A light scattering method for measuring droplet drift

Abstract

This invention discloses a light scattering method for testing droplet drift, comprising a bottom support, a guide rail, a first instrument body, a second instrument body, and photodetectors. The guide rail is mounted on the bottom support at both ends. The first and second instrument bodies are movably mounted on the guide rail. Two photodetectors are mounted on the first and second instrument bodies, respectively. A sheet-like laser emitter is housed within the first instrument body. The sheet-like laser emitter has an optical path formed by a laser, an aperture, a Powell prism, and an aspherical lens arranged sequentially. The laser emits a parallel beam, which is filtered through the aperture, compressed into a sheet-like diverging beam by the Powell prism, and finally collimated by the aspherical lens to become a parallel sheet light source. This invention saves time and costs, simplifies the experimental procedure, protects testing personnel, and provides reliable experimental results.

Description

Technical Field

[0001] This invention relates to a technology for measuring droplet drift, specifically a device for measuring droplet drift using the light scattering method. Background Technology

[0002] The droplet drift measurement method is mainly conducted in a wind tunnel using a PTFE rope (or a similar rope). The test involves collecting drift droplets on the rope, including complex steps such as rinsing, weighing, and analysis. The rope is prone to saturation during the test, necessitating effective control of the total droplet flow rate. The droplet drift measurement method is prone to saturation.

[0003] The test requires multiple testers to work together in the wind tunnel. Since the test mainly involves measuring the amount of pesticide droplets, it can cause harm to the testers' health. The test process is also quite complex, with many steps and a lot of human intervention, so the test results are often unstable and the test costs are relatively high. Summary of the Invention

[0004] In view of the shortcomings of existing technologies, such as the saturation phenomenon of the test rope in the droplet drift test and the instability of test results due to many human intervention factors, the present invention aims to provide a light scattering method droplet drift test device that does not produce saturation phenomenon, has minimal human intervention, and provides stable and repeatable test results.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] The present invention discloses a light scattering method for measuring droplet drift, comprising a bottom support, a guide rail, a first instrument body, a second instrument body, and a photodetector. The guide rail is mounted on the bottom support, and the first and second instrument bodies are slidably mounted on the guide rail. Two photodetectors are respectively mounted on the first and second instrument bodies, and a sheet-like laser emitter is provided inside the first instrument body.

[0007] The sheet laser emitter has an optical path formed by a laser, an aperture, a Powell prism, and an aspherical lens arranged in sequence. The laser emits a parallel light spot, which is filtered through the aperture, then compressed into a sheet-like diverging light spot by the Powell prism, and finally collimated by the aspherical lens to become a parallel sheet light source.

[0008] The control unit is installed inside the main body of the second instrument.

[0009] The present invention has the following beneficial effects and advantages:

[0010] 1. This invention uses laser scattering to test the amount of fog droplet drift. It can generate a sheet-like laser. When a fog droplet enters the test area, the sheet-like laser will produce scattered light similar to water ripples. The light is then collected by a photodetector, and the amount of fog droplet drift is calculated. This saves time and costs, simplifies the test procedure, protects test personnel, and provides reliable test results.

[0011] 2. Since this invention uses laser scattering to test the drift of droplets, there is no saturation of the test PTFE rope due to excessive flow. This avoids errors caused by manual rinsing and weighing of the test PTFE rope later. Electronic control is used to realize the whole process of droplet drift testing, which has good repeatability and high reliability of test data and results. It avoids the unreliability of test results caused by the failure of a certain test link.

[0012] 3. This invention uses laser scattering to test droplet drift, building upon existing methods. It employs ultra-long signal transmission, allowing testers to remotely control the experiment and avoid contact between personnel and (toxic or harmful) droplets, thus preventing harm to the testers. Furthermore, the distance and measurement width for measuring drift can be adjusted as needed, offering great flexibility in settings. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the light scattering method for measuring droplet drift of the present invention.

[0014] Figure 2 This is a schematic diagram of the optical path structure of the sheet laser emitter in the device of the present invention.

