• Journal of Bio-Environment Control
• /
• v.22 no.4
• /
• pp.303-308
• /
• 2013

A remote controlled sprayer has designed, manufactured and experimented to spray well on pear trees with pesticides. This study was executed to automate pest management of pear trees. Types of spray nozzle, which was used on the system, were analyzed experimentally to find an optimal spray equipment configuration with several nozzles. Attributions of ultrasonic sensors were analyzed to adjust spraying distance of an unmanned sprayer system. This paper investigated shapes of pear trees and cultivating environment of pear orchard. In order to select optimal spray environment, liquid distribution was measured while angle of nozzle was changed. Additionally, liquid distribution by distance and sprayed liquid capacity by side distance were measured. According to information of shapes of pear trees and cultivating environment of pear orchard, sprayer frames of an unmanned sprayer system were manufactured and sprayer frames were suitable for interval of pear trees. The sprayer system could adjust width of sprayer frames to 2.5 m and height of sprayer frames to 1.7 m. Optimal angle of nozzle, and optimal distance between objects and nozzle were $15^{\circ}$ and 0.8 m. When side distance was placed from 1.2 m to 1.8 m, sprayed capacity reached to the highest amount.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.6
• /
• pp.1-7
• /
• 2017

The atomization of a liquid into multiple droplets has many important industrial applications, including the atomization of fuels in combustion processes and coating of surfaces and particles. Ultrasonic atomizing nozzle has a transducer that receives electrical input in the form of a high frequency signal from a power generator and converts that into mechanical energy at the same frequency. Liquid is atomized into a fine mist spray using high frequency sound vibrations. In coating applications, the unpressurized, low-velocity spray reduces the amount of overspray significantly because the droplets tend to settle on the substrate, rather than bouncing off it. The spray can be controlled and shaped precisely by entraining the slow-moving spray in an ancillary air stream using specialized types of spray-shaping equipment. The desired patterns of spray can be obtained using an air stream. To simulate the water mist behavior of an ultrasonic atomizing nozzle using an air stream, the Lagrangian dispersed phase model was employed using the commercial code FLUENT. The effects of the nozzle contraction shape, water droplet size and the pneumatic pressure drop on the spray characteristics were investigated to obtain the optimal condition for coating applications.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2002.02a
• /
• pp.426-431
• /
• 2002

본 연구에서는 DGPS와 칼라 CCD 카메라를 이용한 잡초의 검출을 위한 영상처리 시스템과 분무시스템을 개발하고 통합하여 정밀 방제 시스템을 개발하였다. 방제 요구부위에 실제 정밀한 살포를 위해 펌프, 노즐 및 레귤레이터로 구성된 장치를 구성하고 컨트롤러를 제작 통합하여 분무 시스템을 개발하였다. 개별 노즐별로 ON/OFF에 의한 변량 살포가 가능하도록 각 노즐별로 레귤레이터를 장착하였다. 정밀 방제용 이동식 차량을 제작하고 노즐별로 ON-OFF 제어가 가능한 살포장치를 부착하였으며, 알고리즘을 통합하여 정밀방제 시스템을 개발하였다. 개발한 시스템은 영상 획득 $\longrightarrow$ DGPS 좌표 획득 $\longrightarrow$ 자이로 컴파스 데이터 획득 $\longrightarrow$ 데이터베이스로부터 작물의 위치정보 획득 $\longrightarrow$ 영상처리를 이용한 방제요구부위 검출 $\longrightarrow$ 노즐별 개별 방제 작업이 순서적으로 반복해서 진행되었다. 완성된 시스템의 성능 및 안정성을 평가하기 위해서 서울대학교 부속 과수원에서 무를 대상으로 개발된 시스템을 검증하였다. 개발된 시스템은 RS-232C 통신을 이용하여 데이터의 전송을 수행할 수 있었으며, 순차적인 진행이 가능하도록 통합 프로그램을 제작하였으며, 검증 결과 정밀방제의 가능성을 보였다.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.12 no.5
• /
• pp.9-17
• /
• 2008

Pseudo-3D spatial distribution of spray droplets is investigated by using Dual-mode Phase Doppler Anemometry (DPDA) in order to examine the disintegration and spreading behavior of spray exiting from liquid-propellant thruster injector. Spray injected from nozzle orifice with length-to-diameter ratio ($L/d_o$) of 1.67 and under the injection pressure of 27.6 bar is aligned to the vertical. Vertical and horizontal mean velocities of droplets, Sauter Mean Diameter (SMD), and volumetric flux decrease as droplets travel from center/upstream toward outer region/downstream of spray. Although the distribution of spray characteristic parameters is symmetric against the geometric axis of nozzle orifice, their absolute values are asymmetric.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.2 no.4
• /
• pp.100-111
• /
• 1994

