High-combustion-efficiency pintle injector with mutual striking and design method thereof

Abstract

The invention discloses a high-combustion-efficiency pintle injector with mutual strike and a design method of the pintle injector. The pintle injector comprises a hemispherical injection panel, mutual strike pintle injection units, a fuel inlet connector and an oxidizing agent inlet connector. Wherein the mutual-striking pintle injection units are distributed on the hemispherical inner wall face of the hemispherical injection panel according to a central symmetry array, and a fuel liquid accumulation cavity, a fuel tangential hole, a fuel channel, an oxidizing agent tangential hole and an oxidizing agent axial channel are designed in each mutual-striking pintle injection unit. The design of the pintle injector with high combustion efficiency is realized by utilizing the structural characteristics of the pintle injector and combining the high combustion efficiency of the mutual impact injector. By reasonably arranging the mutual-striking pintle injection units and arranging the mutual-striking inclined small holes in the pintle head, the propellant atomization effect can be improved when the injector works, the combustion efficiency of the injector is improved, and the temperature reliability of the pintle head in the startup and shutdown process is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of liquid engine design, and in particular to a high-efficiency needle-plug injector with mutual impact and its design method. Background Art

[0002] Needle-type injectors are characterized by their simple structure and low cost. Their combustion characteristics are less affected by flow rate changes, making them an ideal injector for variable-thrust engines. However, achieving high combustion efficiency in current needle-type injectors remains challenging. Because they utilize axial and radial liquid film impacts to form a conical atomized spray for combustion, the combustion efficiency is generally affected by atomization uniformity, typically ranging from 87% to 92%. To achieve high combustion efficiency of over 96% for needle-type injectors, it is essential to improve atomization uniformity and enhance propellant mixing. Summary of the Invention

[0003] The present invention aims to provide a high-combustion-efficiency needle-plug injector with mutual impact and its design method, so that the injector has both the uniform atomization of mutual impact and the simple structure of needle plug, and achieves high combustion efficiency of needle plug injector on the basis of easy manufacturing, so as to better meet the requirements of low cost and high performance of aerospace engine.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A high-efficiency needle-plug injector with mutual impact includes:

[0006] A hemispherical injection panel, wherein the hemispherical injection panel is a hemispherical cavity shell, the hemispherical cavity shell includes a hemispherical inner wall surface and a hemispherical outer wall surface with the same center, and the hemispherical inner wall surface and the hemispherical outer wall surface contain mutually isolated fuel chambers and oxidizer chambers, wherein the hemispherical inner wall surface has a plurality of injection unit mounting holes arranged in a centrally symmetrical array, and the hemispherical outer wall surface has connector mounting holes;

[0007] The reciprocating needle plug injection unit is located within the injection unit mounting hole and includes a coaxially arranged needle plug head and needle plug sleeve. The needle plug head extends outward from the first axial end face of the needle plug sleeve along its axial direction. A fuel accumulator cavity communicating with a fuel chamber is formed on the second axial end face of the needle plug sleeve. A fuel tangential hole is formed on the inner wall of the fuel accumulator cavity. The fuel tangential hole communicates with a circular fuel channel inside the needle plug sleeve and coaxial with the needle plug sleeve. The axial end face of the fuel channel away from the fuel tangential hole forms a fuel outlet. The needle plug head has an annular surface coaxial with the fuel channel. The outer diameter of the annular surface is larger than the outer diameter of the fuel channel. The annular surface and the fuel outlet are spaced apart to form a fuel reversing outlet. This allows the fuel flowing axially out of the fuel outlet to be ejected radially from the fuel reversing outlet after being launched through the annular surface. The outer surface of the needle sleeve has an oxidant tangential hole that communicates with the oxidant cavity. The oxidant tangential hole is connected to an annular oxidant axial channel located inside the needle sleeve and coaxial with the needle sleeve. The inner ring diameter of the oxidant axial channel is larger than the outer ring diameter of the fuel channel. The axial end face of the oxidant axial channel away from the oxidant tangential hole forms an oxidant outlet. The oxidant ejected from the oxidant outlet mixes axially with the fuel that is radially ejected from the fuel reversing outlet.

[0008] A fuel inlet connector, one end of which is installed in a connector mounting hole and communicates with the fuel chamber;

[0009] An oxidant inlet connector, one end of which is installed in a connector mounting hole and communicates with the oxidant cavity.

