Droplet Volume Median Diameter Research Articles

Atomization of High Viscous Liquids Using a MEMS Vibrating Mesh With Integrated Microheater

Aerosol generation is important for a wide range of applications including drug delivery, additive manufacturing, spray cooling, and numerous other applications. However, current aerosol generation devices often have poor droplet uniformity or are limited to low viscosity liquids ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 2 cp). This work presents the development of a Microelectromechanical systems vibrating mesh atomizer capable of atomizing higher viscosity fluids while maintaining high droplet size uniformity. The overall system consists of microfabricated silicon vibrating mesh atomizer, a piezoelectric film, and a flexible thin film microheater. The Si vibrating mesh atomizer was designed to increase atomization thresholds, while the microheater is designed to reduce liquid viscosity to meet the atomization threshold. Atomizers with varying nozzle dimensions were experimentally validated using liquids with varying viscosity and physiochemical properties, such as water, glycerol, propylene glycol, and vegetable glycerin. The microheater was designed to provide local rapid heating with low power consumption of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 1 W. The droplet size distribution results show that when fluid viscosity increases, the volume median diameter of droplets increases, and the spray angle decreases. The Si-vibrating mesh atomizer was able to atomize liquids up to 49.73 cP at room temperature compared to normal metallic vibrating mesh atomizers which have a threshold of approximately 2 cP. The integrated heater enabled atomization of liquids with viscosities as high as 111 cP with low heating ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> C). 2023-0042

"H" sprayer effect on liquid deposition on cucumber leaves and powdery mildew prevention in the shed.

To clarify the effect of droplet size on solution deposition and powdery mildew control on greenhouse cucumber leaves, the effect of volume median droplet diameter (VMD) on solution deposition and maximum retention, as well as the effect of flusilazole on powdery mildew control on cucumber, was determined using the stem and leaf spray method. The VMD of the typical fan nozzles (F110-01, F110-015, F110-02, F110-03) of the selected US Tee jet production differs by approximately 90 μm. The results showed that the deposition of flusilazole solution on cucumber leaves decreased as the VMD of the droplets increased and that the deposition of the solution in the treatments with VMD of 120, 172, and 210 μm decreased by 22.02%, 10.37%, and 46. 97%, respectively, compared to that observed with treatment with 151 μm VMD. The deposition of the solution on cucumber leaves showed the highest deposition efficiency of 63.3% when the applied solution volume was 320 L/hm2, and the maximum stable retention of the liquid on the leaves was 6.6 µl/cm2. The control effects of different concentrations of flusilazole solution on cucumber powdery mildew differed significantly, and the best control effect was achieved at the dosage of 90 g/hm2 of the active ingredient, which was 15%-25% higher than that observed at the dosage of 50 and 70 g/hm2 of the active ingredient per hectare. A significant difference in the effect of droplet size on the control of cucumber powdery mildew was observed at any specific liquid concentration. Nozzle F110-01 showed the best control effect when the dosage of the active ingredient was 50 and 70 g/hm2 per hectare, which did not differ significantly from that observed with nozzle F110-015 but differed significantly from those observed with nozzles F110-02 and F110-03. Hence, we concluded that the use of smaller droplets with VMD of 100-150 μm, i.e. the choice of F110-01 or F110-015 nozzles, for application on the leaf parts of cucumber in the greenhouse under conditions of high liquid concentration, can significantly improve the effective use of pharmaceuticals and the disease control effect.

Compatibility and aerosol characteristics of beclomethasone mixed with N-acetylcysteine

Mixing different kind inhalation medications for simultaneous inhalation is widely used in the treatment of chronic respiratory diseases, and it can minimize the administration time and improve patient adherence. To our knowledge, it is unclear whether beclomethasone (BDP, Clenil®) can bemixed with acetylcysteine (NAC, Fluimucil®), because the in vitro physico-chemical compatibility and aerosol characteristics of the mixture are unknown. In this study, we investigated physical compatibility, including the appearance, pH, osmotic pressure and chemical stability, as well as aerosol characteristics, including particle size corresponding to 10%/50%/90% of the cumulative percentage of total particle volume (X10/X50/X90), volume median droplet diameter (VMD), mass median aerodynamic diameter (MMAD), fine particle fraction (FPF), fine particle dose (FPD) and geometric standard deviation (GSD), delivery rate, and total delivery of the above solutions. After mixing, there were no significant changes in visual appearance, pH, osmolality and drug content of the mixtures at room temperature for 12 h. The FDP of BDP in the mixture decreased by 16.49%, whereas the NAC increased by 10.85%. The delivery rates of BDP and NAC in the mixture decreased by 66.05% and 45.54%, and total delivery increased by 13.20% and 25.29%, respectively. However, the MMAD, FPF, particle size and GSD of the mixture were almost unchanged. We demonstrated that these admixtures are physico-chemically compatible but that coadministration of beclomethasone with acetylcysteine can markedly affect output and aerosol characteristics.

