• Title/Summary/Keyword: Heat intensity

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An Experimental Study on the Thermal Properties of High Strength Concrete in the Range of $40{\sim}100MPa$ at High Temperature (고온시 $40{\sim}100MPa$ 범위의 콘크리트 열적특성에 관한 실험적 연구)

  • Kim, Heung-Youl;Jeon, Hyun-Kyu
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.425-428
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    • 2006
  • In order to estimate the reduction of laodbearing capacity, followed by the attributive change of heat while high strength concrete structure is revealed on fire it is necessary to evaluate, it is necessary to evaluate the property of material under high temperature such as thermal conductivity, specific heat, compressive strength, modulus of rigidity and diminution figure. Therefore, this study is for the purpose of presenting evaluation data for the analysis of thermal behavior about the high strength concrete material under high temperature, through the experiment by manufacturing concrete(40, 50, 60, 80, 100 MPa) commonly used in the construction field. As a result of the study, in the case of physical attribute, it demonstrates a greater fluctuation of change than the one of 30 MPa concrete. In case of specific heat, the high strength concrete, shown the serious diminution between $500{\sim}600^{\circ}C$, presents the thermal change area corresponding to the change of high strength concrete. In compressive strength, regardless of intensity of concrete, all of them show the first intensity loss between normal temperature and $100^{\circ}C$, the dramatic loss beyond $400^{\circ}C$. The concrete weighing above 50 MPa shows a twice lower dramatic intensity loss than the one weighing $30{\sim}40MPa$. The concrete ranging from $60{\sim}80MPa$, shows the biggest diminution of modulus of elasticity under $400^{\circ}C$, which implies the structural unstability of temperature.

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Determination of thermal Stress Intensity Factors for General Cusp-Crack Shaped Rigid Inclusion (일반 형상의 커프스형 강체균열에 대한 열응력세기계수 결정)

  • 이강용;장용훈
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.6
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    • pp.1216-1220
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    • 1992
  • In case that a general cusp-crack shaped inclusion expressed in a polynominal form of conformal mapping function exists in a two dimensional elastic body under uniform heat flow, the complex potential and thermal stress intensity factors are derived. Two thermal boundary conditions are considered, one an insulated rigid inclusion and the other a rigid inclusion with fixed boundary temperature. The previous solutions of the thermal stress intensity factors for symmetrical airfoil and lip type rigid inclusions are obtained from the general solution of the thermal stress intensity factors.

용접부 쉐브론노치 형상에 대한 균열전파 특성

  • 김엽래
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1996.10a
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    • pp.194-197
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    • 1996
  • The high-strength aluminum alloy 7075-T651 was used to observe the fatigue-crack-propagation behavior for the various stress ratios with constant amplitude loading and thus to predict the fatigue life. With a chevron notch in the specimen the fatigue-crack-propagation behavior of through crack was investigated. Crack propagation behavior of through crack in the depth direction and crack growth of weldments were experimentally studied. Base material heat affected zone and weld material were considered in the fracture of weldments. The change of crack-propagation length with respect to several parameters such as stress intensity factor range(ΔK) effective stress intensity factor range(ΔKeff)ration of effective stress intensity factor range(U) stress intensity factor of crack opening point(K op) maximum stress intensity factor(K max) and number of cycles(Nf)was determined. The crack length of through crack of weldments was 2.4mm and the remaining part was a base material. The experiment was accomplished by making the crack propagate near the base material.

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THE COMBUSTION CHARACTERISTICS OF THE CATALYTIC HEAT EXCHANGER WITH FIN TUBES (핀 튜브를 이용한 촉매 열 교환기의 연소특성)

  • Yu, Sang-Phil;Seo, Yong-Seog;Cho, Sung-June;Kang, Sung-Kyu
    • 한국연소학회:학술대회논문집
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    • 2000.05a
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    • pp.169-177
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    • 2000
  • The catalytic heat exchanger, which integrates two functions of heat generation and heat exchange into one equipment, was designed and its characteristics were investigated by the experiment and numerical simulation. The surface of the fin tube was deposited with Pd catalyst. The conversion of the mixture in the catalytic heat exchanger was more significantly affected by the inlet velocity of the mixture than by the inlet temperature and equivalence ratio of the mixture. It was found that the catalytic surface area of the fin tubes should be sufficiently increased to make the combustion intensity of the catalytic heat exchanger as high as possible. Results showed that the fin tubes, placed in the triangularly staggered form, should be adjusted so that the mixture flows uniformly over all the catalytic fin surfaces. Numerical simulation results demonstrated that the flow pattern of the mixture significantly affected the conversion of the mixture.

