A monodisperse and uniform droplet device and a method for arranging the nozzle holes of an atomizing nozzle in an array

Abstract

The present invention relates to the technical field of micron-scale jets and uniform atomization, and specifically to a monodisperse uniform droplet device and a method for arranging the orifice array of an atomizing nozzle. The monodisperse uniform droplet device includes a driving source, a liquid supply device, and a nozzle; the nozzle is a monodisperse atomizing nozzle, the driving source is an ultrasonic signal generating system, the liquid supply device supplies a constant-pressure fluid to the nozzle, and the nozzle forms a monodisperse spray under the drive of the high-frequency sound waves of the ultrasonic generating system; Method for arranging the orifice array of the atomizing nozzle: set a smaller orifice spacing in the micro-deformation regions near the center and both side constraint ends of the orifice plate; set a larger safety spacing in the large-deformation region between the constraint end of the orifice plate and the center of the orifice plate to prevent the intersection caused by the intersection of jets. The device and the arrangement method solve problems such as the mutual interference between large-scale array jets; they can effectively improve the controllability of the scale and velocity of monodisperse atomized droplets, thereby generating a large number of micro-droplets with uniform scale and concentrated velocity.

Description

Technical Field

[0001] The present invention relates to the technical field of micron-scale jets and uniform atomization, and particularly to a monodisperse uniform droplet device and a method for arranging an array of atomizing nozzle orifices. Background Art

[0002] In the field of micron-scale jets and uniform atomization, monodisperse jets and fine atomization technologies have broad application prospects, especially in advanced manufacturing processes such as physical cleaning of integrated circuits, photoresist coating, film spraying, and pharmaceutical equipment and particle drying. These processes pose extremely high requirements for the size, distribution, and velocity of atomized droplets. For example, in the physical cleaning process of integrated circuits, it is necessary to achieve a high particle removal rate while avoiding any mechanical damage to the micro-nano device structure. In addition, high-quality photoresist coating and film spraying also require smaller and more uniform droplets to ensure the thickness and uniformity of the film.

[0003] In recent years, the advanced process of integrated circuits has entered a new technology node (10nm), which poses higher requirements for the physical cleaning process: it is necessary to achieve a high particle removal rate while avoiding any mechanical damage to the micro-nano device structure. In addition, high-quality photoresist coating and film spraying also pose new requirements for atomization technology. To produce thinner (<5μm) and more uniform (<10%) films, smaller droplets and higher uniformity are required. These requirements all pose higher demands on the controllability and concentration of atomized droplets. Therefore, there is an urgent need to develop a new atomization technology with high droplet controllability to generate a large number of micro-droplets with uniform size and concentrated velocity.

[0004] However, current typical liquid atomization technologies, such as two-fluid atomization and ultrasonic atomization, all have insurmountable limitations. The two-fluid atomization technology is based on the instability between the gas-liquid phases. Although it can generate a large number of micro-droplets, its atomization effect is significantly affected by the airflow, and it is difficult to independently control the droplet velocity and particle size. Ultrasonic atomization uses high-frequency vibration to excite the oscillation of the liquid interface to form fine droplets, but the atomization effect also depends on the vibration frequency and amplitude, and the droplet diameter and velocity distribution show a normal distribution characteristic, making it difficult to precisely control.

[0005] Although inkjet technology can generate micro-droplets with uniform size, its jet velocity is low, the flow rate is small, the cost is high, and the pressure resistance performance is poor, which has limitations in industrial-level spraying with large flow rates and high speeds. In addition, the compact orifice layout is prone to cause adhesion and blockage of the orifice plate due to wetting, affecting the uniformity and stability of spraying. When the working pressure in the spray chamber is too high, the orifice plate will also deform, resulting in the deviation of the jet direction and even the confluence of jets, further reducing the stability and concentration of spraying.

