• 한국분무공학회지
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• 제21권1호
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• pp.13-19
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• 2016

Atmospheric spray characteristics were experimentally compared between liquid-gas and liquid-liquid sprays of a pintle injector. In order to study spray characteristics, water and air were used as the simulants and the visualization technic was adopted. Spray images were acquired by using a backlight method by a high-resolution CMOS camera. As a result, when the pintle opening distance increased, liquid sheets became unstabled and fluttering droplets increased. In the liquid-gas case, the breakup performance increased as the pressure of gas injected from the annular orifice increased. In the liquid-liquid case, atomization efficiency decreased as the pressure of liquid injected from the annular orifice increased. Spray angles presented a similar trend between two cases. At the same momentum ratio, the spray angle of liquid-liquid case was lower than the angle of liquid-gas case.

• 한국환경복원기술학회지
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• 제11권6호
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• pp.81-90
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• 2008

Recently, geofiber(polyester) reinforced soil was added on soil-seed mixture spray to control erosion and to improve vegetation growth on rocky slope sites. This research was conducted to compare vegetation effects and soil hardness on three types of soil-seed mixture spray on stone gabion river bank [A type : soil-seed mixture spray underlying 30cm thick sand with geofiber(geofiber reinforced soil system), B type : soil-seed mixture spray underlying 30cm thick sand without geofiber, C type : soil-seed mixture spray]. Evaluation were made concerning vegetation coverage, soil hardness and moisture content. The results of this study showed that A type system was effective for the growth of vegetation and soil hardness when compareed to B type and C type. A type and B type showed higher covering rate than C type on stone gabion river bank, and especially A type showed the highest covering rate. Soil hardness and water content were high on A type vegetation system compared to B type and C type. We noted that high soil hardness and high moisture content with geofiber(geofiber reinforced soil system) were effective both to control erosion from water current impact and to be high coverage and species of vegetation on stone gabion river bank.

• 한국전산유체공학회지
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• 제12권1호
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• pp.28-34
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• 2007

This study evaluates the performance of the packed bed scrubber and proposes the optimization of spray system for improvements of collection efficiency. The packed bed scrubber is used primarily in the semiconductor manufacturing process. The mean diameter of entering solid particles in scrubber is the submicron. The impaction between water droplets and solid particles is an important factor in removing the solid particles. Thus, the coverage area of spray system influences on the collection efficiency. The collection efficiency of a single droplet is calculated through the mathematical model and numerical calculations are performed for coverage area for each nozzle type (Droplet diameters: 500, 319.5, $289.5{\mu}m$) and injected directions (0, 15, $30^{\circ}$). In case of nozzle type 3, the collection efficiency of a single droplet is highest but the collection efficiency of spray system has lowest value because the ratio of flow rate between the gas and water is below 0.1. The results show the coverage area ratio is about 85% in the case of nozzle type 3 and downward sirection $15^{\circ}$. It was shown that a coverage area increase by two times than an existing spray system. In simulation of demister, collection efficiency by demister is predicted about 80% and the pressure drop in demister is below 3.5 Pa.

• 마이크로전자및패키징학회지
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• 제10권4호
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• pp.65-71
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• 2003

압전 세라믹스를 이용하여 약품 분사용 초음파분사 노즐을 제작하였다. 정수장의 혼화 공정에 사용되는 약품(응집제)의 고효율 분산을 위해 분사 노즐을 설계하였으며 압전세라믹을 최적화하였다. 제작된 초음파 약품 분사 노즐을 패키징하여 정수장의 약품 혼화 과정에 적용하여 약품사용의 고 효율화와 사용량 저감을 위한 연구를 진행하였다. 압전체는 실리콘으로 마감처리를 하였으며 Al으로 패키징하였다. 본 초음파 분사 노즐 시스템을 적용하여 혼화지에 실험한 결과 약품의 순간 혼화를 촉진시키는 기술로 투입 약품량을 저감시킬 수 있을 것으로 판단된다. 초음파 발진 약품 분사시, 무발진과 비교하여 대장균 제거 효율에서 현저하게 높아졌다.

• 대한기계학회논문집
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• 제17권12호
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• pp.3179-3186
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• 1993

The study on the spray characteristics of TBI(Throttle Body Injection) injector has been carried out in this paper. The objective of this study is to improve the performance of TBI injector. The increase in the injection pressure and the utilization of assisted air are considered. The spray patten of TBI injector take the hollow-cone shape with $60^{\circ}~70^{\circ}$ spray angle regardless of injection pressure and injection pulse width. SAMD(Sauter Mean Diameter) of water in TBI injector are 510-$550{\mu}m$ and 310-$370{\mu}m$ respectively when injection pressures are $0.75 kgf/cm^{2}$ and $2.8 kgf/cm^{2}$. Then SMD of gasoline is estimated 380~$410{\mu}m$ and 230~$280{\mu}m$ respectively. The improvement of spray characteristics in TBI injector can be obtained with assisted air. If $W_{A}/W_{L}$ was over 0.2, SMD of water can be made under $50{\mu}m$.

