• Title/Summary/Keyword: Thermal analysis characteristics

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A Study about Flow Characteristics of Impinging Jet for Thermal Control (I) (전열제어를 위한 충돌제트의 유동특성에 관한 연구(I))

  • 김동균;김정환;배석태;김시범;이영호
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.6
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    • pp.1330-1335
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    • 2001
  • A present study is the flow characteristics of impinging jet by PIV measurement and numerical analysis. The flow characteristics of impinging jet flow are affected greatly by nozz1e inlet velocity An circular sharp edged nozzle type($45^{\circ}$ ) was used to achieve uniform mean velocity at the nozz1e inlet, and its diameter is 10 mm(d). Therefore, the flow characteristics on the impinging jet can be changed largely by the control of main flow In this parent study, we investigate the effects of inlet velocity, its variable is nozzle inlet Reynolds numbers (Re=1500, 3000, 4500, 6000 and 7500)

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Effect of the Combustor Geometries on Combustion and NOx Emission Characteristics in a Lean Premixed Micro Gas Turbine (희박예혼합 마이크로 가스터빈 연소기 형상에 따른 연소특성 및 NOx 배기특성에 관한연구)

  • Choi, Minsung;Won, Onnuri;Kim, Minkuk;Na, Jongmoon;Choi, Gyungmin;Kim, Duckjool
    • 한국연소학회:학술대회논문집
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    • 2012.11a
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    • pp.229-231
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    • 2012
  • A numerical analysis of a lean premixed combustor in a micro gas turbine was carried out to investigate the correlation between the turbulent mixing and emission characteristics on the combustor geometries. The interaction between the burners, by flow direction and momentum, significantly influenced on the turbulent mixing and combustion characteristics. The vortex which was generated by thermal expansion was observed during the combustion process, this was distinguished from the combustor geometries. The results showed that these characteristics can affect the NOx emission.

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Performance Characteristics of Tubular Linear Iduction Motor (동기형 직선유도전동기의 동작특성)

  • Lee, Eun-Ung
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.36 no.3
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    • pp.153-162
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    • 1987
  • The purpose of this paper is to analysis and develop theoretically the characteristics of tubular linear induction motor, which is a special industrial motor that generates directly thrust force from electrical power. The Poisson equation about vector potential which is created by the application of Maxwell electromagnetic equation with the speed considered, results in modified Bessel equation by the assumption that is applied to each region of the experimental motor. Vector potential, magnetic flux density, secondary current, and thrust force according to its region respectively were found out by substituting boundary condition for this equation and rearranging. Besides, a attendant materials, that is, thermal characteristic, which is one of the characteristics under the operation of experimental motor each part's magnetic flux distribution characteristics within active zone, the required time for reciprocating motion, and variation of power factor vs. a slip were found.

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Resonance characteristics and electrical properties of PZT-piezoelectric transformer (PZT계 압전변압기의 공진특성과 전기적 성질)

  • 박순태;정수태;이종헌
    • Electrical & Electronic Materials
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    • v.8 no.1
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    • pp.27-34
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    • 1995
  • The analysis of nonlinear equivalent circuit and the resonance characteristics of input current and output voltage were simulated, and their electrical properties are discussed in the transverse-type piezoelectric ceramic transformer. The nonlinear resonance characteristics of input current and output voltage showed by the thermal effect due to a higher driving current, the nonlinearity increased greatly as driving current increased. When load resistor was 100[M.ohm.], the nonlinear coefficient was -1.3. The nonlinear resonance curve of input current and output voltage for a variation of input voltage and load resistor agreed with the discussed theory. The output voltage increased nearly proportioned to input voltage when load resistors were below 50[M.ohm.], the voltage step-up ratio decreased when a load resistor was 100[M.ohm.] and their maximum value was 950.

