음향장에서 열전달 촉진에 관한 연구

오율권,양호동 조선대학교 에너지.자원신기술연구소 2003 에너지·자원신기술연구소 논문지 Vol.25 No.1

The enhancement of hat transfer in a square cavity was investigated in th absence of and in the presence of acoustic streaming induced by ultrasonic vibrations. In the present study, applying ultrasonic vibrations to the liquid were found induce acoustic streaming which was clearly observed using PIV and thermal infrared camera. Also, the profiles of the augmentation ratio of heat transfer coefficient was experimentally measured and was compared with those of the acoustic pressure obtained by numerical prediction. Experimental and numerical studies clearly show that acoustic pressure variations are closely related to enhancement of heat transfer.

Air-Water 모델에서 기포특성에 관한 실험적 연구

오율권,서동표 한국산업안전학회 2003 한국안전학회지 Vol.18 No.1

The structural development of air-water bubble plumes has been measured under different condition on air flow rate in a cylindrical bath. The time-averaged structure of plumes has been measured with an oscilloscope and an electro-conductivity probe. The temperature of bubbles was also obtained by a thermal-infrared camera. Gas volume fraction and bubble frequency were high since bubbles concentrated on the nozzle. In general, their axial and radial values tended to decrease with increasing distance. Bubble temperature reached water temperature within a short time. The present study showed that thermal equilibrium between bubbles and water was completed before bubbles flow became stable.

垂直圓周에서 二相流의 數値的 硏究

吳栗權,羅基大 조선대학교 동력자원연구소 1996 動力資源硏究所誌 Vol.18 No.1

Applicability of a theoretical model, based on the fundamental governing equations of fluid motion is investigated to prodict two-phase bubbly air-sater flow structure through vertical columns. The model predictions are compared to experimental data for a wide range of foow parameters. The relative importance of various modes of interfacial momentum transfer, under different flow conditions, is also examined. It is found that correct estimation of the interfacial momentum transfer is necessary for agreement between the predictions and experimental data. The present study shows that the flow structure for air-water flows through vertical columns depend on the inlet flow conditions. The model predicts the experimentally observed trends well and in most cases the experimental data of local liquid velocity and gas volume fraction agree well with the calculated values.

수치해석을 이용한 음향장내의 압력장 해석에 관한 연구

오율권,양호동,서동표 조선대학교 에너지.자원신기술연구소 2004 에너지·자원신기술연구소 논문지 Vol.26 No.2

Applying ultrasonic waves in a medium enhance the heat transfer, judging from the facts that applying ultrasonic waves to the liquid medium gives rise to areas of high and low local pressure. Therefore, in the present study, a coupled finite element-boundary element method(FE-BEM) was used to calculate the acoustic pressure in a medium. For the numerical analysis, we performed the process of finite element modeling. This modeling data was converted to the boundary element data by SVS(Structure Vibtation Simulator). SVS programmed was composed of FORTRAN language and based on a coupled FE-BEM. The results of numerical analysis reveal that acoustic pressure is increased by 60% at the ultrasonic intensity of 340W and the higher acoustic pressure distribution near two ultrasonic transducers.

기체 주입 Ladle내에서 유동특성에 관한 연구

오율권,서동표 조선대학교 에너지.자원신기술연구소 2003 에너지·자원신기술연구소 논문지 Vol.25 No.1

In the air-water model, the characteristics of flow parameters were experimentally investigated. When gas was injected into the liquid bath, several flow patterns were observed bubble-liquid plumb, the spout flow that occurred at the free surface, liquid circulation flow by bubble's behavior, etc. In the pure liquid region, the large and small several vortices were formed and irregularly circulated. These irregular repetition and circulation play a important role of mixing in the bath. The vortices were developed in the upper and the side wall regions and the movement of flow in the low region was very small. It is known as "dead zone". The bubble rise velocity in the bottom region was relatively lower than in the upper region because the energy generated by bubbles' behavior in the near nozzle region was almost converted into kinetic energy. But bubble rise velocity increases with the increasing the axial distance since kinetic energy of bubbles is added to buoyancy force.

Ladle 내에서 기포에 따른 액상 영역의 유동학적 특성에 관한 가시적 연구

오율권,서동표,양호동 조선대학교 에너지.자원신기술연구소 2004 에너지·자원신기술연구소 논문지 Vol.26 No.2

In the present study, the gas injection system based on air-water model was designed to investigate the fluid-dynamics characteristics of liquid zone into a ladle. PIV system and camera techniques were applied to analysis flow patterns at the liquid zone. Gas flow rate is one of most important factors which could feature a flow pattern in a gas injection system. At low gas flow rate, upward bubble flow induced by buoyancy force is predominant and does not make an impact on mixing due to a weak circulation flow. However, with increasing gas flow rate, the kinetic energy of bubble increases and a strong circulation flow develops in the liquid. Such a flow in the liquid develops vortex and improve the mixing process. Due to the centrifugal force, circulation flow was well developed near both wall sides and upper region respectively.

