Influence of Airspeed and Adjuvants on Droplet Size Distribution in Aerial Applications of Glyphosate

2018 ◽  
Vol 34 (3) ◽  
pp. 507-513 ◽  
Author(s):  
Bruno C Vieira ◽  
Guilherme S Alves ◽  
Fernando K Carvalho ◽  
João Paulo AR Da Cunha ◽  
Ulisses R Antuniassi ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Size Distribution ◽  
Droplet Size ◽  
High Speed ◽  
Droplet Size Distribution ◽  
Laser Diffraction ◽  
Flight Speed ◽  
Central Research ◽  
Operating Pressure ◽  
Size Spectra

Abstract. Drift is one of the most hazardous consequences of an improper aerial application of glyphosate. Wind, droplet size, application height, and distance to sensitive areas are the most important factors for drift. Droplet size is affected by nozzle, operating pressure, flight speed, deflection angle, and physicochemical properties of the spray solution. The objective of this study was to evaluate the effect of flight speed and the use of adjuvants on droplet size spectra in aerial applications of glyphosate. The study was conducted in a high-speed wind tunnel at the Pesticide Application Technology Laboratory (University of Nebraska-Lincoln, West Central Research and Extension Center, North Platte, Neb.). Aerial applications were simulated with four different airspeeds (44.4, 52.8, 61.1, and 69.4 m/s) and glyphosate combined with adjuvants (high surfactant oil concentrate, microemulsion drift reduction agent, nonionic and acidifier surfactant, polyvinyl polymer, and glyphosate alone). Droplet size spectra were evaluated using a Sympatec Helos laser diffraction instrument measuring 90 cm from the nozzle tip (CP11-4015). The volumetric droplet size distribution parameters (VMD, DV0.1, and DV0.9) and the percentage of droplets smaller than 100 µm were reported. The relative span was calculated to indicate the droplet size homogeneity [(DV0.9 - DV0.1) / DV0.5]. Glyphosate solutions with adjuvants had a larger VMD than the glyphosate alone solution at 44.4 m/s wind speed. At 69.4 m/s only the glyphosate solution with polymer had a larger VMD. Conversely, the glyphosate with polymer had the smallest DV0.1, and the greatest relative span and percentage of droplets smaller than 100 µm. Generally, adjuvants influence on droplet size was diminished or muted as the airspeed was increased. The polymer tested in this study failed as a drift agent reduction agent, especially at higher airspeeds. While not all polymers were tested, cautions should be taken if using these types of adjuvants in aerial applications. The interaction of airspeed and adjuvants influencing droplet size distribution in aerial applications of glyphosate should be considered by applicators in order to mitigate glyphosate drift to the surrounding environment. Further studies are necessary to better understand the interaction between solution viscosity and air shear effect on the atomization process and droplet size distribution, as well as confirm that trends hold true for other adjuvants in the polymer class. Although applicators tend to operate aircrafts with increased flight speeds in order to optimize the application time efficiency, this practice can reduce or mute adjuvants effects, decrease the droplet size distribution, and increase drift potential in aerial applications of glyphosate. Keywords: Drift reduction technologies, Flight speed, High-speed wind tunnel, Laser diffraction.

MODELING DROPLET SIZE DISTRIBUTION NEAR A NOZZLE OUTLET IN AN ICING WIND TUNNEL

2006 ◽  
Vol 16 (6) ◽  
pp. 673-686 ◽  
Author(s):  
Laszlo E. Kollar ◽  
Masoud Farzaneh ◽  
Anatolij R. Karev
Keyword(s):  
Wind Tunnel ◽  
Size Distribution ◽  
Droplet Size ◽  
Droplet Size Distribution ◽  
Nozzle Outlet

scholarly journals Evaluating the capabilities and uncertainties of droplet measurements for the fog droplet spectrometer (FM-100)

2012 ◽  
Vol 5 (9) ◽  
pp. 2237-2260 ◽  
Author(s):  
J. K. Spiegel ◽  
P. Zieger ◽  
N. Bukowiecki ◽  
E. Hammer ◽  
E. Weingartner ◽  
...  
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Stochastic Approach ◽  
Mie Scattering ◽  
Size Distributions ◽  
Literature Study ◽  
Size Spectra ◽  
Wind Speeds

