scholarly journals Spatial Positioning and Operating Parameters of a Rotary Bell Sprayer: 3D Mapping of Droplet Size Distributions

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 165 ◽  
Author(s):  
Adnan Darwish Ahmad ◽  
Binit B. Singh ◽  
Mark Doerre ◽  
Ahmad M. Abubaker ◽  
Masoud Arabghahestani ◽  
...  
Keyword(s):  
Droplet Size ◽  
Flow Rate ◽  
Rotational Speed ◽  
Operating Parameters ◽  
Size Distributions ◽  
Theoretical Formulation ◽  
Wide Range ◽  
Droplet Sizes ◽  
Spatial Positioning ◽  
The Impact

In this study, we evaluated the fundamental physical behavior during droplet formation and flow from a rotary bell spray in the absence of an electrostatic field. The impact of a wide range of operating parameters of the rotary bell sprayer, such as flow rates, rotational speeds, and spatial positioning, on droplet sizes and size distributions using a three-dimensional (3-D) mapping was studied. The results showed that increasing the rotational speed caused the Sauter mean diameter of the droplets to decrease while increasing flow rate increased the droplet sizes. The rotational speed effect, however, was dominant compared to the effect of flow rate. An increase in droplet size radially away from the cup was noted in the vicinity of the cup, nevertheless, as the lateral distances from the cup and rotational speed were increased, the droplet sizes within the flow field became more uniform. This result is of importance for painting industries, which are looking for optimal target distances for uniform painting appearance. Furthermore, the theoretical formulation was validated with experimental data, which provides a wider range of applicability in terms of environment and parameters that could be tested. This work also provides an abundance of measurements, which can serve as a database for the validation of future droplet disintegration simulations.

scholarly journals Computational Analysis on Numerical Simulation of Internal Flow Physics for Pump as Turbine in Renewable Small Hydro Energy Generation

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Du Jianguo ◽  
Daniel Adu ◽  
Emmanuel Acheaw ◽  
Shakir Hafeez ◽  
Eric Ofosu Antw
Keyword(s):  
Flow Rate ◽  
Rotational Speed ◽  
Human Life ◽  
Three Dimensional ◽  
Internal Flow ◽  
Hydroelectric Power ◽  
Small Hydropower ◽  
Speed Increase ◽  
Blade Thickness ◽  
The Impact

Energy contributes significantly in almost all aspects of human life as well as economic activities and plays a crucial role in the infrastructural development of a county to alleviate poverty. Generating energy from a renewable source such as small hydropower through the application of pump operating as a turbine mode called Pump as Turbine is one of the best alternatives to provide clean and inexpensive energy. Using Pump as Turbine helps in generating reasonably priced hydroelectric power for communities in underdeveloped counties. This study investigates the effects of internal flow behaviour and performance of Pump as Turbine under different rotational speed and flow rate. The rotational speed is an essential physical parameter as it affects the Pump as Turbine operation. A model-specific speed centrifugal pump model with head 32 (m), flow rate of 12.5 (m3/h) and the rotational speed of 2900 rpm, has been selected for the study. Numerical simulations have been conducted using the k-ω turbulence model to solve three-dimensional (3D) equations. The pump mode experimental data were used to confirm the results for better analysis. The results predicted that vortex and turbulent kinetic energy increase per rotational speed increase. Also, at the higher rotational speed, very high recirculation of flow is detected at the blade suction chamber, although the pressure side has a smooth flow. This study provides beneficial information which will serve as a reference to help improve PAT performance along with selecting PAT for a small hydropower site. Future works will consider the impact of blade thickness and cavitation in Pump as Turbine.

Study on Dynamic Behavior of a Gas Pressure Relief Valve for a Big Flow Rate

2013 ◽  
Author(s):  
Victor Sverbilov ◽  
Dmitry Stadnick ◽  
Georgy Makaryants
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Dynamic Properties ◽  
Gas Pressure ◽  
Pressure Relief Valve ◽  
Relief Valve ◽  
Pressure Relief ◽  
Wide Range ◽  
The Impact ◽  
Pilot Valve

The paper investigates instable behavior of a poppet-type gas pressure relief valve operating at a big flow rate (more than 2 kg/s) under super critical pressure drop. Instability is experienced as noise and vibration and leads to severe damage of a seat and other elements. Significant and unsteady flow forces coupled with small inherent damping make it difficult to stabilize the system. In previous works, the analytical and experimental research was carried out to reveal the most essential factors influencing stability and dynamic properties of the valve. The impact of the pilot valve dynamics on the system behavior was studied for the purpose of obtaining required accuracy and stability in a wide range of flow rate. It was shown in some testing that unstable behavior of the main valve occurred when the pilot valve was stable. This paper considers inherent stability of the main valve in the gas flow. CFD software ANSYS FLUENT is employed to study the effect of the poppet geometry on aerodynamic lifting force and valve stability in axial and lateral direction. The results have been verified through comparison with experimental data.

