An aviation fuel atomizing nozzle device

Abstract

This invention discloses an aviation fuel atomizing nozzle device, relating to the field of aviation nozzles. The nozzle includes an inlet pipe, a swirling groove, a swirling chamber, and a nozzle outlet. The inlet pipe is connected to the swirling groove, which is connected to the swirling chamber. The swirling chamber is connected to the nozzle outlet. An air column is formed at the central axis of the swirling chamber, and the nozzle outlet is a straight section. Liquid enters the swirling chamber from the swirling groove and is pressurized, then exits through the nozzle outlet, exhibiting both axial and tangential velocities. Atomization cone angle is formed at the outer edges of the liquid on both sides. By changing the nozzle outlet diameter, the size and velocity of the central air column at the nozzle outlet are altered. The ratio of the swirling chamber diameter to the nozzle outlet diameter is set to 2.5. This invention, by changing the nozzle outlet diameter, the size and velocity of the central air column at the nozzle outlet, changes atomization characteristics such as the atomization cone angle and liquid film thickness, thereby enhancing the atomization effect.

Description

Technical Field

[0001] This invention relates to the field of aviation nozzles, and in particular to an aviation fuel atomizing nozzle device. Background Technology

[0002] An aircraft engine is a highly complex and precise thermodynamic machine. As the heart of an aircraft, it not only powers the aircraft's flight but also serves as a vital driving force for the development of the aviation industry. Every major transformation in the history of human aviation has been inseparable from the technological advancements in aircraft engines.

[0003] Among the many components of an aero-engine, the fuel nozzle is one of the core components of the main combustion chamber, with a complex structure and diverse functions. The main function of the fuel nozzle is to atomize aviation kerosene, increasing the contact area between fuel and air, improving the rate of heat and mass exchange during combustion, accelerating the combustion process, influencing fuel combustion efficiency and characteristics, and reducing pollutant emissions at the combustion chamber exit. Based on their structure, fuel nozzles can be classified into direct-injection nozzles, centrifugal nozzles, evaporator nozzles, and pneumatic atomizing nozzles, among others.

[0004] The atomization cone angle of a centrifugal nozzle is affected by the size of the nozzle orifice. If the atomization cone angle is too large, fuel will be sprayed onto the inner wall of the combustion chamber, and the heat generated by combustion will cause wall erosion, thus affecting the normal operation of the entire combustion chamber. If the atomization cone angle is too small, it is not conducive to fuel atomization and combustion, because the droplets will gather near the center of the axis, which will have an adverse effect on the complete combustion of fuel and the uniform distribution of the temperature field.

[0005] Therefore, it is necessary to provide an aviation fuel atomizing nozzle device to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide an aviation fuel atomizing nozzle device that, by changing the diameter of the fuel nozzle outlet, the size and velocity of the central air column at the nozzle outlet, alters atomization characteristics such as the atomization cone angle and liquid film thickness, thereby enhancing the atomization effect.

[0007] To achieve the above objectives, the present invention provides an aviation fuel atomizing nozzle device, wherein the nozzle includes an inlet pipe, a swirling groove, a swirling chamber, and a nozzle outlet. The inlet pipe is connected to the swirling groove, the swirling groove is connected to the swirling chamber, the swirling chamber is connected to the nozzle outlet, an air column is formed at the central axis of the swirling chamber, and the nozzle outlet is a straight section.

[0008] The liquid enters the swirling chamber through the swirling channel and is pressurized. It is then ejected from the nozzle outlet, exhibiting both axial and tangential velocities. Atomization cones are formed on both outer edges of the liquid. By changing the diameter of the nozzle outlet, the size and velocity of the central air column at the nozzle outlet are altered. The ratio of the diameter of the swirling chamber to the diameter of the nozzle outlet is set to 2.5.

