• 대한조선학회논문집
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• 제47권5호
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• pp.743-749
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• 2010

Multi-nozzle spray painting procedure of the inorganic zinc shop primer was established in order to obtain uniform film thickness. The shop primer paint prevents the corrosion of steel block during shipbuilding. When the dry film thickness of shop primer is insufficient, rust will be generated on the steel block. Otherwise, thick coating of shop primer may be a problem of weld defect. So, it is important to obtain the uniform film thickness of shop primer. The uniformity of dry film thickness is affected by spray speed, distance from spray gun to target surface and overlapping span of spray path. In order to uniformly maintain coating thickness of shop primer, the coating procedure was established based on the correlation of shop primer spray variables.

• Journal of Welding and Joining
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• 제7권3호
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• pp.55-62
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• 1989

Variation of the spray droplet velocity with spraying distance and the microstructural characteristics of spray deposits fromed by oxy-fuel thermal spraying with Ni-base alloy powder contained chrome boride for hard facing were examined. Measurements of spray droplet velocity as a function of distance from the nozzle tip were inexcellent agreement with computer simulated predictions. Optimum condition for thermal spray deposits in this experiment was found to be under #10kg/cm^2$ of acceleration gas pressure with 15cm of spraying distance. Fine microstructure and higher microhardness of the initial part of the deposits due to rapid solidification were found to be able to maintained in a thickness up to 0.4mm, and this initial microstructure and properties could be maintained throughout the thickness of a thick spray deposits by performing the multipass spraying with 0.4mm thickness of each pass.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.251-255
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• 2005

본 연구에서는 스월 인젝터의 기하학적 형상에 따른 분무특성 파악을 위해 액막두께 측정방법을 사용하였다. 액막두께 측정을 위해 특별히 제작된 인젝터를 사용하였으며, 백홀과 스월챔버 그리고 오리피스의 길이에 따른 분무특성을 확인하였다. 분무특성 파악을 위해 분사압에 따른 유량변화, 오리피스 하단의 액막두께와 분무각을 측정하였다.

• 한국분무공학회지
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• 제9권1호
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• pp.21-29
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• 2004

The flow characteristics of a swirl injector were investigated with the variation of the flow condition and geometric dimensions, such as orifice length for considering the viscous effect and tangential entry port area for considering the swirl intensity. The liquid film thickness strongly influencing on the formed drop size of the spray was measured using a new technique. The film thickness measurement technique proposed here, used the attenuation of fluorescence signal near the injector exit. The breakup length that is important for the flame location as well as the spray cone angle which influences on the ignition performance was measured using a backlit stroboscopic photography technique. From the experimental results, it is found that an increase in injection pressure decreased the film thickness and breakup length, and also enlarged the spray cone angle. A decrease in orifice length and tangential entry port area has a similar tendency of thinner film thickness, shorter breakup length and larger spray cone angle. In the present study, we proposed empirical models of the flow characteristics of the swirl injectors.

• 한국분무공학회지
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• 제7권4호
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• pp.1-8
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• 2002

This paper investigates the spray angle and the outline shape of the liquid sheet discharged from a simplex swirl nozzle. A theoretical model was proposed and the corresponding experimental data were presented for comparison. Axial and tangential velocities and thickness of the liquid sheet at the nozzle exit were also predicted. The liquid sheet thickness at nozzle exit, as well as the discharge coefficient, turned out to be a sole function of the swirl Reynolds number. However, the axial and tangential velocities at nozzle exit and the spray angle could not be expressed only with the swirl Reynolds number. The predicted outline shape and spray angle of the liquid sheet agreed reasonably with the measured data.