[0010] Furthermore, the mounting holes of the injection units are distributed on the latitude lines of the sphere on which the hemispherical injection panel is located, and multiple mounting holes of the injection units located on the same latitude line are arranged with equal central angles.

[0011] Furthermore, the end face of the needle plug away from the fuel accumulation chamber is spherical.

[0012] Furthermore, the high-efficiency needle-plug injector with mutual impact also includes an oblique orifice located at the needle plug head. The first end of the oblique orifice penetrates the annular surface of the needle plug head and communicates with the fuel outlet of the fuel channel. The second end of the oblique orifice penetrates the end face of the needle plug head away from the fuel accumulation chamber.

[0013] Furthermore, multiple oblique orifices are distributed on a conical surface coaxial with the needle plug head, with the first end of each oblique orifice located on the bottom surface of the conical surface and the second end located on the top surface. Here, the bottom surface is the end with the larger diameter on the conical surface, and the top surface is the end with the smaller diameter; the bottom surface is closer to the fuel passage.

[0014] Alternatively, the taper angle of the conical surface is 60°.

[0015] The aforementioned design method for a high-efficiency needle-plug injector with mutual impact includes:

[0016] Under the premise that the injector axis is parallel to the injector's resultant momentum angle, the atomization cone angle value corresponding to each injector unit mounting hole is calculated based on the position information of the injector unit mounting holes arranged in a centrally symmetrical array on the hemispherical injector panel. Then, based on the atomization cone angle value, the ratio of the radial momentum of the fuel reversing outlet to the axial momentum of the oxidizer outlet in the mutual-firing pin injector unit is calculated.

[0017] Specifically:

[0018] The radial momentum can be adjusted by changing the flow area and velocity of the fuel reversing outlet in the mutual firing pin injection unit.

[0019] The axial momentum can be adjusted by changing the flow area and flow velocity of the oxidant outlet in the mutual firing pin injection unit.

[0020] Traditional impact injectors require machining of each orifice, and each orifice requires high precision. In contrast, this invention adopts a needle-type structure, which can modularize the injection unit and effectively balance high combustion efficiency with manufacturing difficulty, simplifying the design and manufacturing of the injector while ensuring high combustion efficiency.

[0021] Compared with the prior art, the present invention, by rationally arranging multiple mutually impacting needle-type injection units, causes the cones formed by propellant atomization to collide with each other, forming multiple mutually impacting streams in the combustion chamber, thereby further improving the atomization and mixing of the propellant, and thus preparing a high combustion efficiency needle-type injector with mutual impact and a combustion efficiency of not less than 96%. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a needle-operated injection device with mutual impact.

[0023] Figure 2 This is a schematic diagram of a needle-plug injection unit with mutual impact.

[0024] Figure 3 This is a schematic diagram of the working principle of the mutual-action needle-bolt injection unit;

[0025] Figure 4 This is a schematic diagram of an array arrangement of mutually striking needle plug injection units;

[0026] Figure 5 This is a schematic diagram illustrating the process of calculating the combined momentum angle based on the atomization cone angle;

[0027] In the figure: 1—Hemispherical injection panel; 2—Mutual-action needle plug injection unit; 3—Fuel inlet connector; 4—Oxidant inlet connector; 5—Fuel tangential hole; 6—Oxidant tangential hole; 7—Needle plug head; 8—Angled small hole; 9—Fuel accumulator chamber; 10—Oxidant axial channel; 11—Fuel channel. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0029] First, if Figure 2 and Figure 3 As shown, the high-efficiency needle-bolt injector's mutual-impact needle-bolt injection unit 2 is divided into a fuel unit and an oxidizer unit. The fuel unit is located in the inner ring of the mutual-impact needle-bolt injection unit 2, with a central structure featuring a fuel accumulation chamber 9 and a fuel tangential hole 5. Fuel can flow out through the fuel tangential hole 5 to form a radial liquid film (after flowing out of the fuel tangential hole 5 through the fuel accumulation chamber 9, which serves as the central channel, the fuel first flows along the axially distributed fuel channels 11, and finally forms a radial liquid film under the interception and reflection of the annular surface of the needle head 7, and then atomizes by impact with the axial liquid film formed by the oxidizer). The oxidizer unit is located in the outer ring of the mutual-impact needle-bolt injection unit 2, flowing into the oxidizer axial channel 10 through the oxidizer tangential hole 6 to form an axial liquid film. By rationally arranging the flow area of ​​the axial slot (i.e., the oxidizer outlet) and the radial slot (i.e., the fuel reversing outlet), the momentum in the axial direction (oxidizer ejection direction) and radial direction (fuel ejection direction) is changed, achieving propellant atomization during injector operation.