Optimization-Design and Atomization-Performance Study of Aerial Dual-Atomization Centrifugal Atomizer

The aerial atomizer is the most essential component of the plant protection UAV (unmanned aerial vehicle). However, the structural optimization of existing aerial atomizers lacks comprehensive consideration of spray parameters and structural parameters, and there is a shortage of available atomizer spray models, resulting in the unstable effect of UAV application. In our previous work, an aerial dual-atomization centrifugal atomizer was developed. In order to obtain an aerial atomizer with good atomization effect and its atomization model, structural optimization at different rotation speeds and flow rates of the atomizer, and its atomization performance, are studied in this paper. Firstly, with the droplet volume median diameter (VMD) and spectral width (SRW) as the evaluation index, through the single-factor, Plackett–Burman and Box–Behnken tests, the influence of rotation speed, flow rate, tooth number and tooth shape were studied. The regression models of the droplet VMD and SRW were established using multiple quadratic regression fitting of the test data. Secondly, in order to achieve the lowest droplet VMD and SRW, the response surface method and post-hoc multiple comparison method were used to obtain the optimized structure of the atomizer’s rotation ring at different rotation speeds (600–7000 r/min) and flow rates (500–1000 mL/min). Lastly, with the effective swath width (ESW) of the optimized atomizer as the evaluation index, through the Box–Behnken test, the influence of rotation speed, flow rate and spray height were studied. The multiple quadratic regression model of ESW was established with the test data. The test results indicated that rotation speed, flow rate and tooth number had a significant effect on droplet VMD and SRW; tooth shape had no significant effect on the droplet VMD and SRW, however, the square tooth shape had the best atomization effect; and rotation speed, flow rate and spray height had a significant effect on ESW. The optimized structural parameters were tooth shape: square, and tooth number: 20. The determination coefficient R2 of the regression model of VMD, SRW and ESW were 0.9976, 0.9770 and 0.9974, respectively, which indicates that the model was accurate, and can evaluate and predict the spray effect. This paper provides an optimized dual-atomization centrifugal atomizer, and its regression models of VMD, SRW and ESW for UAV applications can provide a reference for efficient UAV spraying.

Understanding Spray Attributes of Commercial UAAS as Impacted by Operational and Design Parameters

Unmanned aerial application systems (UAAS) have recently gained momentum for the application of crop protection (CP) products. Due to their high operational efficiency, mobility, and low cost, UAAS may be perceived as a more viable option for spray application when compared to conventional application techniques, especially backpack/knapsack sprayers. However, being a relatively new technology and not a common practice in the USA, there are no best management practices or guidelines for testing UAAS spray performance. Therefore, this study was undertaken to assess the impact of different attributes pertinent to UAAS flight (e.g., altitude, speed, etc.), application (e.g., droplet size, tank additive, etc.), and UAAS design (e.g., nozzle placement relative to a the rotor) on spray performance. The spray performance was evaluated in terms of swath and spray drift (ground and airborne) using water-sensitive papers (WSP) and mylar card/string samplers, respectively. The samplers were respectively analyzed using image processing and fluorometry techniques. The different treatments under study were UAAS type (MG-1P and AG V6A+), flight altitude (1.5, 2.5, and 4.0 m) and speed (2 and 3 ms−1), and nozzle type (XR11001 and XR8002 flat fan nozzles) with different droplet volume median diameter (VMD) at ~207 kPa (very fine [140 µm] and fine [196 µm], respectively). The results indicated a highly variable swath for both platform types. While nozzles under each rotor may be a common design in commercial UAAS, the results indicated that placement of nozzles out on a boom might have a less variable swath and a lower drift potential. In addition, flying slower, using a relatively larger droplet VMD (i.e., 196 µm at ~207 kPa) may reduce both ground and airborne drift. This study may serve as a guideline for growers/operators to evaluate their UAAS platforms and optimize key attributes pertinent to UAAS operation for effective spraying.