[0015] Among them, 1 is the bottom support, 2 is the guide rail, 3 is the first instrument body, 4 is the photodetector, 5 is the sheet laser, 501 is the laser, 502 is the aperture, 503 is the Powell prism, 504 is the aspherical lens, and 6 is the second instrument body. Detailed Implementation

[0016] The present invention will now be further described with reference to the accompanying drawings.

[0017] like Figure 1 As shown, the present invention discloses a light scattering method for measuring droplet drift, comprising a bottom support 1, a guide rail 2, a first instrument body 3, a second instrument body 6, and a photodetector 4. The guide rail 2 is mounted on the bottom support 1, and the first instrument body 3 and the second instrument body 6 are movably mounted on the guide rail 2. There are two photodetectors 4, which are respectively mounted on the first instrument body 3 and the second instrument body 6. A sheet-like laser emitter is provided inside the first instrument body 3.

[0018] like Figure 2As shown, the sheet laser emitter has an optical path formed by the sequential arrangement of a laser 501, an aperture 502, a Powell prism 503, and an aspherical lens 504. The laser 501 emits a parallel light spot, which is filtered through the aperture 2, then compressed into a sheet-like diverging light spot by the Powell prism 3, and finally collimated by the aspherical lens to become a parallel sheet light source.

[0019] The dimensional parameters of the parallel sheet light source, such as sheet thickness and sheet width, are controlled by selecting the optical parameters of the Powell prism and aspherical lens. This invention achieves a sheet light source with a thickness of 0.5 mm using a sheet laser emitter, allowing for a very close proximity of droplets entering the beam. This reduces signal errors caused by repeated beam entry for high-concentration droplets, thus improving measurement accuracy.

[0020] The first instrument body 3 and the second instrument body 6 are mounted on the high-precision guide rail 2. The bottom bracket 1 is used to fix the high-precision guide rail 2. The distance between the instrument body 3 and the instrument body 6 can be manually adjusted. The advantage is that the lateral distance of the droplet drift can be adjusted to adapt to different nozzles or on-site environmental requirements.

[0021] The first instrument body 3 and the second instrument body 6 are arranged opposite each other, and both are external shell structures. Two photodetectors 4 are installed at the same height on the upper part of the opposite surface of the shell structure.

[0022] The sheet laser emitter inside the first instrument body 3 emits a sheet laser with a thickness of 0.5 mm. Two photodetectors 4 are installed on the first instrument body 3 and the second instrument body 6 (i.e., in front and behind the sheet light source). No matter where the droplet falls on the sheet light source, its scattered light intensity is the sum of the light intensities detected by the two photodetectors. This ensures that the detected light intensity is independent of the position of the droplet falling on the beam, thus ensuring the accuracy of the test results.

[0023] The adjustable distance between the two photodetectors is 10–2000 mm.

[0024] In this invention, the guide rail 2 is a double guide rail, installed in parallel between two bottom supports 1; the bottom of the first instrument body 3 and the second instrument body 6 are provided with multiple wheels, which are tightly fitted with the double guide rail. The tightly fitted wheels and guide rail will not roll easily and are not easily moved by external forces.

[0025] The adjustable distance between the two photodetectors is 10 to 2000 mm, and in this embodiment it is 50 mm.

[0026] The control core of the control unit in this invention is installed within the second instrument body 6. The control unit uses an FPGA parallel acquisition method to simultaneously acquire data from two AD converters. The FPGA operates in fully parallel mode, enabling true simultaneous acquisition and improving the AD reading speed. The data is then transferred to the STM32 microcontroller via DMA, without consuming internal STM32 resources. Simultaneously, two 64Kbyte FIFOs are established within the STM32, working alternately to ensure that each output is 64Kbyte, thus guaranteeing the timeliness of the acquired data. While improving the AD acquisition and reading speeds, without improving the transmission speed between the STM32 and the PC, even a faster acquisition speed is meaningless to the PC. Therefore, to ensure the validity of the acquired data, the transmission speed between the STM32 and the PC must be improved. Currently, USB 2.0 (30 times faster than USB 1.1) is used for data transmission. With the addition of a USB330PHY chip and a high-speed USB driver, the data transmission capacity is larger, accommodating higher acquisition speeds. The theoretical speed can reach 48Mbyte, and actual testing shows a speed of ≥38Mbyte, fully meeting the requirements.