• Journal of Advanced Marine Engineering and Technology
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• 제24권4호
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• pp.454-459
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• 2000

Diesel engine which has high thermal efficiency is one of the major movers. Recently, as people pay attention to the environmental pollution, the emission of Diesel engine becomes an important problem. So it is needed to understand the characteristics of diesel fuel spray injected into a combustion chamber to reduce the emission. The factors which control the diesel fuel spray are the injection pressure, the nozzle diameter, the impinging angle and the variation of an ambient pressure and temperature. In this paper, the experiments were conducted in the free spray and the impinging spray with various ambient temperatures(273K, 373K, 573K). And the behaviors of the diesel fuel spray, such as penetration, spray angle and axial distance in the free spray and axial distance and spray thickness in the impinging spray were studied.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.410-415
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• 2000

A diesel engine is one of the major prime movers to its high thermal efficiency. But due to the recent attention far the environmental pollution, the emissions of diesel engine became to a important problem. So it is needed to understand the characteristics of diesel spray injected into a combustion chamber. The factor which controls the diesel spray are the injection pressure, the nozzle diameter, the impinging angle and the variation of pressure and temperature. In this paper, experiments were conducted far the variation of the environmental temperature(273k, 373k, 573k), free spray and impinging spray. And the notions of penetration, spray angle, axial distance for free spray, and axial distance, spray thickness from impinging wall fur impinging spray.

• 한국분무공학회지
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• 제12권1호
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• pp.1-10
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• 2007

The low frequency combustion instability phenomena generated by pressure drop oscillation such as propellant shake in feed line are studied. To generate the flowrate oscillation by the pressure pulsation up to 400Hz without flow discontinuities and cavitations, a hydrodynamic mechanical pulsator of rotating disk type was produced. Injection pressure conditions are 5, 7 and 9 bar and pressure fluctuation frequency conditions are 0, 4, 6 and 8 Hz. When the injection pressure was oscillated by a mechanical pulsator, the spray shape was pulsated regularly. During the pulsated state of the spray with a mechanical pulsator, the spray characteristics, such as spray angle and liquid film thickness in orifice exit, were measured and compared with those in steady state without a mechanical pulsator. Though the mean injection pressure was fixed in the steady and fluctuating state, there were some differences in all measured values, i.e. liquid film thickness and spray cone angle, between both states.

• 대한조선학회논문집
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• 제31권3호
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• pp.100-111
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• 1994

고속정은 spray를 수반하는 흐름 특성을 가지고 있다. 본 연구에서는 이러한 spray의 흐름 특성을 파악하기 위해 몇가지 실험을 수행하였다. 우선 아크릴판으로 만든 주상활주선형을 이용하여, 예인수조에서 흐름의 가시화를 수행하고, 그 기록으로부터 화상해석을 통하여 spray흐름의 방향, 유속등을 계측하였다. Spray에 의해 발생하는 모델의 양력, 항력을 구하기 위해서는 spray의 두께가 주요한 계측 항목이 된다. 본 연구에서는 운동량 이론을 이용한 새로운 spray의 두께 계측법을 제시하였다. Spray의 두께를 국부적으로 계측하여 저항성분을 구하여 적분하므로써, 본 실험모델이 받는 저항성분중 spray저항을 평가하였다. 또한 활주모델의 저면에서 압력을 계측하여 spray가 발생하는 원리를 보여 주었으며, 계측된 압력을 적분하므로써 모델에 작용하는 압력저항성분을 평가하였다.

• 한국가시화정보학회지
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• 제21권3호
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• pp.33-38
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• 2023

Spray cooling is a method of cooling high-temperature heating elements by spraying droplets. Recently, spray cooling has been proposed for use in next-generation nuclear reactors. When droplets are sprayed onto the outer wall of a heat exchanger tube, a film boiling occurs on the outer wall. Over time, the outer wall temperature decreases, and a liquid film forms on the outer wall, and the heat exchanger outer wall is subsequently cooled by the liquid film. In this case, the liquid film thickness has a great influence on the heat removal performance. In this study, an experimental study was conducted to measure the liquid film thickness distribution in a droplet spray environment. For this purpose, a method using the electrical conductivity of the liquid was adopted.