산불 진화를 위한 회전식 고압 중간연결밸브 개발

오건제,이해수,김창,오석범 한국화재소방학회 2023 한국화재소방학회 학술대회 논문집 Vol.2023 No.2

대수응력모델을 사용한 선체 프로펠러면 주위의 점성유동해석

오건제 慶南大學校 附設 工業技術硏究所 1999 硏究論文集 Vol.17 No.-

선체와 같은 심한 굴곡을 갖는 형상주위의 유동은 아주 복잡하다. 특히 선미 Bulk를 갖는 저속 비대선의 경우는 선미 부근에서 유선의 곡률이 심하고 프로펠러 평면에서 vortex가 나타난다. 선체 주위 유동해석을 위하여 최근까지 와점도형 난류모델이 주로 적용되어 왔으나 프로펠로면에서 일어나는 복잡한 유동현상의 예측은 매우 힘들다.이러한 문제점을 해결하기 위하여, 유선의 곡률이 심하거나, vortex가 있는 경우에 잘 적용될 수 있는 대수응력모델을 사용하여 선체 주위의 점성 난류유동을 계산하였다. ITTC 표준모형선인 Tanker 및 실적선인 179K DWT 살몰 모형선에 대하여 수치해석을 수행하였으며, 프로펠러 면에서의 결과를 표준 k-ε 난류 모델 사용결과 및 실험결과와 비교 검토하였다. Viscous flow around the propeller plane of the ship with rapid curvature is very complex. Especially, the flow around a full slow ship with stern bulb shows highly curved streamlines and vortex on the propeller plane. Recently eddy-viscosity type turbulence models mostly have been used for the calculation of the flow around a ship. However, it is hard to analyse these complex flow on the propeller plane using the eddy-viscous type turbulence model. To resolve this problem, an Algebraic Stress Model(ASM) is applied. The ASM is suitable for the flow with highly curved streamlines and vortices. Calculations are performed for ship models of the HSVA Tanker and the 179K Bulk Carrier; the former is an ITTC standard model ship and the latter is a real constructed ship. The results on the propeller plane are discussed and compared with those of standard k-ε turbulence model and experiments.

냉각탑용 축류형 팬의 성능해석 기법

오건제 경남대학교 공업기술연구소 2001 硏究論文集 Vol.19 No.-

냉각탑용 축류형 팬의 성능곡선을 구하기 위하여 팬 날개 주위의 2차원 비점성유동 해석에 기초한 성능해석 기법을 개발하였다. 날개 주위의 유동관계식 경험식, 실험식 등을 이용해서 팬의 형상이 주어진 상태에서 설치각의 변화와 유량 변화에 따른 전압상승, 축동력, 효율 등에 대한 성능곡선을 구하였다. 본 해석기법의 타당성을 검증하기 위해서 실제 팬 형상에 적용하였다. 성능곡선은 일반적인 축류형 유체기계의 성능특성을 잘 나타내 주었으며, 설계점에서 설계변수와 일치하는 결과를 얻을 수 있었다. A technique to predict performance characteristics of the cooling tower fan is presented. This technique is developed using the equations for the 2-dimensional inviscid flow through the fan blade, the empirical equations, and the experimental correlations. The performance curves can be obtained for a given blade geometry and operating condition. The present method is used to generate the performance curves for a fan model. The predictions show typical performance characteristics of the axial flow fan very well. The values of the performance parameters at the design point in the curves is in mood agreement with those at the design stage.

수직 디푸져 연구에서 작동하는 소형 프로펠러 팬 주위의 점성유동해석 ( Numerical Analysis of Viscous Flow Around a Small Propeller Fan Operating at the Inlet of Vertical Diffuser )

오건제,강신형 대한기계학회 1996 대한기계학회 춘추학술대회 Vol.- No.-

디퓨져 앞에 위치한 팬의 성능특성 해석

오건제 慶南大學校 附設 工業技術硏究所 1997 硏究論文集 Vol.15 No.1

본 연구에서는 디퓨져 입구에서 작동하는 소형 프로펠러 팬에 대한 성능특성을 해석 하였다. 팬 주위의 점성유동을 Navier-Stokes 방정식을 이용하여 해석하고 이로부터 팬의 성능에 관한 변수들을 예측하여 실험결과와 비교하였다. 예측결과는 실험결과와 비교적 잘 일치 하였으며 본 해석방법이 팬의 성능특성을 잘 해석하고 있음을 알 수 있었다. Numerical prediction of performace characteristics of a small axial type fan operating at the inlet of a diffuser are performed using the Navier-Stokes computation. Viscous flow calculations are carried out for the flow in the whole domain employing the Navier-Stokes equations. The Reynolds stresses for turbulent transport are modelled by the k-εturbulence model. Numerical method is Finite Volume Method with the hybrid convection scheme and the SIMPLE algorithme. Computation results of the performance parameters are obtained for the five cases of the flow rate and compared with the measured ones. Predictions are reasonably following the trend of variations of the measurements and it is conformed that performance characteristics are reasonably resolved in the simulation.

