• Title/Summary/Keyword: computational calculation

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ANALYSIS OF FLOW AROUND SHIP USING UNSTRUCTURED GRID (비정렬 격자를 이용한 선체 주위의 유동 해석)

  • Jun, Jae-Hyoung;Lee, Sang-Eui;Kwon, Jae-Woong;Son, Jae-Woo
    • 한국전산유체공학회:학술대회논문집
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    • 2011.05a
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    • pp.187-193
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    • 2011
  • In this report, We compared the actual test with the result of pow calculation and Resistance/Self-propulsion of the ship using STAR-CCM+ which is the commercial Reynolds Averaged Navier-Strokes(RANs) Solver. The calculation model was the KRISO Container Ship and 205K Bulk Carrier of Sungdong shipbuilding company. For this calculation, We used Realizable K-Epsilon model for flaw analysis, VOF method for the free surface creation, Moving Reference Frame method for reducing the POW calculation time, and Sliding Mesh method for Self-Propulsion analysis. Calculation of Resistance and Self-Propulsion includes the free-surface. And all calculations in this report were based on unstructured grids.

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An Accurate and Efficient Method of the Spray Paint Simulation for Robot OLP (로봇 Off-Line Programming을 위한 페인트 스프레이 시뮬레이션 방법론 개발)

  • Lee, Seung-Chan;Song, In-Ho;Borm, Jin-Hwan
    • Korean Journal of Computational Design and Engineering
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    • v.13 no.4
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    • pp.296-304
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    • 2008
  • Recently, various attempts are being done to apply off-line programming system to field of paint robot. But most commercial simulation softwares have problems that are slow simulation speed and not support various painting paramenters on simulation. This paper proposes enhanced paint simulation method for off-line programming system. For these, this method used the mathematical model of flux field from a previous research. The flux field has the flux distribution function, which reflects on the feature of paint spray. A previous research derived this flux distribution function for an integral function and calculated paint thickness function for an integral function. But if flux distribution function is defined as an integral function, it is inadequate to use for real-time simulation because a number of calculation is needed for estimation of paint thickness distribution. Therefore, we defined the flux distribution function by numerical method for reducing a mount of calculation for estimation of paint thickness. We derived the equation of paint thickness function analytically for reducing a mount of calculation from the paint distribution function defined by numerical method. In order to prove proposed paint simulation method this paper compares the simulated and measured thickness. From this comparison this paper show that paint thickness distribution is predicted precisely by proposed spray paint simulation process.

Development of a Compressor Design System Using Configuration Design Method (편집설계 기법을 이용한 압축기 설계 시스템 개발)

  • Lee, Kang-Soo
    • Korean Journal of Computational Design and Engineering
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    • v.16 no.1
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    • pp.52-60
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    • 2011
  • In this research, we developed a design system for a compressor of an air conditioner using solid CAD system. The developed design system has some characteristics. First, the design system used a configuration design method, so a designer can design a compressor very quickly by using the constructed master libraries. Next, the system was developed to be used not only by engineers but also by salesmen. It is very easy for a user to use it, so a salesman can get a result very easily with the design system. And it has some design modules which give a considerable convenience to designers. Actually, designers are accustomed to the module based design. Then, it has calculation and analysis functions. Volume and mass of a part, and interference between parts are calculated by using the geometric calculation function of a solid CAD system. Also a packaging calculation was implemented to get the smallest space to package compressors for transportation and storing. An interface with a program to analyze the vibration of a compressor was developed in this design system. The design system is similar to CBD (Case-Based Design) system in the view of the whole design process.

Numerical Analysis of Thermal Environments and Comfort for Local Air Conditioning System (수치해석에 의한 국부냉방시스템의 온열환경 및 쾌적성 분석)

  • 엄태인;경남호;신기식
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.4
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    • pp.318-328
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    • 2003
  • Numerical simulation using computational fluid dynamics (CFD) is performed to calculate the velocities and temperature profiles of air in adjacent to a worker within the individual local air conditioning system. The calculation domain is the space of ㄴ between walls and a worker in the climate room. The fresh air is supplied from the three different inlets located on the right, left and center wall in the climate room. In this study, the calculated data of velocities and temperature profiles of air in the nearest the skin of a worker are used to calculate the PMV (Predicted Mean Vote) for evaluation of thermal comfort of a worker in the local air conditioning system. Because the data of veto-cities temperature profiles of air in adjacent to a worker and the PMV of a worker are the design parameters of the local air conditioning system. The results of calculation show that the fresh air velocity and injection position are closely related to the PMV value. In individual air condition system of ㄴ, the appropriate PMV are obtained when the fresh air velocity and position are 1.0 m/s, throat of a worker and are 1.5 m/s, head of a worker, respectively. The method of numerical calculation is effective to obtain the optimum velocity and position of the fresh air for optimum the PMV and energy saving in individual local air conditioning system.

A study on the deviation angle of the rotating blade row in an axial- flow compressor (軸流壓縮機 回轉翼列의 流出偏差角에 관한 硏究)

  • 조강래;방영석
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.6
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    • pp.1407-1414
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    • 1988
  • Deviation angles are predicted by numerical calculation of three-dimensional compressible flow through the rotating blade row in axial flow compressor. Three-dimensional flow fields are analyzed by the quasi three-dimensional combination of blade-to blade surfaces and hub-to shroud stream surfaces and calculated by the finite element method in the cyclic calculation of both stream surfaces. In the blade-to blade calculations the method of boundary stream line correction is used and in the hub-to shroud calculations the loss effects due to viscous flow are included. The computational results are compared with the available experimental one. It is shown that the computational results from blade-to-blade flow calculation are correct for incompressible, compressible low subsonic and high subsonic flow at the inlet, and the loss effects on the deviation angle can be neglected in the range of the subsonic flow less than the critical Mach number for the axisymmetric flow and even for 3-D non-axisymmetric flow with loss. And it is found that the present results are better agreed with the experimental data than Lieblein's one.