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Real Time Estimation in 1-Dimensional Temperature Distribution Using Modal Analysis and Observer (모드해석과 관측기를 이용한 1차원 온도분포의 실시간 예측)

  • An, Jung-Yong;Park, Yeong-Min;Jeong, Seong-Jong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.2
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    • pp.195-201
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    • 2001
  • An inverse heat conduction problem(IHCP) arises when unknown heat fluxes and whole temperature field are to be found with temperature measurements of a few points. In this paper, observers are proposed as solution algorithm for the IHCP. A 1-dimensional heat transfer problem is modeled with modal analysis and state space equations. Position of the heat source is estimated through test heat inputs and the autocorrelation among a few of temperature data. The modified Bass-Gura method is used to design a state observer to estimate the intensity of heat source and the whole temperature field of a 1-dimensional body. To verify the reliability of this estimator, analytic solutions obtained from the proposed method are compared.

Experimental Study of Radiation Heat Flux for the Pool and Spill Fire in Petroleum Storage Tanks (석유류 저장 탱크에서의 액면 및 유츌화재에 대한 복사열의 실험적 연구)

  • Kim, Hong;Park, Hyung-Ju
    • Journal of the Korean Society of Safety
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    • v.19 no.1
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    • pp.88-93
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    • 2004
  • This experimental study was carried out to evaluate effect of the radiation heat flux for the pool and spill fire in petroleum storage tanks, which were made form steel. Each of them had the capacity of 250, 2500 and 25000 liter, respectively. The effects of the radiation heat flux are as follows; 1) The intensity of radiation heat flux from a flame decreased exponentially with increasing distance from outside wall of tanks, and increased significantly with surface area of tank and dyke. 2) In the case of 25000L tank, the radiation heat flux was about max. 98.9kW/$m^2$ in 1m from wall of tank. 3) The distance, that was able to ignite wood or plastics by radiation heat flux of approximately 12.5kW/$m^2$, was about 3.14m from wall of 25000L tank.

Stress Intensity Factors for Axial Cracks in CANDU Reactor Pressure Tubes (CANDU형 원전 압력관에 존재하는 축방향 균열의 응력확대계수)

  • Lee, Kuk-Hee;Oh, Young-Jin;Park, Heung-Bae;Chung, Han-Sub;Chung, Ha-Joo;Kim, Yun-Jae
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.7 no.1
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    • pp.17-26
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    • 2011
  • CANDU reactor core is composed a few hundreds pressure tubes, which support and locate the nuclear fuels in the reactor. Each pressure tube provides pressure boundary and flow path of primary heat transport system in the core region. In order to guarantee the structural integrity of pressure tube flaws which can be found by in-service inspection, crack growth and fracture initiation assessment have to be performed. Stress intensity factors are important and basic information for structural integrity assessment of planar and laminar flaws (e. g. crack). This paper reviews and confirms the stress intensity factor of axial crack, proposed in CSA N285.8-05, which is an fitness-for-service evaluation code for pressure tubes in CANDU nuclear reactors. The stress intensity factors in CSA N285.8-05 were compared with stress intensity factors calculated by three methods (finite element results, API 579-1/ASME FFS-1 2007 Fitness-For-Service and ASME Boiler and Pressure Vessel Code Section XI). The effects of Poisson's ratio and anisotropic elastic modulus on stress intensity factors were also discussed.

Thermal Stress Intensity Factors for Traction Free Cusp Cracks (트랙션이 없는 커스프 균열의 열응력세기계수에 관한 연구)

  • 이강용;최흥섭
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.2
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    • pp.286-294
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    • 1988
  • The thermal stress intensity factors (TSIF's) for the cusp cracks such as hypocycloid crack, symmetric airfoil crack and symmetric lip crack are determined by using Bogdanoff's complex variable approaches in plane thermoplasticity. The results are expressed in terms of the periodic functions of the direction of uniform heat flow. The TSIF's are shown to be sensitive to both the direction of uniform heat flow and be thermal boundary conditions. It is also shown that Fourence's solutions for an insulated circular hole and Sih's solutions for an insulated Griffith crack are derived from the results of the stress and displacement fields for the hypocycloid crack and the TSIF's for the various cusp cracks, respectively.

Spectral Weighted-Sum-of-Gray-Gases Modeling of Narrow Band for Prediction of Radiative Heat Transfer Induced from Liquid Engine Plume (액체 엔진 플룸 복사 열전달 예측을 위한 파장별 회체가스 중합법의 좁은밴드 적용)

  • Ko, Ju-Yong;kim, In-Sun
    • Aerospace Engineering and Technology
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    • v.8 no.1
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    • pp.17-25
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    • 2009
  • The precise calculation of gas absorption coefficient in the radiative transfer equation is very important to the prediction of radiative heat transfer induced from liquid engine plume in view of base insulation design. For this purpose, the WNB model for gas absorption coefficient is described with the selection of important parameters and then the calculated results are compared with those of SNB model for validation. Total emissivity, narrow band averaged intensity and total intensity are calculated and compared to the results of SNB model. As results, the total emissivity and the total intensity are well matched within 3.1% and roughly 5 % error, respectively. Moreover, the gas modeling database is constructed with estimation of the combustion gas composition of $CO_2$ and $H_2O$ for liquid engine plume.

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