A cyclone synergistic ultra-fine atomizing nozzle based on piezoelectric ultrasonic excitation and a fuel ultra-fine atomizing system

Abstract

The application aims to provide a swirl synergic superfine atomization nozzle and fuel superfine atomization system based on piezoelectric ultrasonic excitation, belonging to the field of engines. The nozzle comprises a fuel supply pipe shell and a nozzle shell. The fuel forms a stable liquid film in the swirl chamber after rectification and swirling. The ultrasonic excitation assembly generates ultrasonic vibration under the pre-tightening action and is coupled to the fuel flow to induce micro-scale disturbance. The gas is sprayed in the gas-liquid mixing area, which cools the piezoelectric ceramic on one hand and implements high-speed shearing on the liquid film to realize secondary breaking, simultaneously providing additional momentum for superfine atomized droplets and effectively improving the spray penetration distance. Through the synergistic effect of swirling, ultrasonic disturbance and airflow shearing, stable superfine atomization can be realized under lower injection pressure, which significantly reduces the Sauter mean diameter and improves the spray uniformity, stability and jet penetration ability, solving the problems of low atomization efficiency and insufficient penetration distance under high viscosity or low working condition.

Description

Technical Field

[0001] The present invention relates to an engine, specifically a fuel injection system. Background Technology

[0002] With the development of engines, industrial combustion equipment, and the application of new low-carbon fuels, fuel injection systems are placing higher demands on atomization quality, especially on achieving smaller droplet sizes and higher spray uniformity under limited injection pressure. Existing swirl nozzles primarily rely on fuel pressure to form a rotating liquid film within the swirl chamber, which is then broken up and atomized at the outlet. However, under conditions of high viscosity, low flow rate, or fluctuating operating conditions, insufficient swirl intensity and increased liquid film thickness lead to larger droplet sizes and decreased spray stability. Some technologies employ pneumatically assisted atomization to improve atomization, but these often suffer from complex structures, low energy efficiency, and adverse effects on thermal load and reliability. On the other hand, ultrasonic atomization can enhance liquid atomization through high-frequency vibration and cavitation effects; however, insufficient coupling between ultrasonic excitation and the flow channel, or a large operating temperature rise, can cause a decrease in atomization effect and reduced lifespan. Summary of the Invention

[0003] The purpose of this invention is to provide a piezoelectric ultrasonic-excited swirling synergistic ultrafine atomizing nozzle and fuel ultrafine atomizing system that can reduce atomized particle size, improve spray stability, and enhance reliability.

[0004] The objective of this invention is achieved as follows: This invention discloses a piezoelectric ultrasonic-excited swirling-coordinated ultrafine atomizing nozzle, characterized by comprising a fuel supply pipe shell and a nozzle shell. The fuel supply pipe shell is installed above the nozzle shell, and a fuel supply pipeline is provided inside the fuel supply pipe shell. A fuel supply chamber is provided inside the nozzle shell, and the fuel supply pipeline connects to the fuel supply chamber. An ultrasonic excitation component is installed inside the nozzle shell, and a swirling atomizing chamber wall is provided below the ultrasonic excitation component. A swirling atomizing chamber is formed inside the swirling atomizing chamber wall, and a swirling generator is installed inside the swirling atomizing chamber. The fuel supply pipe shell and the nozzle shell form an auxiliary gas pipeline, and the end of the auxiliary gas pipeline communicates with the swirling atomizing chamber, with their intersection forming a gas-liquid mixing zone.

[0005] The piezoelectric ultrasonic-excited swirling synergistic ultrafine atomizing nozzle of the present invention may further include: 1. The vortex generator is provided with a tangential guide groove.

[0006] 2. The tangential guide grooves are evenly distributed circumferentially.

[0007] 3. A preload spring is installed in the fuel supply chamber. Above the preload spring is the fuel supply pipe shell, and below the preload spring is the swirl generator. 4. The pre-tensioning spring applies a continuous pre-tensioning force to the swirl generator in the axial direction, so that the swirl generator fits against the wall of the swirl atomization chamber.

[0008] 5. Under the pressure of the fuel supply line, fuel enters the fuel supply pipe shell through the fuel supply line and flows sequentially through the swirl generator and the swirl atomization chamber. Under the guidance of the tangential guide groove, it obtains a tangential velocity component and forms a continuous rotating liquid film in the swirl atomization chamber. The ultrasonic excitation component generates high-frequency ultrasonic vibration under the excitation of an external electrical signal. This ultrasonic vibration is coupled to the fuel fluid through the nozzle shell and the fuel supply pipe shell, inducing the generation of microscale cavitation bubbles inside the fuel. The cavitation bubbles are periodically generated and collapsed in the rotating flow field, causing local transient pressure disturbances inside the fuel. The auxiliary gas is ejected from the auxiliary gas line and applies shear to the fuel liquid film carrying the bubbles, realizing a gas-liquid synergistic secondary atomization process.