개방된 챔버 입구에서 작동하는 소형 프로펠러 팬 주위의 난류유동해석

오건제,강신형,O, Geon-Je,Gang, Sin-Hyeong 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.12

Performance characteristics of a small propeller fan are numerically investigated solving the continuity and Reynolds-averaged Navier-Stokes equations. The Reynolds stresses for turbulent transport are modelled using a k-.epsilon. turbulence model. The present numerical procedure is constructed using the Finite Volume Method with the SIMPLE algorithms. The performance parameters obtained from the calculations are compared with the measured values for the various flow rates. A performance test of the fan shows different characteristics between a radial type at small flow rates and an axial type at large flow rates. Comparisons between the predictions and the measurements show that the predicted results are in good agreement with the measured values and reasonably reproduce the sharp variations of the power and head coefficient around a flow coefficient .PHI.=0.3. These comparisons indicate that the present numerical method is capable of resolving the performance characteristics with reasonable accuracy. At low flow rates, it is found that the flow enters the fan in an axial direction and is discharged radially outward at the tip which happens in the centrifugal fan. The centrifugal effect makes a significant difference in the characteristics of a fan at the low and high values of flow coefficient.

LARGE EDDY SIMULATION OF THE COMPRESSIBLE FLOW OVER A CAVITY WITH HIGH ASPECT RATIO

오건제 한국전산유체공학회 2004 한국전산유체공학회지 Vol.9 No.1

Large eddy simulation is used to investigate the compressible flow over a cavity with high aspect ratio. The sub-grid scale stresses are modeled using the dynamic model. The compressible Navier-Stokes equations are solved with the sixth order accurate compact finite difference scheme in the space and the 4th order Runge-Kutta scheme in the time. The buffer zone techniques are used for non-reflecting boundary conditions. The results show the shear layer oscillation over the cavity. The votical disturbances, the roll-up of vorticity, and impingement and scattering of vorticity at the downstream cavity edge can be seen in the shear layer. Several peaks for the resonant frequencies are found in the spectra of the vertical velocity at the center-line. The most energetic peak near the downstream edge is different from that at the center part of the cavity. The pressure has its minimum value in the vortex core inside the cavity, and becomes very high at the downstream face of the cavity. The variation of the model coefficient predicted by the dynamic model is quite large between 0 and 0.3. The model coefficient increases in the stream-wise evolution of the shear layer and sharply decreases near the wall due to the wall effect.

변압기를 모델링한 두 개의 동심 원형 실린더 내에서 난류 자연대류의 수치해석

오건제,하수석 대한설비공학회 1999 설비공학 논문집 Vol.11 No.2

Numerical calculations of turbulent natural convection in an enclosure of the 20 kYA oil-immersed transformer model are presented. The transformer is modelled as two concentric cylinders with different heights and diameters. The thermal boundary layers are well represented in the temperature distributions along the wall of the transformer model. The flow stratification between the hot and cold walls can not be seen in the transformer model. The turbulence eddy viscosity has its maximum at the center of the core and its maximum values at the top of the core are larger than those at the bottom of the core.

냉각탑용 축류형 F.R.P. 팬의 개발

오건제,김선숙 대한설비공학회 2007 설비공학 논문집 Vol.19 No.10

An axial F.R.P. fan model for cooling tower is developed. The fan is designed using the equations for one dimensional inviscid flow through the fan blade. Fan shape is swept forward with a parabolic function. Calculations of the three dimensional turbulent flow around the fan are carried out to investigate performance of the fan. Data of the total pressure rise and hydraulic efficiency can be obtained for the various setting angles. Calculated values of the total pressure rise and hydraulic efficiency at the design point are less than those of the design specification. The prototype of the F.R.P. fan is made by laminating of the fiberglass and epoxy resins on the mold of fan shape.

개방된 챔버입구에서 작동하는 소형 프로펠러 주위의 점성 해석 ( Numerical Analysis of Viscous Flow Around a Small Propeller Fan Operating at the Inlet of Open Chamber )

오건제,강신형 대한기계학회 1996 대한기계학회 춘추학술대회 Vol.- No.-