• Title/Summary/Keyword: Three-layer configuration

Search Result 75, Processing Time 0.028 seconds

Development of multi-cell flows in the three-layered configuration of oxide layer and their influence on the reactor vessel heating

  • Bae, Ji-Won;Chung, Bum-Jin
    • Nuclear Engineering and Technology
    • /
    • v.51 no.4
    • /
    • pp.996-1007
    • /
    • 2019
  • We investigated the influence of the aspect ratio (H/R) of the oxide layer on the reactor vessel heating in three-layer configuration. Based on the analogy between heat and mass transfers, we performed mass transfer experiments to achieve high Rayleigh numbers ranging from $6.70{\times}10^{10}$ to $7.84{\times}10^{12}$. Two-dimensional (2-D) semi-circular apparatuses having the internal heat source were used whose surfaces of top, bottom and side simulate the interfaces of the oxide layer with the light metal layer, the heavy metal layer, and the reactor vessel, respectively. Multi-cell flow pattern was identified when the H/R was reduced to 0.47 or less, which promoted the downward heat transfer from the oxide layer and possibly mitigated the focusing effect at the upper metallic layer. The top boundary condition greatly affected the natural convection of the oxide layer due to the presence of secondary flows underneath the cold light metal layer.

Comparisons of 2-D and 3-D IVR experiments for oxide layer in the three-layer configuration

  • Bae, Ji-Won;Chung, Bum-Jin
    • Nuclear Engineering and Technology
    • /
    • v.52 no.11
    • /
    • pp.2499-2510
    • /
    • 2020
  • We performed 3-D (3-dimensional) IVR (In-Vessel Retention) natural convection experiments simulating the oxide layer in the three-layer configuration, varying the aspect ratio (H/R). Mass transfer experiment was conducted based on the analogy to achieve high RaH's of 1.99 × 1012-6.90 × 1013 with compact facilities. Comparisons with 2-D (2-dimensional) experiments revealed different local heat transfer characteristics on upper and lower boundaries of the oxide layer depending on the H/R. For the 3-D shallow oxide layer, the multi-cell flow patterns appeared and the number of cells was considerably increased with the H/R decreases, which differs with the 2-D experiments that the number of cells was independent on H/R. Thus, the enhancement of the downward heat transfer and the mitigation of the focusing effect were more noticeable in the 3-D experiments.

The near wake of three circular cylinders in an equilateral triangular arrangement at a low Reynolds number Re=100

  • Bai, Honglei;Lin, Yufeng;Alam, Md. Mahbub
    • Wind and Structures
    • /
    • v.30 no.5
    • /
    • pp.451-463
    • /
    • 2020
  • Two-dimensional numerical simulations are conducted at a low Reynolds number Re = 100 to investigate the near wake of three identical circular cylinders that are arranged in an equilateral triangular configuration. The incident angle of the three-cylinder configuration with respect to incoming flow is varied from θ = 0° to 60°, while the spacing between adjacent cylinders (L) covers a wide range of L/D = 1.25-7.0, where D is diameter of the cylinder. Typical flow structures in the near wake of the three-cylinder configuration are identified, including a single Karman vortex street, bistable flip-flopping near wake, anti-phase and/or in-phase vortex shedding, shear layer reattachment, and vortex impingement, depending on the configuration (L/D, θ). The behavior of Strouhal number (St) is discussed in detail, echoing the distinct structures of near wake. Furthermore, fluid forces on the individual cylinders are examined, which, though highly depending on (L/D, θ), exhibit a close correlation to the near wake behavior.

Calculation of three-dimensional boundary layer near the plane of symmetry of an automobile configuration (자동차 중앙대칭단면 부근의 3차원경계층 계산)

  • 최장섭;최도형;박승오
    • Journal of the korean Society of Automotive Engineers
    • /
    • v.10 no.2
    • /
    • pp.61-69
    • /
    • 1988
  • The finite-difference three-dimensional boundary layer procedure of Chang and Patel is modified and applied to solve the boundary layer development on the automobile surface. The inviscid pressure distribution needed to solve the boundary layer equations is obtained by using a low order panel method. The plane of symmetry boundary layer exhibits the strong streamline divergence up to the midbody and convergence thereafter. The streamline divergence in front of the windshield helps the boundary layer to overcome the sever adverse pressure gradient and avoid the separation. The relaxation of the pressure right after the top of the wind-shield, on the other hand, makes the overly thinned boundary layer to readjust and prompts the streamlines to converge into the symmetry plane before the external streamlines do. The three-dimensional characteristics are less apparent after the midbody and the boundary layer is similar to that of the two-dimensional flow. The results of the off-plane-of-symmetry boundary layer are also presented.

  • PDF

Numerical Analysis of Multi-Layer Multi-Coupled Microstrip Lines (쉬해석에 의한 다층 다중 결합 마이크로스트립 선로 해석)

  • Seo, Cheol-Heon
    • The Journal of the Acoustical Society of Korea
    • /
    • v.13 no.1E
    • /
    • pp.5-10
    • /
    • 1994
  • It is obtained the general expessions of the numerical method are applied for the TEM-mode analysis of multu-layer multi-coupled microstrip lines, In this paper, coupled microstrip are replaced by three-coupled microstrip lines in special aplications. Three-layer versions of three-coupled microstrip lines are specially attactive because of the additional flexibilities offered by three-layer configuration. This structure can be used for obtaining large capacitance and preventing coupling among microstrip lines in filter and coupler. Sappihre is chosen for anisotropic substrates material. The permittivity parallel to the optical axis is higher than the permittivity in the plane perpendicular to this axis.

