Gas-liquid coaxial centrifugal nozzle for inhibiting self-excited oscillation based on central solid structure

Abstract

The utility model discloses a gas-liquid coaxial centrifugal nozzle for inhibiting self-excited oscillation based on a central solid structure, which comprises an outer shell and an inner shell of a rotary body structure, and the outer shell is provided with a liquid inlet, a gas inlet, a spray outlet and a retraction chamber; the inner shell is coaxially arranged on the outer shell, a liquid centrifugal flow channel is formed in the inner shell, and a gas circular seam flow channel is defined between the inner shell and the outer shell; the first end of the liquid centrifugal flow channel is communicated with the liquid inlet, the first end of the gas circular seam flow channel is communicated with the gas inlet, the second end of the liquid centrifugal flow channel and the second end of the gas circular seam flow channel are both communicated with the first end of the retraction chamber, and the second end of the retraction chamber is communicated with the spray outlet; a central solid body of a rod-shaped structure is coaxially arranged in the liquid centrifugal flow channel so as to effectively restrain generation of self-oscillation. The self-oscillation suppression device is applied to the field of suppression of self-oscillation and unstable combustion of a liquid rocket engine, and can effectively suppress self-oscillation on the premise of not influencing the atomization effect of a nozzle, so that reliable and stable combustion of the engine is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of self-excited oscillation and unstable combustion suppression of liquid rocket engines, in particular to a gas-liquid coaxial centrifugal nozzle based on a central entity structure for suppressing self-excited oscillation. Background Art

[0002] In liquid rocket engines, the nozzle connects the supply system and the combustion chamber, is responsible for the injection and atomization of the fuel, and plays a decisive role in the evaporation, mixing and combustion of the fuel. Since the interaction between gas and liquid can significantly improve the atomization performance of the nozzle and thus enhance the combustion efficiency, the gas-liquid coaxial nozzle is widely used in bipropellant liquid rocket engines. However, it is precisely because of the intense gas-liquid interaction that this type of nozzle will experience self-excited oscillation under certain structures and working conditions.

[0003] When self-excited oscillation occurs, the pressure and flow rate at the nozzle outlet will oscillate periodically, accompanied by sharp nozzle whistling. The typical self-excited oscillation spray is in the shape of a "Christmas tree", with an oscillation frequency between 1kHz and 10kHz. Studies have found that self-excited oscillation can cause oscillations in the flame and pre-fuel injection pressure. Under certain operating conditions, self-excited oscillation can stimulate unstable combustion, which has an adverse effect on the engine spray combustion process and needs to be suppressed.

[0004] Currently, the way to suppress self-excited oscillations is mainly through changing the gas-liquid injection conditions and the nozzle retraction length. For a specific liquid rocket engine, the nozzle design conditions are usually determined, and adjusting the retraction length often greatly affects the atomization effect and combustion performance, which may lead to consequences such as poor atomization effect and reduced combustion efficiency. Utility Model Content

[0005] In view of the deficiencies in the above-mentioned prior art, the utility model provides a gas-liquid coaxial centrifugal nozzle based on a central solid structure to suppress self-excited oscillations, which can effectively suppress self-excited oscillations without affecting the atomization effect of the nozzle, thereby achieving reliable and stable combustion of the engine.

[0006] To achieve the above-mentioned purpose, the utility model provides a gas-liquid coaxial centrifugal nozzle based on a central solid structure to suppress self-excited oscillation, comprising an outer shell and an inner shell of a rotating body structure, and the outer shell is provided with a liquid inlet, a gas inlet, a spray outlet and a retracting chamber;

[0007] The inner shell is coaxially arranged on the outer shell, a liquid centrifugal flow channel is arranged in the inner shell, and a gas annular gap flow channel is formed between the inner shell and the outer shell;

[0008] The first end of the liquid centrifugal flow channel is connected to the liquid inlet, the first end of the gas annular gap flow channel is connected to the gas inlet, the second end of the liquid centrifugal flow channel and the second end of the gas annular gap flow channel are both connected to the first end of the retraction chamber, and the second end of the retraction chamber is connected to the spray outlet;

[0009] A central entity of a rod-shaped structure is coaxially arranged in the liquid centrifugal flow channel to effectively suppress the generation of self-excited oscillation.

