• 제목/요약/키워드: thermal dynamics

검색결과 710건 처리시간 0.023초

Design and Analysis of Permanent Magnet Synchronous Generator Considering Magnetically Coupled Turbine-Rotor System

  • Kim, Byung-Ok;Choi, Bum-Seog;Kim, Jeong-Man;Cho, Han-Wook
    • Journal of Electrical Engineering and Technology
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    • 제10권3호
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    • pp.1002-1006
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    • 2015
  • In this paper, design and analysis of permanent magnet synchronous generator for ocean thermal energy conversion (OTEC) considering magnetically coupled turbine-rotor system is discussed. In particular, the rotor dynamics considering bearing span and journal shaft diameter is highlighted. The two topologies of permanent magnet synchronous generator with magnetic coupling are employed for comparison of computed rotor dynamics and generating characteristics. The analysis results show that the critical speed of the turbine-rotor system is higher when the rotor is coupled by magnetically coupling. Finally, the experimental results confirmed the validity of the proposed design and analysis scheme and successful development.

COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF THE CANADIAN DEUTERIUM URANIUM MODERATOR TESTS AT THE STERN LABORATORIES INC.

  • KIM, HYOUNG TAE;CHANG, SE-MYONG
    • Nuclear Engineering and Technology
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    • 제47권3호
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    • pp.284-292
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    • 2015
  • A numerical calculation with the commercial computational fluid dynamics code CFX-14.0 was conducted for a test facility simulating the Canadian deuterium uranium moderator thermal-hydraulic. Two kinds of moderator thermal-hydraulic tests at Stern Laboratories Inc. were performed in the full geometric configuration of the Canadian deuterium uranium moderator circulating vessel, which is called a calandria tank, housing a matrix of horizontal rod bundles simulating calandria tubes. The first of these tests is the pressure drop measurement of a cross flow in the horizontal rod bundles. The other is the local temperature measurement on the cross section of the horizontal cylinder vessel simulating the calandria system. In the present study, the full geometric details of the calandria tank are incorporated in the grid generation of the computational domain to which the boundary conditions for each experiment are applied. The numerical solutions are reviewed and compared with the available test data.

시일 동특성에 미치는 열응력의 영향에 관한 연구 (The Effects of Thermal Stress on Seal Dynamics)

  • 양보석
    • Tribology and Lubricants
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    • 제7권2호
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    • pp.36-40
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    • 1991
  • The dynamic characteristics of the annular pressure seal employed in pump have been theoretically deduced with consideration of the effects of elastic deformation due to the thermal stress. The thermal deformation is developed for the two-dimensional steady thermal stress distribution in a infinite circular cylinder subject to heating of the seal and shaft surface into the surrounding fluid. To demonstrate this analysis, the effects of thermal stress on rotordynamic coefficients and logarithmic decrement for annular plain seals was shown.

적응제어방식 성능비교를 위한 실험실용 프로세스의 제작 및 실험 (Manufacture and experiments of thermal process for comparative study of adaptive control)

  • 주성준;공재섭;박용식;김영철;양홍석
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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    • pp.333-338
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    • 1990
  • Most verification of improvements for adaptive control schemes are. dependent on computer simulations, but these computer simulations have much limitation, because (if complex actual conditions of system. This paper is concerned with the constructions of a thermal process system for experiments with various control schemes. This thermal process system is composed of a water tank, PC-XT, AD/DA converters power supply and thermal sensors. We estimate. the algorithms of pole-assignment adaptive control in the manifold disturbances and environments, changing system dynamics. The system equations for thermal press are included.

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단상 LSPM의 열해석 모델링 및 특성 해석 (Thermal modeling and analysis of single phase LSPM)

  • 함상환
    • 전기학회논문지
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    • 제64권3호
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    • pp.411-416
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    • 2015
  • This paper presents the thermal modeling and analysis of Line power Start Permanent magnet Motor (LSPM). Thermal analysis of electrical machines is important because temperatures that are consistently too high will reduce the life time of machines and may lead to serious failure. Coefficients of convection are calculated according to the types of operating conditions. And computational fluid dynamics (CFD) technique is performed in order to predict thermal characteristic. The results are compared to the test results.

Modification of DC Flashover Voltage at High Altitude on the Basis of Molecular Gas Dynamics

  • Liu, Dong-Ming;Guo, Fu-Sheng;Sima, Wen-Xia
    • Journal of Electrical Engineering and Technology
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    • 제10권2호
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    • pp.625-633
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    • 2015
  • The effect of altitude on thermal conduction, surface temperature, and thermal radiation of partial arc was investigated on the basis of molecular gas dynamics to facilitate a deep understanding of the pollution surface discharge mechanism. The DC flashover model was consequently modified at high altitude. The validity of the modified DC flashover model proposed in this paper was proven through a comparison with the results of high-altitude simulation experiments and earlier models. Moreover, the modified model was found to be better than the earlier modified models in terms of forecasting the flashover voltage. Findings indicated that both the thermal conduction coefficient and the surface thermodynamics temperature of partial arc had a linear decrease tendency with the altitude increasing from 0 m to 3000 m, both of which dropped by approximately 30% and 3.6%, respectively. Meanwhile, the heat conduction and the heat radiation of partial arc both had a similar linear decrease of approximately 15%. The maximum error of DC pollution flashover voltage between the calculation value according to the modified model and the experimental value was within 6.6%, and the pollution flashover voltage exhibited a parabola downtrend with increasing of pollution.