[0006] Therefore, there are still many difficulties in the existing atomization technologies to meet the high requirements of advanced manufacturing processes for droplet size, velocity, and controllability. To address these issues, the present invention proposes a monodisperse uniform droplet device and a method for arranging the nozzle hole arrays of an atomizing nozzle, aiming to improve the controllability of monodisperse atomized droplet size and velocity by optimizing the arrangement design of the nozzle hole arrays, thereby generating a large number of micro-droplets with uniform size and concentrated velocity to meet the urgent needs of advanced manufacturing processes. Summary of the Invention

[0007] To solve the above problems, the present invention provides a monodisperse uniform droplet device and a method for arranging the nozzle hole arrays of an atomizing nozzle, which can solve problems such as mutual interference between large-scale array jets; effectively improve the controllability of monodisperse atomized droplet size and velocity, thereby generating a large number of micro-droplets with uniform size and concentrated velocity.

[0008] The technical solution of the present invention is as follows:

[0009] A monodisperse uniform droplet device includes a driving source, a liquid supply device, and a nozzle; the nozzle is a monodisperse atomizing nozzle, the driving source is an ultrasonic signal generating system, the liquid supply device supplies a constant-pressure fluid to the nozzle, and the nozzle forms a monodisperse spray under the drive of the high-frequency sound waves of the ultrasonic generating system.

[0010] The ultrasonic signal generating system includes a signal generator, a power amplifier, and a piezoelectric transducer. The signal generator is connected to the power amplifier, and the ultrasonic signal is amplified by the power amplifier and then used as a driving source to connect to the piezoelectric transducer.

[0011] The nozzle includes a nozzle plate and a pressure-resistant cavity. The nozzle plate is hermetically arranged at the bottom of the pressure-resistant cavity, and the piezoelectric transducer is arranged on the opposite side of the nozzle plate and is pasted on the outer surface of the pressure-resistant cavity.

[0012] The piezoelectric transducer has three optional shapes, namely a square piezoelectric sheet, a disc-shaped piezoelectric sheet, or a cylindrical piezoelectric sheet. The nozzle can be selected as a square nozzle, a cylindrical nozzle, or a tubular nozzle corresponding to the shape of the piezoelectric transducer.

[0013] The overall nozzle hole array of the square nozzle is arranged in a rectangular pattern, and the nozzle hole spacing is equal in the same row or the same column;

[0014] The overall nozzle hole array of the cylindrical nozzle is arranged in a circular pattern, the nozzle holes are arranged along concentric circles, the nozzle holes are evenly distributed on the same circle, and the circle is concentric with the disc-shaped piezoelectric sheet;

[0015] The nozzle holes of the tubular nozzle are arranged on the opposite side of the cylindrical piezoelectric sheet, and the nozzle hole array is arranged at equal intervals along the length direction of the tubular nozzle.

[0016] The jet hole spacing near the center of the jet hole plate and at both side restraint ends is smaller than that in the area between the restraint ends and the center of the hole plate.

[0017] A fixed-end restraint is provided at the center of the jet hole plate.

[0018] The minimum safe spacing of the jet holes on the jet hole plate is:

[0019]

[0020] where: d is the aperture of the jet hole;

[0021] t0 is the spacing between jet holes;

[0022] σ is the surface tension of the fluid;

[0023] P is the liquid supply pressure;

[0024] P0 is the reference pressure;

[0025] C is an empirical parameter.

[0026] A method for arranging the jet hole array of the atomizing nozzle of a monodisperse uniform droplet device, in the slightly deformed areas near the center of the jet hole plate and at both side restraint ends, a smaller jet hole spacing is set; in the large deformation area between the restraint end of the jet hole plate and the center of the jet hole plate, a larger safe spacing is set to prevent the intersection caused by the confluence of jets.

[0027] The minimum safe spacing of the jet holes on the jet hole plate is calculated according to the following formula:

[0028]

[0029] where: d is the aperture of the jet hole;

[0030] t0 is the spacing between jet holes;

[0031] σ is the surface tension of the fluid;

[0032] P is the liquid supply pressure;

[0033] P0 is the reference pressure;

[0034] C is an empirical parameter.

