• Title/Summary/Keyword: 액적직경

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Indirect Verification of the Icing Test Condition Using Ice Thickness (얼음두께를 이용한 결빙시험조건의 간접 확인기법)

  • Kim, Yoo Kyung;Park, Nameun;Choi, Gio
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.11
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    • pp.944-951
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    • 2018
  • Artificial icing test and wind tunnel test can be performed to reduce the development period when a rotorcraft is required operation under icing situations. Artificial icing test of the KUH(Korean Utility Helicopter) was performed in advance to verify anti-icing and de-icing performance before natural icing test. Although high-precision sensor, the CCP(Cloud Combination Probe) is used to measure icing test condition parameters such as LWC(Liquid Water Content) and MVD(Median Volume Diameter), the measured values need to be verified in various methods due to the possibility of uncertainties which are the test atmosphere environment, sensor errors, and etc. The calculated LWC from the ice thickness cumulated on the fuselage of the KUH is compared to the measured value by CCP, and the results show the effective indirect method to check the test conditions.

Study on the Combustion Characteristics of Methanol Fuel Droplet (Methanol 연료 액적의 연소 특성에 관한 연구)

  • Suh, Hyun Kyu
    • Journal of ILASS-Korea
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    • v.19 no.3
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    • pp.109-114
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    • 2014
  • The main purpose of this study is to provide basic information of droplet burning, extinction process and flame behavior of methanol fuel and improve the ability of theoretical prediction of these phenomena. For the improved understanding of these phenomena, this paper presents the experimental results on the methanol droplet combustion conducted under various initial droplet diameters ($d_0$), ambient pressure ($P_{amb}$), and oxygen concentration ($O_2$) conditions. To achieve this, the experimental study was conducted in terms of burning rate (K) with normalized droplet diameter ($d/d_0$), flame diameter ($d_f$) and flame standoff ratio (FSR) under the assumptions that the droplet combustion can be described by both the quasi-steady behavior for the region between the droplet surface and the flame interface and the transient behavior for the region between the flame interface and ambient surrounding.

Effect of liquid viscosity on the degree of uniformity of drops from swirl spray nozzles (와류 분무 노즐에 의해 형성되는 액적들의 균일도에 액체의 점도가 미치는 영향)

  • 이상용;김인구;조한권
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.3
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    • pp.538-546
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    • 1989
  • Effect of liquid viscosity was studied experimentally on the drop size distributions of the liquid sprays from swirl atomizers. Glycerine-Water mixtures were used as test fluids for the experiments. Drop sizes of the liquid sprays were measured with the light scattering method. The concept of the standard deviation was introduced to represent the degree of uniformity of the drop size distributions. Experimental results show that the spray drops become coarser and less uniform with the liquid of higher viscosity. The effect of viscosity on the Sauter mean diameter and the standard deviation appeared to be more significant with the lower injection pressure. It was also confirmed that the Sauter mean diameter increases with the increase of the liquid viscosity and with the decrease of the injection pressure.

Two-Dimensional Distribution of Spray Droplets Emanating from an Injector of Liquid-Propellant Thruster (액체추진제 추력기 인젝터 분무액적의 2차원 공간분포)

  • Jung, Hun;Kim, Jin-Seok;Kim, Jeong-Soo;Kim, Sung-Cho;Park, Jeong;Jang, Ki-Won;Su, Hyuk
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.11a
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    • pp.135-138
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    • 2007
  • Two-dimensional distribution characteristics on the spray droplets emanating from an injector employed in a liquid-propellant thruster are investigated through dual-mode phase Doppler anemometry (DPDA). Spray-breakup characteristic parameters such as spray droplet velocity, turbulent intensity, Sauter mean diameter (SMD), number density, and volumetric flux are quantified to scrutinize the macroscopic behavior of injector-spray breakup. The present study will be able to contribute to the comprehension for performance features of the thruster in current use and to the design engineering of a brand-new thruster as well.

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Fabrication of Polymeric Microcapsules in a Microchannel using Formation of Double Emulsion (마이크로채널 내 이중유화 액적 형성을 통한 마이크로캡슐 제조)

  • Nam, Jin-Oh;Choi, Chang-Hyung;Kim, Jongmin;Kang, Sung-Min;Lee, Chang-Soo
    • Korean Chemical Engineering Research
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    • v.51 no.5
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    • pp.597-601
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    • 2013
  • In this study, we present simple microfluidic approach for the synthesis of monodisperse microcapsules by using droplet-based system. We generate double emulsion through single step in the microfluidic device having single junction while conventional approaches are limited in surface treatment for the generation of double emulsion. First, we have injected disperse fluid containing FC-77 oil and photocurable ethoxylated trimethylolpropane triacrylate (ETPTA) and water containing 3 wt% poly(vinyl alcohol) (PVA) as continuous phase into microfluidic device. Under the condition, we easily generate double emulsion with high monodispersity by using flow focusing. The double emulsion droplets are transformed into microcapsules under the UV irradiation via photopolymerization. In addition, we control thickness of double emulsion's shell by controlling flow rate of ETPTA. We also show that the size of double emulsions can be controlled by manipulation of flow rate of continuous phase. Furthermore, we synthesize microcapsules encapsulating various materials for the application of drug delivery systems.

