapid design of combustion systems required for different engine models. It achieves optimized design of the combustion system through three-dimensional combustion simulation, which is faster and less costly than experimental selection. By optimizing the combustion system design, uniform mixing of natural gas and air within the combustion chamber and uniform ignition by the fuel injector can be achieved, shortening the combustion duration and improving the engine's thermal efficiency. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of a combustion system using coupled injectors in the prior art. Figure 1 ;

[0033] Figure 2 This is a schematic diagram of a combustion system using coupled injectors in the prior art. Figure 2 ;

[0034] Figure 3 This is a schematic diagram of a combustion system using dual injectors in the prior art;

[0035] Figure 4 This is a schematic cross-section of the combustion system provided in the embodiment of the present invention within a first preset plane. Figure 1 ;

[0036] Figure 5 This is a schematic cross-section of the combustion system provided in the embodiment of the present invention within a first preset plane. Figure 2 ;

[0037] Figure 6 This is a cross-sectional schematic diagram of the fuel injector provided in the embodiment of the present invention within a second preset plane;

[0038] Figures 7 to 9 This is a process state diagram of the fuel injected by the fuel injector igniting the natural gas jet of the natural gas injector, provided in an embodiment of the present invention.

[0039] Figure 10 This is a flowchart of the combustion system design method provided in the embodiments of the present invention.

[0040] In the picture:

[0041] 1000' Natural gas injector; 2000' Fuel injector;

[0042] 1. Fuel injector; 11. First fuel injection orifice; 12. Second fuel injection orifice; 2. Natural gas injector;

[0043] 100, First preset plane; 200, Second preset plane; 300, Baseline. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0045] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0047] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0048] like Figures 4 to 9 As shown, an embodiment of the present invention provides a combustion system including a piston, a cylinder head, a natural gas injector 2, and a fuel injector 1. A combustion chamber is formed between the piston and the cylinder head. An air intake passage is provided on the cylinder head, and the air intake passage is configured to cause the airflow in the combustion chamber to flow in the form of a vortex along the circumference of the combustion chamber. The natural gas injector 2 is arranged coaxially with the piston, and the natural gas injector 2 is provided with a plurality of natural gas injection holes arranged circumferentially at intervals. It should be noted that how the air intake passage is designed to cause the airflow entering the combustion chamber through the air intake passage to flow in the form of a vortex along the circumference of the combustion chamber is prior art in the art and will not be described in detail here.

[0049] The intersection point of the central axis of the fuel injector 1 and the first preset plane 100 is the first intersection point, and the intersection point of the central axis of the natural gas injector 2 and the first preset plane 100 is the second intersection point. The first preset plane 100 is perpendicular to the central axis of the piston, and the line connecting the first intersection point and the second intersection point is the reference line 300.

[0050] The fuel injector 1 is provided with a first fuel injection hole 11 and a second fuel injection hole 12. The first fuel injection hole 11 and the second fuel injection hole 12 are located on both sides of the reference line 300. The angle between the central axis of the first fuel injection hole 11 and the reference line 300 is α, and the angle between the central axis of the second fuel injection hole 12 and the reference line 300 is β, where α > β.

[0051] The plane perpendicular to the baseline 300 and containing the central axis of the fuel injector 1 is the second preset plane 200. The first fuel injection hole 11 is located on the side of the second preset plane 200 closer to the natural gas injector 2. The angle between the fuel jet injection direction of the second fuel injection hole 12 and the tangential direction of the airflow flowing in the form of a vortex through the fuel injector 1 is an acute angle.

[0052] The combustion system has the natural gas injector 2 coaxial with the piston, and the fuel injector 1 located on one side of the natural gas injector 2. The first fuel injection hole 11 and the second fuel injection hole 12 are located on both sides of the reference line 300, with α > β. The angle between the fuel jet injection direction of the second fuel injection hole 12 and the tangential direction of the airflow flowing in the form of a vortex as it passes through the fuel injector 1 is an acute angle. The fuel jet injected by the second fuel injection hole 12 ignites a portion of the natural gas jet on the same side as the second fuel injection hole 12, and under the action of the vortex in the combustion chamber, it propels the natural gas jet along the second fuel injection hole 12. 12 continuously injects fuel jets, which ignite the natural gas jets, and the flames formed gradually lengthen along the vortex direction. Thus, the fuel jets injected through the second fuel injection hole 12 ignite the natural gas jets on the side of the natural gas injector 2 opposite to the fuel injector 1. The fuel jets injected through the first fuel injection hole 11 ignite the remaining natural gas jets, thereby maximizing the ignition effect of the fuel jets injected by the fuel injector 1 on both sides of the baseline 300. This achieves the goal of igniting all natural gas jets with the least amount of fuel jets, improving the ignition effect of using fuel to ignite natural gas, resulting in higher thermal efficiency and lower emissions.

