• 한국분무공학회지
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• 제3권1호
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• pp.27-33
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• 1998

Correlations of drop size and velocity in a spray from the disintegration of liquid jet and liquid film from an internal mixing twin-fluid atomizer, were determined by phase Doppler method. The distribution pattern of Sauter mean diameter(SMD) in a spray was changed by a behavior of liquid flow. As smaller droplets became faster and slower easily by the surrounding conditions, the correlation between drop size and mean velocity was found to be varied as next 3 steps; firstly smaller droplets have a higher mean velocity at the area near atomizer, droplets have almost the same mean velocity and finally larger droplets have a higher mean velocity at the area far from an atomizer.

• 한국분무공학회지
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• 제4권4호
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• pp.24-29
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• 1999

In the pressure swirl atomizer, the liquid is injected through tangential passages into a swirl chamber, from which it emerges with both tangential and axial velocity components to form a thin conical sheet at the nozzle exit. This sheet rapidly attenuates, finally disintegrating into ligaments and then drops. The purpose of this study is to measure the spray characteristics according to variation of viscosity of the spray produced by the pressure swirl atomizer. The nozzle tested here were especially designed for this investigation. The discharge coefficient is determined by measuring the volume flow rate with a flow meter and the cone angle of the liquid sheets issuing from the nozzle is obtained from series of photographs of the sheet for various liquid viscosity and injection pressure. And mean drop size is measured by image processing method. It is found that the geometrical characteristics of the nozzle and the variation of viscosity were the influential parameters to determine the spray characteristics such as the cone angle, discharge coefficients and SMD.

• 한국분무공학회지
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• 제11권2호
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• pp.59-68
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• 2006

Experimental results of the metal powder production with internal mixing, internal impinging and the atomizer coupled with substrate design are presented in this paper. In a test with internal mixing atomizer, mean powder size was decreased from $37{\mu}m\;to\;23{\mu}m$ for Pb65Sn35 alloy as the gas-to-melt mass ratio was increased from 0.04 to 0.17. The particle size further reduces to $16.01{\mu}m$ as the orifice area is increased to $24mm^2$. The micrograph of the metal powder indicates that very fine and spherical metal powder has been produced by this process. In a test program using the internal impinging atomizers, the mean particle size of the metal powder was decreased from $22{\mu}m\;to\;12{\mu}m$ as the gas-to-melt-mass ratio increased from 0.05 to 0.22. The test results of an atomizer coupled with a substrate indicates that the deposition rate of the molten spray on the substrate is controlled by the diameter of the substrate, the height of the substrate ring and the distance of the substrate from the outlet of the atomizer. This in rum determines the powder production rate of the spraying processes. Experimental results indicate that the deposition rate of the spray forming material decreases as the distance between the substrate and the atomizer increases. For example, the deposition rate decreases from 48% to 19% as the substrate is placed at a distance from 20cm to 40cm. On the other hand, the metal powder production rate and its particle size increases as the subsrate is placed far away from the atomizer. The production of metal powder with mean particle size as low as $3.13{\mu}m$ has been achieved, a level which is not achievable by the conventional gas atomization processes.

• 대한기계학회논문집A
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• 제37권12호
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• pp.1473-1482
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• 2013

벨 디스크(Bell disc, 오토마이저 Atomizer)를 사용한 회전식 도장기술은 뛰어난 도료 전달효율, 도장 패턴 및 입자크기의 균일성, 스프레이 건 방식에 비해 적은 압축공기 사용량 등의 장점이 있다. 또한 회전식 분무기는 모든 페인트 재료에 적용할 수 있고 자동차 연속도장 같은 대규모 도장이 필요한 환경에 적합하다. 도장기기의 성능과 밀접하게 관계된 도장품질은 벨 디스크 표면설계에 따른 액적 크기와 균일성에 의해 결정된다. 따라서 이번 연구는 도료의 점성, 밀도, 표면친화도 등의 염료 특성이 고려된 작동하는 벨 디스크의 회전수, 직경, 표면의 각도, 무화시의 박막두께에 대한 모델링을 시행하여 표면설계 방법의 기초를 수립하였다.

• 청정기술
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• 제9권4호
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• pp.163-168
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• 2003

회전형 도장기기의 핵심 부품인 공기 터빈 및 무화 디스크 설계를 위한 기본 설계개념 및 방법을 제시하였고, 이를 이용하여 도장기기를 설계, 제작하였다. 제작된 도장기기의 회전수 및 유량의 측정 결과는 전산유체역 학적 해와 잘 일치하였다. 또한 공기 터빈 및 디스크 설계 사양에 따라 도장기기의 회전수가 현저히 변화됨을 알 수 있었고, 공기 터빈의 유로 기울기 $20^{\circ}$, 노즐 수 2개일 때의 도장기기 성능이 가장 우수하였다.