[0010] In one embodiment, the liquid centrifugal flow channel includes a cyclone chamber, a contraction section, an equal straight section and an expansion section which are connected in sequence;

[0011] The inner diameter of the cyclone chamber is larger than that of the straight section, and the cyclone chamber is connected to the liquid inlet, and the expansion section is connected to the retraction chamber;

[0012] The first end of the central entity is located in the cyclone chamber and is fixedly connected to the inner wall of the first end of the inner shell, and the second end of the central entity extends into the straight section.

[0013] In one embodiment, the liquid inlet is provided at the top of the housing;

[0014] The first end of the inner shell is located inside the outer shell, and a liquid collecting cavity is formed between the outer wall of the first end of the inner shell and the inner wall of the outer shell, and the liquid inlet is connected to the liquid collecting cavity;

[0015] A plurality of tangential holes are provided at intervals along the circumferential direction on the side of the first end of the inner shell, one end of each of the tangential holes is communicated with the liquid collecting cavity, and the other end is communicated with the cyclone chamber.

[0016] In one embodiment, the gas inlet is provided on a side of the housing;

[0017] The second end of the inner shell is located inside the outer shell, and the gas annular gap flow channel is located between the outer wall of the second end of the inner shell and the inner wall of the outer shell;

[0018] An air collecting cavity is formed between the outer wall of the middle region of the inner shell and the inner wall of the outer shell, and the gas inlet, the air collecting cavity and the gas annular gap flow channel are connected in sequence.

[0019] In one embodiment, there are multiple gas inlets, and each of the gas inlets is circumferentially spaced apart on a side of the housing.

[0020] In one embodiment, the side of the inner shell is provided with a circumferential skirt, and the outer shell includes an upper cover body and a lower base body;

[0021] The first end of the inner shell is located in the upper cover body, the liquid inlet is arranged on the top of the upper cover body, and the bottom of the upper cover body is connected to the top of the skirt;

[0022] The second end of the inner shell is located in the lower base, and the top of the lower base is connected to the bottom of the skirt, the spray outlet is arranged at the bottom of the lower base, and the gas inlet is arranged at the side of the lower base.

[0023] In one embodiment, the cross-sectional shape of the central entity is circular, elliptical or polygonal.

[0024] Compared with the prior art, the utility model has the following beneficial technical effects:

[0025] The utility model coaxially sets a central entity of a certain length and diameter in the liquid centrifugal flow channel of the gas-liquid coaxial centrifugal nozzle, so that when the liquid fuel flows in the liquid centrifugal flow channel, the generation of the dominant surface wave and the amplitude-frequency characteristics of the surface wave can be suppressed. In addition, due to the violent centrifugal motion, a central air core will be generated on the axis of the liquid centrifugal flow channel. The central entity can also shorten the size of the central air core to a certain extent and suppress the oscillation of the central air core, thereby suppressing the generation of self-excited oscillation from the source without affecting the nozzle atomization effect, thereby achieving reliable and stable combustion of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0027] Figure 1 It is an axial cross-sectional view of the overall structure of the gas-liquid coaxial centrifugal nozzle in the embodiment of the utility model;

[0028] Figure 2 This is an axial cross-sectional view of the inner shell in the embodiment of the utility model;

[0029] Figure 3 It is a cross-sectional view of the gas-liquid coaxial centrifugal nozzle at the tangential hole in the embodiment of the utility model;

[0030] Figure 4 It is a cross-sectional view of the gas-liquid coaxial centrifugal nozzle at the gas annular gap flow channel in the embodiment of the utility model;

[0031] Figure 5 It is a schematic diagram of another implementation of the gas-liquid coaxial centrifugal nozzle in the embodiment of the utility model.

[0032] Figure numbers: outer shell 1, upper cover body 101, lower base body 102, inner shell 2, skirt 201, tangential hole 202, liquid inlet 3, gas inlet 4, spray outlet 5, retracted chamber 6, liquid centrifugal flow channel 7, cyclone chamber 701, contraction section 702, straight section 703, groove 7031, protrusion 7032, expansion section 704, gas annular flow channel 8, central entity 9, liquid collecting cavity 10, gas collecting cavity 11.

