• 대한기계학회논문집B
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• 제20권6호
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• pp.1941-1947
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• 1996

Droplet size measurement technique was established for the sprayed viscous fluid by virtue of the installation of the sprayed-droplet size measurement system employing light scattering method. Atomization test results showed that the mean droplet size of the sprayed viscous fluid is decreased with the increase of the mass ratio of air to fuel and in case of the same air/fuel ratio, also with the increase of viscous fluid flow rate, and is increased with the distance from atomizer tip. Basic design data for the manufacture of external-mixing type, Y-Jet type, and internal-mixing type atomizers was acquired from the atomization tests.

• 대한기계학회논문집B
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• 제21권8호
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• pp.1056-1067
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• 1997

Present study visualized flow pattern and investigated spray characteristics of twin-fluid atomization with converging-diverging nozzles. Particle sizes were measured by using the Malvern particle analyzer, and the radial size distributions were evaluated by using the tomographic transform technique. The results show that the SMD generally increases in the radial direction at a prescribed liquid flow rate and the increasing rate in the SMD becomes gradual as atomizing gas pressure increases. The SMD decreases as the liquid flow rate increases at a fixed GLR (gas/liquid mass ratio). The atomization performance of the protrusion-type nozzle turned out to be superior to that of the flush-type. However, in the case of the protrusion-type, flow separation occurs outside the liquid delivery tube when the pressure at the gas nozzle chamber is high enough, which may deteriorate the atomization performance.

• 한국분무공학회지
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• 제23권4호
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• pp.205-211
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• 2018

Y-jet nozzle has various advantages over other twin-fluid nozzles and are used in industrial boilers. However, it costs large energy consumption because of assisted air and its design is complex. The Y-jet nozzle is consisted of a liquid and gas port and a mixing chamber. The diameter of the port and the length of the mixing chamber greatly affect spray and atomization characteristics, therefore, they are the most important factors in nozzle design. In this study, The experimental setup is consisted of a laboratory scale spray system. The characteristics of the Y-jet nozzle according to the design parameters were observed. As a result, it was found that the length of the mixing chamber did not have effect on the flow rate and the choking condition. The droplet size was measured using a Malvern type measuring device. In addition, measurements were conducted in the front and the right directions of the nozzles. Based on the results, the SMD View Ratio is defined. It is the asymmetrical design characteristics of the Y-jet nozzle.

• 한국분무공학회지
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• 제6권1호
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• pp.9-17
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• 2001

The effect of air entrainment in twin-fluid spray structure is investigated experimentally by varing the amount of itemizing air. The air entrainment is expected to affect on droplet size and velocity, droplet number density, turbulent kinetic energy and vorticity. PDA(Phase Doppler Anemometer) and PIV(Particle Image Velocimetry) system are used to measure those important factors in analyzing spray structure. The results show that spray structure consists of three distinctive regions ; the atomizing region near nozzle, characterizing strong convective effect, the central core region where droplets are accelerated, and the spray sheath region where droplets are decelerated due to air entrainment. The local air entrainment rate is largest near nozzle, characterizing strong turbulent kinetic energy and vorticity but deceases along axial distance.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.338-343
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• 2003

Computations were performed to investigate the spray characteristics of the twin fluid nozzle in three stage heavy-oil combustion burner. The burner geometry and flow conditions were provided by a burner company. The goal of the study is to estimate mean droplet size, initial velocity and spread factor of the nozzle through comparison between experiments and numerical analyses. Air stage ratio is 2:4:4 by mass, and O2 in exhaust gas is about 4 % by volume. Here, the agreement between the experiment and numerical analyses is evaluated by NOx generation. Spray characteristics will be linearly interpolated between fuel consumption rate l20L/h and 240 L/h.