內燃機關의 排氣騷音이 性能에 미치는 影響

吳栗權,張熙碩,吳炯俊,車京玉 明知大學校 産業技術硏究所 1988 産業技術硏究所論文集 Vol.7 No.-

The theoretical analysis of the exhaust noise of an internal combustion entwine contains various difficult factors. The exhaust system is closely related with these problems, that is, the resistance of tile exhaust system is a factor governing the fuel economy and dynamic performance of an internal combustion engine, while exhaust noise and radiated noise from the system are one of the main factor affecting the quietness of an internal combustion engine and also one of the main sources of external noise of all internal combustion engine. Reducing tile resistance and lowering the exhaust and radiated noise are contracdictory requirements and it has been considered difficult to satisfy these requirements simultaneously. Almost all the studies on the attenuation characteristics of a muffler are an analysis based on the assumption that the time of intake-exhaust valve opening - closing is deadpoint. This paper introduces a practical exhaust system for internal combustion engine newly developed as the result of studies on the reduction of the exhaust system, pulsating noise and draft noise.

환기시스템의 효율 향상을 위한 후드 내 유해물질 포착속도 개선에 관한 연구

오율권,김영선,박경수 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.1

Most of the hood maximize on capture velocity concentrate in inhalation capacity of harmful materials on hood of center. But, decrease generally ventilation system efficiency because, the edge of hood decrease capture velocity of harmful materials. So, development on the gas-guidance-device for increase of capture velocity of harmful materials in hood increase generally ventilation system efficiency. In this study, flow in hood doing visibility after numerical analysis using the Phoenics 3.1 on commercial code of heat and fluid using finite volume method. And, boundary conditions establish the same condition as work space that it is temperature is 20 degrees, pressure in 1 atm, velocity in duct is 6.85m/s, diameter is 400mm. Also, gas-guidance-device draw optimum shape as a result comparison and analysis as being numerical analysis of variety shape. As the result of study, compare hood have gas-guidance-device with hood have no gas-guidance-device identify increase on harmful materials capture velocity. Also, gas-guidance-device identify best inhalation efficiency in hood when it is 125mm wide and a ratio of 4 to 6 on side. So, safety of worker and work environment improvement expect helped as a result remove effective on harmful materials in work space and cut down on expenses of occurrence when the inhalation volume again design for efficiency improvement of ventilation system.

FEM을 이용한 자동차 타이어용 알류미늄 합금 금형의 열변형 특성에 관한 연구

오율권,서동표,양호동,박근욱,김용범 朝鮮大學校 機械技術硏究所 2006 機械技術硏究 Vol.9 No.1

대부분의 타이어 제조를 위한 금형생산 공정은 실험적인 결과에 바탕을 두어 거의 경험치에 의존하고 있다. 이러한 방법은 금형제품을 생산하는데 있어 비효율적이고 비경제적인 측면이 많다. 따라서, 정밀도를 향상시키고 품질이 좋은 타이어를 제조하기 위해 금형의 제조공정은 재평가가 이루어져야 한다. 본 연구에서는 자동차 타이어용 알루미늄 합금 금형의열변형 및 특성을 조사하기 위해 유한요소법을 이용하여 수치해석적으로 연구를 수행하고자 하였다. 알루미늄 합금의 금형의 열변형 및 특성에 관해 조사하기 위해, 알루미늄 합금 금형 내부에서 발생되는 온도분포, 수축량, 응력 그리고 변형량을 수치해석적으로 계산하는연구를 수행하였다. 뿐만 아니라, 정밀도를 향상시키고 좋은 품질의 금형을 얻기 위해, 알루미늄 합금과 연강의 수치해석 결과를 비교하였다. 결국, 수치해석을 통해 얻은 결과들은향후 효과적이고 최상의 금형 제품을 제작하는데 도움을 줄 수 있으리라 본다. Most the mold product process is based on a experimental results and is almost dependent on experiments for tire manufacturing. This method produced the mold product is not only the ineffectiveness but also the bad economy. So, the product process of metal mold should be revaluated to produce the improved precision and good quality of tires. In this study, numerical analysis applied a finite element method (FEM) was used to predict the thermal strain characteristics of Aluminum (AI) alloy mold for automobile tire. To investigate the thermal strain and characteristics of Al alloy mold, it was performed that the temperature distribution. the contraction rates, the stress and the strain occurred on the inside of Al alloy mold was calculated by numerical works. Moreover, numerical analysis results of Al alloy mold were compared with those of mild steel mold in order to obtain the improved precision and good quality of mold. So, the numerical results of this study will be presented to help to make the effective and the best mold products.

Air-Water 모델에서 액상의 유동특성에 관한 연구

오율권,서동표,박설현 한국안전학회 2004 한국안전학회지 Vol.19 No.1

In the present study, the gas injection system based on air-water model was designed to investigate the flov< characteristics of liquid phase. A PIV system was applied to analyze the flow pattern in a ladle which gas started to rise upward from the bottom. Gas flow is one of most important factors which could feature a flow pattern in a gas injection system. As the gas injected into the liquid, the kinetic energy of bubble transfer to liquid phase and a strong circulation flow develops in the liquid phase. Such a flow in the liquid develops vortex and improve the mixing process. Due to the centrifugal force, circulation flow was well developed near both wall sides and upper region respectively. Increasing gas flow was helpful to remove dead zone but, weak flow zone still exists in spite of the increasement of gas flow rate.