[0027] The working process and principle of this invention are as follows:

[0028] The droplets are ejected from the nozzle. When the droplets enter the test area, i.e., between the two photodetectors 4, light scattering occurs. The photodetectors 4 receive the scattered light and convert it into an electrical signal, which is then transmitted to the signal acquisition and transmission module and sent to the computer for data processing to determine the amount of droplet drift.

[0029] The sheet laser emitter in the first instrument body 3 emits a 0.5mm thick sheet laser beam, which enters the light trap (a device that prevents backscattering after the beam enters) in the second instrument body 6, thus avoiding the influence of reflected light on the test. When drifting droplets enter the sheet laser 5, light scattering occurs. The scattered light is received by two photodetectors 4, which convert the light signal into an electrical signal. The electrical signal is processed by the signal acquisition and transmission module, and then the computer calculates the droplet drift. Because droplets of different sizes produce different intensities of scattered light, droplets of different sizes can be distinguished on the photodetectors. These droplets are accumulated based on their volume content to statistically determine the droplet drift.

[0030] Because this invention utilizes laser scattering to test droplet drift, it avoids the saturation problem of the PTFE rope due to excessive flow, thus preventing errors caused by manual washing and weighing of the PTFE rope later. This invention uses electronic control to achieve full-process testing of droplet drift, resulting in good repeatability and high reliability of experimental data and results. It avoids the previous assumption that failure in a single testing step would lead to unreliable results. The instrument employs ultra-long signal transmission, allowing testers to operate the instrument remotely, avoiding contact with (toxic and harmful) droplets and thus preventing harm to testers. The distance and measurement width for drift measurement can also be adjusted as needed, offering highly flexible settings. In summary, this invention, by using laser scattering to test droplet drift based on existing methods, saves time and costs, simplifies the experimental procedure, protects testers, and provides reliable experimental results.

[0031] This invention can perform tests independently or in series according to testing requirements, with no limit on the number of units, and can meet the testing of droplet drift at different distances.

Claims

1. A device for measuring droplet drift using light scattering, characterized in that: The instrument includes a bottom support, a guide rail, a first instrument body, a second instrument body, and a photodetector. The guide rail is mounted on the bottom support on both sides. The first and second instrument bodies are movably mounted on the guide rail. There are two photodetectors, which are respectively mounted on the first and second instrument bodies. The first instrument body contains a sheet-like laser emitter. The sheet laser emitter has an optical path formed by the sequential arrangement of a laser, an aperture, a Powell prism, and an aspherical lens. The laser emits a parallel spot, which is filtered through the aperture, then compressed into a sheet-like diverging spot by the Powell prism, and finally collimated by the aspherical lens to become a parallel sheet light source. When a droplet enters the test area, the sheet laser will produce scattered light, which is then collected by a photodetector to calculate the amount of droplet drift. The sheet laser emitter inside the first instrument body emits a sheet laser with a thickness of 0.5 mm. Two photodetectors are installed on the first instrument body and the second instrument body respectively. No matter where the droplet falls on the sheet light source, its scattered light intensity is the sum of the light intensities detected by the two photodetectors. This ensures that the detected light intensity is independent of the position of the droplet falling on the beam, thus ensuring the accuracy of the test results. The first instrument body and the second instrument body are arranged opposite each other, both of which are shell structures. The two photodetectors are installed at the same height on the upper part of the opposite surface of the shell structure.

2. The light scattering method for measuring droplet drift according to claim 1, characterized in that: The guide rail is a double guide rail, which is installed in parallel between two bottom supports; the bottom of the first instrument body and the second instrument body are equipped with multiple wheels that fit tightly with the double guide rail.

3. The light scattering method for measuring droplet drift according to claim 1, characterized in that: The adjustable distance between the two photodetectors is 10~2000mm.

4. The light scattering method for measuring droplet drift according to claim 1, characterized in that: The control unit is installed inside the main body of the second instrument.

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