• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.258-264
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• 2017

Purpose: This study determines the spray characteristics and effective spray width of a tractor-mounted commercial boom sprayer through experiments. Methods: Performance tests were conducted to investigate the spray characteristics of the nozzles on a commercial boom sprayer. The flow rate and spray width of a single nozzle were measured at three levels of spray pressure (0.5, 0.7, and 1.0 MPa) and spray height (15, 30, and 45 cm), respectively. The average value of three repetition tests was used as the representative value. A coefficient of variation (CV) was used as an index of spray uniformity, and the width that guarantees CV values of approximately 15% was determined as the effective spray width. The spray characteristics of the overall boom sprayer were derived analytically by superimposing the spray characteristics of a single nozzle. Results: The test results for a single nozzle showed that the spray width tended to increase as the spray height and spray pressure increased. The effective spray width for a single nozzle was the largest at a spray pressure of 1.0 MPa and spray height of 45 cm, which resulted in a coverage of 84 cm of width. The effective spray width for the entire boom sprayer was also the largest at the spray pressure of 1.0 MPa and spray height of 45 cm, with a magnitude of 424.5 cm. The chemical spraying work in an actual field was simulated by applying a spray width of 400 cm. As a result of the operation for three swaths, the CV value was less than 10% for 1,200 cm of the overall spray width, which meant that uniform application was achieved. Conclusions: It was reasonable to set the effective spray width of the boom sprayer used in this study to 400 cm.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.251-262
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• 1995

The goal of this study is to provide fundamental information on the design of a new diesel injector system. The cylindrical disk spray was made by an impinging disk insited below the exit of air-assist atomizor. The disintegration processes on a twin-fluid atomization by air-assist atomizor were investigated. Liquid jet was disintegrated at the condition that wavelength was equal and longer than the circumference of the liquid jet, .lambda. .geq. .pi.do. However, the wavelength and the diameter of the liquid jet were decreased according to the increasing of air velocity. The relative density distribution of droplets and pattern of spray by impinging disk were investigated with a C-CCD. Optimum design conditions for cylindrical disk spray were also achieved. The pattern of cylindrical spray can classified according to the size of the disk and the distance from the nozzle tip to the disk. When the space of the disk and the nozzle tip was narrow and the diameter of the disk was larger than that of the air orifice of the nozzle exit, the good distribution of spray could be achieved. When the air flowrate was constant, the spray width was decreased according to the increasing of the liquid flowrate. When the liquid flowrate was constant, the spray width was decreased according to the increasing of the air flowrate.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.182-190
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• 1998

Behaviour of ultra-high pressure diesel spray in a constant-volume pressure chamber was studied with injection pressure ranging from 20 to 160㎫. Sprays were observed by the right angle scattering method. As a result, the spray tip penetration is first proportional to a time, and after that, it is proportional to 0.52 of the time during at the time of injection pressure and back pressure increase. An empirical correlation was made for the parameters of injection pressure, air-fuel density ratio, spray tip distance, spray angle, jet angle of spray and max. spray width.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.10
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• pp.8-19
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• 2019

In this study, the spray pattern of a centrifugal fertilizer distributor with two shutter holes was analyzed and an effective driving width that satisfies proper spray uniformity was derived. The centrifugal fertilizer distributor was mounted on a tractor with a rated power of 23.7 kW and static and dynamic spray pattern tests were performed according to the standard procedure proposed by the American Society of Agricultural and Biological Engineers Standard ASAE S341.5. The height of the fertilizer distributor was 80 cm from the ground and the PTO (power take-off) shaft speed of the tractor was fixed at 540 rpm. The fertilizer scattered in space was collected using 275 evenly spaced collectors at shutter opening ratios of 25%, 50%, 75%, and 100%. The spray pattern was analyzed via the amount of sprayed fertilizer at each collector location and the coefficient of variation was used as an indicator of spray uniformity. Using the analyzed spray pattern, the effective driving width that satisfied less than 15% of the coefficient of variation was derived for different tractor driving patterns (race track mode, back and forth mode). From the results, spray uniformity increased as the shutter opening ratio decreased. The largest effective driving width was 8 m at a shutter opening ratio of 25% for both driving patterns.

• Journal of ILASS-Korea
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• v.14 no.2
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• pp.71-76
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• 2009

The aim of this investigation is to study the effect of the high injection pressure on the dimethyl ether (DME) spray characteristics injected through a common-rail diesel injector under various ambient pressures. In order to investigate the effect of the injection pressure and ambient condition, the common-rail injection system with two high pressure pumps and high pressure chamber pressurized up to 40 bar were used, respectively. Spray images of DME fuel obtained from a visualization system composed of high speed camera and two metal halide lamps as the light source. From the obtained images, the spray behaviors such as a spray development process, spray tip penetration, spray width, and spray cone angle were measured for analyzing the DME spray characteristics under various experimental conditions. It was found that the spray development slowed as the ambient pressure increased and spray tip penetration at injection pressure of 90 MPa is longer than that at 50 MPa. In addition, the spray width at the end stage of injection decreased under the atmospheric conditions due to the evaporation property of DME fuel, and DME spray shows narrow spray cone angle according to the injection pressure increased.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.145-153
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• 2020