scholarly journals Needleless Electrospinning Using a Flat Wheel Spinneret

2017 ◽  
Vol 12 (3) ◽  
pp. 155892501701200 ◽  
Author(s):  
Usman Ali ◽  
Amir Abbass ◽  
Furqan Khurshid ◽  
Sarmad Aslam ◽  
Abdul Waqar
Keyword(s):  
Electric Field ◽  
Production Rate ◽  
Mass Production ◽  
Solution Concentration ◽  
Poly Vinyl Alcohol ◽  
Operating Parameters ◽  
Fiber Morphology ◽  
Sequence Generation ◽  
Wide Range ◽  
The Impact

Nanofibers have a wide range of applications, however; the mass production of nanofibers is still an obstacle to wider industrial application. In this paper, a flat wheel was used as a spinneret for production of poly (vinyl) alcohol nanofibers. Electric field comparative analysis was done between the flat wheel and other spinnerets such as a cylinder, disk and ring. It was found the flat wheel falls between the cylinder and disk and ring spinnerets. Sequence generation of polymer jets was observed from the both edges of the wheel and as well as from the surface of the wheel. The impact of operating parameters on fiber morphology was studied and it was found that smooth, uniform nanofibers with diameter around 350nm could be produced by using this spinneret. Influence of strength of applied electric field and solution concentration on the production rate was also examined and it was noted that the production rate of nanofibers using a flat wheel spinneret is several times higher than that obtained using a conventional needle electrospinning setup.

Impact of Auxin Herbicides on Palmer amaranth Groundcover

2021 ◽  
pp. 1-32
Author(s):  
Grant L Priess ◽  
Jason K Norsworthy ◽  
Rodger B Farr ◽  
Andy Mauromoustakos ◽  
Thomas R Butts ◽  
...  
Keyword(s):  
Droplet Size ◽  
Field Experiments ◽  
Palmer Amaranth ◽  
Clear Understanding ◽  
Spray Droplet ◽  
Extended Range ◽  
Droplet Sizes ◽  
Auxin Herbicides ◽  
Control Technologies ◽  
The Impact

Abstract In current and next-generation weed control technologies, sequential applications of contact and systemic herbicides for POST control of troublesome weeds are needed to mitigate the evolution of herbicide resistance. A clear understanding of the impact auxin herbicide symptomology has on Palmer amaranth groundcover will aid optimization of sequential herbicide applications. Field and greenhouse experiments were conducted in Fayetteville, AR and a laboratory experiment was conducted in Lonoke, AR, in 2020 to evaluate changes in Palmer amaranth groundcover following an application of 2,4-D and dicamba with various nozzles, droplet sizes, and velocities. Field experiments utilized three nozzles: Extended Range (XR), Air Induction Extended Range (AIXR), and Turbo TeeJet Induction (TTI), to assess the effect of spray droplet size on changes in Palmer amaranth groundcover. Nozzle did not affect Palmer amaranth groundcover when dicamba was applied. However, nozzle selection did impact groundcover when 2,4-D was applied; the following nozzle order XR>AIXR>TTI reduced Palmer amaranth groundcover the greatest in both site-years of the field experiment. This result (XR>AIXR> TTI) matches percent spray coverage data for 2,4-D and is inversely related to spray droplet size data. Rapid reductions of Palmer amaranth groundcover from 100% at time zero to 39.4 to 64.1% and 60.0 to 85.8% were observed 180 minutes after application in greenhouse and field experiments, respectively, regardless of herbicide or nozzle. In one site-year of the greenhouse and field experiments, regrowth of Palmer amaranth occurred 10080 minutes (14 days) after an application of either 2,4-D or dicamba to larger than labeled weeds. In all experiments, complete reduction of live Palmer amaranth tissue was not observed 21 days after application with any herbicide or nozzle combination. Control of Palmer amaranth escapes with reduced groundcover may potentially lead to increased selection pressure on sequentially applied herbicides due to a reduction in spray solution contact with the targeted pest.