[0053] In some embodiments, the diameter of the first fuel injection orifice 11 is D1, and the diameter of the second fuel injection orifice 12 is D2, where D1 > D2. Since the fuel jet injected from the first fuel injection orifice 11 is against the vortex direction, the airflow flowing in the form of a vortex in the combustion chamber will limit the injection distance of the fuel jet injected from the first fuel injection orifice 11. By limiting D1 > D2, it is possible to ignite the fuel jet injected from the first fuel injection orifice 11 and other natural gas jets located on the same side of the reference line 300 as the second fuel injection orifice 12, except for the natural gas jet on the side of the natural gas injector 2 facing away from the fuel injector 1.

[0054] In some embodiments, 5°≤α≤60°, 5°≤β≤60°. This ensures that the fuel jet injected from the first fuel injection hole 11 does not contact the side of the natural gas injector 2, and that the fuel jet injected from the second fuel injection hole 12 does not contact the side of the natural gas injector 2, thereby extending the service life of the natural gas injector 2.

[0055] It should be noted that α can be any value between 5° and 60°, such as 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, and 60°. β can also be any value between 5° and 60°, such as 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, and 60°.

[0056] In some embodiments, the central axis of the first fuel injection orifice 11 and the central axis of the second fuel injection orifice 12 are coplanar. The angle between the central axis of the first fuel injection orifice 11 and the central axis of the fuel injector 1 is the first injection cone angle, and the angle between the central axis of the second fuel injection orifice 12 and the central axis of the fuel injector 1 is the second injection cone angle. The first injection cone angle is equal to the second injection cone angle, and both are θ, where θ ≤ 90°. This configuration ensures that the fuel jet injected by the first fuel injection orifice 11 can contact the natural gas jet located on the same side of the reference line 300 as the first fuel injection orifice 11, and that the fuel jet injected by the second fuel injection orifice 12 can contact the natural gas jet located on the same side of the reference line 300 as the second fuel injection orifice 12.

[0057] In some embodiments, the combustion chamber includes a combustion chamber recess on the top surface of the piston, a central boss is provided at the bottom of the combustion chamber recess, and an annular boss is provided around the circumferential sidewall of the combustion chamber recess around the central boss, forming a first recess between the annular boss and the bottom of the combustion chamber recess; the angle between the central axis of the natural gas injection hole and the central axis of the natural gas injector 2 is γ, 60°≤γ≤85°.

[0058] It should be noted that γ can be any value between 60° and 85°, such as γ can be any value among 60°, 65°, 70°, 75°, 80°, and 85°.

[0059] This configuration allows the natural gas injection orifice to inject natural gas into the first depression, where it is drawn into a vortex by the second depression, thus improving the uniformity of the natural gas within the first depression.

[0060] In some embodiments, the cross-sections of the combustion chamber in any predetermined plane of symmetry are symmetrically arranged about the central axis of the combustion chamber, which lies within the predetermined plane of symmetry. This allows the entire combustion chamber to have a symmetrical structure.

[0061] In some embodiments, eight natural gas injection holes are provided, which are evenly distributed circumferentially along the central axis of the natural gas injector 2. By using eight natural gas injection holes evenly distributed circumferentially along the natural gas injector 2, in conjunction with a symmetrically arranged combustion chamber, the uniformity of natural gas within the combustion chamber can be improved.

[0062] In some embodiments, the central axis of each natural gas injection hole and the central axis of the natural gas injector 2 are both located on a third preset plane, and the fuel injector 1 is located within the area enclosed by two adjacent third preset planes. This arrangement ensures that the fuel jets from the first fuel injection hole 11 and the second fuel injection hole 12 can ignite all the natural gas, improving the ignition effect of using fuel to ignite natural gas.