The purpose of this study is to compare the injection and spray characteristics of single-hole GDI injectors using injection rate and mie-scattering spray images. Five types of single-hole injectors with different nozzle hole diameters were used, and the spray rate, spray tip penetration, spray area, and spray width were analyzed. As a result, the diameter of the nozzle hole had a direct effect on the injection and spray characteristics. It was confirmed that the larger the diameter of the nozzle hole, the higher the injection quantity, the spray tip penetration, the spray area, and the spray width. In addition, it was confirmed that the near-field spray, which has little influence of ambient air, has a great correlation with the injection rate.

• International Journal of Automotive Technology
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• v.6 no.2
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• pp.87-93
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• 2005

Spray patterns were visualized using the shadowgraph method, and the droplet size and velocity were measured using PDPA for high-pressure injections up to 2,600 bars. The spray pattern and spray characteristics, such as penetration, spray width, spray angle, droplet size, injection duration, and droplet velocity, were investigated to determine the suitable injection pressure. Spray penetration, width, angle, and velocity increased continuously up to 2,600 bars with the injection pressure in a high-pressure region. The rate of improvement of the above spray characteristics, however, declined rapidly, when the injection pressure reached 2,000 bars. The injection duration and droplet size generally decreased with the increase in the injection pressure, while the rate of improvement decreased abruptly after 2,000 bars. Consequently, the improvement rate of the spray characteristics became blunt at over 2,000 bars. This means that the suitable injection pressure is around 2,000 bars.

• Journal of ILASS-Korea
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• v.28 no.1
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• pp.32-42
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• 2023

In this study, spray characteristics of n-heptane and propane were investigated under different injection pressure using various imaging techniques such as Mie-scattering, DBI (diffuse back-illumination), and Schlieren imaging techniques. NI compact RIO system was used to control a test injector. Spray penetration length, length-to-width ratio and number of black pixels were calculated by using MATLAB software to compare spray characteristics of each fuel. Longer spray penetration length and higher length-to-width ratio were observed in propane spray because of flash boiling caused by high saturated vapor pressure. Spray collapse occurred in propane spray due to the high plume-to-plume interaction. Moreover, rapid evaporation occurred in propane spray, so that nozzle tip wetting could not be observed. Rapid evaporation of propane also caused fewer residual droplets compared to n-heptane spray. Therefore, propane is advantageous in reducing the generation of soot emission from large droplets that are not atomized. However, additional evaluation should be conducted considering combustion efficiency and the possibility of deposits by nozzle tip icing during fuel injection.

• Journal of ILASS-Korea
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• v.26 no.4
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• pp.189-196
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• 2021

Spray drift of agricultural nozzles has become a big issue because it causes low precision targeting and environmental pollution. In order to reduce the spray drift, study spray characteristics of agricultural nozzles is virtually important. In this study, shadowgraph and Mie-scattering visualization techniques were used to study the macroscopic spray and atomization characteristics of an agricultural nozzle. PDPA was used to measure the atomization characteristics of spray. The injection pressure is set to 1 bar, 3 bar and 5 bar, which covers the working range of the nozzle. For the PDPA experiment, 75 points were measured in an area of 160 mm × 120 mm at 10 mm intervals directly below the nozzle to grasp the overall atomization characteristics of the spray. It was found that the spray width and sheet width showed a linear correlation. As the injection pressure increased, the sheet expansion in the 0-degree direction and the sheet swing in the 90-degree direction jointly promoted the breakup of the sheet. In addition, the area close to the central axis had a large droplet velocity, and since a large droplet velocity promoted atomization of spray, the area close to the central axis had a smaller spray droplet diameter than the left and right regions.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.5
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• pp.818-826
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• 2004

The spray-induced mixing characteristics and thermal decomposition of aqueous urea solution into ammonia have been studied to design optimum sizes and geometries of the mixing chamber in SCR(Selective Catalytic Reduction) system. The cold flow tests about the urea-injection nozzle were performed to clarify the parameters of spray mixing characteristics such as mean diameter and velocity of drops and spray width determined from the interactions between incoming air and injected drops. Discrete particle model in Fluent code was adopted to simulate spray-induced mixing process and the experimental results on the spray characteristics were used as input data of numerical calculations. The simulation results on the spray-induced mixing were verified by comparing the spray width extracted from the digital images with the simulated Particle tracks of injected drops. The single kinetic model was adopted to predict thermal decomposition of urea solution into ammonia and solved simultaneously along with the verified spray model. The hot air generator was designed to match the flow rate and temperature of the exhaust gas of the real engines The measured ammonia productions in the hot air generator were compared with the numerical predictions and the comparison results showed good agreements. Finally, we concluded that the design capabilities for sizing optimum mixing chamber were established.