Evaluation of Spray Droplets Characteristics Depending on the Configuration of Boomless Nozzle

Using hollow cone nozzles is a common in different spraying processes for controlling the pests. The aim of the study was to evaluate the spray droplet characteristics deposited on the eggplant plants at flowering vegetative growth stage. The study was performed in a Complete Block Random Design (CBRD) with a 3x4 factorial scheme, consisting of three working pressures 2, 3, and 5 bar, and four spray patterns of nozzles with three blocks. For obtaining micro details about spray droplets characteristics, white paper cards were used, which later had their images digitized and analyzed by the ImageJ software. The following values were measured in this study: volume median droplet diameter, spray coverage percentage, and droplet density per centimeter square. Then, the values found were subjected to analysis to show the significance between them. These values were compared by t test at 5% probability level. For each factor, separately, the coefficients of variation were analyzed and then the correlation between these factors was performed. The main results showed that the spray droplet characteristics were affected by both of operating pressure and spray pattern configuration. Higher operating pressure of 5bar produced the smallest median diameter and greatest number of droplets, and spray coverage percentage. Results also showed that the using of a combination spray pattern led to an increase in droplet density thereby coverage percentage into plant canopy in comparison to other pattern configurations.

Numerical analysis of a water mist spray: The importance of various numerical and physical parameters, including the drag force

This paper presents a comprehensive set of numerical simulations for the characterization of a water mist spray emerging from a nozzle positioned at 2.2 m from floor level and operating at a pressure of 1.0 MPa. The droplet volume-median diameter is about 90 μm and the spray half-angle is around 42°. The spray shape is visualized using a laser sheet and the water flux density distribution on the ground is measured with a ‘bucket’ test. An initial comprehensive numerical study using the Fire Dynamics Simulator (FDS) has been carried out by varying several numerical and physical models and parameters (e.g., cell size and turbulence modelling). The simulated sprays were very narrow (in comparison to the actual spray), yielding overestimations of the peak water flux density at floor level by about 430% (on average). Subsequently, it was found that there is a significant impact of the drag force modelling because the spray at hand is dense (near the nozzle). An ad-hoc reduction of the drag coefficient to a constant value leads to better results. The current study calls upon new developments for droplet aerodynamic modelling in dense sprays.

Motion model for describing the quantity of air in droplets through changing the structure of air induction nozzle

Air induction nozzles possess good anti-drift performance, the throat and orifice sizes of the nozzles are main design parameters that affecting atomization. Therefore, Venturi tube nozzles and conventional flat fan nozzles were assembled together to investigate the flow rate, droplet size, the quantity of air in droplets affected by single design parameter of nozzles with applying high speed camera and Spraytec laser diffraction system. The results showed that: the flow rate of the air induction nozzle depended only on the throat size of Venturi tube and pressure, and it was proportional to the throat size of Venturi tube at the same pressure; The flat fan nozzle’s orifice size and Venturi tube size significantly affected volume median diameter of droplets, which generally increased after adding surfactant; A new model was established after optimizing classical equation for calculating the percentage of intake air in droplets and studying the effects of throat and orifice size of air induction nozzles on spray characteristics. By variance analysis, it was verified that the new model of quantity of air in droplets produced by all connected nozzles was correct. The calculation showed that the bubbles sizes ranged at 200-900 μm and were in proportion to the droplet size with the percentage of intake air of 10% to 90%. Contrast to the change of volume median diameter and droplet velocity, existence of intake air could influence their change degree to some extent. Keywords: throat orifice, spray characteristic, model of droplet motion, air induction nozzle DOI: 10.25165/j.ijabe.20211405.5513 Citation: Hu J, Liu C X, Wang Z C, Li Y F, Song J L, Liu Y J, et al. Motion model for describing the quantity of air in droplets through changing the structure of air induction nozzle. Int J Agric & Biol Eng, 2021; 14(5): 35–40.