[0009] The present invention discloses a fuel ultra-fine atomization system, characterized in that it includes an ECU control unit, a diesel tank, a fuel pump, a heat exchanger, an air source, and an atomizing nozzle as described above. The fuel pump is connected to the diesel tank and the heat exchanger respectively. The heat exchanger is connected to the fuel supply line of the atomizing nozzle through a fuel regulating valve. The air source is connected to the auxiliary gas line of the atomizing nozzle through an air supply regulating valve. The fuel regulating valve, the air supply regulating valve, and the fuel pump are all connected to the ECU control unit.

[0010] The fuel ultrafine atomization system of the present invention may further include: 1. An oil separator is installed between the diesel tank and the fuel pump.

[0011] The advantages of this invention are as follows: By introducing ultrasonic high-frequency excitation on the basis of swirling atomization, microscale cavitation effect is generated in the fuel during the swirling flow, reducing the stability of the liquid film; at the same time, combined with the shearing effect of the outer auxiliary gas, the fuel liquid film is synergistically broken up in a secondary manner, while providing radial additional momentum and increasing the spray penetration distance, thereby significantly reducing the spray Sotter average diameter and improving the spray uniformity; in addition, through the systematic fuel and auxiliary gas supply structure, the nozzle has good atomization stability and adaptability under different operating conditions, and the overall structure is compact, making it suitable for combustion and injection applications with high requirements for ultra-fine atomization performance. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the atomizing nozzle of the present invention; Figure 2 This is a schematic diagram of the atomization system of the present invention. Detailed Implementation

[0013] The invention will now be described in more detail with reference to the accompanying drawings: Combination Figure 1-2The nozzle body structure, along with the fuel supply system and auxiliary gas supply system connected to it, together constitute a complete fuel ultrafine atomization device.

[0014] The fuel supply system is located upstream of the nozzle tip and includes a diesel tank 12, a fuel separator 13, a fuel pump 14, and a fuel regulating valve 16. The diesel tank 12 stores fuel to be atomized. After flowing out of the diesel tank 12, the fuel first enters the fuel separator 13, which separates and settles any entrained gases and impurities in the fuel to improve the stability of the fuel entering the nozzle. The fuel processed by the fuel separator 13 is pressurized and delivered by the fuel pump 14, with its flow rate and pressure regulated by the fuel regulating valve 16, and then enters the nozzle through the fuel supply line 1.

[0015] The heat exchanger 15 is located downstream of the fuel pump 14 and is used to regulate the heat exchange of fuel, thereby improving fuel physical properties and enhancing atomization stability. The fuel processed by the heat exchanger 15 enters the fuel regulating valve 16, which is connected to the ECU control unit 17. The ECU control unit 17 receives external operating condition signals and controls the fuel regulating valve 16 according to a set control strategy, thereby achieving precise adjustment of the nozzle fuel supply state and providing stable fuel supply boundary conditions for subsequent swirling atomization and ultrasonic excitation processes.

[0016] The auxiliary gas supply system includes a gas supply regulating valve 18 and a gas source 19. The gas source 19 is used to supply compressed air or other auxiliary gases. After being regulated by the gas supply regulating valve 18, the auxiliary gas enters the nozzle housing 4 through the auxiliary gas pipeline 2. The gas supply regulating valve 18 is also controlled by the ECU control unit 17, so that the introduction state of the auxiliary gas can be adjusted according to different operating conditions.

[0017] The nozzle structure includes a fuel supply pipe shell 3 and a nozzle housing 4, which are coaxially arranged and together form the main structure of the nozzle. The nozzle has an axisymmetric structure, and its interior is arranged axially in sequence with a fuel supply channel, a swirling atomization structure, and a gas-liquid mixing zone 11. At the same time, an independent auxiliary gas passage is set outside the fuel supply channel to introduce auxiliary gas into the nozzle.

[0018] An axisymmetric structure helps ensure the symmetry of forces acting on the fuel during its flow within the nozzle, avoiding rotational flow deviation or uneven spraying caused by structural asymmetry. Furthermore, arranging the fuel supply channel, swirling atomization structure, and gas-liquid mixing zone 11 sequentially along the axial direction allows the fuel to undergo different physical mechanisms during injection, with close connections between each stage, thus promoting progressively enhanced atomization.

[0019] Fuel supply line 1 is located upstream of the nozzle and is used to connect to an external fuel supply system. Under pressure, fuel enters the fuel supply housing 3 through fuel supply line 1. After flowing axially, the fuel enters the swirl generator 7 through the swirl generator inlet 8.

