• Title/Summary/Keyword: Numerical Calculation

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NUMERICAL ANALYSIS OF INTERIOR BALLISTICS WITH MOVING SOLID PROPELLANTS (고체추진제 이동을 고려한 강내탄도의 수치 해석)

  • Sung, H.G.;Jang, J.S.;Choi, D.W.;Roh, T.S.
    • 한국전산유체공학회:학술대회논문집
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    • 2009.04a
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    • pp.310-314
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    • 2009
  • A numerical code for the interior ballistics has been investigated. The method of the ghost cell extrapolation has been used for the moving boundary with the projectile movement. The porosity effect and the Ergun's Equation have been used in the numerical calculation for the grain combustion. The calculation results of the numerical code have been compared and verified through those of the lumped parameter method. Computerization techniques of the numerical analysis for the interior ballistics have been developed.

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A Study on the Safe Maneuvering Technology Based on the Thermal Calculation of Membrane Type LNG Carrier (멤브레인형 LNGC의 열계산에 기초한 안전운항기술에 관한 연구)

  • Jin, Chang-Fu;Kim, Kyung-Kuen;Oh, Cheol
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.8
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    • pp.1192-1200
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    • 2008
  • This paper is concerned with the thermal design of the $138,000m^3$ class membrane type LNGC. To predict the temperature distribution, BOG and BOR, 3-dimensional numerical calculation was carried-out for the quarter of No.3 LNG tank. These sequence analyses were performed under the standard conditions of IMO ship design condition, USCG ship design condition and the Korean flag LNGC's route condition according to the 6-voyage modes. As the results, temperature behavior, heat flux, total penetrating heat, BOG and BOR were obtained, and those were compared with the maneuvering results considering the real temperature variation of air and sea water temperature at noon time. For securing the safety of LNGC during the ballast voyage, optimum control patterns of pressure and temperature in LNG tank is suggested in this paper.

A Numerical Study on the Mixed Convection in Open-Ended Inclined Channels (양 끝이 개방된 경사진 채널 내에서의 혼합대류에 관한 수치적 연구)

  • Piao Ri-Long;Bae Dae-Seok
    • Journal of Advanced Marine Engineering and Technology
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    • v.29 no.1
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    • pp.78-85
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    • 2005
  • A numerical calculation is performed to study the effects of buoyancy force on the heat transfer characteristics of laminar forced convection flow in inclined parallel plates with the upper part cooled and the lower Part heated uniformly. Numerical results are presented for the Reynolds number ranges from $4.0\times10^{-3}$ to $1.13\times10^{-1}$. the angle of inclination, $\theta$. from 0 to 90 degree and Pr of the high viscosity fluid is 909. It is found that the flow pattern of mixed convection in inclined parallel Plates can be classified into four patterns which affected by Reynolds number and the angle of inclination.

Viscous Flow Analysis for the Rudder Section Using FLUENT Code (FLUENT 코드를 이용한 타 단면의 점성 유동 해석)

  • 부경태;한재문;송인행;신수철
    • Journal of the Society of Naval Architects of Korea
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    • v.40 no.4
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    • pp.30-36
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    • 2003
  • Lately, the cavitation and erosion phenomena in the rudder have been increased for high-speed container ships. However, cavitation is not prone to occur in model experiments because of low Reynolds number. In order to predict the cavitation phenomena, the - analysis of the viscous flow in the rudder gap is positively necessary In this study, numerical calculation was applied to the two-dimensional flow around the rudder gap using FLUENT code. The velocity and pressure field were numerically acquired and cavitation phenomena could be predicted. And the case that the round bar was installed in the rudder gap was analyzed. For reducing the acceleration force when fluid flow through the gap, modified rudder shape is proposed, It is shown that modified rudder shape restrain the pressure drop at the entrance of the gap highly both in the computational results and in the model experiment, and reduce the cavitation bubbles.

Analysis of added resistance of a ship advancing in waves (파랑중에서 전진하는 선박의 부가저항 해석)

  • 이호영;곽영기
    • Journal of Ocean Engineering and Technology
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    • v.11 no.2
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    • pp.91-99
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    • 1997
  • This paper presents theoretical formulations and numerical computations for predicting first-and second-order hydrodynamic force on a ship advvancing in waves. The theoretical formulation leads to linearized radiation and diffration problems solving the three-dimensional Green function integral equations over the mean wetted body surface. Green function representing a translating and pulsating source potantial for infinite water depth is used. In order to solve integral equations for three dimentional flows using Green function efficiently, the Hoff's method is adopted for numerical calculation of the Green function. Based on the first-order solution, the mean seconder-order forces and moments are obtained by directly integrating second-order pressure over the mean wetted body surface. The calculated items are carried out for analyzing the seakeeping characteristics of Series 60. The calculated items are hydrodynamic coefficients, wave exciting forces, frequency response functions and addd resistance in waves.