M형 Ba-Ferrite에서 Fe 이온의 열 진동에 관한 연구 (The Thermal Dynamics of Fe Ion on the M-type Ba-ferrite)

  • 서정철;김진수;최정완
    • 한국자기학회지
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    • 제21권1호
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    • pp.5-9
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    • 2011
  • M형 Ba-ferrite 결정에서 5가지 자리에 위치한 Fe 이온의 열 진동에 관하여 M$\ddot{o}$ssbauer 분광법과 Raman 분석으로 연구하였다. 결정의 c-축 방향을 기준으로 감마선을 여러 방향으로 조사하여 각 방향에 대한 열진동의 형태를 측정 분석하였다. 특히 2b 자리에서 c-축 방향의 진동은 다른 방향 보다 매우 활발하여 M$\ddot{o}$ssbauer 공명 흡수에 큰 변화를 일으키고 있으며 Raman 측정에서도 2b 자리의 진동이 매우 크게 나타나는 특이한 성질을 나타내고 있다.

Transport Properties of Lennard-Jones Mixtures: A Molecular Dynamics Simulation Study

  • Lee, Song-Hi
    • Bulletin of the Korean Chemical Society
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    • 제29권3호
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    • pp.641-646
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    • 2008
  • Equilibrium molecular dynamics simulations in a canonical ensemble are performed to evaluate the transport coefficients of several Lennard-Jones (LJ) mixtures at a liquid argon states of 94.4 K and 1 atm via modified Green-Kubo formulas. Two component mixture of A and B is built by considering the interaction between A and A as the attractive (A) potential, that between A and B as the attractive potential (A), and that between B and B as the repulsive potential (R), labelled as AAR mixture. Three more mixtures - ARA, ARR, and RAR are created in the same way. The behavior of the LJ energy and the transport properties for all the mixtures is easily understood in terms of the portion of attractive potential (A %). The behavior of the thermal conductivities by the translational energy transport due to molecular motion exactly coincides with that of diffusion constant while that of the thermal conductivities by the potential energy transport due to molecular motion is easily understood from the fact that the LJ energy of AAR, ARR, and RAR mixtures increases negatively with the increase of A % from that of the pure repulsive system while that of ARA changes rarely.

분자동역학법을 이용한 초격자 내부의 경계면 열저항의 해석 (Analysis on Thermal Boundary Resistance at the Interfaces in Superlattices by Using the Molecular Dynamics)

  • 최순호;이정혜;최현규;윤석훈;오철;김명환
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 춘계학술대회
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    • pp.1382-1387
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    • 2004
  • From the viewpoint of a macro state, there is no thermal boundary resistance (TBR) at an interface if both surfaces at an interface are perfectly contacted. However, recent molecular dynamics (MD) studies reported that there still exists the TDR at the interface in an ideal epitaxial superlttice. Our previous studies suggested the model to predict the TBR not only quantitatively also qualitatively in superlattices. The suggested model was based on the classical theory of a wave reflection, and provided highly satisfactory results for an engineering purpose. However, it was not the complete model because our previous model was derived by considering only the effects from a mass ratio and a potential ratio of two species. The interaction of two species presented by the Lennard-Jones (L-J) potential is governed by the mutual ratio of the masses, the potential well depths, and the diameters. In this study, we performed the preliminary simulations to investigate the effect resulting from the diameter ratio of two species for the completion of our model and confirmed that it was also a ruling factor to the TBR at an interface in superlattices.

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열에너지 저장을 위한 지하 암반공동 내 열성층화 거동에 대한 수치해석적 연구 (Numerical Study on the Thermal Stratification Behavior in Underground Rock Cavern for Thermal Energy Storage (TES))

  • 박도현;김형목;류동우;최병희;선우춘;한공창
    • 터널과지하공간
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    • 제22권3호
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    • pp.188-195
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    • 2012
  • 본 연구에서는 전산유체역학 코드인 FLUENT를 이용하여 열에너지 지하 저장을 위한 최초의 대규모 암반공동인 스웨덴 Lyckebo 저장소의 열성층화 거동을 분석하였다. 열에너지의 반복적인 저장 및 생산으로 인한 주변 암반의 히팅이 열성층화와 열손실에 미치는 영향을 분석하기 위해 암반의 온도조건을 달리하여 열전달 해석을 수행하였으며, 성층화 지수를 토대로 열에너지 저장 후 시간경과에 따른 열성층화의 변화를 정량적으로 분석하였다. 분석결과, 주변 암반이 히팅되지 않은 저장공동의 초기 운영단계에서는 시간경과에 따라 저장된 열에너지의 성층화가 빠르게 저하되는것으로 나타났으며, 저장공동의 운영기간이 늘어남에 따라 주변 암반의 히팅으로 인해 열성층화의 변화 및 열손실이 줄어드는 것을 확인하였다.