• 한국유체기계학회 논문집
• /
• 제16권2호
• /
• pp.10-14
• /
• 2013

The present study conducts CFD analyses on the internal flow fields of roots type vacuum pumps of semiconductor fabrication facility, and the computed CFD results for internal pressure and temperature distributions are applied to structural analyses of the pumps. The coupled analysis results between flow and structure show that the deformation of pump structure is mainly resulted from the thermal expansion of gas in pump, and the deformed impeller and housing produce their severe contact and impact phenomena causing mechanical damage and fracture.

• 한국기계가공학회지
• /
• 제13권6호
• /
• pp.37-45
• /
• 2014

Ball valves are used as a key element in the process industries. The industrial development of valves has increased steadily, but continued improvement requires high design reliability and long service life. Currently, the development of high performance valves is not easy because of the lack of relevant technology in Korea. Valves are being imported at a level of up to 58 percent of the domestic market, which represents a value of almost 7 million US dollars. Therefore, in this work, the improvement of the design and performance of industrial valves has been studied in an attempt to achieve valves that will have longer service life and better output during operation. The structural stability was evaluated using the ANSYS FSI (Fluid-Structural Interaction) module. Moreover, to obtain maximum product reliability, torque analysis simulation was performed to compare and experimental results. The simulation results were used to predict the change in torque by changes in shape, thereby reducing the time and cost of manufacturing a number of prototypes for experimental validation.

• 대한기계학회논문집A
• /
• 제38권4호
• /
• pp.451-457
• /
• 2014

최근에는 법공학 분야에 구조해석 및 구조-유동 연성해석을 이용한 다양한 시뮬레이션 기법을 활용하여 안전사고 및 재난사고에 대한 법적 책임문제를 해명하고, 보다 정확한 원인분석을 통해 원인을 규명하고 있는 추세이다. 본 연구에서 다룬 플레이트 거더교 사고는 교각과 교대 사이의 기존 교각에 대하여 확장 교각을 신설하던 중 방호벽 콘크리트 타설이 완료되는 시점에 전도 추락되어 발생되었다. 본 사고는 설계와 다른 시공 작업과 설계 시 고려되지 않은 추가 하중 등으로 인해 확장 교량에 부반력이 발생하여 구조적 불안정을 가져와 붕괴된 사고로 MIDAS 구조 해석을 통해 설계와 실제 시공 시 작업 하중에 대한 구조적 안정성을 비교 평가하여 정확한 공학적 사고의 원인을 규명하고자 한다.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
• /
• pp.420-425
• /
• 2006

Measurements results of flow-structure-interactions (FSI) of an air-lifted body are introduced. An adaptive stereoscopic-PIV system has been constructed for the measurements of the air-lifted body. The measurement system consists of two cameras and optical sensors. The flow characteristics around a lifted cylinder body(length=60mmm, diameter =10mm, polystyrene) in the swirling flow field in a vertical pipe (length=600mm, inner diameter=) are investigated by the use of the constructed adaptive stereoscopic-PIV system. The images of the two cameras were used for the analysis of the flow fields around the floated cylinder body. The images of the cylinder body captured by the two cameras were used for the analyses of its motions. Four optical sensors (LED) were used for the detection of the postures of the freely-lifted cylinder body. The FSI analyses have been carried out to find the physical conditions at which the floating body is stabilized with its upright postures.

• 한국유체기계학회 논문집
• /
• 제15권2호
• /
• pp.5-11
• /
• 2012

In this paper, the heat transfer coefficient measurement techniques using TSP(temperature sensitive paint) were introduced and the results of a comparative study on the heat transfer coefficient measurement by steady state and transient TSP techniques were discussed. The distributions of heat transfer coefficient by a single $60^{\circ}$ inclined impingement jet on a flat surface were measured by both techniques. Tested Reynolds number based on the jet diameter (d) was 30,000 and the distance between jet exit and target plate (L) was fixed at 10d. Results showed that the measured Nusselt number by both techniques indicated significant difference except near the center of impingement jet. Also, the heat transfer coefficients measured by the transient TSP technique were affected by the reference temperature of the jet. Based on the measured data, characteristics of both TSP techniques were analyzed and suggestions for applying them were also given.

• 한국기계가공학회지
• /
• 제15권1호
• /
• pp.129-135
• /
• 2016

Various type of valves are manufactured for different industrial uses. Among them, check valves are used to allow fluid to flow in one direction but not in the opposite direction. There are many different types of check valves, but Y-shaped check valves are widely used these days. Not many studies have been carried out on Y-shaped check valves and the flow coefficients obtained through numerical analysis have the problem of low reliability. In order to solve this problem, this study performed flow analysis, flow-structure coupled analysis, and flow coefficient measurement experimentally, and through these analyses derived and verified the flow coefficients and assessed the structural safety based on numerical analysis.