Droplet Size Spectrum, Activation Pressure, and Flow Rate Discharged from PWM Flat-Fan Nozzles

2021 ◽  
Vol 64 (1) ◽  
pp. 313-325
Author(s):  
Zhiming Wei ◽  
Heping Zhu ◽  
Zhihong Zhang ◽  
Ramón Salcedo ◽  
Degang Duan
Keyword(s):  
Droplet Size ◽  
Duty Cycle ◽  
Solenoid Valve ◽  
Variable Rate ◽  
Size Distributions ◽  
Flow Rates ◽  
Nozzle Orifice ◽  
Duty Cycles ◽  
Droplet Sizes ◽  
Droplet Size Distributions

HighlightsDroplet sizes, activation pressures acting on nozzle orifices, and flow rates were investigated.Droplet sizes varied with duty cycles, nozzle orifice sizes, and PWM solenoid valve manufacturers.Activation pressures decreased as duty cycles decreased and increased as nozzle orifice sizes decreased.Flow rates increased with increases in both duty cycles and nozzle orifice sizes.Abstract. Pulse width modulated (PWM) spray systems can produce variable spray rates for precision applications of pesticide and fertilizer; however, there are also concerns over their spray performance stability. Droplet size distributions, activation pressures acting on nozzle orifices, and flow rates discharged from nozzles were investigated for test combinations of ten PWM duty cycles (10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%), six flat-fan nozzles with different orifice sizes (XR8001, XR8002, XR8003, XR8004, XR8005, and XR8006), and two PWM solenoid valves from two different manufacturers. Test results showed that the droplet size distribution, activation pressure, and flow rate varied with the duty cycle, nozzle orifice size, and PWM solenoid valve source. For XR8001 and XR8002 nozzles, droplet sizes did not vary significantly with all duty cycles from 10% to 100%. To obtain relatively consistent droplet size distributions, XR8003 and XR8004 nozzles required PWM duty cycles of at least 20%, while XR8005 and XR8006 nozzles required duty cycles of 30% or greater. The activation pressure directly on nozzle orifices increased as the duty cycle increased but decreased as the nozzle orifice size increased. In addition, the same nozzles coupled with PWM solenoid valves from two different manufacturers discharged different flow rates for the same duty cycle in the range of 10% to 90%. Therefore, careful selection of PWM solenoid valves for different orifice nozzles operated at different duty cycles was necessary to achieve consistent variable-rate spray performances. Keywords: Droplet diameter, Variable rate, PWM solenoid valve, Pesticide, Fertilizer, Precision farming.

Computational Study of the Unsteady Flow Structure of the Buoyancy-Driven Rotating Cavity With Axial Throughflow of Cooling Air

2009 ◽  
Author(s):  
Zain Dweik ◽  
Roger Briley ◽  
Timothy Swafford ◽  
Barry Hunt
Keyword(s):  
Flow Structure ◽  
Rotational Speed ◽  
Operating Conditions ◽  
Structure Evolution ◽  
High Rotational Speed ◽  
Wide Range ◽  
Recirculation Zones ◽  
Cooling Air ◽  
The Impact ◽  
Engine Power

Buoyancy driven flows such as the one that occurs in the inter-disk space of an axial compressor spool plays a major role in determining the gas turbine engine projected life and performance. Details of the developed flow structure inside these spaces largely impact the operating temperatures on the rotating walls of the compressor hardware and therefore impact the life of the machine. In this paper the impact of engine power condition (Idle, Highpower, and Shutdown) on the flow structure for these rotating cavities is studied under a wide range of operating conditions encountered by realistic turbomachines. A computational analysis is performed using commercially available computational tools for grid generation (ICEM-CFD) and turbulent-flow simulation (CFX). A computational test case was developed to imitate the rig-test conditions of Owen and Powell, and computed results were assessed and validated by comparison with their experimental results. A total of fifteen unsteady CFD cases covering a wide range of operating conditions (Rossby Number Ro, Rotational Rayleigh Number Raφ, and axial Reynolds Number Rez) were analyzed. The computed flow results revealed that the flow structure evolution, starting from a steady state solution, is such that radial arms of different number (according to the engine power condition), surrounded by a co-rotating (cyclonic) and counter-rotating (anti-cyclonic) pair of vortices, start to form at different locations. Cold air from the central jet enters the cavity in these arms under the combined action of the centrifugal buoyancy and the Coriolis forces. As time proceeds, the flow structure tends to become virtually invariant with time in a repeatable pattern. The number of radial arms, strength of recirculation zones, and the degree of invasion of the central cooling air toward the shroud are all dependent on the engine power condition. The computations also revealed that at high rotational speed the flow stabilizes, and the unsteady features of the flow structure (cyclonic and anti-cyclonic recirculation zones surrounding the radial arms, radial invasion of the cooling air in the radial arms, and its final impingement upon the shroud surface) eventually disappear after a threshold value of the rotational speed is reached.