Abstract. Droplet size spectra measurements are crucial to obtain a quantitative microphysical description of clouds and fog. However, cloud droplet size measurements are subject to various uncertainties. This work focuses on the error analysis of two key measurement uncertainties arising during cloud droplet size measurements with a conventional droplet size spectrometer (FM-100): first, we addressed the precision with which droplets can be sized with the FM-100 on the basis of the Mie theory. We deduced error assumptions and proposed a new method on how to correct measured size distributions for these errors by redistributing the measured droplet size distribution using a stochastic approach. Second, based on a literature study, we summarized corrections for particle losses during sampling with the FM-100. We applied both corrections to cloud droplet size spectra measured at the high alpine site Jungfraujoch for a temperature range from 0 °C to 11 °C. We showed that Mie scattering led to spikes in the droplet size distributions using the default sizing procedure, while the new stochastic approach reproduced the ambient size distribution adequately. A detailed analysis of the FM-100 sampling efficiency revealed that particle losses were typically below 10% for droplet diameters up to 10 μm. For larger droplets, particle losses can increase up to 90% for the largest droplets of 50 μm at ambient wind speeds below 4.4 m s−1 and even to >90% for larger angles between the instrument orientation and the wind vector (sampling angle) at higher wind speeds. Comparisons of the FM-100 to other reference instruments revealed that the total liquid water content (LWC) measured by the FM-100 was more sensitive to particle losses than to re-sizing based on Mie scattering, while the total number concentration was only marginally influenced by particle losses. Consequently, for further LWC measurements with the FM-100 we strongly recommend to consider (1) the error arising due to Mie scattering, and (2) the particle losses, especially for larger droplets depending on the set-up and wind conditions.

Herbicide Formulation, Spray Nozzle Design, and Operating Pressure Affects the Droplet Size Spectra of Agricultural Sprays

2019 ◽  
pp. 1-7 ◽  
Author(s):  
Joshua A. McGinty ◽  
Gaylon D. Morgan ◽  
Peter A. Dotray ◽  
Paul A. Baumann
Keyword(s):  
Wind Tunnel ◽  
Droplet Size ◽  
The United States ◽  
Spray Drift ◽  
Operating Pressure ◽  
Spray Nozzle ◽  
Spray Droplet ◽  
Size Spectra ◽  
Drift Potential ◽  
Spray Droplets

Aims: Determine the droplet size spectra of agricultural sprays as affected by herbicide formulations, spray nozzle designs, and operating pressures. Place and Duration of Study: This study was conducted in April 2014 at the United States Department of Agriculture Agricultural Research Service Aerial Application Technology Research Unit Facility in College Station, Texas. Methodology: The spray droplet size spectra of six herbicide formulations as well as water alone and water with nonionic surfactant were evaluated in a low-speed wind tunnel. These spray solutions were conducted with five different flat-fan spray nozzle designs, producing a wide range of spray droplet sizes. The wind tunnel was equipped with a laser diffraction sensor to analyze spray droplet size. All combinations of spray solution and nozzle were operated at 207 and 414 kPa and replicated three times. Results: Many differences in droplet size spectra were detected among the spray solutions, nozzle designs, and pressures tested. Solutions of Liberty 280 SL exhibited the smallest median droplet size and the greatest proportion of spray volume contained in droplets 100 µm or less in size.  Solutions of Enlist Duo resulted in smaller median droplet size than many of the solutions tested, but also exhibited some of the smallest production of fine spray droplets. Median droplet size was found to vary greatly among nozzle designs, with the greatest droplet size and smallest drift-prone fine droplet production observed with air-inclusion designs utilizing a pre-orifice. Increasing the operating pressure from 207 to 414 kPa resulted in a decrease in median droplet size and an increase in the production of droplets 100 µm or less in size. Conclusion: Herbicide formulations and spray nozzle designs tested varied widely in droplet size spectra and thus the potential for spray drift. Increasing operating pressure resulted in decreased droplet size and an increase in the production of drift-prone droplets. Additionally, median droplet size alone should not be used to compare spray drift potential among spray solutions but should include relative span and V100 values to better predict the potential for spray drift due to drift-prone spray droplets.

scholarly journals Evaluating the capabilities and uncertainties of droplet measurements for the fog droplet spectrometer (FM-100)

2012 ◽  
Vol 5 (3) ◽  
pp. 3333-3393 ◽  
Author(s):  
J. K. Spiegel ◽  
P. Zieger ◽  
N. Bukowiecki ◽  
E. Hammer ◽  
E. Weingartner ◽  
...  
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Stochastic Approach ◽  
Liquid Water Content ◽  
Mie Scattering ◽  
Size Distributions ◽  
Literature Study ◽  
Size Spectra

