Double-rotational-flow liquid atomizing nozzle

Abstract

The invention discloses a double-swirl liquid atomizing nozzle which comprises a nozzle body, a needle valve and a pressure cavity, the double-swirl liquid atomizing nozzle is formed by mutually combining the nozzle body and the needle valve, the needle valve is arranged in a central cavity of the nozzle body, the pressure cavity is formed between the bottom of the needle valve and the nozzle body, a plurality of groups of spray holes are formed in the bottom of the nozzle body, and the spray holes are communicated with the nozzle body. Counter bores are formed in the two sides of the pressure cavity, the counter bores are communicated with the spraying holes, the axes of the spraying holes are tangent to the edge of the pressure cavity, and rotational flow grooves are formed in inlets of the ends, close to the pressure cavity, of the spraying holes; dual rotational flow formed by the eccentric nozzle structure and the tangent groove structure can promote atomization, the spray penetration distance is effectively shortened, the spray angle is increased, and heat transfer loss caused by wall-attached combustion is reduced. The shearing force of the vortex formed by the vortex increases the surface fluctuation and the breaking trend quantity of the liquid fuel.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel injection for thermal engines, and particularly to a dual-swirl liquid atomizing nozzle. Background Art

[0002] The fuel nozzle is an important component in the fuel injection device of the internal combustion engine fuel supply system. Its design and performance are key factors affecting the mixture gas, and also affect the efficiency and economy of the combustion process. Its spray quality and shape play a decisive role in the combustion efficiency. Better spray quality can achieve better fuel and air mixing, make the fuel burn fully, and reduce the generation of unburned fuel and harmful emissions. The arrangement method and injection angle of the nozzle head also affect the fuel injection and mixing effect. An appropriate injection angle can make the fuel injection mix better with the intake air.

[0003] In Chinese Patent No. 201910252634.9, most of the existing fuel nozzles have an axisymmetric structure, and the fuel is finally mostly distributed near the cylinder wall, which is not conducive to the utilization of air in the central area of the cylinder, and problems such as large heat transfer losses caused by wall-attached combustion occur. Therefore, the present invention proposes a dual-swirl liquid atomizing nozzle to solve the problems existing in the prior art. Summary of the Invention

[0004] In view of the above problems, the object of the present invention is to provide a dual-swirl liquid atomizing nozzle. The rotating fuel airflow formed by the eccentric nozzle structure of the dual-swirl liquid atomizing nozzle can effectively shorten the spray penetration distance, increase the spray angle, and reduce the heat transfer loss caused by wall-attached combustion. In the present invention, a central vortex is easily formed in the pressure chamber at the nozzle head. The shear force of the vortex formed by the vortex increases the surface fluctuation and fragmentation tendency of the liquid fuel jet, promotes the evaporation and cavitation of the liquid fuel, will promote the mixing with the surrounding air, improve the formation of the mixture gas, and at the same time enhance the flexibility and effect of the liquid fuel control.

[0005] To achieve the object of the present invention, the present invention is realized through the following technical solutions: A dual-swirl liquid atomizing nozzle includes a nozzle body, a needle valve, and a pressure chamber. The dual-swirl liquid atomizing nozzle is formed by the combination of the nozzle body and the needle valve. The needle valve is arranged on one side of the nozzle body. A pressure chamber is formed between the bottom of the needle valve and the nozzle body. Multiple groups of spray holes are arranged at the bottom of the nozzle body. Counterbores are arranged on both sides of the pressure chamber. The counterbores are communicated with the spray holes. The axis of the spray hole is tangent to the edge of the pressure chamber. A swirl groove is arranged at the entrance of the spray hole near the pressure chamber. A primary swirl rotating around the axis of the pressure chamber is arranged inside the pressure chamber. A secondary swirl is arranged inside the spray hole.

[0006] A further improvement lies in that: the shape of the spray hole is a cylindrical hole, the distance between the interiors of the pressure chambers is the eccentricity, and the eccentricity extends from the middle of the pressure chamber towards the inner wall.

[0007] A further improvement lies in that: an air flow disk is arranged outside the pressure chamber, the air flow disk is arranged below the inside of the nozzle body, and the air flow disk wraps the pressure chamber.

[0008] A further improvement lies in that: the internal structure of the spray hole is an eccentric design, and the spray hole does not coincide with any cross-section passing through the axis of the nozzle.

[0009] A further improvement lies in that: a low-pressure area is provided at the central position of the secondary swirl formed at the entrance of the spray hole, and a spray field is arranged at the exit of the spray hole.

[0010] A further improvement lies in that: a plurality of swirl grooves are provided at the entrance of the spray hole, so that a transverse swirl is formed inside the spray hole.

[0011] A further improvement lies in that: the spray hole is parallel to the plane between the nozzle axis, and there are multiple groups of counterbores, and the size specifications of each group of counterbores are the same.

