청소기의 흡입일률 예측을 위한 CFD 해석 자동화

신정호(Jeongho Shin),윤상문(Sang-Moon Yoon),류대호(Dae-Ho Ryoo),김태영(Tae-Young Kim),김수옥(Su-Ok Kim),윤경수(Kyung-Soo Yoon) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

This paper introduces the automation of CFD analysis for predicting the suction power of the cyclone-type vacuum cleaner. To develop a new vacuum cleaner with the desired performance, 3 steps including the detail design, making engineering sample and the measurement of its performance must be repeated several times. It takes so much time and cost to make engineering samples. Therefore the process of trial and error results in much loss of the total production cost and the developing time. Instead of the predicting the performance from the engineering sample, CFD analysis can be applied and reduce the number of trials. However, it also takes so much time for the field engineers to learn and apply CFD analysis. Most of them are not familiar with CFD analysis, but familiar with CAD systems. So the new interface that enables the automated CFD analysis in CAD environment has been developed. With the help of this interface, users can apply CFD analysis to predict the suction power using the CAD model which is very familiar with them. The developed system asks the user the minimal input for CFD analysis and shows the processed final result from the automated CFD analysis in the background. It is illustrated that the automated CFD interface can contribute to reducing the total developing time through predicting the performance in advance.

정사각형 수조 진동대실험에 대한 상관해석

손일민,김재민,최형석,백은림 한국구조물진단유지관리공학회 2017 한국구조물진단유지관리공학회 논문집 Vol.21 No.1

이 연구에서는 유체저장탱크의 내진 설계 고도화에 활용하기 위하여 정사각형 수조의 슬러싱 진동대실험에 대한 상관해석을 수행 하였다. 이를 위하여 CFD 프로그램인 ANSYS CFX를 이용하였다. CFD 해석 프로그램 검증을 위해 슬러싱 공진이 발생하는 운동에 대한 해석 모델의 요소크기 및 난류모델에 대한 슬러싱응답의 민감도해석을 수행하였다. 그 결과, 수직방향 요소크기 뿐만 아니라 수평방향 요소크기에 따라 수위 예측에 민감한 영향을 미치는 것을 알 수 있었다. 또한, SST 난류모델을 사용한 CFD해석 결과가 실험 결과와 매우 잘 일치하는 것을 알 수 있었다. 이로부터 결정된 CFX 해석모델을 사용하여, 가진 주파수와 가진 진폭이 다른 3가지 실험 결과에 대하여 상관해석을 수행하였다. 그 결과, CFD해석모델을 사용하여 지진해석을 수행할 경우, 슬러싱응답이 실험 결과와 매우 잘 일치하는 것을 알 수 있었다. In this study, a post-correlation analysis for shaking table test of square water storage tank is presented for the use of advances in earthquake-resistant design of liquid storage tank. For this purpose, the ANSYS CFX program is selected for the CFD analysis. Sensitivity analysis for resonant sloshing motion in terms of grid size and turbulence model suggested that (1) horizontal grid size as well as vertical grid size is a key variable in the sloshing analysis, and (2) the SST turbulence model is best for the sloshing analysis. Finally, correlation analyses for a non-resonant harmonic input and scaled earthquake excitation of the El Centro (1940) NS component are carried out using the grid and turbulence model established through the post-correlation analysis for the resonant motion. As a result, sloshing time histories by the CFD analysis agreed very well with the test results.

CFD 해석에 의한 산악지형의 풍속할증 영향에 관한 연구

조강표,정승환,박강근 한국풍공학회 2008 한국풍공학회지 Vol.12 No.3

Wind speed-up effects due to topography for isolated three-dimensional hills are investigated by performing computational fluid dynamics (CFD) analysis. In the CFD analysis, four hill models having four different slopes are taken into account, and topographic factors for three-dimensional hills are estimated for the along-wind and crosswind directions. Also, the results of the CFD analysis about wind speed-up are compared with those from not only the wind tunnel experiment, but also Korean and international standards. In the CFD analysis, very large wind speed-up occurred near the crest of a hill, and wind speed increased about 48% to 56%. At various locations on the hillside and at the foot of a hill in along-wind direction, wind speed increased slightly or decreased, however at the same levels in the crosswind direction, wind speed increased. In the crosswind direction, the wind speed increased about 31% to 50% on the hillside at the mid-height of a hill, and about 19% to 27% at the foot of a hill. In the study, the difference between topographic factors obtained from the CFD analysis and those from the wind tunnel experiment ranged approximately from 3% to 8%, and the effect of topography on wind speed-up near the foot of a hill in the crosswind direction was not negligible.