Abstract. Droplet size spectra measurements are crucial to obtain a quantitative microphysical description of clouds and fog. However, cloud droplet size measurements are subject to various uncertainties. This work focuses on the evaluation of two key measurement uncertainties arising during cloud droplet size measurements with a conventional droplet size spectrometer (FM-100): first, we addressed the precision with which droplets can be sized with the FM-100 on the basis of Mie theory. We deduced error assumptions and proposed how to correct measured size distributions for these errors by redistributing the measured droplet size distribution using a stochastic approach. Second, based on a literature study, we derived corrections for particle losses during sampling with the FM-100. We applied both corrections to cloud droplet size spectra measured at the high alpine site Jungfraujoch for a temperature range from 0 °C to 11 °C. We show that Mie scattering led to spikes in the droplet size distributions using the default sizing procedure, while the stochastic approach reproduced the ambient size distribution adequately. A detailed analysis of the FM-100 sampling efficiency revealed that particle losses were typically below 10% for droplet diameters up to 10 μm. For larger droplets, particle losses can increase up to 90% for the largest droplets of 50 μm at ambient windspeeds below 4.4 m s−1 and even to >90% for larger angles between the instrument orientation and the wind vector (sampling angle) at higher wind speeds. Comparisons of the FM-100 to other reference instruments revealed that the total liquid water content (LWC) measured by the FM-100 was more sensitive to particle losses than to re-sizing based on Mie scattering, while the total number concentration was only marginally influenced by particle losses. As a consequence, for further LWC measurements with the FM-100 we strongly recommend to consider (1) the error arising due to Mie scattering, and (2) the particle losses, especially for larger droplets depending on the set-up and wind conditions.

Study on atomization particle size characteristics of two-phase flow nozzle

2021 ◽  
pp. 1-12
Author(s):  
Haoqi Lilan ◽  
Junbin Qian ◽  
Nan Pan
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Droplet Size ◽  
High Speed ◽  
Droplet Size Distribution ◽  
Average Diameter ◽  
Spray Atomization ◽  
Two Phase ◽  
Nozzle Pressure ◽  
Local Observation

Nozzle spray atomization is widely used in industrial and agricultural production processes and is a very complicated physical change. The spray atomization of the nozzle is a process in which the droplets are continuously broken into finer particles under the action of force, in order to study the effect of nozzle atomization, that is, droplet size distribution characteristics. The experimental average mathematical model of droplet size distribution was established by introducing the average diameter of Sutter (SMD). The droplet size distribution in the atomization field of the nozzle is studied by simulation. In the experimental study, the high-speed camera, external mixing air atomizing nozzle platform experimental device and image processing were used, and the atomization field was divided into multiple observation areas. Through the measurement of several local observation areas, the droplet size distribution of the whole atomization field is constructed. It provides a reference for the study of the atomization field of the nozzle and a basis for the intuitive understanding of the droplet size distribution in the atomization field of the nozzle. The effective atomization area of the nozzle atomization was selected to study the influence of the liquid flow rate, the liquid temperature and the nozzle pressure on the atomized particle size distribution of the externally mixed atomizing nozzle. The internal law is obtained, which provides a basis and reference for effectively controlling the atomization effect in the atomization field.

scholarly journals Evaluation of Aerial Spray Technologies for Adult Mosquito Control Applications

2013 ◽  
Vol 53 (3) ◽  
pp. 222-229 ◽  
Author(s):  
Wesley Clint Hoffmann ◽  
Bradley Keith Fritz ◽  
Muhammad Farooq ◽  
Todd William Walker ◽  
Zbigniew Czaczyk ◽  
...  
Keyword(s):  
High Pressure ◽  
Wind Tunnel ◽  
Vector Control ◽  
Droplet Size ◽  
High Speed ◽  
Laser Diffraction ◽  
Operating Conditions ◽  
Adult Mosquito ◽  
Size Spectrum ◽  
Spray Droplet

Abstract Spray droplet size has long been recognized as an important variable that applicators of vector control sprays must be aware of to make the most effective spray applications. Researchers and applicators have several different techniques available to assess spray droplet size from spray nozzles. The objective of this study was to compare the droplet size spectrum produced by three nozzles commonly used in vector control in a high-speed wind tunnel, when characterized using three different laser-based droplet size measurement systems. Three droplet sizing systems: Malvern Spraytec laser diffraction, Sympatec HELOS laser diffraction, and TSI Phase Doppler Particle Analyzer (PDPA), were simultaneously operated, but under different operating conditions, to measure the spray droplet size-spectra for three spray nozzles. The three atomizers: a TeeJet® 8001E even flat fan nozzle, a BETE® PJ high pressure fog nozzles, and a Micronair ® AU5000 rotary atomizer were evaluated in a high speed wind tunnel at airspeeds of 53 and 62 m/s (120 and 140 mph). Based on the results of this work, only the BETE® PJ high pressure fog nozzles met the label requirements for both Fyfanon® and Anvil®. While the other nozzle might met the Dv0.5 (VMD - volume median diameter) requirement for Fyfanon®, the resulting Dv0.9 values exceeded labeled size restrictions. When applying Anvil with the BETE PJ high pressure fog nozzles, it is important to use the smaller two orifice sizes. The larger sizes tended to result in Dv0.9 values that exceeded label recommendations

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