• 오토저널
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• 제5권4호
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• pp.10-16
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• 1983

액체의 미립화는 기계산업분야 뿐만 아니라, 농약살포, 화학 공학의 분무건조, 반응의 촉진, 분 체제조, 식품공업 등 폭넓게 이용되며 또한 각분야에서 그 필요성이 강조되고 있다. 특히 기계 산업분야에서는 액체연료의 분무연소(boiler, gas turbine, 자동차용engine등) 원자로 노심의 spray cooling, spray drying, spray painting 등 그 이용도는 날로 증가되는 추세에 있다. 액체를 미 립화하는 이유는 각각의 분야나 사용하는 목적에 따라 다르지만, 대별하면 다음과 같다. (1) 액체의 단위 체적당 표면적을 증대시키기 위하여 (2) 직경이 작은 입자의 필요성 (3) 균일한 입경의 액적군을 얻기 위하여 등을 들 수 있다. 액체의 미립화에 대한 요구는 산업의 발당, 대기오염, 생energy 등의 문제가 중요시됨에 따라 다양화되고 있다. 따라서 응용면에서는 atomizer의 성능개선과 설계법, 새로운 미립화방법, 상업에의 분무이용기술, 분무계측법 등의 개발이 필요하게 된다. 액체미립화에서 취급하는 사항은 그 내용에 따라 다음과 같이 분류된다. (1) 액체의 미립화기구 : 기액계면의 불안정성과 분열기구에 관한 것으로, 액체형상으로써 액주, 액막 및 액적으로 나눌 수 있다. (2) 액체의 미립화 방법과 특성 : energy의 종유와 부가방식에 따랄 나누어진다. (3) 합체, 분산, 증발 등 분무의 운동이나 열적거동 (4) 분무입경이나 운동의 계측법과 특성도시 (5) 액체미립화의 각종응용 본보에서는 상기의 각 항목중, 특히 액체의 미립화방법과 분무특성에 대해서만 말하기로 한다.

• 한국분무공학회지
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• 제11권3호
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• pp.155-160
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• 2006

Spray characteristics of charge injected 2-fluid nozzle for non-conducting liquid have been studied. Spray current, specific charge and SMD of diesel have been measured. Spray current and specific charge are proportional to applied voltage. Air flow did not effect on spray current and specific charge. SMD decreases as air flow rate increases and decreases as applied voltage increases additionally. Spray angle increases as applied voltage increases. Fine droplets are obtained by charge injected 2-fluid nozzle without charge loss.

• 농업과학연구
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• 제14권1호
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• pp.81-97
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• 1987

병충해방제(病蟲害防除)에 있어서 효율적(效率的)인 분무립자(噴霧粒子)의 크기는 $20{\mu}m$ 이내(以內)이지만 비산(飛散)의 해(害)를 감안하여 $140{\sim}200{\mu}m$를 추천하고 있다. 그러나 우리나라 수도방제기(水稻防除機)의 주종(主種)인 총포노즐의 경우 입자(粒子)크기는 $220{\sim}750{\mu}m$로 과대(過大)한 실정(實情)이다. 우리나라에서 널리 이용(利用)되고 있는 과권(過卷) 노즐의 구조(構造)를 Figure 2와 같이 고안(考案)하여 공기(空氣)를 혼합(混合)시킨 약액(藥液)을 이용(利用)함으로써 과실내(過室內)에서의 예비무화효과(豫備霧化效果), 약액(藥液)의 감소된 표면장력(表面張力) 및 점주(粘住), 분사액(噴射液)의 증가된 주파수(周波數)의 효과(效果)를 이용(利用)하여 분무립자(噴霧粒子)를 개선(改善)하고저 실시(實施)된 실험결과(實驗結果)는 다음과 같다. 분무립자(噴霧粒子) 크기는 분무압력(噴霧壓力)(본(本) 실험(實驗)에서는 $0.70kg/cm^2$부터 $6.33kg/cm^2$까지 실시(實施)) 이 증가(增加)됨에 따라서 점차로 미립화(微粒化)되었고 이 경향(傾向)은 표준(標準)노즐의 결과(結果)와 같다. 동일(同一)한 분무압력하(噴霧壓力下)에서 분무립자(噴霧粒子)의 크기 및 분포상태(分布狀態)를 표준(標準)노즐의 비교(比較)할 때 체적평균직경(體積平均直徑)이 작아졌고 입자(粒子)크기 분포(分布)도 개선(改善)되었다. 입자(粒子)크기 분포(分布)는 분무형(噴霧型)의 중심(中心)으로부터 외측(外側)으로 향(向)하면 체적평균직경(體積平均直徑)이 작아지는 현상(現象)이었다.

