• Title/Summary/Keyword: 냉각 해석

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1-D Analysis for Water Spray Cooling of Exhaust Gas in Combustor Test Facility (물 분무를 이용한 연소가스 냉각 1차원 해석)

  • Im, Ju Hyun;Kim, Myung Ho;Kim, Yeong Ryeon
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.1
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    • pp.61-67
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    • 2015
  • The cooling of hot exhaust gas is an important issue for the construction of combustor test facility. Water spray is an effective method for exhaust gas cooling due to its large latent heat in process of evaporation. In this study, 1-D analysis has been performed based on continuity, energy conservation, and saturated vapor property to understand water spray cooling of combustion gas. In the exhaust duct of combustor test facility, the injected water decreases combustion gas temperature, and evaporates in the combustion gas. However, some of the injected water is collected in the sump due to condensation. The evaporation of water helps combustion gas cooling, but causes pressure increase inside the exhaust duct due to increase of vapor pressure. These phenomena has been analyzed by 1-D modeling in this study. From 1-D analysis, the adequate mass flow rate of water spray to cool combustion gas and to avoid excessive pressure rise inside the exhaust duct has been decided.

A Study on Pump Selecting for Oil Direct Cooling Type Power Transformer (강제송유 냉각방식 변압기 펌프선정 기준 정립에 관한 연구)

  • Kim, Seong Eon
    • Proceedings of the KIPE Conference
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    • 2014.11a
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    • pp.62-63
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    • 2014
  • 전력용 변압기에서 강제송유 냉각방식을 채택할 경우 절연유 강제 순환을 위한 펌프가 필요한데, 매 설계 시 마다 유동해석 혹은 설계 프로그램을 통해 펌프를 선정하게 되면 상당한 시간이 소요된다. 이러한 시간적 손실을 줄이고자 유동해석 및 유체 이론에 근거하여 간단하게 엑셀 시트로 프로그램화 하였다.

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A Study on the Optimum Design of Heat Sink for Radiant Heat of LED Lighting (LED 조명의 방열을 위한 히트싱크의 최적 설계에 관한 연구)

  • Jang, Han-I;Lee, Dong-Ryul
    • Proceedings of the KAIS Fall Conference
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    • 2012.05b
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    • pp.680-684
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    • 2012
  • 본 연구는 히트싱크의 효율적인 설계를 위하여 히트싱크 휜의 형상을 변화시켜 냉각성능에 대한 연구를 수행하였다. 휜의 형상을 Vertical, Round, S-Curve, Triangle의 네 가지와 휜의 개수를 16개와 64개로 설계해, 총 8가지로 설계 및 해석 하였다. 이와 같이 설계된 히트싱크는 Fluent 6.3.26 으로 수치해석 하였고, 해석 결과 약간의 형상을 변경하는 것 보다는 휜의 개수를 늘리는 것이 냉각성능을 높이는데 더 효과적인 것으로 드러났다. 히트싱크의 온도분포와 열전달계수에 대한 수치해석을 통해 휜의 개수가 64개이고 S-Curve의 형태에서 냉각성능이 가장 우수한 것으로 나타났다.

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Numerical Prediction of Spray Combustion and Film Cooling in a Liquid Rocket Engine (액체로켓 엔진의 분무연소 및 막냉각에 대한 수치해석)

  • 박태선;류철성
    • Journal of the Korean Society of Propulsion Engineers
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    • v.6 no.2
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    • pp.9-17
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    • 2002
  • For turbulent spray combustion flows a coupled numerical procedure was developed, This method was discretized by using generalized curvilinear coordinates to handle complex geometries. The preconditioning and eigenvalue rescaling techniques were employed to provide efficient convergences over a wide range of subsonic Mach numbers. The accuracy was validated by simulating the laminar cavity flow. The film cooling effect of a liquid rocket engine (KSR-III) were investigated by a spray combustion analysis. The film cooling showed a negative effect on the combustion efficiency. In the combustion chamber wall, the film cooling effect was revealed to be promoted by the production of fuel rich zone.

Detection and Evaluation of Microdamages in Composite Materials Using a Thermo-Acoustic Emission Technique (열-음향방출기법을 이용한 복합재료의 미세손상 검출 및 평가)

  • 최낙삼;김영복;이덕보
    • Composites Research
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    • v.16 no.1
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    • pp.26-33
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    • 2003
  • Utilizing a thermo-acoustic emission (AE) technique, a study on detection and evaluation of microfractures in cross-ply laminate composites was performed. Fiber breakages and matrix fractures formed by a cryogenic cooling at $-191^{\circ}C$ were observed with ultrasonic C-scan, optical and scanning electron microscopy. Those microfractures were monitored in a non-destructive in-situ state as three different types of thermo-AE signals classified on the basis of Fast-Fourier Transform and Short-Time Fourier Transform. Thus, it was concluded that real-time estimation of microfracture processes being formed during cryogenic cooling could be accomplished by monitoring such different types of thermo-AEs in each time-stage and then by analyzing thermo-AE behaviors for the respective AE types on the basis of the AE signal analysis results obtained during thermal heating and cooling load cycles.