Comparative Field Evaluation of Auto-Rotate Gun Sprayer for Control of Bemisia tabaci in a Cotton Crop

Field evaluation of an auto-rotate gun sprayer and comparison with a knapsack sprayer was carried out to control whitefly Bemisia tabaci (Genn.) in the cotton crop. Two experiments were conducted at six locations of farmers' fields in southwestern (cotton-growing region) of Punjab state. The number of adult whiteflies was counted before and 3, 7 and 10 days after spray. Water-sensitive papers were attached at upper and under side of the leaves at three different points (top, middle and bottom) of plant canopy to find sprayers performance parameters, viz. droplet diameter, droplet density, per cent area covered and volume of spray deposition. Droplet density, area covered and volume of spray deposition were found significantly higher in case of the auto-rotate gun sprayer as compared to that of a knapsack sprayer. However, the volume median diameter of droplets was found significantly lesser in case of an auto-rotate gun sprayer, i.e. 286.95 µm as compared to the knapsack sprayer, i.e. 347.85 µm. The per cent whitefly control in the cotton crop in first experiment was found as 68.06 % and 65.90 % for auto-rotate gun and knapsack sprayer, respectively, by using pyriproxyfen 100 g active ingredient (g a.i.)/ha. Although in the second experiment the per cent whitefly control for auto-rotate gun sprayer was significantly higher, i.e. 83.27 % as compared to knapsack sprayer having 70.87 % control by using flonicamid 75 g a.i./ha. However, the bio-efficacy of auto-rotate gun sprayer was found higher for the both experiments as compared to the knapsack sprayer. The cost of operation of the auto-rotate gun sprayer was found to be US$4.11/ha as compared to knapsack sprayer with $6.85/ha. The cost, labour and time-saving in the spraying with the auto-rotate gun sprayer as compared to the knapsack sprayer was found to be 39.98, 93.44 and 96.64 %, respectively.

Potential of Outdoor Ultra-Low-Volume Aerosol and Thermal Fog to Suppress the Dengue Vector, Aedes aegypti, Inside Dwellings.

A field study investigated penetration of outdoor ground ultra-low-volume (ULV) aerosol and thermal fog adulticide applications into a dwelling to control the dengue vector Aedes aegypti (L). Four applications of Kontrol 4-4 (4.6% permethrin active ingredient [AI], 4.6% piperonyl butoxide) at the maximum label rate were made at 25-30 m in front of a house at Camp Blanding Joint Training Center, Starke, FL, during summer 2016. The ULV sprayer and thermal fogger nozzles were oriented horizontally, and vehicle travel speeds were 16 and 24 km/h, respectively. All doors and windows of the house were left open. Spray efficacy was assessed using caged female mosquitoes positioned 30 cm above ground, outside and inside of the house. Interior cages were placed in open areas and cryptic sites (i.e., in a closet or cardboard box). A spinner holding 2 rods sized 3 mm × 75 mm was deployed next to each cage (except cryptic sites) to sample droplets and to quantify AI deposition. Thirty minutes after application, cages were removed, slides collected, and mosquitoes transferred to clean cages in the laboratory where mortality was assessed at 24 h posttreatment. The ULV application to the south side of the house produced 100% mortality in outdoor and indoor cages and 24% mortality at cryptic sites. Similarly applied thermal fog resulted in 85% mortality outdoors, 34% indoors, and only 4% in cages at cryptic sites. Application of either method from the west resulted in 19-61% mortality outdoors and 0.5-6.5% indoors. Droplet volume median diameter (Dv0.5) on rods from the ULV application was significantly larger compared with the thermal fogger outdoors, but similar indoors. Outdoors and indoors, the AI deposition from ULV was significantly higher than from thermal fog. Our results show the potential for controlling dengue vectors inside houses with outdoor ground ULV applications in areas where doors and windows are left open for ventilation.

The Ceiling Height Limits for Water Mist Protection of Two Solid Combustible Fire Hazards in Open Environment