[0009] Preferably, the greater the intensity of liquid rotation, the greater the ratio of tangential velocity to axial velocity, and the larger the atomizing cone angle. Utilizing the equilibrium condition of the rotating liquid, a micro-element liquid flow with radius r and thickness dr is selected; the ray at the nozzle outlet is tangential to the nozzle axis, equal to the ratio of tangential velocity to axial velocity.

[0010]

[0011] in, Indicates tangential velocity, Indicates axial velocity;

[0012] The angular momentum remains constant, according to Bernoulli's equation:

[0013]

[0014] Where P is the pressure inside the nozzle, v is the fluid velocity, ρ is the fuel density, and h is the liquid level height;

[0015] Let h Bx =h, introducing a constant:

[0016]

[0017] have to:

[0018]

[0019] With r=0, the angular momentum remains constant, the liquid velocity is infinite, and the pressure is an infinitely large negative value. In reality, the minimum pressure is the outlet ambient pressure. The center of the nozzle will not be filled with liquid, but will form an air core.

[0020] Preferably, the ratio of the diameter of the swirling chamber to the diameter of the nozzle outlet is less than 2.5. Increasing the diameter of the nozzle outlet expands the air column inside the swirling chamber, reducing the liquid velocity, with the axial velocity being more affected than the tangential velocity.

[0021] The ratio of the diameter of the cyclone chamber to the diameter of the nozzle outlet is greater than 2.5. The velocity distribution on different cross sections is characterized by a large center and small edge structure. The gas-liquid disturbance on the tower wall is stable, while the gas-liquid disturbance on the central axis inside the tower is intense.

[0022] The ratio of the diameter of the cyclone chamber to the diameter of the nozzle outlet is 2.5. The nozzle center velocity is the highest, the gas-liquid disturbance is the most intense, the atomization cone angle is the largest, and the liquid film thickness at the outlet is the smallest.

[0023] Preferably, the aviation fuel atomization process is simulated using Fluent simulation technology, and the calculation process is as follows:

[0024] S1: Establish a three-dimensional geometric model of the nozzle;

[0025] S2: Uses realizable Turbulence models are used to simulate and analyze the nozzle atomization process;

[0026] S3: Select and determine the physical property parameters of the gas and fuel involved in the atomization process;

[0027] S4: Using an explicit VOF model, air is set as the first phase and fuel as the second phase, and the surface tension between the two phases is set to simulate the fuel flow inside the nozzle.

[0028] S5: Select the tracking discrete phase frequency and the breakage and collision model;

[0029] S6: Enable Vof-to-dpm model conversion. Based on the two conversion criteria of equivalent diameter and non-sphericity, the irregularly shaped liquid clumps generated by the first crushing are converted into spherical droplets. The discrete droplet group is processed by the discrete phase model DPM to realize the numerical simulation of the atomization crushing process.

[0030] S7: Boundary condition settings: Set the inlet pressure to 1 MPa, which is the actual engine fuel injection pressure, and set the wall to a non-slip wall.

[0031] S8: Calculation method: PISO is selected for the pressure-velocity coupling method, and the second-order upwind mode is selected for the other differences;

[0032] S9: Post-processing of calculation results: Obtain the changes in liquid film and droplets, changes in fuel atomization cone angle, fuel velocity distribution and droplet size distribution during fuel atomization;

[0033] S10: Results Analysis and Mechanism Revelation: The fuel atomization process is analyzed, and the atomization results under the influence of different parameters are analyzed to obtain the fuel atomization law and obtain the nozzle configuration with the optimal atomization effect.

[0034] Therefore, the present invention employs the above-mentioned aviation fuel atomizing nozzle device, which has the following beneficial effects:

[0035] (1) The present invention changes the atomization characteristics such as atomization cone angle and liquid film thickness by changing the diameter of the fuel nozzle outlet, the size and velocity of the air column at the center of the nozzle outlet, thereby enhancing the atomization effect.

[0036] (2) The present invention accelerates the chemical reaction rate and improves the combustion efficiency, thereby reducing the emission of pollutants at the combustion chamber outlet.