[0035] The beneficial effects of the present invention are as follows:

[0036] 1. The monodisperse uniform droplet device and the method for arranging the orifice array of the atomizing nozzle disclosed by the present invention design orifice arrays with different geometric configurations, ensuring the uniformity of the jet regulated by the sound field in nozzles with different structures; piezoelectric wafers with different shapes have different vibration distribution laws, and the atomization effect during high-speed jet is extremely sensitive to the sound field difference; the orifice array proposed by the present invention takes into account the sound field distribution of typical piezoelectric elements to ensure the consistency of the ultrasonic excitation received by different jets. On the one hand, it ensures that the sound field distribution laws at orifices in different positions of the array are the same, and on the other hand, it avoids the disorder of the sound field caused by the internal eddy current caused by the jet, thereby reducing the particle size deviation between different orifices.

[0037] 2. The jet direction offset compensation orifice layout proposed by the monodisperse uniform droplet device and the method for arranging the orifice array of the atomizing nozzle disclosed by the present invention can greatly reduce the abnormal jet direction; by adjusting the orifice spacing to adapt to the deformation law of the orifice plate, the direction offset of different orifices on the same axis is compensated; by setting fixed constraints on the orifice plate, its deformation displacement is restricted, thereby weakening the degree of jet direction offset; on the one hand, this layout ensures the controllability of the jet direction, which plays an important role in optimizing process parameters; on the other hand, the correction of the jet direction offset can also reduce the intersection probability of jets caused by factors such as eddy currents; this layout method improves the stability and durability of large-scale and high-throughput monodisperse spraying.

[0038] 3. The minimum safety spacing design criterion between adjacent orifices proposed by the monodisperse uniform droplet device and the method for arranging the orifice array of the atomizing nozzle disclosed by the present invention can effectively reduce the mutual interference between adjacent jets; through numerical simulation and experimental verification, considering factors such as fluid physical properties, jet velocity, cavity pressure, orifice diameter, and driving frequency, and combining with test data, an empirical criterion for the minimum safety spacing is proposed; the orifice array designed according to this criterion effectively weakens the influence of the eddy current generated in the spatial flow field during jet generation on adjacent jets, realizes the stability and uniformity of monodisperse spraying under specific process parameters, ensures the compactness of the orifice array, and improves the spraying efficiency.

[0039] 4. The monodisperse uniform droplet device and the method for arranging the orifice array of the atomizing nozzle disclosed by the present invention have unique advantages of uniform droplet size, concentrated velocity distribution, controllable jet direction, and independent and precise regulation of particle size and velocity. At the same time, by optimizing the orifice arrangement, the spraying flow rate is increased, and the atomization stability during long-term operation of the nozzle is enhanced. Description of the Drawings

[0040] By reading the detailed description of the preferred embodiments below, the solutions and advantages of the present application will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention.

[0041] Figure 1 Schematic diagram of the composition of a monodisperse and uniform droplet device according to an embodiment of the present invention;

[0042] Figure 2 Schematic diagram of the structure of the nozzle of a monodisperse and uniform droplet device according to an embodiment of the present invention;

[0043] Figure 3 Schematic diagram of the structures of three piezoelectric transducers and the nozzle of a monodisperse and uniform droplet device according to an embodiment of the present invention;

[0044] Figure 4 For Figure 3 Schematic diagram of the geometric configuration of the nozzle hole arrangement corresponding thereto;

[0045] Figure 5 Schematic diagram of the deformation of the nozzle plate caused by pressure;

[0046] Figure 6 Schematic diagram of the jet direction deviation on the same axis caused by the deformation of the nozzle hole;

[0047] Figure 7 Schematic diagram of the nozzle hole layout method for compensating jet deviation;

[0048] Figure 8A Schematic diagram of fixing constraints to compensate jet deviation;

[0049] Figure 8B Schematic diagram of the deformation and deviation of the nozzle plate before and after fixing constraints;