[0033] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0035] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] like Figures 1 to 4The present embodiment shows a gas-liquid coaxial centrifugal nozzle for suppressing self-excited oscillation based on a central entity structure, which mainly includes an outer shell 1 and an inner shell 2 of a rotating body structure, and the outer shell 1 is provided with a liquid inlet 3, a gas inlet 4, a spray outlet 5 and a retracting chamber 6. The inner shell 2 is coaxially arranged on the outer shell 1, and a liquid centrifugal flow channel 7 is provided in the inner shell 2. A gas annular gap flow channel 8 is formed between the inner shell 2 and the outer shell 1. The first end of the liquid centrifugal flow channel 7 is connected to the liquid inlet 3, and the first end of the gas annular gap flow channel 8 is connected to the gas inlet 4. The second end of the liquid centrifugal flow channel 7 and the second end of the gas annular gap flow channel 8 are both connected to the first end of the retracting chamber 6, and the second end of the retracting chamber 6 is connected to the spray outlet 5. A central entity 9 of a rod-shaped structure is coaxially arranged in the liquid centrifugal flow channel 7 to effectively suppress the generation of self-excited oscillation.

[0038] In this embodiment, the liquid centrifugal flow channel 7 includes a cyclone chamber 701, a contraction section 702, an equal straight section 703 and an expansion section 704 which are connected in sequence. The inner diameter of the cyclone chamber 701 is larger than that of the equal straight section 703, and it is the main centrifugal area of ​​the liquid centrifugal flow channel 7. The cyclone chamber 701 is connected to the liquid inlet 3, and the expansion section 704 is connected to the retracted chamber 6. The first end of the central entity 9 is located in the cyclone chamber 701, and the first end of the central entity 9 is fixedly connected to the inner wall of the first end of the inner shell 2 by welding, threaded connection or integral molding, and the second end of the central entity 9 extends into the equal straight section 703. Among them, the cross-sectional shape of the central entity 9 is circular, elliptical or polygonal, and is preferably circular in this embodiment.

[0039] In a specific implementation process, a skirt 201 is provided along the circumferential direction on the side of the inner shell 2 , and the outer shell 1 includes an upper cover body 101 and a lower base body 102 .

[0040] The first end of the inner shell 2 is located in the upper cover 101, and the liquid inlet 3 is opened at the center of the top of the upper cover 101. The bottom of the upper cover 101 is fixedly connected to the top of the skirt 201 by means of a sealing ring, a snap connection, a bolt connection or a threaded connection. The outer wall of the first end of the inner shell 2 and the inner wall of the upper cover 101 form a liquid collecting chamber 10, and the liquid inlet 3 is connected to the liquid collecting chamber 10. At the same time, the side of the first end of the inner shell 2 is provided with a plurality of spaced-apart liquid inlets 101 along the circumferential direction. Figure 3 As shown in the tangential holes 202, one end of each tangential hole 202 is connected to the liquid collecting chamber 10, and the other end is connected to the swirl chamber 701. In specific applications, the liquid fuel first enters the liquid collecting chamber 10 through the liquid inlet 3, and then enters the swirl chamber 701 through the tangential holes 202, and is ejected from the expansion section 704 under the action of centrifugal force to form a conical liquid film.

[0041] The second end of the inner shell 2 is located in the lower base 102, the gas inlet 4 is opened at the upper side of the lower base 102, and the top of the lower base 102 is fixedly connected to the bottom of the skirt 201 by means of a sealing ring, a snap connection, a bolt connection or a threaded connection, and the spray outlet 5 is opened at the bottom of the lower base 102. The inner wall of the lower base 102 near the top and the outer wall of the inner shell 2 are clearance fit or interference fit, the inner wall of the lower base 102 near the middle and the outer wall of the inner shell 2 form a gas collecting cavity 11, the inner wall of the lower base 102 near the bottom and the outer wall of the inner shell 2 form a gas annular gap flow channel 8, and the inner wall of the lower base 102 at the bottom separately forms a retraction chamber 6, and the gas inlet 4, the gas collecting cavity 11, the gas annular gap flow channel 8 and the retraction chamber 6 are connected in sequence. Among them, the number of gas inlets 4 is multiple, and each gas inlet 4 is spaced along the circumferential direction on the side of the lower base 102. In specific applications, the liquid fuel first enters the gas collecting chamber 11 through the gas inlet 4, then enters the retracted chamber 6 through the gas annular gap flow channel 8, and violently interacts with the liquid fuel forming a conical liquid film, and then is sprayed out from the spray outlet 5, thereby completing the crushing atomization process.