  • PDF

Broad-Band Underwater Acoustic Transducer for Doppler Velocity Log (도플러 속도계(DVL)를 위한 광대역 수중 음향 트랜스듀서)

  • Yun, Cheol-Ho;Lee, Yeoung-Pil;Ko, Nak Yong;Moon, Yong-Seon
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.19 no.9
    • /
    • pp.755-759
    • /
    • 2013
  • A broad-band underwater acoustic transducer that uses thickness vibration mode, derived from a disk type piezoelectric ceramic, has been proposed and designed for DVL (Doppler Velocity Log). Three different types of acoustic transducer were evaluated with respect to the transmitting voltage response, receiving voltage sensitivity and bandwidth of the transducer. The effect of the acoustic impedance matching layer and backing layer is discussed. The results demonstrated that three matching layer with lossy backing layer is the best configuration for underwater transducer. The trial underwater acoustic transducer with three matching layer has a frequency bandwidth of 55%, maximum transmitting voltage response of 200 dB and a maximum receiving voltage sensitivity of -187.3 dB.

E-commerce Architecture Evaluation Through Web Stress Test (웹 스트레스 테스트를 통한 전자상거래 아키텍쳐 평가)

  • Lee, Young-Hwan;Park, Jong-Soon
    • Information Systems Review
    • /
    • v.3 no.2
    • /
    • pp.277-288
    • /
    • 2001
  • Of critical importance to the success of any e-commerce site are the two factors: rapid application development and quick response time. A three-tier architecture composed of presentation layer, business layer, and data access layer emerges to allow rapid changes in user interface, business logic, and database structures. Too often, such a logical three-tier architecture is considered as requiring a three-tier physical architecture: Web server, application server, and database server running on separate computers. Contrary to the common belief, a Web stress test reveals that the three-tier logical architecture implemented on a two-tier physical platform guarantees a quicker response time due to the reduction in cross-machine communications. This would lead business firms to economize their spending on e-commerce: increasing the number of physical servers to expedite transaction is not necessarily the best solution. Before selecting a particular hardware configuration, a Web stress test needs to be conducted to compare the relative merits of alternative physical architectures. Together with capacity planning, Web stress test emerges as a powerful tool to build robust, yet economical e-commerce sites.

  • PDF

The Prediction of Geometrical Configuration and Ductile Fracture Using the Artificial Neural network for a Cold Forged Product (신경망을 이용한 냉간 단조품의 기하학적 형상 및 연성파괴 예측)

  • Kim, D.J.;Ko, D.C.;Park, J.C.
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.13 no.10
    • /
    • pp.105-111
    • /
    • 1996
  • This paper suggests the scheme to simultaneously accomplish prediction of fracture initiation and geomeytical configuration of deformation in metal forming processes using the artificial neural network. A three-layer neural network is used and a back propagation algorithm is adapted to train the network. The Cookcroft-Lathjam criterion is used to estimate whether fracture occurs during the deformation process. The geometrical configuration and the value of ductile fracture are measured by finite element method. The predictions of neural network and numerical results of simple upsetting are compared. The proposed scheme has successfully predicted the geometrical configuration and fracture initiation.

  • PDF

Effect of inlet configuration on the growth rate of GaN layer in a MOCVD reactor (MOCVD 반응로내 GaN 성장에 미치는 입구형상의 영향)

  • Yun, Sung-Kyu;Baek, Byung-Joon;Pak, Bock-Choon
    • Proceedings of the KSME Conference
    • /
    • 2003.11a
    • /
    • pp.67-72
    • /
    • 2003
  • Numerical calculation has been performed to investigate the effect of inlet configuration on the growth rate of GaN layer on the heated susceptor. The conventional single inlet, where the gas is mixed by force in the inlet, is compared with separated flow inlet. Two-parallel gas flow $H_{2}$ and $NH_{3}$ are separated by a plate with finite length which are also parallel to the susceptor. The effect of separated plate length, carrier gas and flow rate of each precursor on the mixing of reactant gases and growth rate were investigated. Furthermore the three dimensional model is employed to predict the transverse variation of growth rate.

  • PDF

Magnetic Properties and Relaxation of Vanadium Monolayer on Pd(001) Surface

  • Landge, Kalpana K.;Bialek, Beata;Lee, Jae-Il
    • Journal of Magnetics
    • /
    • v.15 no.2
    • /
    • pp.45-50
    • /
    • 2010
  • We investigated the magnetism of vanadium monolayers on a Pd(001) surface. The electronic structure and the magnetic properties of the V/Pd(001) system were determined with the use of the full-potential linearized augmented plane-wave method within the general gradient approximation. Three magnetic configurations were studied: non-, ferro-, and antiferromagnetic. From the total energy calculations, we found that the V/Pd(001) system is the most stable in the antiferromagnetic configuration. The importance of relaxation on the magnetic properties of the systems was also studied. It was found that the Pd(001) surface covered with a V monolayer undergoes considerable relaxation in which the spacing between Pd layers increases in all three magnetic configurations. Contrary to the Pd interlayer spacing, the distance between the V overlayer and the topmost Pd layer is reduced. The interlayer spacing between the V overlayer and the Pd surface layer is the largest for the antiferromagnetic configuration. In the relaxed antiferromagnetic structure, the magnitude of the calculated magnetic moments on the V atoms was $1.31\;{\mu}_B$. The presence of the vanadium monolayer does not affect the paramagnetic properties of the Pd(001) surface.