[0020] The fuel supply line 1 ensures that the fuel enters the nozzle in a relatively stable flow state, avoiding adverse effects of inlet turbulence or pressure fluctuations on subsequent swirl formation. The swirl generator inlet 8 serves as a transition and guide, ensuring a relatively uniform axial velocity distribution of the fuel before it enters the swirl generator 7, thereby improving the stability of the rotating flow within the swirl generator 7.

[0021] The swirl generator 7 is equipped with several tangential guide grooves 9 evenly distributed circumferentially. Under the guidance of the tangential guide grooves 9, the fuel acquires a significant tangential velocity component and forms a stable swirling flow within a short axial distance. The fuel accelerated by the tangential guide grooves 9 enters the swirl atomization chamber 10, where it is subjected to centrifugal force and flows radially outward to form a continuous and stable liquid film.

[0022] The number, width, and inclination angle of the tangential guide channels 9 can be designed according to the fuel flow rate and physical properties, enabling the fuel to obtain sufficient angular momentum within the limited structural space. The swirling atomizing chamber 10 provides a stable space for the formation and development of the rotating liquid film, and its structural dimensions have a significant impact on the liquid film thickness, rotational intensity, and axial propulsion speed. By rationally matching the structural parameters of the swirling generator 7 and the swirling atomizing chamber 10, the liquid film can be kept in a state of easy instability while maintaining continuity, creating conditions for subsequent atomization enhancement.

[0023] The preload spring 5 is located at the axial connection between the vortex generator 7 and the vortex atomizing chamber 10. The preload spring 5 is used to apply a continuous preload force to the vortex generator 7 in the axial direction, so that the vortex generator 7 and the vortex atomizing chamber 10 always maintain a tight fit. This can effectively eliminate the assembly gap between the vortex generator 7 and the vortex atomizing chamber 10, and avoid relative loosening or slight displacement under high pressure oil supply or high frequency disturbance conditions, thereby ensuring the geometric stability and flow consistency of the vortex structure.

[0024] The swirl generator 7 and the swirl atomizing chamber 10 are fixed by axial compression to avoid fluctuations in swirl intensity or instability in liquid film morphology due to minor structural changes, which is beneficial for the nozzle to maintain stable atomization performance during long-term operation.

[0025] An ultrasonic excitation component 6 is installed inside the nozzle housing. The ultrasonic excitation component 6 is fixedly installed inside the nozzle housing 4, and the ultrasonic vibration generated by it is transmitted to the fuel flow area inside the nozzle through the coupling between the nozzle housing 4 and the fuel supply pipe housing 3.

[0026] When the ultrasonic excitation component 6 operates under external electrical signal excitation, it generates high-frequency ultrasonic vibrations. These vibrations are transmitted through the nozzle housing 4 and adjacent structures to the fuel fluid within the swirling atomization chamber 10, causing periodic high-frequency pressure disturbances in the fuel during its swirling flow. Under the influence of these pressure disturbances, a large number of microscale cavitation bubbles are induced inside the fuel, creating favorable conditions for the subsequent atomization and breakup process.

[0027] Microscale cavitation bubbles exhibit a random distribution in a rotating flow field. Their generation and collapse processes create local transient disturbances within the fuel, reducing the mechanical integrity of the rotating liquid film. The cavitation-enhanced liquid film is more prone to rupture under subsequent external disturbances, thereby lowering the energy threshold required for atomization.

[0028] Downstream of the nozzle, the swirling atomization chamber 10 is connected to the gas-liquid mixing zone 11. The fuel, after being atomized by swirling and enhanced by cavitation, enters the gas-liquid mixing zone 11 while maintaining certain rotational characteristics. At the same time, auxiliary gas enters the nozzle through the auxiliary gas pipeline 2 and flows to the gas-liquid mixing zone 11 along an independently provided gas channel.

[0029] The auxiliary gas is ejected at high speed in the gas-liquid mixing zone 11. On the one hand, it continuously cools the ultrasonic excitation component 6 inside the nozzle, effectively reducing the temperature rise caused by long-term high-frequency operation, thereby delaying performance degradation and improving service life. On the other hand, the high-speed airflow exerts a strong shearing effect on the liquid film in the gas-liquid mixing zone 11, causing it to break down further and realizing a secondary atomization process of gas-liquid synergy.

[0030] The high-speed ejected auxiliary gas provides additional momentum to the working fluid at the back end of the ultrasonic excitation in the gas-liquid mixing zone 11, effectively reducing the radial momentum reduction caused by ultrasonic excitation. This ensures droplet atomization while increasing the spray penetration distance, enabling the nozzle to achieve stable ultrafine atomization at a lower injection pressure.

