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Optimization of an agricultural air induction Nozzle
Reza Alidoost Dafsari,Seunghwa Yu,Young Choi,Jeekeun Lee 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12
Delivering the pesticide has always been challenging in the agricultural field due to the drift potential of the harmful pesticides leading to water and soil pollution. Therefore, air induction nozzles have been employed as target spraying method. The geometry of the air induction nozzle governs the performance of it, namely, the air to liquid mass ratio, spray angle, and droplet size. This study investigates the effect of variable geometrical parameters on the resulting spray through the design and manufacturing of individual components of an in-house designed AI nozzle. Spray structure was captured using a planner laser sheet visualization system and droplet size was measured by employing a laser diffraction method. Geometrical parameters mainly the jet-pump (ventury) and the nozzle tip were found to control the spray structure and nozzle hydraulic performance. The results can be of prime importance for nozzle design optimization to reach the target air-to-liquid ratio and droplet size.
Drift Potential of Agricultural Spray caused by Downwash Flow of Sprayer Drone
Reza Alidoost Dafsari(레자알리두스트다프사리),Xuesong Bai(백설송),Seunghwa Yu(유승화),Jeekeun Lee(이지근) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.8
Controlling the spray drift is of high environmental demands to protect surface water and soil from chemical contamination. Agricultural drones are being increasingly used as a target spraying method with the aim of carrying pesticide atomizers on the farm to control the chemical drifts. However, the downwash flow of the rotor blade affects the spray structure. The axial component of velocity gives rise to the droplet acceleration and the radial and tangential velocity components cause side drift to the spray droplets. The rotational speed of the rotor blade as the main parameter to identify the downwash flow intensity and the radial position of the nozzle below the rotor as the spatial characteristic can control this effect. Magnification of both mentioned parameters is the main objective of this study. The spray structure influenced by controlling the test parameters was captured with the Mie-scattering imaging method using a CCD camera synchronized to a Nd:Yag laser. The captured images were then post-processed. The results were analyzed qualitatively and quantitatively to show the effect of test parameters on the magnitude of the drift. The operational conditions were tested for various agricultural nozzles producing a range of droplet size from fine to coarse to cover the role of nozzle performance in drift potential. Large droplet generating nozzles showed to have essentially better drift resistance compared to finer spray. The rotational speed of the rotor blade (RPM) increases the drift and has to be considered as a design parameter since it’s dependent on the weight of the drone. The radial position of the nozzle from the center of the blade was found to have a great impact on the matter. To minimize the drift occurrence, the ideal position of the nozzle is when the center of the nozzle coincides radially with the center of the blade.
Reza Alidoost Dafsari(레자알리두스트다프사리),Xuesong Bai(백설송),Seunghwa Yu(유승화),Jeekeun Lee(이지근) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.8
With the increasing application of drones in multiple industries, it is essential to understand the flow structure by the movement of the rotor blade. The current study exhibits the downwash flow structure and velocity distribution of an in-house designed and manufactured rotor blade for the agricultural application. The purpose of this drone is to carry pesticide sprayer nozzles in the farm. The downwash flow caused by the rotation of the blades affect the spray structure and gives raise to the air-liquid interaction of the issuing droplets. Therefore, understanding the physics of the resulting flow is the main objective of this study. The flow velocity distribution and turbulence characteristics were measured in a dense 3D grid using a Dantec Hot-wire anemometer. The measured values were then reconstructed and illustrated as a flow field to analyze the effect of the rotational speed of the rotor (RPM) on the downwash flow in various axial levels below the rotor blade. The flow behavior was shown using physical indicators such as mean and fluctuated velocity components, turbulence, and Reynolds stress in 2D and 3D coordinates. The results of this study initially show the general velocity distribution structure and furthermore, how increasing the rotational speed increases the velocity components and turbulent intensity and the significance of this decays further downstream from the rotor blade.
EFFECT OF SWIRL CHAMBER LENGTH ON DROPLET SIZE DISTRIBUTION IN A PRESSURE SWIRL ATOMIZER
( Reza Alidoost Dafsari ),( Rakhul Chandrahasan ),( Jeekeun Lee ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-
An experimental study on a specially designed pressure swirl nozzle is conducted to investigate the effects of swirl chamber length and relative Length/Diameter ratio of swirl chamber on spray characteristics. The unique nozzle investigated is capable of providing a range of swirl chamber length ([1.137, 4.89] mm) while maintaining other dimensions constant. Spray characteristics such as spray angle, droplet diameter and distribution, relative span factor as well as velocity components were measured to gain a better understanding of performance of the atomizer governed by swirl chamber length/diameter effect. Measurements of droplet size and velocity components were done by using a 2D Phase Doppler Particle Analyzer (PDPA) device. Also spray cone angle was calculated by image processing on pictures captured by a set of Nd:YAG laser and high Speed Camera. Spatial volume distribution was derived from 2D patternator and number density from PDPA result. Analyzing the experimental results determined that swirl chamber length and relative length/diameter ratio has significant effects on atomizer performance. The transition regime from hollow-cone to solid-cone type caused by swirl chamber effect is compared and studied. The spray pattern for the shortest chamber was observed as hollow-cone type where generated spray gradually reshaped to solid-cone type with increasing the swirl chamber length. Effective length of swirl chamber in this nozzle was found to be in range of [1.137, 2.38] mm where all the dramatic changes occur.
Reza Alidoost Dafsari,Sangho Lee,Foad Vashahi,Jeekeun Lee(이지근) 한국자동차공학회 2016 한국자동차공학회 학술대회 및 전시회 Vol.2016 No.11
Flow and spray characteristics of a pressure swirl nozzle of which the spray angle is adjustable with the variation of swirl chamber length was investigated experimentally. The swirl chamber length of the nozzle was adjusted by rotating the specially manufactured nozzle cap, and it was varied from 1.14 mm to 4.89 mm. According to swirl chamber length, the discharge coefficient (Cd) of the nozzle and the spray characteristics, such as spray pattern, spray angle, and mean droplet diameter, were measured by applying a 2D Particle Image Velocimetry (PIV) system and Phase-Doppler Anemometry (PDA) system. The result showed that the swirl chamber length of the nozzle had a great impact on the discharge coefficient (Cd), spray angle and the Sauter mean diameter (SMD).