[0050] Figure 9A Schematic diagram of abnormal interference and instability of adjacent jets;

[0051] Figure 9B Schematic diagram of the velocity eddy current distribution on both sides of adjacent jets;

[0052] Figure 10A Schematic diagram of the triangular nozzle hole arrangement method that complies with the safety spacing rule;

[0053] Figure 10B Schematic diagram of the square nozzle hole arrangement method that complies with the safety spacing rule;

[0054] Figure 11 Particle size distribution of monodisperse spray;

[0055] Figure 12 Velocity concentration of monodisperse spray;

[0056] Figure 13 Microscopic local morphology of monodisperse spray;

[0057] The components represented by the reference numerals in the figure are:

[0058] The present invention: 140, spray head, 141, square spray head, 142, cylindrical spray head, 143, tubular spray head, 150, safety valve, 200, signal generator, 210, power amplifier, 230, monitor and control box, 240, LED light source, 250, waste liquid recovery, 260, high-speed industrial camera, 270, liquid droplet, 280, piezoelectric transducer, 281, square piezoelectric sheet, 282, disc-shaped piezoelectric sheet, 283, cylindrical piezoelectric sheet, 290, liquid supply device, 310, pressure-resistant cavity, 320, sealing ring, 330, spray hole plate, 340, spray hole. Detailed implementation manners

[0059] A method and device for arranging a spray hole array of a monodisperse atomizing spray head aims to improve the uniformity and stability of a monodisperse atomizing array jet. Specifically, spray hole arrays with different geometric configurations are designed according to the sound field distribution in a specific structure chamber to ensure uniform transmission of ultrasound at different spray holes; considering the deformation of the hole plate caused by pressure, a special spray hole layout scheme is designed to compensate for the jet deviation caused by the deformation of the hole plate, and a method of setting fixed constraints is provided to limit the deformation of the hole plate, effectively ensuring the controllability of the jet direction; further, a design criterion for the minimum safety distance between spray holes is proposed, which avoids the instability caused by mutual interference between jets while ensuring the maximum atomization efficiency. The innovative spray hole array arrangement method proposed by the present invention solves the common problems of poor stability and uneven jet in conventional atomization technologies, and realizes large-flux monodisperse atomization with uniform scale and concentrated velocity.

[0060] As Figure 1 shown, a monodisperse uniform droplet device includes a driving source, a liquid supply device 290 and a spray head 140; the spray head 140 is a monodisperse atomizing spray head, the driving source is an ultrasonic signal generating system, the liquid supply device 290 supplies a constant-pressure fluid to the spray head 140, and the spray head 140 forms a monodisperse spray under the drive of high-frequency sound waves of the ultrasonic generating system.

[0061] The ultrasonic generating device includes a function signal generator 200, a high-voltage power amplifier 210 and a piezoelectric transducer (PZT piezoelectric ceramic sheet) 280; the signal generator 200 is directly connected to the power amplifier 210, and the ultrasonic signal is directly used as a driving source to connect the piezoelectric ceramic sheet 280 after being amplified by the power amplifier 210. The observation device includes a high-speed industrial camera (industrial CCD camera) 260 and an LED light source (stroboscopic light source) 240, etc., and the high-speed industrial camera (industrial CCD camera) 260 is communicatively connected to the monitor and control box 230.

[0062] The function signal generator 200 can generate high-frequency alternating current signals with different waveforms; the signal generator 200 is directly connected to the power amplifier 210, and the ultrasonic signal is directly used as a driving source after being amplified by the power amplifier 210.

[0063] The liquid supply device 290 includes a high-flow high-pressure micropump, a buffer / energy storage cartridge, a PTFE filter, a back pressure valve, a high-precision pressure sensor, a microcontroller, and a liquid source. The high-flow high-pressure micropump directly supplies liquid to the buffer cartridge and transports it to the monodisperse atomizing nozzle through the PTFE filter. The high-precision pressure sensor and the controller provide real-time feedback and adjust the ink path pressure.