• 대한기계학회논문집B
• /
• 제38권5호
• /
• pp.423-430
• /
• 2014

파이프 유동 내에서 일어나는 소음 및 진동현상의 경우 일반적으로 난류유동과 근처의 벽면사이의 유동유기진동에 의해 일어나게 된다. 복잡한 난류유동을 가지는 확장관의 단순한 경우에서 본 연구는 수행되었지만, 방사소음의 경우 주어진 모델에서 크기와 형상 그리고 두께 등에 상당히 영향을 받게 된다. 또한, 방사소음은 그 파가 퍼져나가면서 주위 시스템에 교란특성이나 불안정성을 야기시키게 되는데 결국 중요한 파단과 파손을 일으키게 된다. 본 연구는 다양한 상용프로그램들 (Fluent, NASTRAN, 그리고 VIRTUAL LAB)을 이용하여 이러한 현상을 파악하고자 하였다. 이 연구를 통해 유동소음에 있어 깔려있는 물리현상들을 이해하고자 하였다. 확장관의 경우 단면적의 급격한 변화에 의해 박리와 높은 압력강하를 겪게 되는데, 방사소음의 계산으로 이 방사소음의 크기가 100에서 500Hz영역에서 전체적으로 약 20dB정도 감소시킬 수 있는 것을 확인할 수 있었다.

• 한국지반환경공학회 논문집
• /
• 제10권7호
• /
• pp.33-41
• /
• 2009

지중전력선과 같은 원형 지하매설관의 경우 관의 하단부 다짐효율이 낮아 파손등과 같은 구조적 문제점에 항상 노출되어있다. 이러한 문제점들 때문에 다양한 방법들이 강구되어 왔으며 그중 하나가 유동성이 뛰어난 저강도 콘크리트의 개발이다. 외국에서는 이미 오래전부터 연구개발을 진행하여 전력회사를 중심으로 이미 실용화 단계에 와있다. 따라서 본 연구에서는 개발된 지중 전력케이블 유동성 뒷채움재의 거동특성을 확인하기 위해서 개발된 유동화 뒷채움재와 일반모래를 이용하여 DB-24차량하중에 대해서 매설관의 거동을 평가하기 위해서 실증실험을 수행하고 그 결과를 수치해석 및 이론식과 비교분석하였다. 그 결과 매설관의 변형은 뒷채움재의 종류에 영향을 받는 것으로 나타났다. 유동성 뒷채움재가 모래다짐 보다 관로에 미치는 토압 및 변형 특성이 우수한 것으로 확인되었다. 하지만, 실증실험 결과와 비교검토를 위해서 수행한 수치해석 및 이론식 값들이 실증실험값과 차이가나 향후 유동성 뒷채움재에 맞는 해석방법 개발이 필요할 것으로 판단된다.

• 대한기계학회논문집A
• /
• 제32권2호
• /
• pp.127-134
• /
• 2008

The aerodynamically excited vibration and natural frequency of rotating disks are analytically studied in this paper. The theoretical analysis uses a fluid-structure model where the aerodynamic effects are represented in terms of elastic, lift and drag forces. The explicit expressions on natural frequencies of the air coupled disk are obtained as functions of the aerodynamic coefficients. for the three cases where the disk rotates in three different cases (in vacuum, in open air without enclosure, and close to rigid wall). The theoretical results give that the natural frequencies of rotating disks in air are smaller than those in vacuum, because the effect of the added fluid mass decreases the frequencies. This paper also proposes an analytical method to predict the flutter speed of a rotating disk.

• 동력기계공학회지
• /
• 제12권6호
• /
• pp.29-35
• /
• 2008

This study is conducted to provide the proper analysis method to evaluate the stability of a container crane under wind load. Two analysis method, namely structure analysis and fluid-structure interaction, are adopted to evaluate the stability of a container crane in this investigation. To evaluate the effect of wind load on the stability of the crane, 50-ton class container crane widely used in container terminals is adopted for analysis model and 19-values are considered for wind direction as design parameter. We conduct structure analysis and fluid-structure interaction for a container crane with respect to the wind direction using ANSYS and CFX. Then we compare the uplift forces yielded from two analysis with it yielded from wind tunnel test. The results are as follows: 1) A correlation coefficient between structure analysis and wind tunnel test is lower than 0.65(as $0.29{\sim}0.57$), but between fluid-structure interaction and wind tunnel test is higher than 0.65(as $0.78{\sim}0.86$). 2) There is low correlation between structure analysis and wind tunnel test but very high correlation between fluid-structure interaction and wind tunnel test.