[0030] Secondly, the mutual-punch-pin injection unit 2 is arranged on a hemispherical injection panel 1 as required. The internal cavity of the hemispherical injection panel 1 is divided into two layers, serving as flow channels for fuel and oxidizer respectively. By calculating and adjusting the atomization cone angle of the mutual-punch-pin injection unit 2, the combined momentum angle of the entire injector can be calculated, so that the combined momentum angle of the propellant is distributed along the axial direction (axial direction refers to...). Figure 1 The axis at the center of the hemispherical injection panel (i.e., the direction of the injector axis) allows for better organization of propellant atomization and combustion. For example... Figure 4In this embodiment, the interlocking needle-bolt injection units 2 are arranged in a centrally symmetrical array on the hemispherical injection panel 1. The interlocking needle-bolt injection units 2 are distributed along different latitudes of the hemisphere corresponding to the hemisphere of the hemisphere. At the central vertex of the hemisphere where the hemisphere is located, there is one injection unit mounting hole as the first ring. Following the direction outward from the central vertex, the second ring has 4 injection unit mounting holes evenly distributed along its latitudes, the third ring has 8, the fourth ring has 12, and the fifth ring has 16. Alternatively, the second ring may have 3, the third ring 6, the fourth ring 9, and the fifth ring 12.

[0031] according to Figure 4 The design scheme of the five-ring mutual impact injection unit 2 is as follows: Let the atomization cone angles of the mutual impact injection units 2 from the 1st to the 5th ring be θ1, θ2, θ3, θ4, and θ5, respectively. Assume that the atomization cone angle formed after the impact of a single needle-bolt injection unit 2 is considered as a whole, and then it impacts the atomization cone angles formed by the remaining single needle-bolt injection units 2. Using the formula q = K√ΔP, where q is the flow rate, K is the fluid characteristic coefficient, and ΔP is the pressure drop, assuming that the propellant is only mixed and not burned, the propellant flow rate can be controlled by the pressure drop of the mutual impact needle-bolt injection units 2, denoted as q1, q2, q3, q4, and q5, respectively. Based on the flow rate and the flow area, the velocities of the mutual impact needle-bolt injection units 2 after impact are v1, v2, v3, v4, and v5, respectively. Therefore, the atomization cone angles θ1, θ2, θ3, θ4, and θ5 of each ring of mutual impact needle-bolt injection units 2 should satisfy the following formula:

[0032] q1v1sin(θ1 / 2)=q2v2 sin(θ2 / 2);

[0033] q2v2sin(θ2 / 2)=q3v3 sin(θ3 / 2);

[0034] q3v3 sin(θ3 / 2)=q4v4 sin(θ4 / 2);

[0035] q4v4 sin(θ4 / 2)=q5v5 sin(θ5 / 2);

[0036] Among them, θ5 / 2 is complementary to the horizontal angle θ6 between the axis of the mutual firing pin injection unit 2 and the axis of the mutual firing pin injection unit 2.

[0037] By controlling the combined momentum angle after the mutual collision, taking into account the hemispherical structure characteristics (symmetry) of the hemispherical injection panel 1, and the symmetry of the mutual impact pin injection unit 2 about the central axis of the hemispherical injection panel 1, the combined momentum angle of the injector is finally made parallel to the injector axis.

[0038] Considering that the atomization cone angle θ of each mutual-firing pin injection unit 2 can be calculated according to the following formula:

[0039] θ = 38.86 (We / C) TMR ) 0.096

[0040] Where:

[0041] C TMR —Momentum ratio, C TMR =q r v r / q a v a q r For radial propellant flow rate, v r q represents the radial propellant velocity; a v is the axial propellant flow rate. a This represents the axial propellant velocity.

[0042] We — Weiber number, We = ρv 2 L / σ. Where ρ is the fluid density, v is the characteristic velocity, L is the characteristic length, and σ is the fluid surface tension coefficient.

[0043] Therefore, after obtaining the values ​​of θ1, θ2, θ3, θ4, and θ5, the flow area and fuel velocity of the fuel reversing outlet in the mutual-punch-pin-injection unit 2, as well as the flow area and oxidant velocity of the oxidant outlet in the mutual-punch-pin-injection unit 2, can be calculated, thereby obtaining the design parameters of the mutual-punch-pin-injection unit 2.