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Characteristics of Strength and Fracture in Strength Mismatched Joint by Dynamic Loading (동적하중 하에서의 강도적 불균질부를 갖는 용접이음재의 강도 및 파괴 특성)

  • ;望月正人;大細充;;豊田政男
    • Journal of Welding and Joining
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    • v.21 no.6
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    • pp.55-63
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    • 2003
  • Welded joint generally has heterogeneity of strength, material, and fracture toughness and it is important to understand the characteristics of material strength and fracture of welded joint considering heterogeneous effect. Characteristics of strength and fracture of an undermatched joint under dynamic loading was studied by round-bar tension tests and thermal elastic-plastic analyses in this paper. The strength and fracture of the undermatched joints should be evaluated based on the effects of the strain rate and the temperature including temperature rise during the dynamic loading. The differences of fracture characteristics like such as ductile-to-brittle transition behavior are well precisely explained from the stress-strain distribution obtained by numerical analysis.

A Study on the Cooling Characteristics of Helical Type Cooling-Jacket according to the Flow Rate (나선형 냉각 자켓의 유량에 따른 냉각 특성)

  • 김태원
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1999.10a
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    • pp.231-235
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    • 1999
  • Cooling characteristics of cooling jacket for spindle system with built-in motor are studied. for the analysis, three dimensional model for the cooling jacket is built by using finite volume method. The three dimensional model includes the estimation on the amount of heat generation of bearing and built-in motor and the thermal characteristic values such as heat transfer coefficients on the boundary. The temperature distributions and the cooling characteristics are analyzed by using the commercial software FLUENT. Numerical results show that stream-wise cross section area and flow rate are important factors for cooling characteristics of cooling jacket. Cooling performance of cooling jacket is good in condition that stream-wise cross section's horizontal length is close to its vertical one and flow rate is high. This results show that heat transfer is dominated by velocity profile and heat transfer area.

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Numerical Analysis on the Flow Field and Heat Transfer Characteristics of Longitudinal Vortices in Turbulent Boundary Layer - On the Common Flow Up - (3차원 난류경계층 내에 존재하는 종방향 와동의 유동장 및 열전달 특성에 관한 수치해석(II) - Common Flow Up에 관하여 -)

  • Yang Jang-Sik
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.9
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    • pp.799-807
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    • 2005
  • The flow characteristics and the heat transfer rate on a surface by the interaction of a pair of vortices are studied numerically. To analyze the common flow up produced by vortex generators in a rectangular channel flow, the pseudo-compressibility viscous method is introduced into the Reynolds-averaged Navier-Stokes equation for 3-dimensional unsteady, incompressible viscous flows. To predict turbulence characteristics, a two-layer $k-\varepsilon$ turbulence model is used on the flat plate 3-dimensional turbulence boundary The computational results predict accurately Reynolds stress, turbulent kinetic energy and flow field generated by the vortex generators. The numerical results, such as thermal boundary layers, skin friction characteristics and heat transfers, are also reasonably close to the experimental data.

A Study about Flow Characteristics of Impinging Jet for Thermal Control (전열제어를 위한 충돌제트의 유동특성에 관한 연구)

  • 김동균;김정환;배석태;김시범;이영호
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2001.05a
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    • pp.34-39
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    • 2001
  • A present study is the flow characteristics of impinging jet by PIV measurement and numerical analysis. The flow characteristics of impinging jet flow are affected greatly by nozzle inlet velocity. An circular sharp edged nozzle type($45^{\circ}$) was used to achieve uniform mean velocity at the nozzle inlet, and its diameter is 10mm(d). Therefore, the flow characteristics on the impinging jet can be changed largely by the control of main flow. In this parent study, we investigate the effects of inlet velocity, its variable is nozzle inlet Reynolds numbers(Re=1500m 3000, 4500, 6000 and 7500)

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The combustion characteristics of vehicle upholsteries

  • Park, Hyung-Ju;Kang, Young-Goo;Kim, Hong
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 1997.11a
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    • pp.211-218
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    • 1997
  • Five parts of vehicle upholsteries were sampled to determine its combustion characteristics. Oxygen Indexer, Smoke chamber, Differential Scanning Calorimetry(DSC) are applied as the analysis apparatus. All LOI values of samples appear less than 21. The combustion phenomena of vehicle upholster primarily depends on properties of each layer material. The amount of smoke generated is the experiment reached the maximum value within 30-90sec after ignition. The experimental results of combustion characteristics and DSC of H/Line also indicated that the layer of foam was melt first and it caused the propagation of flame through the sample. The combustion characteristics of multi layer materials primarily depend on thermal characteristic of single layer material.

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Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.