[0063] Embodiments of the present invention also provide a gas engine, including a cylinder block and a combustion system as described in any of the above embodiments. The cylinder block has a piston bore, and a piston is axially movably disposed within the piston bore. This gas engine has the same technical effects as the combustion system described above, and will not be described in detail here. It should be noted that the fuel injector 1 of this gas engine can be a diesel injector, and the natural gas injected by the natural gas injector 2 can be methanol, methane, etc., and will not be specifically limited here.

[0064] Figure 10 This is a detailed flowchart of the combustion system design method provided in the embodiments of the present invention, such as... Figure 10 As shown, embodiments of the present invention also provide a combustion system design method, which includes the following steps:

[0065] S1. Construct a three-dimensional model of the combustion system;

[0066] S2. Perform three-dimensional combustion simulation based on the three-dimensional model of the combustion system;

[0067] S3. Determine whether the fuel jet injected by the first fuel injection hole 11 can reach the bottom surface of the natural gas injector 2 and / or the top surface of the piston; if yes, reduce the angle between the central axis of the first fuel injection hole 11 and the central axis of the fuel injector 1 to update the three-dimensional model of the combustion system and return to S3; if no, execute S4.

[0068] S4. Determine whether the fuel jet injected by the second fuel injection hole 12 can reach the bottom surface of the natural gas injector 2 and / or the top surface of the piston. If yes, reduce the angle between the central axis of the second fuel injection hole 12 and the central axis of the fuel injector 1 to update the three-dimensional model of the combustion system and return to S3; if no, execute S5.

[0069] S5. Determine whether the fuel jet injected by the second fuel injection hole 12 can touch the side of the natural gas injector 2. If yes, increase the angle between the central axis of the second fuel injection hole 12 and the reference line 300 to update the three-dimensional model of the combustion system and return to S3; if no, execute S6.

[0070] S6. Determine whether the fuel jet injected by the second fuel injection hole 12 can ignite the natural gas jet located on the same side of the reference line 300 as the second fuel injection hole 12, and the natural gas jet on the side of the natural gas injector 2 opposite to the fuel injector 1. If yes, execute S7; if no, increase the aperture of the second fuel injection hole 12 to update the three-dimensional model of the combustion system and return to S3.

[0071] S7. Determine whether the fuel jet injected by the first fuel injection hole 11 can ignite other natural gas jets that are located on the same side of the reference line 300 as the first fuel injection hole 11 and are other than the natural gas jet on the side of the natural gas injector 2 facing away from the fuel injector 1. If yes, the fuel system design ends. If no, increase the diameter of the first fuel injection hole 11 to update the three-dimensional model of the combustion system and return to S3.

[0072] It should be noted that, in step S3, the combustion simulation results determine whether the fuel jet injected from the first fuel injection hole 11 can reach the bottom surface of the natural gas injector 2 and / or the top surface of the piston. In step S4, the combustion simulation results determine whether the fuel jet injected from the second fuel injection hole 12 can reach the bottom surface of the natural gas injector 2 and / or the top surface of the piston. In step S5, the combustion simulation results determine whether the fuel jet injected from the second fuel injection hole 12 can touch the side of the natural gas injector 2. In step S6, the combustion simulation results determine whether the fuel jet injected from the second fuel injection hole 12 can ignite the natural gas jet located on the same side of the reference line 300 as the second fuel injection hole 12, and the natural gas jet on the side of the natural gas injector 2 opposite to the fuel injector 1. In step S7, the combustion simulation results determine whether the fuel jet injected from the first fuel injection hole 11 can ignite other natural gas jets located on the same side of the reference line 300 as the first fuel injection hole 11, except for the natural gas jet on the side of the natural gas injector 2 opposite to the fuel injector 1. As for how to make the above judgment based on the combustion simulation results, it can be done by human observation, which will not be described in detail here.

[0073] The combustion system design method provided in this embodiment can quickly design combustion systems according to the requirements of different engine models. It achieves optimized design of the combustion system through three-dimensional combustion simulation, which is faster and less costly than experimental selection. By optimizing the combustion system design, natural gas and air can be uniformly mixed in the combustion chamber and uniformly ignited by the fuel injector 1, shortening the combustion duration and improving the engine's thermal efficiency.