[0044] On the other hand, high efficiency is accompanied by high heat. To ensure the thermal reliability of the high-efficiency needle-plug injector, an internal flow channel is arranged at the needle plug head 7, so that it is cooled inside the needle plug head 7 and collided with each other at the outlet to form a local low-temperature zone.

[0045] Based on the above design method, a design was created. Figures 1-3 The invention illustrates a high-efficiency needle-type injector with mutual impact, which simultaneously achieves high reliability and high combustion efficiency.

[0046] A high-efficiency needle-plug injector with mutual impact consists of a hemispherical injection panel 1, a mutual impact needle-plug injection unit 2, a fuel inlet connector 3, and an oxidizer inlet connector 4, as shown below. Figure 1As shown. Specifically, it consists of a hemispherical injection panel 1, which has two internal regions: a fuel region and an oxidizer region. These two regions are isolated from each other and do not come into contact during injector operation (to ensure that the fuel and oxidizer do not come into contact within the injector, the fuel and oxidizer are not in contact within the injector). It is mainly used to install the mutual-punch-pin injection unit 2, the fuel inlet connector 3, and the oxidizer inlet connector 4. Depending on the size of the hemisphere, multiple mutual-punch-pin injection units 2 can be evenly arranged in a centrally symmetrical array. By rationally arranging the mutual-punch-pin injection units 2 (i.e., rationally arranging the atomization cone angle of the mutual-punch-pin injection units 2), the mutual-punch momentum angle can be made parallel to the axis of the injector and nozzle. The generated high-temperature gas advances along the combustion chamber towards the nozzle throat, reducing the thermal protection of the combustion chamber wall. The head of the high-efficiency needle injector with mutual impact is provided with two connectors. The fuel inlet connector 3 is connected to the fuel area and is used for fuel input when the injector is working. The oxidizer inlet connector 4 is connected to the oxidizer area and isolated from the fuel area and is used for oxidizer input when the injector is working.

[0047] like Figure 2 The mutual-impact needle-bolt injection unit 2 consists of a needle-bolt head 7 with mutual impact and a needle-bolt sleeve. Three oxidizer tangential holes 6 are evenly arranged tangentially on the needle-bolt sleeve, allowing the oxidizer to be ejected in a rotating manner through the slit between the needle-bolt sleeve and the needle-bolt head 7, forming an axial liquid film. Fuel flows out from the central fuel accumulation chamber 9 through the three fuel tangential holes 5, and is redirected at the outlet by the needle-bolt head 7, forming a radial liquid film. The axial liquid film of the oxidizer collides with the radial liquid film of the fuel, atomizing the propellant into a conical shape. Simultaneously, an oblique small hole 8 is designed at the central needle-bolt head 7. When fuel is ejected from the central channel, some fuel is ejected from the oblique small hole 8 at the needle-bolt head 7 (forming a 60° angle with each other), and atomizes upon impact at the outlet of the needle-bolt head 7, further reducing the temperature of the needle-bolt head 7, improving the propellant atomization effect, and enhancing injection reliability. The working principle of the mutual-impact needle-bolt injection unit 2 is described in [link to relevant documentation]. Figure 3 .

[0048] By rationally arranging multiple mutually impacting needle-bolt injection units 2, the cone angles formed by propellant atomization can collide with each other, forming multiple mutually impacting streams in the combustion chamber, further improving the atomization and mixing of the propellant, thereby achieving a high combustion efficiency needle-bolt injector with mutual impact and a combustion efficiency of not less than 96%.

[0049] The above are the main concepts of the invention. All needle-type injectors with mutual impact designed based on the concepts of this invention fall within the protection scope of this invention.

