Droplet generation and characterization using a piezoelectric droplet generator and high speed imaging techniques

Minov, Sofija Vulgarakis; Cointault, Frédéric; Vangeyte, Jürgen; Pieters, Jan; Nuyttens, David

doi:10.1016/j.cropro.2014.11.012

Cited by 17 publications

(11 citation statements)

References 27 publications

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“…However, few conditions related to the droplet diameter, droplet displacement and droplet velocity in a real spray application exist and are necessary in order to identify the same droplet on two successive images [22,31]. First is the condition of conservation of droplet diameter i.e.…”

Section: Resultsmentioning

confidence: 99%

“…A precision linear micro translation stage (0–25 mm, Edmund Optics, Barrington, NJ, USA) with a straight line accuracy of 10 μm moveable in the Z direction was attached to the lens. The droplet generator was implemented in continuous mode [21,22] using glass nozzles with orifice sizes of 261, 123, 67, 50 and 40 μm. These nozzle orifice sizes were chosen in order to produce a range of droplet sizes from around 100 μm up to 500 μm which is typical of most agricultural hydraulic spray nozzles.…”

Section: Methodsmentioning

confidence: 99%

“…In the continuous mode, to produce a continuous stream of uniformly sized droplets, a suitable amplitude and frequency must be applied. The applied settings of the droplet generator (amplitude and frequency) and the corresponding actual droplet sizes at the focal plane are given in Table 1 [21,22]. …”

Section: Methodsmentioning

confidence: 99%

“…Firstly, an in-focus droplet criterion based on the gray level gradient was introduced to decide whether a droplet is considered to be in focus or not. A calibration system was devised using differently sized droplets generated with a piezoelectric droplet generator and glass nozzles in continuous mode, developed by Vulgarakis Minov et al [21,22], at different distances from the focal plane and lens using a micro translation stage [10]. This enabled measurement of the gray level gradient and the in-focus parameter for every droplet size at various distances from the focal plane [10].…”

Section: Introductionmentioning

confidence: 99%

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Spray Droplet Characterization from a Single Nozzle by High Speed Image Analysis Using an In-Focus Droplet Criterion

Minov

Cointault

Vangeyte³

et al. 2016

Sensors

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Accurate spray characterization helps to better understand the pesticide spray application process. The goal of this research was to present the proof of principle of a droplet size and velocity measuring technique for different types of hydraulic spray nozzles using a high speed backlight image acquisition and analysis system. As only part of the drops of an agricultural spray can be in focus at any given moment, an in-focus criterion based on the gray level gradient was proposed to decide whether a given droplet is in focus or not. In a first experiment, differently sized droplets were generated with a piezoelectric generator and studied to establish the relationship between size and in-focus characteristics. In a second experiment, it was demonstrated that droplet sizes and velocities from a real sprayer could be measured reliably in a non-intrusive way using the newly developed image acquisition set-up and image processing. Measured droplet sizes ranged from 24 μm to 543 μm, depending on the nozzle type and size. Droplet velocities ranged from around 0.5 m/s to 12 m/s. The droplet size and velocity results were compared and related well with the results obtained with a Phase Doppler Particle Analyzer (PDPA).

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spray Droplet Characterization from a Single Nozzle by High Speed Image Analysis Using an In-Focus Droplet Criterion

Minov

Cointault

Vangeyte³

et al. 2016

Sensors

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“…If the object Motion blur is not only a matter of image appearance. In case of metrological applications, such as falling droplet diameter measurement [9], the quality of the object edge is a key factor influencing measurement uncertainty. Even if the movement of the object is relatively slow (0.6 m/s) but the required precision is in the range of micrometers, the exposure ("freezing") time must be below 200 ns.…”

Section: Factors To Consider For Highspeed Imagingmentioning

confidence: 99%

Fast Mover

2015

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The realm of high-speed imaging traditionally provides some of the most visually appealing images for the non-specialist. From bullets passing through objects to the minute details of animal behaviour, the ability to freeze time opens the way to unique insights into the world around us, as well as providing a valuable tool for analysis and test in an industrial environment. Often associated with high costs and complex operation, new approaches to capturing critical high-speed events are being developed which can enable scientists and engineers to use high-speed imaging as a routine tool rather than a specialist discipline. By synchronizing high-power illumination pulses with tightly controlled image sensor exposures, while at the same time providing on-board image storage and in-situ processing, a simple and flexible highspeed imaging architecture is realized, capable of wide ranging application. High-speed imaging provides unique insights into processesFrom the seminal work of Eadweard Muybridge in the late nineteenth century analysing the gait of a galloping horse [1] to the latest advances in femto-photography [2], high-speed imaging has a rich history of providing new information about motions, events, and processes. In today's industrial and scientific environments, highspeed imaging is predominately used for scientific analysis or test and measurement applications, with vehicle collision studies [3] probably the most commonly recognized. Other significant applications include particle imaging velocimetry (PIV) [4] whereby images are taken of fluid flows and particle velocities extracted as a tool for aerodynamic engineering, human motion analysis [5], as well as failure mode dynamics and analysis [6], impact testing, and ballistics research [7]. More recently, there has been increasing interest from the biological and nanotechnology sectors [8] to adapt high-speed techniques and leverage the advantages that high-speed technology brings, such as the visualization of MEMS devices.In each case it is the insight that is obtained by viewing events happening on a timescale much faster than humans are capable of visualizing, which provides the ultimate value to the user. Factors to consider for highspeed imagingHigh-speed imaging relies on the ability to capture an optical image of a scene in a short period of time. Using shorter periods of time for scene capture, generally corresponds to an increased ability to "freeze" fast moving events. It is this ability to capture short moments in time which provides the useful diagnostic information used in applications. A typical approach to capturing an image in a short period of time is to simply decrease the exposure time of the camera. Typical image sensors used within machine vision cameras have minimum exposure times in the range 5-15 microseconds, whilst dedicated high-speed imaging systems can operate with exposure times lower than 200 ns. If the object odos imaging LimitedEdinburgh, Scotland odos imaging Limited is a technology focused company specialising in th...

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Influence of ink properties and voltage parameters on piezoelectric inkjet droplet formation

et al. 2021

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Droplet generation and characterization using a piezoelectric droplet generator and high speed imaging techniques

Cited by 17 publications

References 27 publications

Spray Droplet Characterization from a Single Nozzle by High Speed Image Analysis Using an In-Focus Droplet Criterion

Spray Droplet Characterization from a Single Nozzle by High Speed Image Analysis Using an In-Focus Droplet Criterion

Fast Mover

Influence of ink properties and voltage parameters on piezoelectric inkjet droplet formation

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