The Impact of Spray Droplet Size on the Efficacy of 2,4-D, Atrazine, Chlorimuron-Methyl, Dicamba, Glufosinate, and Saflufenacil

2016 ◽  
Vol 30 (2) ◽  
pp. 573-586 ◽  
Author(s):  
Cody F. Creech ◽  
Jesaelen G. Moraes ◽  
Ryan S. Henry ◽  
Joe D. Luck ◽  
Greg R. Kruger
Keyword(s):  
Droplet Size ◽  
Size Control ◽  
Dry Weight ◽  
Full Potential ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Droplet Sizes ◽  
Fine Spray ◽  
Volunteer Corn ◽  
The Impact

Herbicide applications often do not reach their full potential because only a small amount of the active ingredients reaches the intended targets. Selecting the appropriate application parameters and equipment can allow for improved efficacy. The objective of this research was to evaluate the effect of droplet size on efficacy of six commonly used herbicides. Atrazine (1.12 kg ai ha−1), cloransulam-methyl (0.18 g ai ha−1), dicamba (0.14 kg ae ha−1), glufosinate (0.59 kg ai ha−1), saflufenacil (12.48 g ai ha−1), and 2,4-D (0.20 kg ae ha−1) were applied to seven plant species using an XR11003 nozzle at 138, 276, and 414 kPa and a AI11003 nozzle at 207, 345, and 483 kPa. Each herbicide, nozzle, and pressure combination was evaluated for droplet size spectra. Treatments were applied at 131 L ha−1to common lambsquarters, common sunflower, shattercane, soybean, tomato, velvetleaf, and volunteer corn. Control from 2,4-D was observed to increase approximately 12% on average for all species except common lambsquarters as droplet size increased from medium to very coarse (Dv0.5303 to 462 μm;Dv0.5is droplet size such that 50% of spray volume is contained in droplets of equal or smaller size). Control with atrazine was near 95% for common lambsquarters, common sunflower, and soybean. Atrazine provided the greatest shattercane control using a medium (Dv0.5325 μm) droplet, whereas the same droplet size provided the lowest tomato control. Control of common lambsquarters, shattercane, and tomato with cloransulam-methyl increased 79% when decreasing droplet size from extremely coarse to fine (Dv0.5637 to 228 μm). Dicamba control of common lambsquarters increased 17% using a medium droplet compared with a fine droplet (Dv0.5279 to 204 μm). Dry weight of common sunflower and soybean was reduced 21% using dicamba when using a very coarse spray compared with a fine spray classification (Dv0.5491 to 204 μm). Common lambsquarters control using glufosinate increased 18% using a fine spray classification (Dv0.5186 μm) compared with medium (Dv0.5250 μm) and both very coarse droplet sizes (Dv0.5470 and 516 μm). Conversely, tomato and velvetleaf control with glufosinate was maximized using a very coarse (Dv0.5470 and 516 μm) or extremely coarse droplet (Dv0.5628 μm) with increases of 11 and 25% compared with a fine spray (Dv0.5186 μm). Saflufenacil control of volunteer corn was 38% greater using extremely coarse droplets (Dv0.5622 μm) than fine, medium, and very coarse spray classifications (Dv0.5257 to 514 μm). Overall, spray classifications for the herbicides evaluated play an important role in herbicide efficacy and should be tailored to the herbicide being used and the targeted weed species.

scholarly journals Impacts of operational conditions on oxygen transfer rate, mixing characteristics and residence time distribution in a pilot scale high rate algal pond

2018 ◽  
Vol 78 (8) ◽  
pp. 1782-1791 ◽  
Author(s):  
L. A. Pham ◽  
J. Laurent ◽  
P. Bois ◽  
A. Wanko
Keyword(s):  
Water Level ◽  
Flow Rate ◽  
Rotational Speed ◽  
Time Distribution ◽  
Transfer Rate ◽  
Pilot Scale ◽  
High Rate ◽  
Operational Conditions ◽  
Inlet Flow Rate ◽  
The Impact

Abstract Different combinations of operational parameters including water level, paddle rotational speed and influent flow rate were applied to investigate their impacts on mixing characteristics, residence time distribution and gas transfer rate in a pilot-scale high rate algal pond. In closed condition, the paddle rotational speed had a positive correlation with the Bodenstein number (Bo), water velocity and oxygen volumetric mass transfer coefficient (kLaO2) while increasing water level generated a negative impact on these parameters, although the impact of water level on water linear velocity was small. The amplification effect of water level and paddle rotational speed on the sensitivity of Bo and kLaO2 should be noticed. Moreover, paddle rotational speed had more impact on kLaO2 than on Bo. The study in open condition indicated that effective volume fraction had a positive correlation with inlet flow rate and negative correlation with paddle rotation, while the opposite was observed in the case of Peclet number. The impact of water level variation on these parameters was unclear. Both water level and paddle rotational speed had negative impacts on the short-circuiting index, while no correlation was observed when varying inlet flow rate. In this study, the optimal operational conditions included low water level (0.1 m) and medium paddle rotational speed (11.6 rpm).

Sign in / Sign up

Export Citation Format

Share Document