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Numerical Analysis of Two-Stage Turbopump Turbines (2단형 터보펌프 터빈의 유동해석)

  • Park, Pyun-Goo;Jeong, Eun-Hwan;Kim, Jin-Han
    • Aerospace Engineering and Technology
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    • v.7 no.2
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    • pp.151-156
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    • 2008
  • Numerical analyses of two-stage turbopump turbines were conducted. One of the candidates for the 1st rotor was selected based on the result of the numerical investigation. Besides, the effects of the stator height on the turbine performance were studied. Finally, the performance of the entire two-stage turbine was predicted by numerical calculation. The result showed that the two-stage turbine produces more specific power than a one-stage turbine.

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Scattering Model for Electrical-Large Target Employing MLFMA and Radar Imaging Formation

  • Wu, Xia;Jin, Yaqiu
    • Journal of electromagnetic engineering and science
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    • v.10 no.3
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    • pp.166-170
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    • 2010
  • To numerically calculate electromagnetic scattering from the electrical-large three-dimensional(3D) objects, the high-frequency approaches have been usually applied, but the accuracy and feasibility of these geometrical and physical optics(GO-PO) approaches, to some extent, are remained to be improved. In this paper, a new framework is developed for calculation of the near-field scattering field of an electrical-large 3D target by using a multilevel fast multipole algorithm(MLFMA) and generation of radar images by using a fast back-projection(FBP) algorithm. The MPI(Message Passing Interface) parallel computing is carried out to multiply the calculation efficiency greatly. Finally, a simple example of perfectly electrical conducting(PEC) patch and a canonical case of Fighting Falcon F-16 are presented.

A study on the boundary layer characteristics of TP620 hydrofoil in the steady state (정상상태인 박용 TP620 익형의 경계층 특성 연구)

  • 서봉록;김시영
    • Journal of Advanced Marine Engineering and Technology
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    • v.10 no.4
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    • pp.50-56
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    • 1986
  • This report deals with a study on the boundary layer characteristics of TP620 hydrofoil in the steady state by using two dimensional boundary layer theory. On the basis of complex velocity and laminar and turbulent boundary layer theory, the author attempts to know some tendency by evaluating the performance characteristic values of TP620 hydrofoil working in a uniform flow. In deriving characteristic values, he calculates numerically velocity, momentum thickness, skin friction coefficient, shape factor, and displacement thickness on the TP620 hydrofoil working at each attack angle in a uniform flow. Applying this present numerical calculation using Thwaites' and Head's method, the results of boundary layer on the hydrofoil are shown to be influenced by surface velocity and attack angle.

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A NUMERICAL SIMULATION FOR THE PERFORMANCE CHARACTERIZATION OF HEAT SINKS (Heat Sink의 특성확인을 위한 수치적 Simulation)

  • Kim, Chang Nyung;Moon, Sung-il
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.3 no.2
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    • pp.147-156
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    • 1999
  • A numerical simulation has been carried out for the performance characterization of heat sinks in electronic equipment. Heat transfer characteristics have been analyzed for various design parameters including the shape of heat sink, thickness of fin base and fin pitches. A commercial program called Flotherm has been employed for the numerical calculation. Optimal design of the heat sink has been persued which is closely related with the reduction of heat resistance involved in conduction and convection of heat.

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A Numerical Study on the Automotive Torque Converter(Part I) - Hydraulic Design and Evaluation of Circulation Flow Rate - (자동차용 토크 컨버터의 수치해석적 연구(Part I) - 수력학적 설계와 순환유량의 평가 -)

  • 김홍식;박재인;주원구;조강래
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.5
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    • pp.28-36
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    • 1998
  • In order to establish the hydraulic design process of the torque converter, pump, turbine and stator were designed by reverse design method including one dimensional analysis, angular momentum distribution and forced vortex design. And the significance of evaluation of the circulation flow rate in torus of the torque converter was verified by numerical calculation if the combined blade rows of pump and turbine. It was confirmed that the computational method using interrow mixing model by Park and Cho was reliable to predict the flow-field and performance of the torque converter.

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