CEN and NFPA have expanded the application of water mist in open environments from light solid combustible fire hazards to several in the higher hazard categories. A previous analysis and test evaluation showed that such application expansion is feasible, provided that the water mist spray meets droplet size and application density requirements for the intended fire challenge. However, this evaluation was performed exclusively for water mist sprays discharging at 1.65 m above the burning combustibles. This led to the question of whether the water mist protection could still be effective for larger clearances of nozzle discharge above the combustibles. Therefore, a series of fire tests was conducted subsequently to determine the ceiling height limits for both deluge and automatic nozzle protections. As for the previous evaluation, the two tested fire challenges were a 2-tier (2.74 m) high rack-storage of corrugated cardboard cartons on wood pallets, and a palletized storage of cartoned expanded polystyrene up to 1.68 m high. Both fire challenges were in the CEN OH-3 category, and respectively represented fire hazards in the FM Global HC-2 and HC-3 categories, which in turn corresponded to the NFPA OH-1 and OH-2 fire hazards. Each water mist spray discharged 76 l/min at 16.5 bar, with a volume median droplet diameter of around 220 µm. The nozzles were spaced 3.05 × 3.05 m to provide a designated application density of 8.1 mm/min. Quick-response thermal sensors, with an activation temperature of 74°C and a response index of 27.6 (m s)1/2, were employed to initiate the nozzle discharge. The tests showed that the deluge protection is applicable to both fire challenges for ceiling heights up to 9.1 m. However, for the automatic nozzle protection, the ceiling height limit is reduced to 6.1 m, with a water supply requirement of providing 17 nozzle operations for a safety factor of about 50% over the maximum number of nozzle operations observed in the tests.

Experimental study of an anti-icing method over an airfoil based on pulsed dielectric barrier discharge plasma

Aircraft icing has long been a plague to aviation for its serious threat to flight safety. Even though lots of methods for anti-icing have been in use or studied for quite a long time, new methods are still in great demand for both civil and military aircraft. The current study in this paper uses widely used Dielectric Barrier Discharge (DBD) plasma actuation to anti-ice on a NACA0012 airfoil model with a chord length of 53.5 cm in a closed-circuit icing wind tunnel. An actuator was installed at the leading edge of the airfoil model, and actuated by a pulsed low-temperature plasma power source. The actuator has two types of layout, a striped electrode layout and a meshy electrode layout. The ice accretion process or anti-icing process was recorded by a CCD camera and an infrared camera. Instantaneous pictures and infrared contours show that both types of DBD plasma actuators have the ability for anti-ice under a freestream velocity of 90 m/s, a static temperature of −7 °C, an Median Volume droplet Diameter (MVD) of 20 μm, and an Liquid Water Content (LWC) of 0.5 g/m3. The detected variations of temperatures with time at specific locations reveal that the temperatures oscillate for some time after spraying at first, and then tend to be nearly constant values. This shows that the key point of the anti-icing mechanism with DBD plasma actuation is to achieve a thermal equilibrium on the model surface. Besides, the power consumption in the anti-icing process was estimated in this paper by Lissajous figures measured by an oscilloscope, and it is lower than those of existing anti-icing methods. The experimental results presented in this paper indicate that the DBD plasma anti-icing method is a promising technique in the future.

Oil Droplet Size Distributions in Deep-Sea Blowouts: Influence of Pressure and Dissolved Gases.

To date, experimental investigations to determine the droplet size distribution (DSD) of subsea oil spills were mostly conducted at surface conditions, i.e. at atmospheric pressure, and with dead, i.e. purely liquid, oils. To investigate the influence of high hydrostatic pressure and of gases dissolved in the oil on the DSD, experiments with a downscaled blowout are conducted in a high-pressure autoclave at 150 bar hydrostatic pressure. Jets of "live", i.e. methane-saturated, crude oil and n-decane are compared to jets of "dead" hydrocarbon liquids in artificial seawater. Experiments show that methane dissolved in the liquid oil increases the volume median droplet diameter significantly by up to 97%. These results are not in good accordance with state-of-the-art drop formation models, which are based on oil-only experiments at atmospheric pressure, and therefore show the need for a modification of such models which incorporates effects of hydrostatic pressure and dissolved gases for the modeling of deep-sea oil spills and blowouts.

Intercomparison of oil spill prediction models for accidental blowout scenarios with and without subsea chemical dispersant injection

We compare oil spill model predictions for a prototype subsea blowout with and without subsea injection of chemical dispersants in deep and shallow water, for high and low gas–oil ratio, and in weak to strong crossflows. Model results are compared for initial oil droplet size distribution, the nearfield plume, and the farfield Lagrangian particle tracking stage of hydrocarbon transport. For the conditions tested (a blowout with oil flow rate of 20,000 bbl/d, about 1/3 of the Deepwater Horizon), the models predict the volume median droplet diameter at the source to range from 0.3 to 6mm without dispersant and 0.01 to 0.8mm with dispersant. This reduced droplet size owing to reduced interfacial tension results in a one to two order of magnitude increase in the downstream displacement of the initial oil surfacing zone and may lead to a significant fraction of the spilled oil not reaching the sea surface.