[0037] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0038] Figure 1 This is a structural diagram of an aviation fuel atomizing nozzle device according to the present invention;

[0039] Figure 2 This is a radial cross-sectional view of the nozzle structure of an aviation fuel atomizing nozzle device according to the present invention;

[0040] Figure 3 This is an axial cross-sectional view of the nozzle structure of an aviation fuel atomizing nozzle device according to the present invention;

[0041] Figure 4 This is a schematic diagram of the atomizing cone angle of an aviation fuel atomizing nozzle device according to the present invention;

[0042] Figure 5 This is a diagram showing the nozzle atomization cone angle result of an aviation fuel atomizing nozzle device according to the present invention.

[0043] Attached Figure Captions

[0044] 1. Oil inlet pipe; 2. Swirl channel; 3. Straight section; 4. Swirl chamber; 5. Nozzle outlet. Detailed Implementation

[0045] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0046] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0047] The terms "comprising" or "including" as used in this invention mean that the element preceding the term encompasses the element listed after the term, and do not exclude the possibility of encompassing other elements. Terms such as "inner," "outer," "upper," and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. In this invention, unless otherwise explicitly specified and limited, the term "attached" and similar terms should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can refer to a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two elements or the interaction relationship between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] like Figures 1-5 As shown, the present invention provides an aviation fuel atomizing nozzle device, including a nozzle, the nozzle including an oil inlet pipe 1, a swirling groove 2, a swirling chamber 4 and a nozzle outlet 5. The oil inlet pipe 1 is connected to the swirling groove 2, the swirling groove 2 is connected to the swirling chamber 4, the swirling chamber 4 is connected to the nozzle outlet 5, an air column is formed at the central axis of the swirling chamber 4, and the nozzle outlet 5 is a straight section 3.

[0049] The liquid enters the swirling chamber 4 from the swirling channel 2 and is pressurized. It is then ejected from the nozzle outlet 5, exhibiting both axial and tangential velocities. Atomization cones are formed at the outer edges of the liquid. By changing the diameter of the fuel nozzle outlet 5, the size and velocity of the central air column at the nozzle outlet 5 are altered. The ratio of the diameter of the swirling chamber 4 to the diameter of the nozzle outlet 5 is equal to the radius of the swirling chamber 4. radius of nozzle outlet 5 The ratio is set to 2.5.

[0050] The greater the intensity of liquid rotation, the greater the ratio of tangential velocity to axial velocity, and the larger the atomization cone angle. Utilizing the equilibrium condition of rotating liquid, a micro-element liquid flow with radius r and thickness dr is selected; the rays at the nozzle outlet at point 5 are tangential to the nozzle axis, equal to the ratio of tangential velocity to axial velocity.

[0051]

[0052] in, Indicates tangential velocity, Indicates axial velocity;

[0053] The angular momentum remains constant, according to Bernoulli's equation:

[0054]

[0055] Where P is the pressure inside the nozzle, v is the fluid velocity, ρ is the fuel density, and h is the liquid level height;

[0056] Let h Bx =h, introducing a constant:

[0057]

[0058] have to:

[0059]

[0060] With r=0, the angular momentum remains constant, the liquid velocity is infinite, and the pressure is an infinitely large negative value. In reality, the minimum pressure is the outlet ambient pressure. The center of the nozzle will not be filled with liquid, but will form an air core.

[0061] The ratio of the diameter of the swirling chamber 4 to the diameter of the nozzle outlet 5 is less than 2.5. The increase in the diameter of the nozzle outlet 5 expands the air column inside the swirling chamber 4, reducing the liquid velocity. The axial velocity is more affected than the tangential velocity.

[0062] The ratio of the diameter of the cyclone chamber 4 to the diameter of the nozzle outlet 5 is greater than 2.5. The velocity distribution on different cross sections is characterized by a large center and small edge structure. The gas-liquid disturbance on the tower wall is stable, while the gas-liquid disturbance on the central axis inside the tower is intense.