• 한국화재소방학회논문지
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• 제22권5호
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• pp.55-60
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• 2008

본 연구는 수분무 소화설비의 효용성에 대한 기초평가를 수행할 목적으로 FDS 수치시뮬레이션을 수행하였다. 화재강도(20MW, 50MW) 및 풍속의 변화에 따른 화재시 온도 및 연기농도에 대한 안전성 확보 효과를 분석하였다. 터널내 풍속이 없는 경우 수분무는 냉각효과에 의한 온도 및 연기농도 감소효과가 아주 우수하여 대피자의 안전성 확보에 효과적이었다. 화재강도가 커질수록 연기이동 억제효과는 감소한 결과를 나타났다. 또한 터널내 기류가 존재하는 경우에는 냉각효과에 의해서 연기의 성층화를 교란하며, 대피시 가시도를 저하시키는 것으로 나타났다. 따라서 수분무 소화설비는 화재발생시 대피자가 대피한 후에 이루어져야 할 것으로 판단된다.

• 설비공학논문집
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• 제25권2호
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• pp.55-63
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• 2013

For a large-scale semiconductor manufacturing clean room, the energy consumed in an outdoor air conditioning system to heat, humidify, cool and dehumidify incoming outdoor air is very large. In particular, the energy requirement to humidify outdoor air in the winter season is generally known to be high. Recently, in order to overcome the high energy consumption nature of a steam generator in a conventional steam humidification type outdoor air conditioning system, an air washer is often introduced instead of the steam generator in the outdoor air conditioning system, which can be called a water spray humidification type outdoor air conditioning system. Therefore, the assessment and comparison of the annual energy consumed in the steam humidification type and the water spray humidification type outdoor air conditioning systems deserves to be examined in order to reduce the outdoor air conditioning load of a clean room. In the present study, a numerical analysis was conducted to obtain the annual electric power consumption of the two outdoor air conditioning systems. It was shown from the comparison of the numerical results that the water spray humidification type outdoor air conditioning system can reduce about 30% of annual electric power consumption of the steam humidification type outdoor air conditioning system.

• 대한기계학회논문집
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• 제10권3호
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• pp.326-334
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• 1986

The effects of flow interaction between adjacent sprays in twin-spray system on the spatial distribution of injected liquid (water) and drop size distribution in condensable (steam) environment were carefully observed through experiments. The spatial distribution of injected liquid in twin-spray system appears to be more uniform than the simple superposition of the spatial distributions of liquid obtained from each individual spray. Drop size distribution was obtained by using the immersion sampling technique. It was found that, in the twin-spray, the larger numbers of small drops are collected throughout the spraying region due to the increase of entrainment velocity of ambient steam compared with the case of simple superposition of each individual spray. Moreover, in the overlapped portion of the twin-spray, the drop size distribution was changed also due to the collision between large drops. As a result, the behavior of twin-spray system (and eventually multiple-spray system) can not be predicted precisely by simple superposition of the behaviors of each constituting spray. Hence, for the design of multiple spray system, the effect of flow interaction between sprays should be taken into account seriously.

• 한국추진공학회지
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• 제19권1호
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• pp.61-67
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• 2015

연소기 시험 장치의 구축 시 고온의 연소 가스의 냉각은 중요한 설계요구조건이다. 물 분무(Water spray) 냉각 방식은 증발 과정에서 물의 잠열을 이용하므로, 효과적인 연소 가스 냉각이 가능하다. 본 연구에서는 연소기 시험 설비 구축 과정의 일환으로, 물 분무를 이용한 연소 가스의 냉각을 이해하기 위하여 연속방정식, 에너지 보존식과 포화 증기의 압력-온도 관계식을 이용한 1차원 해석을 수행하였다. 연소기 시험 장치에서 배출되는 고온, 고압의 연소 가스는 냉각수와의 혼합과정에서 배출가스의 온도가 낮아지며, 분무된 물의 일부는 기화하여 연소가스와 함께 배출되고, 일부는 다시 응축 되어 집수조로 모인다. 냉각수는 연소 가스의 온도를 낮춰주는 동시에, 증발된 증기는 연소기 내부의 압력을 증가시키므로 1차원 해석에서 증기의 압력-온도 관계식을 고려하여 해석을 수행하였다. 1차원 해석으로부터 연소가스의 적절한 냉각과 배기 덕트 내부의 압력의 지나친 상승을 피하기 위한 최적의 물 분무량을 확인하였으며, 물 분무 냉각 방식에 대한 물리적 이해를 얻을 수 있었다.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.31-39
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• 1999

A good atomization in uniform size brings the elevation of thermal efficiency in spray combustion, the beautiful painting on surfaces, and the economical sprinkling of chemicals. Ultrasonic atomization has been expected as a good uniform atomization mechanism due to its uniform size distribution. Influx, load, and physical properties of liquids are the effecting factors to atomize liquids. In this study, distilled water and city water are selected as reference liquids and gasoline, kerosene, and petroleum as fuel liquids. Characteristics and affinity to get the maximum effect for the ultrasonic atomization are observed by using the two ultrasonic transducers with 28kHz and 2MHz. Results show that the size distributions of liquid spray dorplet by the direct vibration method prevail over those by the aerosol method in uniform droplet size and as a whole, sizes of spray liquid droplets are increased slightly according to increasing influx in the direct vibration method and quantities of spray droplets in the aerosol method decreasing according to increasing liquid load h.