Observations on the near-nozzle behavior of an unsteady fuel spray through single cylindrical hole nozzle were made by phase Doopler anemometer and microphotographs. At the edge of the spray, droplet velocity peaked during needle opening and closing. Droplet sizes tended to be small on the edge of spray. The near-nozzle spray angle taken from the microphotographs was time-dependent, even though it increased with gas-to-liquid density ratio as expected. The near-nozzle spray angle was the greatest on the initial stage and decreased to a relatively constant value after about one third of the total injection duration regardless of the ambient gas conditions, even in the near-vaccum condition. The wider near-nozzle spray angle in the early stage is due to the flow characteristics inside the nozzle rather than aerodynamic interactions. However, once the spray was established, aerodynamic interactions are essential in the near-nozzle atomization.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.3
• /
• pp.60-66
• /
• 2011

In the present investigation, experimental studies were conducted on the fire suppression performance of twin-fluid water mist spray which is subjected to thermal radiation in a closed space. Downward-directed water-mist sprays, interacting with an under kerosene pool fire, were investigated in a test facility. The mass mean diameter of water-mist droplets were measured by PMAS under various flow conditions. The developed twin-fluid water mit spray nozzle satisfied the criteria of NFPA 750, Class 1. The mechanism of fire suppression by fine water mist was concluded to be the cooling of the fire surface which leads to the suppression of fuel evaporation. It was proved that the automatic twin-fluid water mist spray system under lower pressures could be applied to an industrial facilities.

• Journal of ILASS-Korea
• /
• v.7 no.1
• /
• pp.29-35
• /
• 2002

This study describes the external spray characteristics of deflector nozzle such as the breakup procedures of liquid sheet, spray angle, breakup length and bubble behaviors of spray at deflector nozzle. In order to visualize the spray behaviors shadow graphy technique were used. According to the increase injection pressure, deveopment of the spray passes through the dribbling, distoted jet, closed bubble due to the contraction by form a conical sheet like as the simplex swirl atomizer. As trying the analysis of the ratio of bubble length and width it was found that the ratios is comparable. Spray cone angle was nearly $90^{\circ}$.

• Journal of ILASS-Korea
• /
• v.12 no.3
• /
• pp.138-145
• /
• 2007

In the present work, the breakup mechanism of highly viscous epoxy paints discharged from a fan spray nozzle was examined experimentally. The paints tested were non-Newtonian fluids, composed of epoxy resin, solid particles and other additives. The paint spray discharged from the nozzle was visualized and recorded using a digital camera with back illumination. Due to presence of the solid particles, perforation of liquid sheet was observed in most cases, even at low-Reynolds number conditions (Re < 15,000) where the aerodynamic-wave breakup mode is used to be dominant for pure liquids. However, with the increase of the particle concentration, the sheet became longer and the thickness at breakup became thinner to some extent. This is because, with higher concentration of solid particles, the stabilizing effect by the viscosity increase predominates over the destabilizing effect by perforation.

• Journal of Advanced Marine Engineering and Technology
• /
• v.36 no.8
• /
• pp.997-1002
• /
• 2012

Emission regulations have been strengthened step by step for marine engines. A noble measure is required both inside and outside of the combustion chamber. The combustion characteristics in cylinder have a very close relationship with the exhaust emission characteristics. Injection valve and nozzle hole geometry is an important factor for combustion. The study to improve the spray characteristics has concentrated on nozzle inlet geometry and nozzle hole diameter, but the exit geometry has not considered. In this study the nozzle exit angle variation was tested. The results show that the angle between $30^{\circ}$ and $60^{\circ}$ is more effective than the other cases.

• Solar Energy
• /
• v.11 no.3
• /
• pp.62-73
• /
• 1991

The purpose of the present work is to investigate the atomization characteristics and to find the available working conditions of given nozzles. Experimental investigations were carried out with the nozzles, "Delavan" and "Hago"(pressure atomizing simplex 1.25GPH), with $60^{\circ}$ and $80^{\circ}$ spray angles also at various nozzle pressures. In the present work, Sauter mean-diameter was utilized to describe the quality of the atomization. All sample droplets were microphotographed with high-contrust film at 50X magnification and analyzed by Nukiyama-Tanazawa distribution function. The $80^{\circ}$ spray angle gives better atomization function than $60^{\circ}$ spray angle, and available working conditions were set at approximately $8kg/cm^2$ nozzle pressure.