[0012] The beneficial effects of the present invention are as follows: the eccentric nozzle structure and the swirl formed by the swirl grooves at the entrance of the spray hole in the present invention can promote atomization, effectively shorten the spray penetration distance, increase the spray angle, reduce the heat transfer loss caused by wall-attached combustion. In the present invention, a central vortex is easily formed in the pressure chamber at the nozzle head, and the shear force of the vortex formed by the vortex increases the surface fluctuation and fragmentation tendency of the liquid fuel, promotes the evaporation and cavitation of the liquid fuel, will promote the mixing with the surrounding air, and improve the formation of the mixture; at the same time, it enhances the flexibility and effect of liquid fuel control, increases the internal flow disturbance, improves the turbulence intensity, improves atomization, enhances the ability to entrain air, improves the mixture quality, makes the combustion fast and sufficient, is beneficial to improving the economic performance, emission performance and power performance of the engine, and improves the thermal efficiency. The present invention adopts a counterbore design to offset the orifice nozzle to reduce the orifice length, can effectively reduce the phenomenon of liquid film attachment in the cylinder, and further improve the combustion efficiency. Description of the Drawings

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0014] Figure 1 It is the semi-sectional front view of the structure of the nozzle of the present invention;

[0015] Figure 2 It is a top view of the structure of the nozzle head of the present invention;

[0016] Figure 3 It is a front view of the structure of the nozzle head of the present invention;

[0017] Figure 4 It is a schematic diagram of the streamline inside the nozzle of the present invention;

[0018] Figure 5 It is a schematic diagram of the swirl groove and local vortex line near the orifice inlet of the nozzle head of the present invention;

[0019] Figure 6 It is a schematic diagram of the local cavitation area of the orifice of the nozzle head of the present invention;

[0020] Figure 7 It is a schematic diagram of the internal area of the orifice of the nozzle head of the present invention.

[0021] Reference numerals in the drawings: 1, nozzle body; 2, needle valve; 3, pressure chamber; 4, orifice; 5, counterbore; 6, eccentricity; 7, air flow disk; 8, swirl groove. Specific embodiments

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0023] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0024] In Document 201910252634.9, when the fuel pressure difference between the inlet and outlet of the nozzle is large, the atomization scales of the dual-fuel-path nozzle and the single-fuel-path nozzle for liquid fuel are basically the same. However, under low operating conditions of the gas turbine, the fuel supply pressure of the single-fuel-path nozzle is relatively low, resulting in poor atomization quality of the air atomizing nozzle, thus affecting the combustion efficiency of the unit. However, the dual-fuel-path nozzle can achieve a higher fuel supply pressure, increase the fuel velocity at the nozzle outlet, strengthen the shearing force between the fuel and the air, improve the atomization quality of the nozzle, and is conducive to solving and improving the combustion efficiency of the combustor under low operating conditions of the gas turbine. However, the internal fuel is distributed near the cylinder wall, which is not conducive to the use of air at the central position. The rotating fuel airflow formed by the eccentric nozzle structure in the present invention can promote atomization, effectively shorten the spray penetration distance, increase the spray angle, and reduce the heat transfer loss caused by wall-attached combustion.

[0025] According to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 As shown, this embodiment provides a dual-swirl liquid atomizing nozzle, which includes a nozzle body 1, a needle valve 2, and a pressure chamber 3. The dual-swirl liquid atomizing nozzle is formed by the combination of the nozzle body 1 and the needle valve 2. The needle valve 2 is arranged on one side of the nozzle body 1, and a pressure chamber 3 is provided between the bottom of the needle valve 2 and the nozzle body 1. A plurality of spray holes 4 are arranged at the bottom of the nozzle body 1. An outward-expanded flow will be formed at the outlet of the spray hole 4, and because the radial velocity at the outlet is relatively large, a wider spray field can be formed, the spray penetration distance is reduced, and the near-field spray effect is better. Counterbores 5 are provided on both sides of the pressure chamber 3. The counterbores 5 are designed to offset the orifice nozzle to reduce the orifice length. Its main purpose is to form an outlet perpendicular to the spray hole to prevent liquid droplets from adhering to the wall surface to form carbon deposits, and use the eddy current generated by the stepped hole structure to promote atomization. The design of the distance of the counterbores 5 can ensure that the hole lengths in the standard nozzle and the offset orifice nozzle are constant. The counterbores 5 are interconnected with the spray holes 4, and the axis of the spray hole 4 is tangent to the edge of the pressure chamber 3. Several swirl grooves 8 are provided at the inlet of the end of the spray hole 4 close to the pressure chamber 3. A primary swirl rotating around the axis of the pressure chamber 3 is arranged inside the pressure chamber 3, and a secondary swirl is arranged inside the spray hole 4.

[0026] The shape of the spray hole 4 is a cylindrical hole, and the distance between the interiors of the pressure chambers 3 is the eccentricity 6, and the eccentricity 6 extends from the middle of the pressure chamber 3 towards the inner wall.