[0064] As Figure 2 shown, the monodisperse spray nozzle 140 includes a piezoelectric transducer (PZT piezoelectric ceramic sheet) 280, a nozzle plate 330, a pressure-resistant cavity 310, and a sealing element (sealing ring) 320, etc.; the components are installed by physical methods (mechanical connection or ultrasonic welding) without using any adhesives, which can avoid introducing pollution sources. The liquid supply device 290 supplies a constant-pressure fluid to the monodisperse spray nozzle 140, and under the drive of the high-frequency ultrasonic wave generated by the ultrasonic generating system, the jet is forced to break regularly, and finally monodisperse spray droplets 270 are formed. The nozzle plate can be made of quartz glass, silicon, stainless steel, PEEK, etc. according to the application scenario. The nozzles can be manufactured by laser processing, etching processing, mechanical processing, etc. according to the accuracy and the requirements of the nozzle plate material. The nozzle plate 330 is arranged in the lower half of the pressure-resistant cavity 310, and several nozzles 340 are provided on the nozzle plate 330 and are sealed and installed in the cavity; the piezoelectric transducer (PZT piezoelectric ceramic sheet) 280 is arranged on the opposite side of the nozzle plate 330 and is pasted on the outer surface of the cavity using a two-component epoxy resin adhesive; a safety valve (back pressure valve) 150 is arranged on the other side of the nozzle 140, and a waste liquid recovery (tank) 250 is arranged below the outlet of the safety valve 150.

[0065] The piezoelectric transducer (PZT piezoelectric ceramic sheet) 280 has different implementation modes according to the actual application scenario. For example, Figure 3 shown, it includes: a square piezoelectric sheet 281, a disk-shaped piezoelectric sheet 282, and a 1 / n cylindrical piezoelectric sheet 283. The piezoelectric ceramic sheets are polarized in the thickness direction, that is, the vibration mode is the telescopic oscillation along the thickness direction. By using ANASY WORKBENCH to analyze the vibration modes of the three piezoelectric sheets, it can be known that different-shaped piezoelectric sheets can produce different sound field distribution laws. The square piezoelectric sheet 281 and the disk-shaped piezoelectric sheet 282 both transfer vibrations to the fluid medium in the cavity in a planar form. On the surface of the circular piezoelectric sheet 282, the vibration form is transmitted in a concentric circular harmonic form from the center along the radial direction. Under ideal conditions, the vibration state of any point on its surface is the same as that of the points on the same circle where it is located. The vibration transfer law of the cylindrical piezoelectric sheet 283 is different from that of the other two piezoelectric sheets. The direction of the sound wave generated by it is the same as the normal direction of the inner surface of the piezoelectric sheet, and it focuses along the length direction in the internal space.

[0066] The monodisperse spray nozzle 140 has different embodiments for piezoelectric ceramic sheets 280 of different shapes, such as Figure 3 as shown. The monodisperse spray nozzle 140 can have different embodiments according to the actual application situation, especially for structural adjustment to cope with sound fields with different distribution laws. Figure 3 Three typical embodiments of a square nozzle 141, a cylindrical nozzle 142, and a tubular nozzle 143 are given respectively, corresponding to piezoelectric elements 281, 282, and 283. The cavity structures of the nozzles are all adapted to the sound field transmission law, avoiding the disorder of the sound propagation direction caused by the mismatch of the chamber structure, and ensuring that ultrasonic waves can be evenly transmitted in the chamber and radiated to the bottom spray holes 340. The nozzle embodiments are not limited to the three typical structures proposed. For other special-shaped piezoelectric ceramic sheets, the nozzle embodiments can be made of materials such as metal, engineering plastics, organic glass, and quartz according to the application scenario.

[0067] The optimization arrangement and layout method of the large-scale array spray holes 340 of the monodisperse uniform droplet device include:

[0068] The layout geometric configurations of the spray holes 340 for different nozzle implementation methods are as Figure 4 shown. For the implementation methods of the monodisperse atomizing nozzle 280 matching different specifications of piezoelectric ceramic sheets 140, different geometric configurations of spray hole arrangements are provided: equidistant arrangement, circumferential arrangement, and centerline arrangement, corresponding to the typical square nozzle 141, cylindrical nozzle 142, and tubular nozzle 143 respectively.