[0063] The ratio of the diameter of the swirl chamber 4 to the diameter of the nozzle outlet 5 is 2.5. The nozzle center velocity is the largest, the gas-liquid disturbance is the most intense, the atomization cone angle is the largest, and the liquid film thickness at the outlet is the smallest.

[0064] The aviation fuel atomization process was simulated using Fluent simulation technology. The calculation process is as follows:

[0065] S1: Establish a three-dimensional geometric model of the nozzle;

[0066] S2: Uses realizable Turbulence models are used to simulate and analyze the nozzle atomization process;

[0067] S3: Select and determine the physical property parameters of the gas and fuel involved in the atomization process;

[0068] S4: Using an explicit VOF model, air is set as the first phase and fuel as the second phase, and the surface tension between the two phases is set to simulate the fuel flow inside the nozzle.

[0069] S5: Select the tracking discrete phase frequency and the breakage and collision model;

[0070] S6: Enable Vof-to-dpm model conversion. Based on the two conversion criteria of equivalent diameter and non-sphericity, the irregularly shaped liquid clumps generated by the first crushing are converted into spherical droplets. The discrete droplet group is processed by the discrete phase model DPM to realize the numerical simulation of the atomization crushing process.

[0071] S7: Boundary condition settings: Set the inlet pressure to 1 MPa, which is the actual engine fuel injection pressure, and set the wall to a non-slip wall.

[0072] S8: Calculation method: PISO is selected for the pressure-velocity coupling method, and the second-order upwind mode is selected for the other differences;

[0073] S9: Post-processing of calculation results: Obtain the changes in liquid film and droplets, changes in fuel atomization cone angle, fuel velocity distribution and droplet size distribution during fuel atomization;

[0074] S10: Results Analysis and Mechanism Revelation: The fuel atomization process is analyzed, and the atomization results under the influence of different parameters are analyzed to obtain the fuel atomization law and obtain the nozzle configuration with the optimal atomization effect.

[0075] Example 1

[0076] Numerical simulations were performed using the Vof-to-dpm model in Fluent, which is based on the principle of tracking the cross-section of two-phase or multiphase fluids on a fixed Euler grid. In the VOF model's computational equations, all fluid phases share a single equation, tracking the volume fraction of each phase throughout the computational domain. The VOF multiphase flow model is suitable for simulating laminar flow, free surface flow, liquid injection, liquid oscillation, the rise of large bubbles in liquids, post-dam-break liquid flow, prediction of jet breakup, and steady-state and transient tracking of gas-liquid interfaces. The VOF model is particularly suitable for simulating gas-liquid two-phase flow; it is a mature technology with low computational cost; and it is well-suited for capturing gas-liquid interfaces. The flow of fuel in a centrifugal nozzle is a typical gas-liquid two-phase flow, where the two-phase fluids are primarily affected by surface tension at the interface.

[0077] Based on Fluent's Vof-to-dpm coupled model, the initial jet breakup is predicted using the Volume of Fluid (VOF) method. According to two conversion criteria—equivalent diameter and non-sphericity—the irregularly shaped liquid clumps generated by the initial breakup are transformed into spherical droplets. The discrete droplet swarm is processed by the Discrete Phase Model (DPM), achieving numerical simulation of the atomization breakup process. The calculation captures the evolution of the phase interface inside the nozzle and the details of the external liquid film breakup. The three-dimensional velocity distribution and air core oscillation phenomenon at the nozzle exit plane are analyzed, and the droplet size outside the nozzle is also investigated.