• 한국분무공학회지
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• 제9권3호
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• pp.35-41
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• 2004

The spray characteristics were investigated to study the effect of shroud air with swirl flow on simplex type fuel injector for gas turbine combustor. The spray tests using PDA(Phase Doppler Anemometry) technique were conducted to compare the performance of simplex atomizer with $0^{\circ},\;40^{\circ},\;50^{\circ}$ swirled-shroud air conditions. In this study. we found that the injector with strong swirled-shroud air has the better atomization Performance compared with weaker swirled and non-swirled conditions.

• 한국분무공학회지
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• 제8권2호
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• pp.7-15
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• 2003

The effects of fuel density and fuel viscosity on spray characteristics were investigated under two different gas turbine fuels and various fuel supply pressure conditions through measurement of SMD, number density and volume flux by using PDPA system in dual orifice injector for gas turbine engines. In this study, we found out that the droplet size and spray structure are strongly depend on fuel density for dual orifice injector. The spray characteristics of high density fuel in dual orifice injector are similar with the characteristics of low density fuel in single orifice injector. The shear region between primary main fuel stream and secondary main fuel stream is examined in low density fuel condition but not exist in high density fuel condition, then this shear region is very important in quality of gas turbine spray. There are worth consideration for the effect of fuel density on spray characteristics in frontal device design to improve combustion efficiency.

• 한국분무공학회지
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• 제5권1호
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• pp.13-22
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• 2000

The present study has numerically analyzed the vaporization characteristics of fuel droplets in the high temperature convective flow field. The axisymmetric governing equations for mass, momentum, energy, and species are solved by an iterative and implicite unstructured finite-volume method. The moving boundary due to vaporization is handled by the deformable unstructured grid technique. The pressure-velocity coupling in the density-variable flows is treated by the SIMPLEC algorithm. In terms of the matrix solver, Bi-CGSTAB is employed for the numerically efficient and stable convergence. The n-decane is used as a liquid fuel and the initial droplet temperature is 300K. Computations are performed for the nonevaporating and evaporating droplets with the relative interphase velocity(25m/s). The unsteady vaporization process has been simulated up to the nondimensional time, 25. Numerical results indicate that the mathematical model developed in this study succesfully simulates the main features of the droplet vaporization process in the convective environment.

• 대한기계학회논문집
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• 제12권2호
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• pp.359-372
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• 1988

본 연구에서는 두 노즐간의 거리와 분사압력을 변화시켜 하류로 전개되는 이중분무의 분무형태를 살펴보았다.

• 대한기계학회논문집B
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• 제22권8호
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• pp.1132-1140
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• 1998

The disintegration process of initial spray from high-pressure swirl injector was investigated at different injection pressures. The transient breakup phenomena that were difficult to observe at high injection pressure were easily observed at the low injection pressure of 0.4MPa. The effect of fuel remained inside a nozzle hole volume on the penetration of initial spray was also investigated. The disintegration process of initial spray could be classified four regions: the formation of mushroom shape, the first collision, the second collision, and the development of spray, The liquid film of cup shape was particularly found in the second collision region, and the growth ratio of its length and width at low and high injection pressures were compared.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.693-698
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• 2001

An experimental study was carried out with an aerated nozzle. This nozzle was well known that the performance of the atomization is better than other ones even though the supplied air pressure is lower than that of them. The purpose of this investigation is to provide the essential information of the aerated nozzle from the nozzle exit. The experimental work was performed in order to analyze the characteristics of the overall flow field from the nozzle exit. The 2-D PDPA system was used to acquire the data in the concerned region. The characteristics of the mean velocity distribution, half-width, and SMD were mainly analyzed. Also the correlation between turbulent kinetic energy and SMD was described with ALR.

• 한국분무공학회지
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• 제19권4호
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• pp.211-215
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• 2014

The main purpose of this study is to provide basic information of droplet soot generation of decane fuel. To achieve this, this paper presents the experimental results on the decane droplet combustion conducted under various ambient pressure($P_{amb}$), and oxygen concentration($O_2$) conditions. At the same time, the experimental study was conducted in terms of soot volume fraction($f_v$) and its maximum value. Also, visualization of single fuel droplet was conducted by high resolution CCD camera and ambient pressure($P_{amb}$) and oxygen concentration($O_2$) was changed by control system. It was revealed that higher ambient pressure($P_{amb}$), and oxygen concentration($O_2$) enhanced the soot generation and improved the maximum soot volume fraction( $f_v$).