CFD에 의한 자세변화가 큰 선박의 저항성능 해석

김현수,박동우,양영준 해양환경안전학회 2019 해양환경안전학회지 Vol.25 No.7

This research presents an efficient method based on computational fluid dynamics (CFD) for estimating the resistance performance of a ship with a large settlement amount and a dynamic trim. The settlement of the inviscid flow analysis and the results of dynamic trim were used to set a large attitude for the ship prior to performing a viscous flow analysis; a viscous flow analysis was subsequently performed by Dynamic Fluid Body Interaction (DFBI). This method is termed as method I, in which a simple grating system can be used without employing the overset mesh technique by setting many attitudes before interpretation. Thus, method I is advantageous in reducing calculation time and improving calculation accuracy. The viscous flow analysis was performed using a commercial CFD code STAR-CCM+. Compared with the final convergence result, the first viscous flow analysis result of method I exhibited a variation of less than 1% of resistance. The result was obtained by changing the gratings each time an attitude is changed at each calculation stage, based on the DFBI method provided to STAR-CCM+ using a simple grating system, which is not a superposed grating. This method is termed as method II. Compared with method II of resistance, method I exhibited a difference of 0.03–0.6% for linear velocity. The results of method I were confirmed to be qualitatively and quantitatively appropriate through comparison with several trillion simulations. 본 연구에서는 큰 침하량과 동적트림을 가지는 선박에 대하여 전산유체역학(CFD)을 기반으로 하여 효율적인 저항성능 추정 방법을 제시하였다. 본 방법에서 효율적이라 함은 점성 유동해석 이전에 비 점성 유동해석의 침하량과 동적트림 결과를 이용하여 선박의 큰 자세를 설정하고 DFBI(Dynamic Fluid Body Interaction) 방법에 의한 점성 유동해석을 수행한 것이다. 본 방법을 방법I로 명하였다. 방법I는 해석 전에 큰 자세를 설정함으로 인해 중첩격자(Overset Mesh) 기법을 사용하지 않는 단순한 격자시스템(Fig. 3 참고)을 사용하면 된다. 이로 인해 방법I는 계산시간 단축 및 계산의 정도를 높일 수 있는 장점이 있다. 점성 유동해석은 상용 CFD 코드인 STAR-CCM+를 사용하였다. 방법I의 첫 번째 점성 유동해석 결과는 최종 수렴된 결과와 비교하였을 때 저항 값에서 최대 1% 내에서 차이를 보임을 확인 하였다. 중첩격자가 아닌 단순 격자시스템에 의한 STAR-CCM+에서 제공하는 DFBI 기법을 활용하여 계산단계 별로 변화된 자세에 대하여 매번 격자를 변경하여 수렴된 결과를 도출하였다. 본 방법을 방법II로 명하였다. 방법II의 저항 값과 비교하였을 때 방법I은 선속에 따라 0.03%~0.6%의 차이를 보였다. 방법I의 결과는 수조모형시험과의 비교를 통해서 정성적 그리고 정량적으로 타당함을 확인하였다.

CFD/CSD Coupled Analysis for Flapping Wing using Three-dimensional Co-rotational Beam Analysis with Warping Degree of Freedom

조해성,이남훈,신상준,이승수 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.4

본 논문에서는 플래핑 날개에 대한 전산유체해석(CFD)과 전산구조해석(CSD)의 결합 해석을 수행하였다. 예조건화된 RANS 방정식을 지배 방정식으로 갖는 전산유체해석을 적용하였다. 전산구조해석을 위해 단면 워핑 자유도를 포함한 3 차원 Co-rotational(CR) 보 해석을 적용하였다. 각각의 공력/구조 해석은 내재적 결합 기법을 적용하여 결합하였고 상하 병진 운동을 하는 NACA 0012 단면의 날개에 대한 해석을 수행하였다. 해석 결과는 선행연구의 결과 및 실험적 결과와 비교하였다. 향후, 판/쉘과 같은 고차의 구조해석을 적용한 유체/구조 결합으로 확장할 예정이다. In this paper, a computational approach to simulate flapping wing by coupling between CFD and CSD is presented. A preconditioned Navier-Stokes solution is used for CFD analysis. For CSD analysis, three-dimensional Co-rotational (CR) beam analysis with a restrained warping degree of freedom is employed. Both analyses are coupled by implicit coupling methodology. The present results are compared with those obtained in the previous research and those from the experiment. In the future, the present approach will be extended by using the higher order structural analysis, i.e., nonlinear shell finite element.