[0031] Under the pressure of the fuel supply line, fuel enters the fuel supply shell 3 through the fuel supply line 1 and flows sequentially through the swirl generator 7 and the swirl atomizing chamber 10. Guided by the tangential guide groove 9, it acquires a significant tangential velocity component, forming a continuous rotating liquid film within the swirl atomizing chamber 10. Simultaneously, the ultrasonic excitation component 6 generates high-frequency ultrasonic vibrations under external electrical signal excitation. These ultrasonic vibrations are coupled and transmitted to the fuel fluid through the nozzle shell 4 and the fuel supply shell 3, inducing a large number of microscale cavitation bubbles inside the fuel. These cavitation bubbles are periodically generated and collapsed in the rotating flow field, causing local transient pressure disturbances inside the fuel. Assist gas is ejected at high speed from the assist gas line 2, exerting a strong shearing effect on the fuel liquid film carrying the bubbles, achieving a gas-liquid synergistic secondary atomization process. By organically combining centrifugal swirl, ultrasonically induced microscale cavitation, and gas-liquid shearing and breaking processes, the fuel undergoes two stages sequentially during the entire injection process: structural weakening and energy concentration breaking, thus achieving a stable and uniform ultrafine atomization effect under relatively low fuel supply pressure conditions.

[0032] Through the above structure and working method, the fuel undergoes multiple atomization stages inside the nozzle, such as ultrasonic-induced microscale cavitation enhancement and auxiliary gas shearing secondary fragmentation. The atomization mechanisms are coupled and work together, enabling the nozzle to achieve a spray effect with smaller particle size and more uniform distribution under relatively low fuel supply pressure conditions, effectively reducing the average diameter of the spray and improving the spray stability.

Claims

1. A swirling-coordinated ultrafine atomizing nozzle based on piezoelectric ultrasonic excitation, characterized in that: It includes a fuel supply pipe shell and a nozzle shell. The fuel supply pipe shell is installed above the nozzle shell. A fuel supply line is set inside the fuel supply pipe shell. A fuel supply chamber is set inside the nozzle shell. The fuel supply line is connected to the fuel supply chamber. An ultrasonic excitation component is installed inside the nozzle shell. A swirling atomizing chamber wall is set below the ultrasonic excitation component. A swirling atomizing chamber is formed inside the swirling atomizing chamber wall. A swirling generator is installed in the swirling atomizing chamber. The fuel supply pipe shell and the nozzle shell form an auxiliary gas line. The end of the auxiliary gas line is connected to the swirling atomizing chamber. The intersection of them forms a gas-liquid mixing zone.

2. The swirling-coordinated ultrafine atomizing nozzle based on piezoelectric ultrasonic excitation according to claim 1, characterized in that: The swirl generator is equipped with a tangential guide groove.

3. The swirling-coordinated ultrafine atomizing nozzle based on piezoelectric ultrasonic excitation according to claim 2, characterized in that: The tangential guide grooves are evenly distributed circumferentially.

4. The swirling-coordinated ultrafine atomizing nozzle based on piezoelectric ultrasonic excitation according to claim 1, characterized in that: A preload spring is installed in the fuel supply chamber. Above the preload spring is the fuel supply pipe shell, and below the preload spring is the swirl generator.

5. The swirling-coordinated ultrafine atomizing nozzle based on piezoelectric ultrasonic excitation according to claim 4, characterized in that: The preload spring applies a continuous preload force to the swirl generator in the axial direction, causing the swirl generator to adhere to the wall of the swirl atomization chamber.

6. The fuel ultrafine atomization system according to claim 1, characterized in that: Under the pressure of the fuel supply line, fuel enters the fuel supply pipe shell and flows sequentially through the swirl generator and the swirl atomizing chamber. Under the guidance of the tangential guide groove, it obtains a tangential velocity component and forms a continuous rotating liquid film in the swirl atomizing chamber. The ultrasonic excitation component generates high-frequency ultrasonic vibration under the excitation of an external electrical signal. This ultrasonic vibration is coupled to the fuel fluid through the nozzle shell and the fuel supply pipe shell, inducing the generation of microscale cavitation bubbles inside the fuel. The cavitation bubbles are periodically generated and collapsed in the rotating flow field, causing local transient pressure disturbances inside the fuel. The auxiliary gas is injected from the auxiliary gas pipeline and applies shear to the fuel film carrying air bubbles, realizing a gas-liquid synergistic secondary atomization process.

7. A fuel ultrafine atomization system, characterized in that: The device includes an ECU control unit, a diesel tank, a fuel pump, a heat exchanger, an air source, and an atomizing nozzle as described in claim 1. The fuel pump is connected to both the diesel tank and the heat exchanger. The heat exchanger is connected to the fuel supply line of the atomizing nozzle via a fuel regulating valve. The air source is connected to the auxiliary gas line of the atomizing nozzle via an air supply regulating valve. The fuel regulating valve, the air supply regulating valve, and the fuel pump are all connected to the ECU control unit.

8. The fuel ultrafine atomization system according to claim 7, characterized in that: An oil separator is installed between the diesel tank and the fuel pump.

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