Evolution of droplets in subsea oil and gas blowouts: Development and validation of the numerical model VDROP-J

The droplet size distribution of dispersed phase (oil and/or gas) in submerged buoyant jets was addressed in this work using a numerical model, VDROP-J. A brief literature review on jets and plumes allows the development of average equations for the change of jet velocity, dilution, and mixing energy as function of distance from the orifice. The model VDROP-J was then calibrated to jets emanating from orifices ranging in diameter, D, from 0.5mm to 0.12m, and in cross-section average jet velocity at the orifice ranging from 1.5m/s to 27m/s. The d50/D obtained from the model (where d50 is the volume median diameter of droplets) correlated very well with data, with an R2=0.99. Finally, the VDROP-J model was used to predict the droplet size distribution from Deepwater Horizon blowouts. The droplet size distribution from the blowout is of great importance to the fate and transport of the spilled oil in marine environment.

CFD-Modeling of Heavy Oil Injection into Blast Furnace - Atomization and Mixing in Raceway-Tuyere Area

Auxiliary fuel injection into the air blast benefits blast furnace operation by reducing coke consumption and carbon dioxide emissions, stabilizes process, and increases productivity. Heavy oil is a side stream product of petrochemical industry and it is used to replace part of the coke. Atomization of the heavy oil and mixing it with the air blast is one of the main challenges that limit high injection rates. The aim of this work is to develop CFD model of the raceway-tuyere area of the blast furnace that provides knowledge about droplet sizes and mixing behavior of the heavy oil with air blast. Atomization of the heavy oil is modeled with Wave Breakup Model, where breakup time and droplet size constants have been adjusted and validated using experimental results from physical set-up. CFD models based on the physical set-up and the actual blast furnace were made. Wave Breakup Model coupled with the CFD has good agreement with the experimental study in physical set-up. Further, CFD model is applied to study the actual blast furnace with heavy oil injection. The droplet volume median diameters in a function of the dimensionless air blast velocity are consistent in both cases having valid dynamic similarity. Mixing between the air blast and the heavy oil is poor without nozzle and most of the liquid mass is concentrated in the center of the air blast. With increasing the air blast velocity mixing gets poorer. According to modeling work, improved mixing and atomization was achieved with alternative nozzle geometries used in the tip of the oil lance.

Analysis of a semi-empirical sprinkler spray model

Modelling the atomization process in fire sprinklers has remained a challenge mainly due to the complexity of sprinkler geometry. A review of existing fire sprinkler spray modelling approaches, including film flow and sheet tracking models, showed that they mainly assumed a constant sheet velocity and linear attenuation of the sheet thickness before its disintegration. In the present study, a liquid sheet trajectory sub-model based on the solution of stream-wise conservation equations has been used to predict both sheet thickness and velocity as it radially expands. This will also help to investigate the extent to which a change in the release angle can affect the sheet characteristics. The analysis carried out shows that the proposed approach improves the predictions of mean droplet diameter and initial droplet speed. A semi-empirical approach is further introduced in the study by using experimental volume fraction measurements to characterize sprinkler sprays in the near field. For a given direction predictions have been conducted for droplet volume median diameter, water volume flux and droplet average velocity at different elevation and azimuthal locations. A reasonably good agreement is found for the near field measurements.

Avaliação da Formulação e do Volume de Aplicação na Eficiência do Resíduo da Pulverização de Conídios de &lt;i&gt;Metarhizium acridum&lt;/i&gt; (Driver &amp; Milner) Bischoff, Rehner &amp; Humber, em &lt;i&gt;Schistocerca gregaria&lt;/i&gt; (Forskål) (Orthoptera: Acrididae)