Numerical Simulation on a Reacting Flow Field with Various Injection conditions (소형가스터빈용 인젝터의 분무 특성에 따른 반응 유동장 전산 해석)

  • Kim, Sei-Hwan;Jeung, In-Seuck;Park, Hee-Ho;Na, Sang-Kwon
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.300-303
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    • 2010
  • This work shows the result of numerical simulation on a reacting flow by varying atomization properties which can be obtained from a injector for a small and low power aircraft gas turbine engine. Because the atomization properties mainly affect on the performance of the engine, a lot of efficiency tests are needed when a new injector is developed. Nowadays researches has been actively performed using computational analysis. Using commercial package CFD-ACE+, basic studies on the reacting flow field have been conducted. Those results show that the reaction rate is increased when higher pressure and wider angle spray condition are used. More smaller parcels can also enhance the fuel-air reaction.

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LES on breakup and atomization of a liquid jet into cross turbulent flow in a rectangular duct (사각 덕트내 난류 횡단류 유동장에 분사되는 액체 제트의 분열과 미립화에 관한 LES 해석)

  • Yoo, Young-Lin;Han, Doo-Hee;Sung, Hong-Gye;Jeon, Hyuk-Soo;Park, Chul-Hyun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.4
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    • pp.290-297
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    • 2016
  • A two-phase Large Eddy Simulation(LES) has been conducted to investigate breakup and atomization of a liquid jet in a cross turbulent flow in a rectangular duct. Gas-droplet two-phase flow was solved by a coupled Eulerian-Lagrangian method which tracks every individual particles. Effects of liquid breakup models, sub-grid scale models, and a order of spatial discretization was investigated. The penetration depth in cross flow was comparable with experimental data by varying breakup model and LES scheme. SMD(Sauter Mean Diameter) distribution downstream of jet was analyzed.

Effect of Ultrasonic Frequency on the Atomization Characteristics of Single Water Droplet in an Acoustic Levitation Field (음향 부양장(acoustic levitation field)에서 초음파 주파수(ultrasonic frequency)에 따른 단일 액적의 미립화 특성)

  • Suh, Hyun Kyu
    • Journal of ILASS-Korea
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    • v.18 no.3
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    • pp.126-131
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    • 2013
  • This paper describes the effect of ultrasonic frequency(f) on the atomization and deformation characteristics of single water droplet in an acoustic levitation field. To achieve this, the ultrasonic levitator that can control sound pressure and velocity amplitude by changing frequency was installed, and visualization of single water droplet was conducted with high resolution ICCD and CCD camera. At the same time, atomization and deformation characteristics of single water droplet was studied in terms of normalized droplet diameter($d/d_0$), droplet diameter(d) variation and droplet volume(V) variation under different ultrasonic frequency(f) conditions. It was revealed that increase of ultrasonic frequency reduces the droplet diameter. Therefore, it is able to levitate with low sound pressure level. It also induces the wide oscillation range, large diameter and volume variation of water droplet. In conclusion, the increase of ultrasonic frequency(f) can enhance the atomization performance of single water droplet.

Atomization Effect of Supersonic Liquid Jet by a Nozzle L/d of Subscale High-Pressure Injection System (축소형 초고압 분사 시스템의 노즐 L/d에 따른 초음속 액체 제트의 미립화 특성)

  • Shin, Jeung-Hwan;Lee, In-Chul;Kim, Heuy-Dong;Koo, Ja-Ye
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.04a
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    • pp.196-199
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    • 2011
  • Subscale high-pressure injection system which use two-stage light gas gun composed with high-pressure tube, pump tube and launch tube can make supersonic liquid jet. The supersonic liquid jet enhances droplet atomization by shockwave in front of the jet. In this study, the experiments was executed to identify the atomization characteristics of the supersonic liquid jet using straight cone nozzle. SMD which presents the atomization characteristics was decreased from $151.2{\mu}m$ to $52.25{\mu}m$ by increasing of L/d.

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Variable Orifice De-super Heater for LNG Carrier or Power Plant (LNG선용 / 발전설비용 가변 오리피스형 과열도)

  • Choi, Du-Yeal;Lee, Joung-Soo;Choi, Hyun-Kue;Choi, Soon-Ho
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2005.11a
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    • pp.210-211
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    • 2005
  • Desuperheater is a passive device to control the temperature of steam in various plants. However, in spite of its simple structure, the accurate prediction of a desuperheater is very difficult because there are many designed factors for the design of a desuperheater. In this study, the theory of heat transfer phenomena in a desuperheater was developed and the various design factors are evaluated. As a results, we confirmed that the droplet size of 30 - 200 is best effective for the performance of a desuperheater.

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