Validation of MCS code for shielding calculation using SINBAD

  • Feng, XiaoYong;Zhang, Peng;Lee, Hyunsuk;Lee, Deokjung;Lee, Hyun Chul
    • Nuclear Engineering and Technology
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    • v.54 no.9
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    • pp.3429-3439
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    • 2022
  • The MCS code is a computer code developed by the Ulsan National Institute of Science and Technology (UNIST) for simulation and calculation of nuclear reactor systems based on the Monte Carlo method. The code is currently used to solve two main types of reactor physics problems, namely, criticality problems and radiation shielding problems. In this paper, the radiation shielding capability of the MCS code is validated by simulating some selected SINBAD (Shielding Integral Benchmark Archive and Database) experiments. The whole validation was performed in two ways. Firstly, the functionality and computational rationality of the MCS code was verified by comparing the simulation results with those of MCNP code. Secondly, the validity and computational accuracy of the MCS code was confirmed by comparing the simulation results with the experimental results of SINBAD. The simulation results of the MCS code are highly consistent with the those of the MCNP code, and they are within the 2σ error bound of the experiment results. It shows that the calculation results of the MCS code are reliable when simulating the radiation shielding problems.

A Study on Hydraulic Calculation Procedure of Fire Sprinkler System Design (스프링클러설비 설계의 수리계산 절차에 대한 연구)

  • Jeong, Keesin
    • Fire Science and Engineering
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    • v.32 no.1
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    • pp.24-32
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    • 2018
  • There are two kinds of method on hydraulic calculation of fire sprinkler system design. The one is using the computational program and the other is designer calculate system for oneself. In case of using the computational program, putting the input data in, the program calculate the friction loss, water flow, total height and so forth. If program user or designer doesn't know the basic idea and procedure of hydraulic calculation. Then, the outputs are different from each other. This paper suggests the hydraulic calculation procedure in design area as follow. Equivalent lengths of tees on the branch are selected base on the same pipe diameter which the tees are established, although the diameter of tee outlet is different. Even though there is a different friction loss of head from the other head, the pressure from the hydraulic end is bigger than a head loss, discharge flow is calculated by pressure from the hydraulic end.

NUMERICAL ANALYSIS TO DESIGN HIGH TEMPERATURE HEAT EXCHANGER OF BETA TYPE STIRLING ENGINE IN 3-D COMBUSTION FIELD (3차원 연소장에서의 베타 형태의 스털링엔진 고온 열교환기 설계를 위한 수치해석 연구)

  • Kang, S.H.;Kim, H.J.;Chung, D.H.
    • Journal of computational fluids engineering
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    • v.16 no.2
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    • pp.56-61
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    • 2011
  • Numerical study is conducted to design the high temperature heat exchanger of Stirling engine by using the commercial CFD solver, FLUENT. The Fin-tube type of heat exchanger is designed as a reference model by considering the type of engine which is ${\beta}$-configuration. To find the optimal design of heat exchanger in heat transfer capacity numerical calculation is conducted by changing the shape, the number, and material of reference model in three-dimensional combustion field. Adjusted one-way constant velocity of working fluid that is helium is considered as the representative velocity of oscillating flow. The optimal design of heat exchanger considering the heat transfer capability is suggested by using the calculation results.

5-axis Milling Machining Time Estimation based on Machine Characteristics (기계 특성에 근거한 5축 밀링가공 시간의 예측)

  • So, B.S.;Jung, Y.H.;Jeong, H.J.
    • Korean Journal of Computational Design and Engineering
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    • v.12 no.1
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    • pp.1-7
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    • 2007
  • In this paper, we present a machining time estimation algorithm for 5-axis high-speed machining. Estimation of machining time plays an important role in process planning and production scheduling of a shop. In contrast to the rapid evolution of machine tools and controllers, machining time calculation is still based on simple algorithms of tool path length divided by input feedrates of NC data, with some additional factors from experience. We propose an algorithm based on 5-axis machine behavior in order to predict machining time more exactly. For this purpose, we first investigated the operational characteristics of 5-axis machines. Then, we defined some dominant factors, including feed angle that is an independent variable for machining speed. With these factors, we have developed a machining time calculation algorithm that has a good accuracy not only in 3-axis machining, but also in 5-axis high-speed machining.

On the Accuracy and Efficiency of Calculation with Respect to the Grid Construction Methods for Unstructured Meshes (비정렬 격자계에서 격자계 구성방법에 따른 계산의 정확도와 효율에 관한 연구)

  • Kim S. R;Wang Z. J.
    • Journal of computational fluids engineering
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    • v.9 no.1
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    • pp.48-56
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    • 2004
  • The numerical simulations with unstructured mesh by cell-centered and vertex-centered approaches were peformed for the quadrilateral and triangular meshes. For 2-D inviscid supersonic vortex flow, the simulation results and the analytic solution were compared and the accuracy was assessed. The calculation efficiency was measured by the parameter defined by the consumed CPU time multiplied by absolute error As a results, equilateral triangular mesh yielded the best accuracy and efficiency among the tested meshes. Cell-centered approach gives a little better efficiency than vertex - centered approach.