• 대한기계학회논문집B
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• 제27권10호
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• pp.1457-1463
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• 2003

In this paper, the response surface method using three-dimensional Navier-Stokes analysis to optimize the shape of a multi-blade centrifugal fan, is described. For numerical analysis, Reynolds-averaged Navier-Stokes equations with standard k - c turbulence model are transformed into non-orthogonal curvilinear coordinate system, and are discretized with finite volume approximations. Due to the large number of blades in this centrifugal fan, the flow inside of the fan is regarded as steady flow by introducing the impeller force models for economic calculations. Linear Upwind Differencing Scheme(LUDS) is used to approximate the convection terms in the governing equations. SIMPLEC algorithm is used as a velocity-pressure correction procedure. Design variables, location of cur off, radius of cut off, expansion angle of scroll and width of impeller were selected to optimize the shapes of scroll and blades. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, the efficiency was successfully improved. It was found that the optimization process provides reliable design of this kind of fans with reasonable computing time.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1998년도 유체기계 연구개발 발표회 논문집
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• pp.42-48
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• 1998

Numerical study is presented for the analysis of three-dimensional incompressible turbulent flows in multiblade centrifugal fan. Reynolds-averaged Navier-Stokes equations with standard k - $\epsilon$ turbulence model are transformed to non-orthogonal curvilinear coordinates, and are discretized with finite volume approximations. Linear Upwind Differencing Scheme(LUDS) is used to approximate the convection terms in the governing equations. SIMPLEC algorithm is used as a velocity-pressure correction procedure. The computational area is divided into three blocks; core, impeller and scroll, which are linked by multi-block method. The flow inside of the fan is regarded as steady flow, and mathematical formula established from the cascade theory and empirical coefficient are employed to simulate tile flow through the impeller. From comparisons between the computational results and the experimental data, the validity of the mathematical formula for the blade forces was examined and good results were obtained qualitatively. Hence, we can get the flow characteristics of multi-blade centrifugal fan and it will be a corner stone of the development of the multiblade centrifugal fan.

• Journal of Advanced Marine Engineering and Technology
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• 제32권2호
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• pp.284-291
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• 2008

This study presents an aerodynamic design and numerical analysis of a centrifugal compressor in gas turbines for SOFC-gas turbine hybrid system application. Total-to-total pressure ratio of the compressor is 3.6:1 that could be used widely for small and large SOFC-gas turbine systems. The compressor consists of a centrifugal impeller and a wedge diffuser. Conceptual design and aerodynamic design with mean line analysis and quasi-3D analysis are performed, and aerodynamic parameters as well as design variables are discussed from the design results. A numerical analysis based on the Reynolds-averaged Navier-Stokes equation was performed for the flow analysis of the compressor. The results show that the centrifugal compressor designed meets the design target, and the aerodynamic parameters and results of the compressor can be used for the aerodynamic design of centrifugal compressors and the feasibility study of SOFC-gas turbine system design.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2157-2161
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• 2003

In this paper, the response surface method using three-dimensional Navier-Stokes analysis to optimize the shape of a forward-curved blades centrifugal fan, is described. For numerical analysis, Reynolds-averaged Navier-Stokes equations with standard k-e turbulence model are transformed into non-orthogonal curvilinear coordinate system, and are discretized with finite volume approximations. Due to the large number of blades in forward-curved blades centrifugal fan, the flow inside of the fan is regarded as steady flow by introducing the impeller force models for economic calculations. Linear Upwind Differencing Scheme(LUDS) is used to approximate the convection terms in the governing equations. SIMPLEC algorithm is used as a velocity-pressure correction procedure. Design variables, location of cur off, radius of cut off, expansion angle of scroll and width of impeller were selected to optimize the shapes of scroll and blades. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, the efficiency was successfully improved. It was found that the optimization process provides reliable design of this kind of fans with reasonable computing time

• 대한기계학회논문집B
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• 제34권7호
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• pp.703-714
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• 2010

본 연구에서는 크리깅 기법을 이용하여 엇갈린 핀휜이 부착된 회전하는 내부냉각유로의 형상 최적화를 수행하였다. 냉각유로 형상의 여러 매개변수 중 핀의 지름과 높이의 비, 핀의 지름과 핀과 핀 사이의 거리의 비를 최적설계를 위한 설계변수로 선택하였다. 열전달 관련 목적함수와 마찰손실 관련 목적함수를 가중계수를 이용하여 선형적으로 결합한 목적함수를 정의하였다. 크리깅 모델을 구축하기 위해 라틴하이퍼큐브 샘플링기법에 의해 생성된 20개 실험점에서 목적함수가 SST난류모델을 사용한 삼차원 레이놀즈평균 나비어-스톡스(RANS) 유동해석법에 의해 계산되었다. 크리깅 기법을 통하여 예측된 목적함수값은 RANS해석을 이용해 계산된 값과 매우 작은 오차 범위 내에서 일치하였으며, 최적설계를 통해 목적함수가 11% 감소하는 결과를 얻었다.