Effects of the spray residue of Metarhizium acridum (Driver & Milner) Bischoff, Rehner & Humber, formulated in emulsifiable adjuvant oil and in a mixture of mineral oils, on the mortality of adult desert locusts, Schistocerca gregaria (Forskal), were evaluated. The effects of volume application rates (VARs) and the presence of conidia applied by a spinning disc atomiser, on the spray characteristics of those two kinds of formulations were also evaluated. The conidial formulations were applied to seedlings of wheat by a track sprayer designed to simulate ultra-low volume field spraying in laboratory conditions. No significant differences between the two formulations and between the four VARs on the proportional survival of S. gregaria were revealed, but there were significant differences between doses. The average survival times (AST) of Schistocerca gregaria were calculated and there were significant differences only between doses. When the dose increased, the AST of the insect decreased. Studies on spray characteristics revealed that when the VAR increased, the droplet volume median diameter and the number of droplets/cm2 also increased. Both formulations gave uniform droplet distributions with characteristics of controlled droplet application sprays. When the VAR increased, the droplet volume also increased, the number of conidia/droplet decreased and the number of conidia/cm2 decreased. The emulsifiable adjuvant oil formulation worked as well as the oil formulation in these experimental conditions, and it has a great potential to control insect pests, when sprayed with the appropriate equipment and technique, where the environmental conditions are suitable.

Influence of Alternative Copper Fungicide Formulations on Copper Content in Apple Fruits

Field trials were carried out from 2008 to 2011 at Maribor, Slovenia to determine the effect of new copper fungicide formulations on the copper content in apple fruits, separated in peel and flesh, of seven cultivars at harvest. Apple trees were treated 12–18 times per season with formulations based on copper oxychloride or sulphate (trial standards), copper hydroxide and their complexes or chelates with amino acids, peptides, EDTA, urea, and octanoic or gluconic acids at the same rate of 200 g of pure copper ions (Cu2+) per hectare irrespetive of the product. Copper formulations were applied with Teejet 800067 flat fan nozzles mounted on a vertical boom of the sprayer, which gave a droplet volume median diameter (VMD) of 120 microns and 130–180 droplet impacts per square centimeter, as determined on water sensitive papers. The new formulations of copper in the form of salts of fatty acids or organic complexes or chelates had a higher penetration rate into apple fruit tissue than the traditional formulations based on Cu-hydroxide, Cu-oxychloride and Cu-sulphate. The copper content in the fruit depended on the ratio between copper solubility in the formulation, rate of penetration into the fruit and stability of the copper fungicide deposit on the fruit surface. Despite being applied at lower hectare rates, frequent applications led to the exceeding of the permitted EC maximum residue level of 5 mg/kg fresh mass (FM). MRL was most often exceeded with the application of formulations based on Cu-octanoate and Cu-gluconate and less often in case of the application of complexes of copper with amino acids, peptides or urea. A comparison of the copper content between different cultivars showed that cv. ‘Jonagold’, ‘Golden Delicious’ and ‘Elstar’ accumulated more cooper than other cultivars. Copper concentrations in the peel exceeded that of the flesh at least twice. The potential effects of accumulation of copper in woody tissue of bearing shoots after long-term application of highly systemic copper formulations on growth and blooming of apples are discussed too. Some apple growers may not be aware of much higher penetration rate of these new copper products (fungicides, fertilisers or plant strengtheners) and should be warned about the necessity to adapt their spraying schedules despite applications of a low hectare rates of copper, i.e. the number of treatments and proper seasonal timing, to avoid exceeding of EU MRL of copper in fruit.

Simulation of in‐cloud icing events on Mount Washington with the GEM‐LAM

In‐cloud icing on structures such as transmission lines and wind turbines is an important consideration both for design and operations. It often occurs in coastal areas and over high terrain, where there are virtually no systematic observations. The regional mesoscale model GEM‐LAM of the Canadian Meteorological Center (CMC) was used to model three historical icing events on Mount Washington, where observational data were available. These three events are representative of the most frequent low level wind directions for seven available observation periods. A newly developed sophisticated two‐moment microphysics scheme (Milbrandt‐Yau) is used in GEM‐LAM. The simulated cloud properties and other meteorological data are compared with near surface observational data. Simulation results from the 1‐km resolution run agree best with the observations, with an average RMSE (root mean square error) of 1.6°C for near surface temperature, 4.6 m s−1 for wind speed, 0.23 g m−3 for liquid water content, and 5.8 μm for the median volume droplet diameter. These simulated meteorological fields and cloud properties were used as inputs to a cylindrical sleeve icing model. The modeled icing rate from the GEM‐LAM simulated fields follows the temporal evolution of the observed one with average RMSE of 1.53 g m−1 min−1 compared to an average measured icing rate of 1.98 g m−1 min−1 for all the three cases.