CFD 시뮬레이션을 활용한 화학물질 누출사고 분석에 관한 연구

안수빈,장창봉,이경수,권혜옥 한국산업보건학회 2023 한국산업보건학회지 Vol.33 No.3

Objectives: Chemical accidents cause extensive human and environmental damage. Therefore, it is important to prepare measures to prevent their recurrence and minimize future damage through accident investigation. To this end, it is necessary to identify the accident occurrence process and analyze the extent of damage. In this study, the development process and damage range of actual chemical leakage accidents were analyzed using CFD. Methods: For application to actual chemical leakage accidents using FLACS codes specialized for chemical dispersion simulation among CFD codes, release rate calculation and 3D geometry were created, and scenarios for simulation were derived. Results: The development process of the accident and the dispersion behavior of materials were analyzed considering the influencing factors at the time of the accident. In addition, to confirm the validity of the results, we compared the results of the actual damage impact investigation and the simulation analysis results. As a result, both showed similar damage impact ranges. Conclusions: The FLACS code allows the detailed analysis of the simulated dispersion process and concentration of substances similar to real ones. Therefore, it is judged that the analysis method using CFD simulation can be usefully applied as a chemical accident investigation technique.

전산 유체 해석에 의한 산악 지형 모델의 풍속할증 영향에 관한 연구

정승환(Jeong Seung-Hwan),조강표(Cho Kang-Pyo) 대한건축학회 2009 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.29 No.1(구조계)

Wind speed-up effects due to topography for isolated three-dimensional hills are investigated by performing computational fluid dynamics (CFD) analysis. In the CFD analysis, four hill models having four different slopes are taken into account, and topographic factors the hills are estimated for the along-wind and crosswind directions. Also, the results of the CFD analysis about wind speed-up are compared with those from not only the wind tunnel experiment, but also Korean and international standards. Wind speed increased largely about 48% to 56% near the crest of a hill. At various locations on the hillside and at the foot of a hill in along-wind direction, wind speed increased slightly or decreased, however at the same levels in the crosswind direction, wind speed increased. The difference between topographic factors obtained from the CFD analysis and those from the wind tunnel experiment ranged approximately from 3% to 8%, and wind speed increased near the foot of a hill in the crosswind direction.

CFD-Based Evaluation of the Efficiency for Solar Collectors with Fresnel Lenses

( Kyeong Sik Kang ),( Gwi Hyun Lee ) 한국농업기계학회 2023 한국농업기계학회 학술발표논문집 Vol.28 No.2

The main objectives of this study are to evaluate the performance of a solar thermal collection system utilizing Fresnel lenses through CFD simulation. Solar energy is an infinite energy source, and it can be used for heating and thermal systems. The efficiency of solar thermal energy systems is primarily dependent on the efficiency of the collector unit, leading to the development of various solar thermal systems. In this research, CFD numerical analyses were conducted on two types of solar collection systems using Fresnel lenses to maximize the efficiency of solar energy collection. The first system consists of 16 small Fresnel lenses, a square pipe through which the heat transfers medium flows, and the collector component, forming a flat plate type collector. The second system comprises a single large Fresnel lens and a double-cylinder shell-type absorber that absorbs heat from the lens. To perform CFD analysis, the geometry of the solar thermal collection system was created using 3D modeling software, and a mesh was generated on the 3D model. Subsequently, ANSYS Fluent 2022 R2 software was used to establish the physical models describing the fluid dynamics and heat transfer within the solar thermal collection system, along with setting boundary conditions involving external heat sources. Numerical analysis was then conducted using the software, and the results of both systems were analyzed. While the flat plate collector averaged 60-70% efficiency, a single large Fresnel lens with the double cylindrical shell absorber outperformed it by approximately 5% with an average efficiency of 65-75%. A satisfactory agreement was found when comparing the experimental data from previous studies with the results of this research. In the future, it is anticipated that this system can be further analyzed under various conditions, including different heat transfer media and solar radiation levels. A solar collector of the single large Fresnel lens had demonstrated higher efficiency, and it is believed that improvements in performance and cost-related challenges could make it suitable for applications requiring high energy efficiency, such as hot water supply and heating and cooling systems.