• 한국분무공학회지
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• 제24권3호
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• pp.137-144
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• 2019

The Y-jet nozzle has benefits such as simple design and wide operating conditions. Because of these benefits, it is used in various combustion devices including industrial boilers. The most important variables in the design of the Y-jet nozzle are the mixing chamber length, the supply diameter of the liquid fuel and gas, and the exit orifice diameter. In addition, because of the use of a twin-fluid, optimized data is required depending on the spray condition. In this study, spray experiment was carried out under the pressure condition of 7 bar or more, which is the spraying condition used in industry. There was no change in flow rate with the length of the Y-jet nozzle mixing chamber, but the difference in SMD was confirmed. Adjusting the exit orifice diameter is most important to achieve the desired flow rate. Changes in the liquid and gas inlet port diameters ratio were found to be help improve the operating range and significant difference in SMD was observed.

• 디지털융복합연구
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• 제10권5호
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• pp.283-288
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• 2012

본 연구는 이유체 분무장치 미립화 장치 분무특성을 연구하기 위해 수행되었다. 실험 조건은 상온에서 분사압력을 5 bar에서 10 bar 까지 1 bar 간격과 송풍기로부터 공기유량은 0.5, 1.0, 2.0 mmH2O(X10-2)로 증가하였으며, 사용된 액체는 경유이다. 분무특성을 연구하기위해 SMD를 측정하였다. 이 실험으로 부터 다음과 같은 결과를 얻었다. 1. 분무 압력이 증가할수록 SMD는 점점 감소한다. 2. 압력노즐로부터 측정 거리가 증가할수록 SMD도 증가한다. 3. 송풍공기가 더해지면서 분무되는 경우의 SMD는 상대적으로 감소한 것으로 볼 수 있다. 이 연구의 결과로 알 수 있듯이, 송풍공기가 더해지는 분사 장치는 유용한 SMD의 변화를 볼 수 있다. 이는 이유체 분무장치 미립화 장치 분무특성 설계와 성능평가를 위한 중요한 지표로 사용될 수 있을 것으로 판단된다.

• 한국분무공학회지
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• 제3권2호
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• pp.14-23
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• 1998

The negative pressure as much as 10's mmHg is demanded at nozzle inside, in case of atomizing the large density molten materials. by conventional air jet nozzle. In this study, suction type fluid nozzle is designed by applying the ejector principle in order to clarify the air flow of nozzle inside, mechanism of liquid suction and liquid film formation. The results of this experimental study areas follows. Suction force of liquid is magnified by using liquid nozzle, and it is able to supply the liquid stable. Negative pressure at nozzle inside is varied by throttle angle of liquid nozzle, position and outer diameter of air jet nozzle, and have a influence on liquid suction quantity and liquid film formation.

• 대한기계학회논문집
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• 제15권6호
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• pp.2147-2159
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• 1991

본 연구에서는 가장 다순한 내부혼합형 이류체분사노즐의 기류속도, 액체유량, 노즐직경 및 혼합길이, 기액접촉각을 변화시켜 평균입경(SMD), 분무각, 입도분포, 분 무분사량분포 등을 조사하여 노즐형상에 따른 분무특성의 변화를 자세히 밝혀, 분무특 성을 조절할 수 있는 이류체분사 노즐의 설계에 대한 기초적 자료를 제시하고자 한다.

• Journal of Biosystems Engineering
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• 제27권4호
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• pp.317-326
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• 2002

Characteristics of a twin-fluid spray with ultrasonic vibration were examined in order to obtain a high efficiency of cold-fog spray of the automatic pest control machine which has been widely used in protected horticulture recently. An electrostrictive vibrator of PZT BLT and a magnetostrictive $\pi$-type vibrator were used applied as the ultrasonic transducers with a frequency of 28 kHz. All experiments were conducted in 4 methods of spray ; a conventional spray method without ultrasonic forcing, an indirect vibration method with ultrasonic forcing, an improving-quality method by ultrasonic forced within liquid, and a combined-use method with both of the indirect vibration method and the improving quality method. It was found that the ultrasonic energy increased the atomization efficiency of spray droplets about 10% and especially much more in the case of the combined-use method.