[0042] After the liquid fuel enters the liquid centrifugal flow channel 7, it is rotated and ejected from the second end of the liquid centrifugal flow channel 7 under the centrifugal action to form a conical liquid film. At the same time, it interacts violently with the gas fuel ejected from the gas annular gap flow channel 8 inside the retracted chamber 6 and then ejected from the spray outlet 5, thereby completing the crushing atomization process. In this process, a central air core is generated on the axis of the liquid centrifugal flow channel 7 due to the violent centrifugal motion, and the central air core will bring a certain degree of oscillation. At the same time, a surface wave structure will be generated at the gas-liquid interface. For gas-liquid coaxial centrifugal nozzles, there is usually a certain retracted length in order to improve the atomization performance. For a given gas-liquid injection condition, as the retracted length increases, the surface wave structure at the gas-liquid interface is likely to cause the spray to change from a steady state to a self-excited oscillation state. When the self-excited oscillation frequency is coupled with the inherent acoustic frequency of the combustion chamber, unstable combustion will be induced, which is extremely unfavorable for the reliable and stable combustion of the engine. Based on this, the present embodiment coaxially arranges a rod-shaped central entity 9 in the liquid centrifugal flow channel 7. Since the central entity 9 occupies the axial portion of the main centrifugal area in the liquid centrifugal flow channel 7 and has a certain diameter and length, the size of the central air core can be reduced to a certain extent, thereby suppressing the oscillation caused by the central air core. Due to the contraction of the flow channel, the dominant surface wave starts at the outlet of the contraction section 702 of the liquid centrifugal flow channel 7. In the present embodiment, the diameter of the central entity 9 is determined according to the size of the central air core, and the length of the central entity 9 is greater than or equal to the sum of the axial dimensions of the vortex chamber 701 and the contraction section 702, that is, the second end of the central entity 9 extends into the straight section 703. Due to the presence of the central entity 9, the fluctuation space at the gas-liquid interface at the outlet of the contraction section 702 is reduced, thereby suppressing the generation of the surface wave structure here to a certain extent. Therefore, the central entity 9 can effectively suppress the generation of self-excited oscillations without affecting the nozzle atomization effect, thereby achieving reliable and stable combustion of the engine.

[0043] In the specific implementation process, the central entity 9 needs to be able to suppress self-excited oscillation while minimizing the impact on the centrifugal effect of the liquid centrifugal flow channel 7. Therefore, its length and diameter need to be specifically designed. The specific implementation process is as follows:

[0044] When the entrance Reynolds number of the tangential hole 202 is t When Re is greater than 2400, the central air core inside the nozzle is in a fully developed stable state. For a fully developed stable air core, the size of the air core increases with Re t In order to effectively suppress the generation of dominant surface waves, the diameter of the central entity 9 in this embodiment is set equal to the central air core diameter when the central entity 9 is not set. The length of the central entity 9 is determined according to the mass flow rate of the liquid and should be greater than or equal to the sum of the axial dimensions of the cyclone chamber 701 and the contraction section 702. The fully developed stable air core size formula is:

[0045]

[0046] Among them, D a is the diameter of the gas core, D0 is the diameter of the straight section, D s is the diameter of the cyclone chamber, D p is the tangential hole diameter, L0 is the length of the straight section, and α is the contraction angle of the contraction section;

[0047] Tangential hole entrance Reynolds number Re t The specific calculation formula is:

[0048]

[0049] In the formula, ρ l is the density of liquid fuel, μ l Liquid dynamic viscosity, ω t is the tangential hole entrance velocity, d t is the tangential hole diameter.

[0050] As a preferred embodiment, the inner wall of the straight section 703 is further provided with a groove 7031 and / or a protrusion 7032, wherein the groove 7031 and the protrusion 7032 can be provided as a plurality of grooves 7031 and protrusions 7032 distributed along the circumferential direction and / or axial direction of the straight section 703, for example Figure 5 By providing the groove 7031 and the protrusion 7032 on the inner wall of the straight section 703, a certain disturbance effect can be exerted on the swirl flow in the straight section 703. As the swirl flow is ejected from the expansion section 704, this disturbance destroys and suppresses the surface wave structure at the gas-liquid interface in the retracting chamber 6, thereby also suppressing the generation of self-excited oscillation to a certain extent.