Heater Design of a Cooling Unit for a Satellite Electro-Optical Payload using a Thermal Analysis (열해석을 이용한 위성 광학탑재체 냉각 장치의 히터설계)

  • Kim, Hui-Kyung;Chang, Su-Young;Choi, Seok-Weon
    • Aerospace Engineering and Technology
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    • v.10 no.2
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    • pp.20-28
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    • 2011
  • The electro-optical payload of a low-earth orbit satellite is thermally decoupled with the bus, which supports a payload for a mission operation. The payload has a cooling unit of FPA(Focal Plane Assembly) which has a thermal behavior increasing its temperature instantly during an operation in order to dissipate a waste heat into the space. The FPA cooling unit should include a radiator and heatpipes with a sufficient performance in worst hot condition, and a heater design to maintain its temperature above a minimum allowable temperature in the worst cold condition. In this paper, we analyzed the thermal requirements and the heater design constraints from the thermal analysis results for the current thermal design of the FPA cooling unit and the design elements of the better heater design were found.

A Numerical Prediction for the Thermo-fluid Dynamic and Missile-motion Performance of Gas-Steam Launch System (수치모사를 통한 가스-스팀 발사체계의 열유동과 탄의 운동성능 예측)

  • Kim, Hyun Muk;Bae, Seong Hun;Bae, Dae Seok;Park, Cheol Hyeon;Jeon, Hyeok Soo;Kim, Jeong Soo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.591-595
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    • 2017
  • Numerical simulations were carried out to analyze thermo-fluid dynamic and missile-motion performance by using two-phase flow model and dynamic grid system. To analyze the interaction among the hot gas, coolant, and mixture flow, Realizable $k-{\varepsilon}$ turbulence and VOF(Volume Of Fluid) model were chosen and a parametric study was performed with the change of coolant flow rate. As a result of the analysis, pressure of the canister showed a large difference depending on the presence or absence of the coolant, and also showed a dependancy on the amount of coolant. Velocity and acceleration were dependent on the canister pressure.

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Numerical Analysis of Heat Transfer and Flow Characteristics on Squealer Tip of Gas Turbine Blade (가스터빈 블레이드 팁의 열전달과 유동 특성에 대한 수치적 해석)

  • Jiao, Liu;Kang, Youngseok;Kim, Donghwa;Cho, Jinsoo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.12
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    • pp.1062-1070
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    • 2016
  • The heat transfer and flow characteristics of gas turbine blade tip were investigated in this paper by using the conjugate heat transfer analysis. The rotor inlet boundary condition profile which was taken from the first stage nozzle outlet was used to analyse. The profile contained the velocity and temperature information. This study presents the influence of tip clearance about aerodynamic loss, heat transfer coefficient and film cooling effectiveness with the squealer tip designed blade model which tip clearance variation range from 1% to 2.5% of span. Results showed that the aerodynamic loss and the heat transfer coefficient were increased when the tip clearance was increased. Especially when the tip clearance was 2% of the span, the average heat transfer coefficient on the tip region was increased obviously. The film cooling effectiveness of tip region was increasing with decreasing of the tip clearance. There was high film cooling effectiveness at cavity and near tip hole region.

Design and Thermal Analysis of Focal Plane Assembly Cooling Unit of Earth Observation Camera (저궤도 지구관측위성 주탑재체 냉각유닛 설계와 열해석)

  • Seo, Joung-Ki;Cho, Hee-Ken;Lee, Deog-Gyu;Lee, Seung-Hoon;Choi, Hae-Jin;Kang, Seok-Bong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.6
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    • pp.580-585
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    • 2009
  • Thermal analysis and design of FPA(Focal Plane Assembly)-CU(Cooling Unit) for Earth observation camera is performed. FPA-CU is the first cooling device for a spacecraft which is designed and manufactured by its own technology in Korea. FPA-CU has a special feature, TBM(Thermal Buffer Mass) which is discriminated from typical cooling devices using heat pipes and radiator. TBM can be regarded as a thermal energy reservoir and it shows thermally transient characteristics, which make it difficult to design the size and shape of TBM. In current study, a method to determine the volume and the size of TBM is proposed and validated. The transient thermal analysis for FPA-CU for 5 operational scenarios is performed and validates the final design of FPA-CU (Radiator,TBM, Heat pipe I/F). In case of an abnormal operation of a heat pipe among three radiator heat pipes, the temperature of FPA can be increased $3{\sim}4^{\circ}C$ according to the numerical simulation.

Temperature Characteristics Analysis of Major Heating Region According to Cooling Device Location of Grid-Connected Photovoltaic Inverter (계통연계형 태양광 인버터의 냉각장치 위치에 따른 주요발열부 온도특성 해석)

  • Kim, Min-Seok;Kim, Yong-Jae
    • The Journal of the Korea institute of electronic communication sciences
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    • v.9 no.7
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    • pp.799-804
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    • 2014
  • To combine to the power transmission, photovoltaic inverter is demanded, because the photovoltaic system is generated direct current power. However, photovoltaic inverter is sensitive to high temperature. In the temperature rising such as at noon and on summer, efficiency of machine is decreased due to the loss increment. Because this problem causes national energy loss according to the expanding the photovoltaic industry, countermeasure is demanded. There, in this paper, we installed a cooling system using a thermoelement regardless of the temperature. Also, we analyze the cooling effect according to the position of two fans which improve the effect maximize.