[0069] The spray hole layouts of the different geometric configurations are all realized on the spray hole plate 330 by methods such as laser, etching, or machining. In the equidistant arrangement of the square nozzle 141, the spacing between the spray holes 340 in the same row or column is equal, and the overall spray hole array is arranged in a rectangular shape. In the circumferential arrangement of the cylindrical nozzle 142, the spray holes 340 are arranged along concentric circles, and the spray holes 340 on the same circumference are evenly distributed, and the circumference is concentric with the circular piezoelectric sheet. The array shapes of the above equidistant arrangement and circumferential arrangement of the spray holes 340 correspond to the piezoelectric transducer, and the array area is not larger than the area of the corresponding piezoelectric sheet. In the centerline arrangement of the tubular nozzle 143, the spray hole array is arranged equidistantly along the only centerline. The centerline is along the length direction of the tubular nozzle and is on the opposite side of the cylindrical piezoelectric sheet 283. Through this design, on the one hand, it ensures that the sound field distribution laws at different positions of the spray holes 340 in the array are consistent, and on the other hand, it avoids the disorder of the sound field caused by the internal eddy current caused by the jet flow, thus ensuring the regular transmission of the sound wave in the cavity to the jet flow and improving the uniformity of the array jet flow.

[0070] When the spray hole plate 330 works, it will deform due to the chamber pressure, as Figure 5As shown in the figure. Define the distance from any point on the orifice plate diameter to the center as Ln. Then, the law of jet direction deviation caused by the deformation of the orifice plate 330 is as follows Figure 6 As shown. The deviation of the jet direction is the smallest at the center of the orifice plate 330 and near the constrained end, and the deviation gradually increases between the two. The jet deviation reaches the maximum at the central position between the two. To meet the high-speed and large-flow spray requirements in engineering applications, high-pressure liquid supply and a compact orifice arrangement are required. As the pressure increases, the deformation of the orifice plate increases, and the deviation of the jet direction will also intensify. At the same time, the compact nozzle arrangement increases the probability of jet intersection.

[0071] A method for the orifice layout to compensate for the jet direction deviation is as follows Figure 7 As shown, according to the deformation of the orifice plate 330 and the law of jet deviation, an array of orifices 340 with unequal spacings is set Figure 7 An example of the center line of the orifice 340 array is given. In the small-deformation regions near the center of the orifice plate and at both constrained ends, smaller orifice spacings are set; in the large-deformation region between the constrained end and the center of the orifice plate, larger safety spacings are set to prevent intersection due to jet intersection. Figure 7 The method for the orifice layout to compensate for the jet direction deviation shown in the figure takes the circumferential array arrangement as an example for illustration purposes, and does not represent the array spacing ratio and size in actual applications. Similar array arrangements can also be designed for the equal-spacing arrangement and the center-line arrangement according to this idea.

[0072] In the method for the orifice layout to compensate for the jet direction deviation, the spacing of the orifices 340 can be adjusted according to the atomization parameters. Specifically, for high-pressure spraying, the spacing should be increased to adapt to the increased deformation of the orifice plate; for the setting of the spacing of the orifices 340 on the same circumference, it is necessary to ensure that the jets do not interfere with each other or cause adhesion at adjacent orifices 340 due to orifice plate wetting to block the orifices. This method is applicable to applications with high requirements for the controllability of the atomization direction, especially applicable to the application scenarios of large-flow and high-speed spraying.