[0027] An air flow disk 7 is arranged outside the pressure chamber 3. The air flow disk 7 is arranged below the inside of the nozzle body 1. The air flow disk 7 wraps the pressure chamber 3. Through the design of the air flow disk 7, the compressed air passing through it can form a swirl, and the swirl helps to generate a strong shearing force inside the nozzle for the liquid, thereby breaking the liquid into fine droplets.

[0028] The internal structure of the injection hole 4 is an eccentric design, and the injection hole 4 does not coincide with any cross-section passing through the axis of the nozzle.

[0029] A low-pressure area is provided at the center of the secondary swirl formed at the inlet of the injection hole 4, and a spray field is provided at the outlet of the injection hole 4.

[0030] Multiple groups of recirculation areas are provided at the inlet of the injection hole 4, and a transverse swirl is provided inside the injection hole 4.

[0031] The plane between the injection hole 4 and the axis of the nozzle is parallel, and the eccentricity between the injection hole 4 and the axis of the nozzle can be adjusted according to the actual needs of the injection strategy. Multiple groups of counterbores 5 are provided, and the size specifications of each group of counterbores 5 are the same.

[0032] When the double-swirl liquid atomization nozzle is used, an offset injection hole is provided at the head of the nozzle body 1. By offsetting the axis of the injection hole by a certain distance from the center line position of the nozzle or making the edge of the injection hole tangent to the edge of the pressure chamber 3, different recirculation areas are generated at different lengths of the inlet of the injection hole 4 along the flow direction. Therefore, different velocities are generated at the outlet of the orifice. The injection hole 4 can be a cylindrical hole or a conical hole. Due to the eccentric design of the injection hole 4, the liquid forms a primary swirl rotating around the axis of the pressure chamber in the pressure chamber, as Figure 4 shown. A certain number of swirl grooves 8 are provided at the inlet of the end of the injection hole 4 close to the pressure chamber to guide the liquid entering the injection hole to rotate along the axis of the injection hole 4, and a secondary swirl is formed inside the injection hole 4, as Figure 5 shown. Figure 6 The figure shows the internal velocity field of the nozzle obtained by CFD calculation. It can be observed that a transverse swirl is generated inside the injection hole 4, verifying that the design described in the present invention can indeed generate a secondary swirl in the injection hole. A low-pressure area is generated at the center of the vortex core of the secondary swirl, and due to the eccentric arrangement, the cavitation area will also move in the eccentric direction, as Figure 7 shown. The eccentric area moves towards the eccentric direction of the injection hole 4, that is, towards the lower right. An outward expanding flow will be formed at the outlet of the injection hole 4. And because the radial velocity at the outlet is large, a wider spray field can be formed, the spray penetration distance is reduced, and the near-field spray effect is better.

[0033] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A dual-swirl liquid atomizing nozzle, comprising a nozzle body (1), a needle valve (2) and a pressure chamber (3), characterized in that: The double-swirl liquid atomizing nozzle is composed of a nozzle body (1) and a needle valve (2) combined with each other. The needle valve (2) is arranged in the cavity at the center of the nozzle body (1). A pressure chamber (3) is formed between the bottom of the needle valve (2) and the nozzle body (1). A plurality of spray holes (4) are arranged at the bottom of the nozzle body (1). Counterbores (5) are formed on both sides of the pressure chamber (3). The counterbores (5) are communicated with the spray holes (4). The axis of the spray hole (4) is tangent to the edge of the pressure chamber (3). A swirl groove (8) is formed at the entrance of the end of the spray hole (4) close to the pressure chamber (3). A primary swirl rotating around the axis of the pressure chamber (3) is arranged inside the pressure chamber (3), and a secondary swirl is arranged inside the spray hole (4).

2. The double swirl liquid atomizing nozzle according to claim 1, characterized in that: The shape of the spray hole (4) is a cylindrical hole. The distance between the inner parts of the pressure chamber (3) is an eccentricity (6), and the eccentricity (6) extends from the middle of the pressure chamber (3) to the inner wall.

3. A double swirl liquid atomizing nozzle according to claim 1, characterized in that: An air flow disk (7) is arranged outside the pressure chamber (3). The air flow disk (7) is arranged below the inside of the nozzle body (1), and the air flow disk (7) wraps the pressure chamber (3).

4. The dual-swirl liquid atomizing nozzle according to claim 1, characterized in that: The internal structure of the spray hole (4) is an eccentric design, and the spray hole (4) does not coincide with any arbitrary section passing through the axis of the nozzle.

5. The dual-swirl liquid atomizing nozzle according to claim 1, characterized in that: A low-pressure area is formed at the center position of the secondary swirl formed at the entrance of the spray hole (4), and a spray field is arranged at the outlet of the spray hole (4).

6. A double swirl liquid atomizing nozzle according to claim 1, characterized in that: A plurality of swirl grooves (8) are formed at the entrance of the spray hole (4) to form a transverse swirl inside the spray hole (4).

7. The dual-swirl liquid atomizing nozzle according to claim 1, characterized in that: The plane between the spray hole (4) and the axis of the nozzle is parallel. A plurality of groups of counterbores (5) are arranged, and the size specifications of each group of counterbores (5) are the same.

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