[0078] Numerical simulations were performed on nozzles with swirl chamber diameter to nozzle outlet diameter ratios of 1.43, 1.67, 2, 2.5, 3.33, 4, 5, and 6.67. VOF (Volatile Flow Analysis) was used to study the atomization cone angle, liquid film thickness at the outlet, and flow coefficient of the visualized centrifugal nozzle. DPM (Digital Permeability Model) was used to analyze the microparticle size. The results showed that a swirl chamber diameter to nozzle outlet diameter ratio of 2.5 resulted in optimal atomization, maximizing the contact area between fuel and air, improving combustion efficiency, and thus promoting more complete combustion and reducing pollutant emissions.

[0079] In the spray field of a centrifugal nozzle, droplets undergo rotational centrifugal motion. During this process, the oil film interacts with air, and when the surface tension weakens, air pockets form, causing the spray cone boundary to become a curved shape that is difficult to capture and define. Defining and measuring the cone angle becomes challenging. Typically, a specific distance from the nozzle tip is chosen, and two straight lines are drawn between the tangent point of the nozzle orifice and the spray profile at that point. The angle between these lines is defined as the spray cone angle. Ritzke and Lefebvre theoretically derived the dimensionlessly accurate formula for viscous fluids as follows:

[0080]

[0081] Where θ is the semi-cone angle, Ds is the diameter of the vortex chamber, d0 is the nozzle diameter, and ρ L P is the density of the liquid. L For injection pressure, μ L As a viscous liquid, A P This represents the total area of ​​the inlet tank.

[0082] As can be seen from the above formula, increasing the diameter of the swirl chamber, the nozzle diameter, the liquid density, and the injection pressure will widen the spray cone angle, while increasing the liquid viscosity and the total inlet groove area will decrease the spray cone angle. By changing the nozzle diameter, a nozzle diameter ratio configuration with better atomization effect can be obtained.

[0083] For centrifugal nozzles, the thickness of the annular oil film formed at the nozzle outlet has a strong influence on the average droplet size of the spray. The formed liquid film is generally very thin, often less than 0.5 mm, with surface disturbance waves and poor stability. The tiny droplets adhering to the liquid film are difficult to measure experimentally; therefore, the DPM model is used to measure and analyze the droplet size. The results show that a ratio of 2.5 between the diameter of the vortex chamber and the diameter of the nozzle outlet is most beneficial for improving atomization quality, and the oil film thickness is significantly related to the size of the surface diameter (SMD). Ritzke and Lefebvre used theoretical methods to study the internal flow characteristics of centrifugal nozzles. They derived a general formula for oil film thickness expressing the values ​​of nozzle size, liquid properties, and liquid injection pressure as variables:

[0084]

[0085] Where t is the oil film thickness, d0 is the nozzle diameter, and ρ L P is the density of the liquid. L For injection pressure, μ L For liquid viscosity, m L Let be the liquid mass flow rate, and X be the air core area. The oil film thickness t is inversely proportional to the nozzle diameter d0.

[0086] The nozzle outlet flow rate is one of the most critical parameters of the nozzle, and its relationship with the working pressure is expressed as follows:

[0087]

[0088] Where, q v For nozzle flow rate, ρ L P is the density of the liquid. L For injection pressure, C q Let A0 be the nozzle outlet area and q be the flow coefficient. v With flow coefficient C q The outlet flow rate is related to the nozzle outlet area A0, and is directly proportional to the nozzle orifice diameter.

[0089] Therefore, the present invention employs the above-mentioned aviation fuel atomizing nozzle device, which changes the diameter of the fuel nozzle outlet, the size and velocity of the central air column at the nozzle outlet, thereby altering atomization characteristics such as the atomization cone angle and liquid film thickness, enhancing the atomization effect, accelerating the chemical reaction rate, improving combustion efficiency, and thus reducing the emission of pollutants from the combustion chamber outlet.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An aviation fuel atomizing nozzle device, characterized in that: The device includes a nozzle, which comprises an oil inlet pipe, a swirling groove, a swirling chamber, and a nozzle outlet. The oil inlet pipe is connected to the swirling groove, the swirling groove is connected to the swirling chamber, the swirling chamber is connected to the nozzle outlet, an air column is formed at the central axis of the swirling chamber, and the nozzle outlet is a straight section. The liquid enters the swirling chamber through the swirling channel and is pressurized. It is then ejected from the nozzle outlet, exhibiting both axial and tangential velocities. Atomization cones are formed on both outer edges of the liquid. By changing the diameter of the nozzle outlet, the size and velocity of the central air column at the nozzle outlet are altered. The ratio of the diameter of the swirling chamber to the diameter of the nozzle outlet is set to 2.