[0051] The above description is only a preferred embodiment of the utility model, and does not limit the patent scope of the utility model. All equivalent structural changes made by using the contents of the utility model specification and drawings under the utility model concept, or directly / indirectly used in other related technical fields are included in the patent protection scope of the utility model.

Claims

1. A gas-liquid coaxial centrifugal nozzle based on a central solid structure to suppress self-excited oscillation, characterized in that: It comprises an outer shell and an inner shell of a rotating body structure, and the outer shell is provided with a liquid inlet, a gas inlet, a spray outlet and a retracting chamber; The inner shell is coaxially arranged on the outer shell, a liquid centrifugal flow channel is arranged in the inner shell, and a gas annular gap flow channel is formed between the inner shell and the outer shell; The first end of the liquid centrifugal flow channel is connected to the liquid inlet, the first end of the gas annular gap flow channel is connected to the gas inlet, the second end of the liquid centrifugal flow channel and the second end of the gas annular gap flow channel are both connected to the first end of the retraction chamber, and the second end of the retraction chamber is connected to the spray outlet; A central entity of a rod-shaped structure is coaxially arranged in the liquid centrifugal flow channel to effectively suppress the generation of self-excited oscillation.

2. The gas-liquid coaxial centrifugal nozzle based on the central solid structure to suppress self-excited oscillation according to claim 1, characterized in that: The liquid centrifugal flow channel comprises a cyclone chamber, a contraction section, a straight section and an expansion section which are connected in sequence; The inner diameter of the cyclone chamber is larger than that of the straight section, and the cyclone chamber is connected to the liquid inlet, and the expansion section is connected to the retraction chamber; The first end of the central entity is located in the cyclone chamber and is fixedly connected to the inner wall of the first end of the inner shell, and the second end of the central entity extends into the straight section.

3. The gas-liquid coaxial centrifugal nozzle based on the central solid structure to suppress self-excited oscillation according to claim 2, characterized in that: The liquid inlet is arranged at the top of the housing; The first end of the inner shell is located inside the outer shell, and a liquid collecting cavity is formed between the outer wall of the first end of the inner shell and the inner wall of the outer shell, and the liquid inlet is connected to the liquid collecting cavity; A plurality of tangential holes are provided at intervals along the circumferential direction on the side of the first end of the inner shell, one end of each of the tangential holes is communicated with the liquid collecting cavity, and the other end is communicated with the cyclone chamber.

4. The gas-liquid coaxial centrifugal nozzle based on the central solid structure to suppress self-excited oscillation according to claim 3, characterized in that: The gas inlet is arranged on the side of the housing; The second end of the inner shell is located inside the outer shell, and the gas annular gap flow channel is located between the outer wall of the second end of the inner shell and the inner wall of the outer shell; An air collecting cavity is formed between the outer wall of the middle region of the inner shell and the inner wall of the outer shell, and the gas inlet, the air collecting cavity and the gas annular gap flow channel are connected in sequence.

5. The gas-liquid coaxial centrifugal nozzle based on the central solid structure to suppress self-excited oscillation according to claim 4, characterized in that: There are multiple gas inlets, and each of the gas inlets is spaced apart along the circumferential direction and located at a side of the housing.

6. The gas-liquid coaxial centrifugal nozzle based on a central solid structure to suppress self-excited oscillation according to claim 4 or 5, characterized in that: The side of the inner shell is provided with a circumferential skirt, and the outer shell comprises an upper cover body and a lower base body; The first end of the inner shell is located in the upper cover body, the liquid inlet is arranged on the top of the upper cover body, and the bottom of the upper cover body is connected to the top of the skirt; The second end of the inner shell is located in the lower base, and the top of the lower base is connected to the bottom of the skirt, the spray outlet is arranged at the bottom of the lower base, and the gas inlet is arranged at the side of the lower base.

7. The gas-liquid coaxial centrifugal nozzle based on a central solid structure to suppress self-excited oscillation according to any one of claims 1 to 5, characterized in that: The cross-sectional shape of the central entity is circular, elliptical or polygonal.

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