• International Journal of Fluid Machinery and Systems
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• 제8권4호
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• pp.294-303
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• 2015

The present study is conducted to identify a better design and optimal number of Francis runner blades for sediment laden high head micro hydropower site, Tara Khola in the Baglung district of Nepal. The runner is designed with in-house code and Computational Fluid Dynamics (CFD) analysis is performed to evaluate the performance with three configurations; 11, 13 and 17 numbers of runner blades. The three sets of runners were also investigated for the sediment erosion tendency. The runner with 13 blades shows better performance at design as well as in variable discharge conditions. 96.2% efficiency is obtained from the runner with 13 blades at the design point, and the runners with 17 and 11 blades have 88.25% and 76.63% efficiencies respectively. Further, the runner with 13 blades has better manufacturability than the runner with 17 blades as it has long and highly curved blade with small gaps between the blades, but it comes with 65% more erosion tendency than in the runner with 17 blades.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.152-155
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• 2008

In this paper, the effect of modification of geometric variables on the performance of a centrifugal compressor blade has been studied numerically. The compressor contains six main blades and six splitter blades. Reynolds averaged Navier-Stokes (RANS) equations with shear stress turbulence (SST) model are discretized by finite volume approximations and solved on hexahedral grids for flow analysis. The design variables from blade lean angle at tip and middle of the blade have been modified. The isentropic blade efficiency and pressure have been predicted with the variation of the variables. Frozen rotor simulation is performed and adiabatic wall condition has been used. One of the six blades of compressor has been used for simulation to reduce the computational load. Optimum number of meshes has been selected by grid-dependency test, and this is used for all the simulations with changing geometric variables. The detailed flow analysis results have been reported as well as the effects of the variables.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1222-1227
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• 2000

The optimization study are carried out for helicopter rotor blades with composite box-beam spar. The objective function is to minimize the weight of rotor blades subject to frequency, aeroelastic stability and failure constraints. Design variables include the number of ply and ply angles of the laminated walls. The beam model of a hinge less rotor blade is based on a large deflection beam theory to describe the arbitrary large deflections and rotations. The p-k method and unsteady two dimensional strip theory are used to calculate aeroelastic stability boundary.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.213-216
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• 2006

This paper was a study about noise reduction through flow stabilization in duct using experimental method and numerical analysis at the same time. To determine the fan's type three kinds of fans(axial fan, centrifugal fan, and axial fan with centrifugal type blades) was examined to investigate the suitability for in-line duct. As a result, under the equal number of rotation 2000 RPM, performance of an axial fan with centrifugal type blades was the most superior by 55dBA at 4.3CMM among other fans. After this, analyzed the results of the numerical analysis to find out the optimum design of pitch angle such as $0^{\circ}$, $10^{\circ}$, $15^{\circ}$ and $20^{\circ}$. The intensity of turbulence was low when pitch angle was $15^{\circ}$ and air volume became peak by 5.08 CMM. It was observed that axis component of velocity increased gradually when pitch angle increased from $0^{\circ}$ to $20^{\circ}$, and embodied noise reduction and improvement of air flow rate through flow stabilization.

• 대한기계학회논문집B
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• 제28권11호
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• pp.1332-1338
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• 2004

This paper presents the response surface optimization method using three-dimensional Navier-Stokes analysis to optimize the shape of a forward-curved blades centrifugal fan. For numerical analysis, Reynolds-averaged Navier-Stokes equations with k-$\varepsilon$ turbulence model are discretized with finite volume approximations. In order to reduce huge computing time due to a 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. Three geometric variables, i.e., location of cut off, radius of cut off, and width of impeller, and one operating variable, i.e., flow rate, were selected as design variables. As a main result of the optimization, the efficiency was successfully improved. And, optimum design flow rate was found by using flow rate as one of design variables. It was found that the optimization process provides reliable design of this kind of fans with reasonable computing time.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1726-1731
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• 2004

This paper presents the response surface optimization method using three-dimensional Navier-Stokes analysis to optimize the shape of a forward-curved blades centrifugal fan. For numerical analysis, Reynolds-averaged Navier-Stokes equations with $k-{\varepsilon}$ turbulence model are discretized with finite volume approximations. In order to reduce huge computing time due to a 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. Three geometric variables, i.e., location of cut off, radius of cut off, and width of impeller, and one operating variable, i.e., flow rate, were selected as design variables. As a main result of the optimization, the efficiency was successfully improved. And, optimum design flow rate was found by using flow rate as one of design variables. It was found that the optimization process provides reliable design of this kind of fans with reasonable computing time.

• 한국소음진동공학회논문집
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• 제14권9호
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• pp.819-826
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• 2004

A multi-step optimum strategy for the selection of the locations and directions of strain gauges is proposed in this paper to capture at best the modal response of blade in a series of modes on fan blades. It is consist of three steps including two pass reduction step, genetic algorithm and fine optimization to find the locations-directions of strain gauges. The optimization is based upon the maximum signal-to-noise ratio(SNR) of measured strain values with respect to the inherent system measurement noise, the mispositioning of the gauge in location and gauge failure. Optimal gauge positions for a fan blade is analyzed to prove the effectiveness of the multi-step optimum methodology and to investigate the effects of the considering parameters such as the mispositioning level, the probability of gauge failure, and the number of gauges on the optimal strain gauge position.

• International Journal of Fluid Machinery and Systems
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• 제3권1호
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• pp.39-49
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• 2010

In this paper, a numerical study has been carried out to investigate the influence of jet fan design variables on the performance of a jet fan. In order to achieve an optimum jet fan design and to explain the interactions between the different geometric configurations in the jet fan, three-dimensional computational fluid dynamics and the DOE method have been applied. Several geometric variables, i.e., hub-tip ratio, meridional shape, rotor stagger angle, number of rotor-stator blades and stator geometry, were employed to improve the performance of the jet fan. The objective functions are defined as the exit velocity and total efficiency at the operating condition. Based on the results of computational analyses, the performance of the jet fan was significantly improved. The performance degradations when the jet fan is operated in the reverse direction are also discussed.

• 설비공학논문집
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• 제24권2호
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• pp.136-141
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• 2012

Performance improvement of local exhaust system used in toilet and cooking place are main concern in a field of ventilation. In Korea, There are many high riser residential apartments in recent years. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depends on stack effect. This study investigates on the performance improvement of terminal device, roof fan, of vertical spiral duct used in high riser residential apartments. This paper focuses mainly on the effect of accessories, number or shape of blades, composed of roof fan with function of exhaust air volume of toilet and cooking place. Roof fan with 10 blades is observed at optimum exhaust performance in this study.

• 대한기계학회논문집B
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• 제37권4호
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• pp.423-429
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• 2013

수직축 풍력발전기의 발전 전력을 유동해석을 이용하여 예측하였다. 해석은 블레이드 회전 속도를 고정하고 그 회전 속도에서 토크를 반력으로 추출하였다. 여러 경우의 블레이드의 회전 속도에 대해 토크를 구하고 발전 용량을 계산하였다. 회전 속도에 따른 발전 토크와 발전 용량을 계산함으로써 최적의 발전기와 그 때의 회전 속도를 선정할 수 있었다. 또한, 블레이드의 개수와 블레이드의 형상에 대해 해석을 수행하여 그 영향을 분석하였다. 마지막으로 실험을 수행하여 그 결과를 비교하였다.