5.

2. The aviation fuel atomizing nozzle device according to claim 1, characterized in that: The greater the intensity of liquid rotation, the greater the ratio of tangential velocity to axial velocity, and the larger the atomization cone angle. Utilizing the equilibrium condition of the rotating liquid, a micro-element liquid flow with radius r and thickness dr is selected; the ray at the nozzle outlet is tangential to the nozzle axis, equal to the ratio of tangential velocity to axial velocity. in, Indicates tangential velocity, Indicates axial velocity; The angular momentum remains constant, according to Bernoulli's equation: Where P is the pressure inside the nozzle, v is the fluid velocity, ρ is the fuel density, and h is the liquid level height; Let h Bx =h, introducing a constant: have to: With r=0, the angular momentum remains constant, the liquid velocity is infinite, and the pressure is an infinitely large negative value. In reality, the minimum pressure is the outlet ambient pressure. The center of the nozzle will not be filled with liquid, but will form an air core.

3. The aviation fuel atomizing nozzle device according to claim 2, characterized in that: The ratio of the diameter of the swirling chamber to the diameter of the nozzle outlet is less than 2.

5. Increasing the diameter of the nozzle outlet expands the air column inside the swirling chamber, reducing the liquid velocity. The axial velocity is more affected than the tangential velocity. The ratio of the diameter of the cyclone chamber to the diameter of the nozzle outlet is greater than 2.

5. The velocity distribution on different cross sections is characterized by a large center and small edge structure. The gas-liquid disturbance on the tower wall is stable, while the gas-liquid disturbance on the central axis inside the tower is intense. The ratio of the diameter of the cyclone chamber to the diameter of the nozzle outlet is 2.

5. The nozzle center velocity is the highest, the gas-liquid disturbance is the most intense, the atomization cone angle is the largest, and the liquid film thickness at the outlet is the smallest.

4. The aviation fuel atomizing nozzle device according to claim 3, characterized in that: The aviation fuel atomization process was simulated using Fluent simulation technology. The calculation process is as follows: S1: Establish a three-dimensional geometric model of the nozzle; S2: Uses realizable Turbulence models are used to simulate and analyze the nozzle atomization process; S3: Select and determine the physical property parameters of the gas and fuel involved in the atomization process; S4: Using an explicit VOF model, air is set as the first phase and fuel as the second phase, and the surface tension between the two phases is set to simulate the fuel flow inside the nozzle. S5: Select the tracking discrete phase frequency and the breakage and collision model; S6: Enable Vof-to-dpm model conversion. Based on the two conversion criteria of equivalent diameter and non-sphericity, the irregularly shaped liquid clumps generated by the first crushing are converted into spherical droplets. The discrete droplet group is processed by the discrete phase model DPM to realize the numerical simulation of the atomization crushing process. S7: Boundary condition settings: Set the inlet pressure to 1 MPa, which is the actual engine fuel injection pressure, and set the wall to a non-slip wall. S8: Calculation method: PISO is selected for the pressure-velocity coupling method, and the second-order upwind mode is selected for the other differences; S9: Post-processing of calculation results: Obtain the changes in liquid film and droplets, changes in fuel atomization cone angle, fuel velocity distribution and droplet size distribution during fuel atomization; S10: Results Analysis and Mechanism Revelation: The fuel atomization process is analyzed, and the atomization results under the influence of different parameters are analyzed to obtain the fuel atomization law and obtain the nozzle configuration with the optimal atomization effect.

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