CFD를 이용한 가연성 가스의 확산 및 폭발 Simulation

장창봉(Chang-Bong Jang),이향직(Hyang-Jik Lee),이민호(Min-Ho Lee),민동철(Dong-Chul Min),백종배(Jong-Bae Back),고재욱(Jae Wook Ko),권혁면(Hyuck-Myun Kwon) 한국가스학회 2012 한국가스학회지 Vol.16 No.5

현재 가연성 가스의 누출시 누출된 가스의 확산과 VCE에 의한 과압을 예측하기 위해 여러 모델들이 이용되고 있다. 그러나 이 모델들은 누출설비의 지형과 장애물 그리고 건물들의 영향에 대해서는 충분히 고려하지 않은 단순한 접근방법을 이용하고 있다. 이에 본 연구는 누출된 물질의 연소형태, 설비의 Geometry, 난류, 장애물, 바람의 영향등 여러 변수를 고려하여 보다 정확하게 분석할 수 있는 CFD(Computational Fluid Dynamics) Model을 검토함으로서 누출된 가스의 확산과정과 분포형태 그리고 폭발시 화염과 과압의 결과를 2D와 3D의 가상공간에서 제시하였다. 이러한 CFD분석결과는 폭발에 대한 리스크 분석과 리스크 기반의 설계에 있어 유용하게 활용될 것으로 판단된다. Various models are currently applied to predict the dispersion of leaked combustible gas and overpressure from a vapor cloud explosion(VCE). However, those models use simple approaches where topography and barriers of anti-leakage facilities and the effects of buildings were not sufficiently taken into considerations. For this reason, this study has proposed the dispersion process of leaked gas, distribution patterns, and flames and overpressure generated from gas explosions in 2D and 3D virtual spaces by reviewing more accurately analyzable computational fluid dynamics(CFD) model by considering various variables including combustion types of leaked substances, geometry of facility, warm currents, barriers, the influence of wind, and others. The CFD analysis results are anticipated to be usefully applied for the risk analysis of explosion and for the risk-based design.

가스소화약제 압력누기감시장치의 안전성 분석을 위한 수치적 연구

고아라,임동오,손봉세 한국화재소방학회 2016 한국화재소방학회논문지 Vol.30 No.4

While the demand for the gas system fire extinguishers increases every year, there are insufficient safety measures forassessing the extinguishing performance, such as system safety and reliability in the preparation of increasing demand,which has emerged as a social problem. One of the most critical causes of accidents occurring with the gas extinguishingsystem is pressure leakage from the extinguishing agent storage container. This is considered to be one of the critical factorson which the success of fire suppression depends. In this study, its safety measure was studied, Because it wasdeemed urgently necessary. The newly developed pressure leakage monitoring system is a system monitoring storage condition,pressure, leakage and discharge of the storage container related to agent concentration, which is one of the criticalfactors for fire suppression. This was developed to be applicable to the CO2 and HFC-23 systems. Therefore, for structuralsafety analysis, the safety performance was verified by the fluid structure coupling analysis of the safety problemsthat may occur when the pressure leakage monitoring system is applied to the gas fire extinguisher. For analysis programs,the FloEFD program from Mentor Graphics was used for computational fluid dynamics analysis and ABAQUSfrom Dassault Systems was used for structural analysis. From the result of numerical analysis, the structure of CO2 did notdevelop plastic deformation and its safety was verified. However, plastic deformation and deviation issue occurred withthe HFC-23 monitoring system and therefore verified the structural safety of pressure leakage monitoring system by dataobtained from redesigning and adjusting the condition of numerical interpretation three times. 가스계소화설비의 수요는 매해 증가하고 있으나, 늘어나는 수요에 대비한 시스템의 안전성 및 신뢰성등 소화성능에 필요한 안전대책이 미흡하여 사회적인 문제가 되고 있는 실정이다. 본 연구에서는 이러한 문제점을 해결하기 위하여 가스소화시스템의 사고발생 원인 중에서 가장 심각한 문제인 소화약제 저장용기에서 발생하는 압력누기는 화재진압의 성패를 좌우하는 중요한 요소로 시급한 대책이 요구되는 문제점로 판단하여 연구를 하였다. 새로 개발한 압력누기감시장치는화재진압에 중요한 요소인 소화농도와 관련이 있는 저장용기의 약제확보상태와 압력 및 누기, 방출상태 등을 감시하는장치로 CO2와 HFC-23 시스템에 적용할 수 있도록 개발하였다. 즉, 압력누기감시장치를 가스소화설비에 적용하였을 때발생할 수 있는 구조적 안전성 분석을 위하여 유체-구조연계해석을 통하여 안전성능을 검증하였다. 해석에 사용한 프로그램으로 전산유체해석은 Mentor Graphics사의 FloEFD 프로그램을 사용하였고, 구조해석 프로그램은 Dassault systems사의 ABAQUS를 사용하였다. 수치해석결과 CO2용의 구조에서는 소성변형이 발생하지 않아 안전성을 확인하였으나HFC-23용 감시장치에는 소성변형 및 이탈문제가 발생하여 설계수정과 3차례의 수치해석 조건을 수정하여 얻은 데이터를 기본으로 압력누기감시장치의 구조적인 안전성을 확인하였다.