[0073] In addition, an installation method and an orifice 340 layout method for setting fixed constraints to compensate for jet deviation are proposed, as follows Figure 8A and Figure 8B As shown, the jet direction deviation is caused by the deformation of the orifice plate 330 under pressure. When the spraying device works, the deformation at the center of the orifice plate 330 is the largest, and the deformation at the constrained end is the smallest. An additional setting is made at the center of the orifice plate with the largest deformation to reduce the deformation of the orifice plate 330, which can relieve the jet direction deviation. By increasing the fixed-end constraint, the degree of deformation is relieved, and the direction deviation of the jet is corrected.

[0074] The installation and layout method for the fixed constraint to compensate for the jet direction deviation takes the circumferential array arrangement as an example for illustration purposes, and does not represent the setting position, quantity, and method of the constraint in actual applications. Similar array arrangements can also be designed for the equal-spacing arrangement and the center-line arrangement according to this idea.

[0075] Further, a design criterion for the minimum safe spacing of the array of spray holes 340 is proposed to ensure that the array of spray holes 340 arranged on the spray hole plate 330 has an optimal spacing. Velocity vortices will be generated around the high-speed jet. When the hole pitch is too small, the jet will deflect in direction and even cause the jets to converge. When abnormal interference and instability occur between adjacent jets, as Figure 9A shown, the velocity vortex distribution on both sides of the jet during multi-hole jet atomization is obtained using computational fluid dynamics methods, as Figure 9B shown. Based on the target flow rate, flow velocity, and particle size, the safe spacing between the jets of different specifications of spray nozzles is determined. That is, on the premise of ensuring that the jets do not interfere with each other to cause convergence, a sufficiently compact layout is ensured to improve the atomization efficiency.

[0076] The design criterion for the minimum safe spacing of the array of spray holes 340 is specifically described as follows: By adjusting the spray hole layout and spacing, the induced vortices and bubbles are reduced to improve the stability and uniformity of the injection. Define the hole diameter d, the hole pitch t0, the surface tension of the fluid σ, the supply pressure P, the reference pressure P0, and the empirical parameter C; Define the minimum pressure at which stable jetting can occur under the conditions of determining the fluid type and hole diameter as P0; Obtain the initial value of the empirical parameter C through computational fluid dynamics simulation, and correct C by measuring the minimum spacing t between adjacent jets under different experimental conditions when there is no mutual interference between adjacent jets (as Figure 9A ). Based on the computational fluid dynamics simulation of the flow field distribution and combined with experimental experience, the minimum safe spacing of the array of spray holes 340 is:

[0077]

[0078] Then the actual designed hole pitch . Through the above measures, the interaction between the spray holes is effectively controlled, and the influence of vortices and bubbles that may occur during the injection process is reduced. The design criterion for the minimum safe spacing arrangement of the array of spray holes 340 is applicable to the circumferential arrangement, equidistant arrangement, and centerline arrangement.

[0079] Based on the design criterion for the minimum safe spacing of the array of spray holes 340, typical arrangement methods that comply with the safe spacing rule are proposed. As shown in Figure 10, they include: A triangular distribution and B square arrangement. In the triangular arrangement, the spray holes 340 in adjacent rows are staggered, and in the square arrangement, both adjacent rows and columns are distributed along straight lines. The above hole pitches all meet the design criterion for the minimum safe spacing.

[0080] The monodisperse atomization device with an optimized spray hole arrangement can generate monodisperse spray with uniform scale, concentrated velocity, and controllable direction. Figure 11For the monodisperse spray particle size distribution generated by using the present invention, the particle size concentration is 95%@98±5μm; the monodisperse spray velocity distribution generated is as Figure 12 shown, and the droplet velocity is concentrated at 20.1 - 20.3m / s; Figure 13 is the microscopic local morphology of the monodisperse spray obtained by the in-situ high-speed observation device. It can be seen that the monodisperse atomized jet obtained by the present invention has the advantages of high straightness and controllable direction.

[0081] The monodisperse uniform droplet device and the method for arranging the spray holes of the atomizing nozzle in the present invention can avoid the mutual interference between large-scale array jets; compensate for the jet direction deviation caused by the deformation of the spray hole plate; optimize the sound field distribution to enhance the uniformity and stability of ultrasonic regulation of jet breakup. The present invention can effectively improve the controllability of the monodisperse spray droplet size and velocity, and generate a large number of micro-droplets with uniform size and concentrated velocity.