• 한국수소및신에너지학회논문집
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• 제25권5호
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• pp.550-559
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• 2014

Hydraulic performance of the 1 inch ball valve have been analyzed based on the three-dimensional Reynolds-averaged Navier-Stokes analysis and an experiment. The experimental test rig of the 1 inch ball valve has been developed to investigate pressure drop for the 1 inch ball valve. The numerical model, which has reliability and effectiveness, has been constructed through the grid dependency test and validation with the results of the experiment. Shear stress transport turbulence model has been used to enhance an accuracy of the turbulence prediction in the pipeline and ball valve, respectively. Effects of the ball valve angle on the flow characteristics and friction performance have been evaluated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2690-2695
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• 2007

This work presents numerical optimization for design of a blade stacking line of a low speed axial flow fan with a fast and elitist Non-Dominated Sorting of Genetic Algorithm (NSGA-II) of multi-objective optimization using three-dimensional Navier-Stokes analysis. Reynolds-averaged Navier-Stokes (RANS) equations with ${\kappa}-{\varepsilon}$ turbulence model are discretized with finite volume approximations and solved on unstructured grids. Regression analysis is performed to get second order polynomial response which is used to generate Pareto optimal front with help of NSGA-II and local search strategy with weighted sum approach to refine the result obtained by NSGA-II to get better Pareto optimal front. Four geometric variables related to spanwise distributions of sweep and lean of blade stacking line are chosen as design variables to find higher performed fan blade. The performance is measured in terms of the objectives; total efficiency, total pressure and torque. Hence the motive of the optimization is to enhance total efficiency and total pressure and to reduce torque.

• 한국전산유체공학회지
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• 제13권2호
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• pp.55-61
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• 2008

The Reynolds-Averaged Navier-Stokes(RANS) analysis of the 3-D steady flow around the NREL Phase VI horizontal axis wind turbine(HAWT) rotor was performed. The CFD analysis results were compared with experimental data at several different wind speeds. The present CFD model shows good agreements with the experiments both at low wind speed which formed well-attache flow mostly on the upper surface of the blade, and at high wind speed which blade surface flow completely separated. However, some discrepancy occurs at the relatively high wind speeds where mixed attached and separated flow formed on the suction surface of the blade. It seems that the discrepancy is related to the onset of stall phenomena and consequently separation prediction capability of the current turbulence model. It is also found that strong span-wise flow occurs in stalled area due to the centrifugal force generated by rotation of the turbine rotor and it prevents abrupt reduction of normal force for higher wind speed than the designed value.

• 한국수소및신에너지학회논문집
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• 제31권1호
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• pp.151-159
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• 2020

This study aimed to investigate the performance characteristics of vertical axis turbine of tidal energy convertor. Three-dimensional Reynolds-averaged Navier-Stokes equation with shear stress transport turbulence model has been solved to analyze the fluid flow of the vertical axis turbine. The hexahedral grids have been used to construct the computational domain and the grid dependency test has been performed to find the optimum grid system. Four steps have been carried out to design the vertical axis turbine of the 100 kW class tidal energy convertor.

• 한국유체기계학회 논문집
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• 제3권1호
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• pp.19-27
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• 2000

A numerical study is presented for analysis of three-dimensional incompressible turbulent flows in a multi-blade centrifugal fan. Reynolds-averaged Navier-Stokes equations with a standard $k-{\espilon}$ turbulence model are discretized with finite volume approximations. The computational area is divided into three blocks; inlet core, impeller and scroll parts, which are linked by a multi-block method. The flow inside of the fan is regarded as steady flow, and the mathematical models for the impeller forces were established from a cascade theory and measured data. Empirical coefficients are obtained comparing between computational and experimental results for the case without scroll, and are employed to simulate the flow through the impeller with scroll. In comparisons with experimental data, the validity of the mathematical models for the impeller forces was examined. The characteristics of the flow in the scroll were also discussed.