[0074] Furthermore, the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A combustion system, characterized in that, The system includes a piston, a cylinder head, a natural gas injector (2), and a fuel injector (1). A combustion chamber is formed between the piston and the cylinder head. An air intake passage is provided on the cylinder head. The air intake passage is configured to allow the airflow in the combustion chamber to flow in the form of a vortex along the circumference of the combustion chamber. The natural gas injector (2) is arranged coaxially with the piston. The natural gas injector (2) is provided with a plurality of natural gas injection holes arranged circumferentially at intervals. The intersection point of the central axis of the fuel injector (1) and the first preset plane (100) is the first intersection point, and the intersection point of the central axis of the natural gas injector (2) and the first preset plane (100) is the second intersection point. The first preset plane (100) is perpendicular to the central axis of the piston, and the line connecting the first intersection point and the second intersection point is the baseline (300). The fuel injector (1) is provided with a first fuel injection hole (11) and a second fuel injection hole (12). The first fuel injection hole (11) and the second fuel injection hole (12) are respectively located on both sides of the reference line (300). The angle between the central axis of the first fuel injection hole (11) and the reference line (300) is α, and the angle between the central axis of the second fuel injection hole (12) and the reference line (300) is β, where α > β. The plane perpendicular to the baseline (300) and containing the central axis of the fuel injector (1) is the second preset plane (200). The first fuel injection hole (11) is located on the side of the second preset plane (200) close to the natural gas injector (2). The angle between the fuel jet injection direction of the second fuel injection hole (12) and the tangential direction of the airflow flowing in the form of a vortex through the fuel injector (1) is an acute angle.

2. The combustion system according to claim 1, characterized in that, The diameter of the first fuel injection hole (11) is D1, and the diameter of the second fuel injection hole (12) is D2, where D1 > D2.

3. The combustion system according to claim 1, characterized in that, The central axis of the first fuel injection hole (11) and the central axis of the second fuel injection hole (12) are coplanar.

4. The combustion system according to claim 1, characterized in that, The angle between the central axis of the first fuel injection hole (11) and the central axis of the fuel injector (1) is the first injection cone angle, and the angle between the central axis of the second fuel injection hole (12) and the central axis of the fuel injector (1) is the second injection cone angle. The first injection cone angle is equal to the second injection cone angle and both are θ, where θ ≤ 90°.

5. The combustion system according to claim 1, characterized in that, 5°≤α≤60°，5°≤β≤60°。 6. The combustion system according to claim 1, characterized in that, The angle between the central axis of the natural gas injection hole and the central axis of the natural gas injector (2) is γ, 60°≤γ≤85°.

7. The combustion system according to claim 1, characterized in that, The natural gas injection holes are provided in eight parts, and the eight natural gas injection holes are evenly distributed circumferentially along the central axis of the natural gas injector (2).

8. The combustion system according to claim 7, characterized in that, The central axis of each of the natural gas injection holes and the central axis of the natural gas injector (2) are both located on a third preset plane, and the fuel injector (1) is located in the area enclosed by two adjacent third preset planes.

9. A gas engine, characterized in that, The system includes a cylinder block and a combustion system as described in any one of claims 1 to 8, wherein the cylinder block is connected to the cylinder head, the cylinder block has a piston hole, and the piston is slidably disposed within the piston hole.

10. A combustion system design method, characterized in that, The combustion system design method, applied to any one of claims 1 to 8, comprises the following steps: A three-dimensional model of the combustion system is constructed, and a three-dimensional combustion simulation is performed based on the three-dimensional model of the combustion system; If the fuel jet injected by the first fuel injection hole (11) can reach the bottom surface of the natural gas injector (2) and / or the top surface of the piston, then reduce the angle between the central axis of the first fuel injection hole (11) and the central axis of the fuel injector (1). If the fuel jet injected by the second fuel injection hole (12) can be sprayed onto the bottom surface of the natural gas injector (2) and / or the top surface of the piston, then the angle between the central axis of the second fuel injection hole (12) and the central axis of the fuel injector (1) is reduced. If the fuel jet injected by the second fuel injection hole (12) can touch the side of the natural gas injector (2), then the angle between the central axis of the second fuel injection hole (12) and the central axis of the fuel injector (1) is increased. If the fuel jet injected by the second fuel injection hole (12) cannot ignite the natural gas jet that is located on the same side of the reference line (300) as the second fuel injection hole (12), and the natural gas jet on the side of the natural gas injector (2) that is away from the fuel injector (1), then the diameter of the second fuel injection hole (12) is increased. If the fuel jet injected by the first fuel injection hole (11) cannot ignite other natural gas jets other than the natural gas jet on the side of the natural gas injector (2) opposite to the fuel injector (1), then the diameter of the first fuel injection hole (11) is increased.

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