• 한국추진공학회지
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• 제12권2호
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• pp.57-65
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• 2008

가스터빈엔진에 적용할 수 있는 드럼형 회전연료노즐의 모델링을 통해 원심력이 충분한 연료분사압력을 발생시킴을 보였고, 회전연료분사의 미립화 현상에 대해 실험적으로 연구하였다. 회전연료분사의 미립화기구 및 분무특성을 이해하기 위하여 고속 회전연료노존 시험리그를 이용하여 $5,000\;{\sim}\;40,000rpm$의 영역에서 분무가시화와 PDA를 이용한 분무액적 측정을 실시하여 회전연료분무의 미립화 특징을 규명하고, 미립화성능 향상을 위해서는 회전속도증가를 통해 액적분열시점을 앞당기는 것이 중요함을 알았다.

• 한국분무공학회지
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• 제24권4호
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• pp.185-193
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• 2019

The effervescent atomizer is one of twin-fluid atomizers that aeration gas enters into bulk liquid and two-phase flow is formed in the mixing section. The effervescent atomizer requires low injection pressure and small amount of aeration gas, as compared to other twin-fluid atomizers. In this study, cold flow test was conducted to investigate the spray characteristics of aerated impinging jets. The present effervescent impinging atomizers were composed of the aerator device and like-on-like doublet impinging atomizer which had different impinging angles. To analyze the spray characteristics such as breakup length and droplet size distribution, the image processing technique was adopted by using instantaneous images at each flow condition. Non-dimensional parameters, induced by the homogeneous flow model, were used to predict the breakup length. The breakup length was decreased with the mixture Reynolds number and impinging angle increasing. The result of droplets showed that the size distribution was axisymmetric about the center of the injector and their diameter tended to decrease with increasing GLR.

• 한국분무공학회지
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• 제4권3호
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• pp.32-41
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• 1999

In this research, internal-mixing twin-fluid atomizer using sonic energy is designed and manufactured. We are trying to intimate high efficiency twin-fluid atomizer to obtain good liquid atomization in the low pressure region. Define of geometric form of atomizer, characteristics of spray is influenced by position, depth and height variation of cavity resonator, variation of sound intensity and resonant sound frequency with liquid flow rate. The liquid atomization is promoted by multi-stage disintegration of mixing flow of gas with liquid and the optimum condition of position and depth of cavity resonator according to sonic energy is obtained from the condition at a=2.5mm and L=2mm. The velocity distribution of droplets shows negative value due to recirculation region at the center of axial, and as the radial direction distance is far, the velocity distribution of droplets decrease slowly after having a maximum value. However velocity and SMD show nearly uniform distribution at the down stream and as result compared to Nukiyama and Tanasawa's equation. atomization of mixing flow with air and liquid dispersing from the outlet of the nozzle is promoted by the effect of collision at the cavity resonator.

• 한국분무공학회지
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• 제5권3호
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• pp.27-36
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• 2000

In this study, spray characteristics of a dual airblast atomizer are addressed. Three dimensional characteristics of a dual airblast atomizer with air swirl are measured to provide the significant data. The liquid flow rate was fixed at 0.06 kg/min, and atomizing air was controlled at the liquid-air mass ratio of 4.0. The performance of the spray with co-swirl and counter-swirl flow was investigated at each point in the developed spray region using a three-component phase Doppler particle analyzer. This instrument was also used to evaluate the concentration profiles. The three dimensional mean velocity were investigated of present flow characteristics of the dual airblast atomizer. In addition, drop size distributions, mean droplet size profile, and droplet concentration were analyzed to understand atomization characteristics. This experimental results can be conveniently utilized for the preliminary design of gas turbine engines for aircraft.

• International Journal of Automotive Technology
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• 제2권3호
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• pp.103-107
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• 2001

Many researches on pressure-swirl injectors due to the variety of application have been conducted on the effects of nozzle design, operating conditions, properties of liquid and ambient conditions on the flow and spray characteristics. The breakup length of conical emulsified fuel sheet resulting from pressure-swirl atomizer using in the oil burner was investigated with the digital image processing method with neat light oil and emulsion with water content of lotto% and the surfactant content of 1-3%. The injection pressure ranged from 0.1 to 1.2 MPa was selected. The various regimes for the stage of spray development within the experimental conditions selected in this study is newly suggested in terms of Ohnesorge number and injection pressure. The breakup length for both criteria show the same tendency even though the random nature of perforation and disintegration process of liquid sheet. The stage of spray development is widely different with the physical properties of liquid atomized, mainly viscosity of liquid. The breakup length decreases smoothly with increase in the injection pressure for the lower viscous liquid.