Claims

1. A monodisperse and uniform droplet device, characterized in that It includes a driving source, a liquid supply device (290) and a nozzle (140); the nozzle (140) is a monodisperse atomizing nozzle, the driving source is an ultrasonic signal generating system, the liquid supply device (290) supplies a constant-pressure fluid to the nozzle (140), and the nozzle (140) forms a monodisperse spray under the drive of the high-frequency sound waves of the ultrasonic generating system; The nozzle (140) includes a nozzle plate (330) and a pressure-resistant cavity (310), and the nozzle plate (330) is sealingly arranged at the bottom of the pressure-resistant cavity (310); The nozzle pitch near the center of the nozzle plate (330) and the constraint ends on both sides is smaller than the nozzle pitch in the area between the constraint ends and the center of the orifice plate.

2. The monodisperse and uniform droplet device according to claim 1, characterized in that, The ultrasonic signal generating system includes a signal generator (200), a power amplifier (210) and a piezoelectric transducer (280). The signal generator (200) is connected to the power amplifier (210), and the ultrasonic signal is amplified by the power amplifier (210) and then used as a driving source to connect to the piezoelectric transducer (280).

3. The monodisperse and uniform droplet device according to claim 2, characterized in that, The piezoelectric transducer (280) is arranged on the opposite side of the nozzle plate (330), and the piezoelectric transducer (280) is pasted on the outer surface of the pressure-resistant cavity (310).

4. The monodisperse and uniform droplet device according to claim 3, wherein The piezoelectric transducer (280) has three optional shapes, namely a square piezoelectric sheet (281) or a disc-shaped piezoelectric sheet (282) or a cylindrical piezoelectric sheet (283), and the nozzle (140) can be selected as a square nozzle (141) or a cylindrical nozzle (142) or a tubular nozzle (143) corresponding to the shape of the piezoelectric transducer (280).

5. The monodisperse and uniform droplet device according to claim 4, wherein, The nozzle holes (340) of the square nozzle (141) are generally arranged in a rectangular array, and the nozzle hole pitch in the same row or the same column is equal; The nozzle holes (340) of the cylindrical nozzle (142) are generally arranged in a circular pattern, the nozzle holes (340) are arranged along concentric circles, the nozzle holes (340) on the same circle are evenly distributed, and the circle is concentric with the disc-shaped piezoelectric sheet (282); The nozzle holes (340) of the tubular nozzle (143) are arranged on the opposite side of the cylindrical piezoelectric sheet (283), and the nozzle hole array is arranged at equal intervals along the length direction of the tubular nozzle (143).

6. The monodisperse uniform droplet device according to claim 5, wherein The minimum safe spacing of the spray holes (340) on the spray hole plate (330) is: where: d is the aperture of the spray hole; t0 is the nozzle hole pitch; σ is the surface tension of the fluid; P is the liquid supply pressure; P0 is the reference pressure; C is an empirical parameter.

7. A method for arranging the nozzle hole array of the atomizing nozzle of a monodisperse uniform droplet device, based on a monodisperse uniform droplet device according to any one of claims 1-6, characterized in that In the small-deformation area near the center of the nozzle plate (330) and the constraint ends on both sides, a smaller nozzle pitch is set; in the large-deformation area between the constraint end of the nozzle plate (330) and the center of the nozzle plate (330), a larger safety pitch is set to prevent the intersection caused by the jet intersection.

8. The method for arranging the nozzle hole array of the atomizing nozzle of a monodisperse uniform droplet device according to claim 7, characterized in that, The minimum safe spacing of the spray holes (340) on the spray hole plate (330) is calculated according to the following formula: where: d is the aperture of the spray hole; t0 is the nozzle hole pitch; σ is the surface tension of the fluid; P is the liquid supply pressure; P0 is the reference pressure; C is an empirical parameter.

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