Claims

1. A high combustion efficiency pintle injector with mutual impact, characterized in that: include: A hemispherical injection panel (1), the hemispherical injection panel (1) being a hemispherical cavity shell, the hemispherical cavity shell comprising a hemispherical inner wall surface and a hemispherical outer wall surface with the same spherical center, the hemispherical inner wall surface and the hemispherical outer wall surface containing a fuel cavity and an oxidant cavity isolated from each other, wherein the hemispherical inner wall surface is provided with a plurality of injection unit mounting holes distributed in a centrally symmetrical array, and the hemispherical outer wall surface is provided with a joint mounting hole; A mutual-strike needle-bolt injection unit (2), the mutual-strike needle-bolt injection unit (2) is located in the injection unit installation hole, and comprises a needle-bolt head (7) and a needle-bolt sleeve arranged coaxially, the needle-bolt head (7) extending outwardly from the axial first end face of the needle-bolt sleeve along the axial direction of the needle-bolt sleeve, a fuel liquid accumulation chamber (9) communicating with a fuel cavity is formed on the axial second end face of the needle-bolt sleeve, a fuel tangential hole (5) is formed on the inner wall of the fuel liquid accumulation chamber (9), the fuel tangential hole (5) is communicated with a circular annular fuel channel (11) inside the needle-bolt sleeve and coaxial with the needle-bolt sleeve, the fuel channel (11) is away from the axial end face of the fuel tangential hole (5) to form a fuel outlet, the needle-bolt head (7) has an annular surface coaxial with the fuel channel (11), the outer ring diameter of the annular surface is larger than the fuel channel (11), and the outer ring diameter of the annular surface is larger than the fuel channel (11). The outer ring diameter of the channel (11) is 1.5 mm, and there is a gap between the annular surface and the fuel outlet, thereby forming a fuel reversing outlet, so that the fuel flowing out axially through the fuel outlet is emitted by the annular surface and then radially ejected from the fuel reversing outlet. The outer surface of the needle plug sleeve is provided with an oxidant tangential hole (6) connected to the oxidant cavity. The oxidant tangential hole (6) is connected to a circular annular oxidant axial channel (10) located inside the needle plug sleeve and coaxial with the needle plug sleeve. The inner ring diameter of the oxidant axial channel (10) is larger than the outer ring diameter of the fuel channel (11). The oxidant outlet is formed at the axial end face of the oxidant axial channel (10) away from the oxidant tangential hole (6). The oxidant ejected from the oxidant outlet is mixed axially with the fuel ejected radially from the fuel reversing outlet. A fuel inlet joint (3), one end of which is mounted in the joint mounting hole and communicates with the fuel cavity; An oxidant inlet joint (4), one end of which is installed in the joint installation hole and communicated with the oxidant cavity.

2. A high combustion efficiency pintle injector with mutual impact according to claim 1, characterized in that: The injection unit installation holes are distributed on the latitude of the spherical surface where the hemispherical injection panel (1) is located, and multiple injection unit installation holes located on the same latitude are arranged according to equal central angles.

3. A high combustion efficiency pintle injector with mutual impact according to claim 1, characterized in that: The end surface of the needle plug head (7) away from the fuel liquid accumulation chamber (9) is a spherical surface.

4. A high combustion efficiency pintle injector with mutual impact according to claim 1, characterized in that: The invention also comprises an oblique small hole (8), wherein the oblique small hole (8) is located on the needle bolt head (7), and a first end of the oblique small hole (8) penetrates the annular surface of the needle bolt head (7) and is connected to the fuel outlet of the fuel channel (11), and a second end of the oblique small hole (8) penetrates the end surface of the needle bolt head (7) away from the fuel liquid accumulation chamber (9).

5. A high combustion efficiency pintle injector with mutual impact according to claim 4, characterized in that: The plurality of oblique small holes (8) are distributed on a conical surface coaxial with the needle bolt head (7), and the first ends of the oblique small holes (8) are distributed on the bottom surface of the conical surface, and the second ends are distributed on the top surface of the conical surface.

6. A high combustion efficiency pintle injector with mutual impact according to claim 5, characterized in that: The taper angle of the cone surface is 60°.

7. A design method for a high combustion efficiency pintle injector with mutual impact according to claim 1, characterized in that: include: On the premise that the injector axis is parallel to the injector composite momentum angle, the atomization cone angle value corresponding to each injection unit installation hole is calculated based on the position information of the injection unit installation holes distributed in a centrally symmetrical array on the hemispherical injection panel (1), and then the ratio of the radial momentum of the fuel reversing outlet and the axial momentum of the oxidant outlet in the mutual impact pintle injection unit (2) is calculated based on the atomization cone angle value.

8. The design method of a high combustion efficiency pintle injector with mutual impact according to claim 7, characterized in that: Changing the flow area and flow velocity of the fuel reversing outlet in the mutual impact pintle injection unit (2) to adjust the radial momentum; The size of the axial momentum is adjusted by changing the flow area and flow rate of the oxidant outlet in the mutual impact pintle injection unit (2).

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