• The KSFM Journal of Fluid Machinery
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• v.13 no.2
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• pp.30-35
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• 2010

Pressure characteristics according to the duct shapes of turbo blowers connected in serial have been performed to reduce pressure loss in the piping system. To analyze three-dimensional flow field in the turbo blower system, general analysis code, CFX, is introduced in the present work. SST turbulence model is applied to estimate the eddy viscosity. Throughout the numerical simulation for the turbo blower system having a various shape of a inlet guide, optimal inlet guide can be selected. It is found that the pressure loss in the piping system having the optimal inlet guide can be reduced by minimizing the inflow distortion at the upstream of the impeller. Detailed flow analysis of the blower system serially connected is also performed and analyzed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.768-773
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• 2001

The self-noise from blade cascade at off-design points mainly comes from separated boundary layer and vortex sheddings, and is also dependent on blade shape. If the incidence angle to the cascade increases, the stalling in blades may occur and the noise level increases significantly. The hybrid method using acoustic analogy was employed to compute the far-field noise spectra and directivity patterns from the separated vortex shedding at off-design points of the cascade of impeller. This paper is compared with the experimental data of a stationary cascade in the same conditions. The simulated result is in excellent .agreement with the measured data except th slight under-prediction near the maximum radiation angle for a dipole sound.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.197-200
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• 2007

FCEV uses electric energy generated from fuel cell stack, thus all consisting parts must be re-designed to be suitable for electricity based system. Cathode air blower which supplies compressed air into fuel cell stack has similar shape of turbocharger, but a radial turbine of traditional turbocharger is removed and high speed BLDC motor is installed . Generally, maximum 10% of electric power of fuel cell stack is consumed in air blower, therefore an effective design of air blower can improve the performance of FCEV directly. This study will present an aerodynamic design process of an air blower and compare computational results with experimental data.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.240-243
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• 2008

In this paper, the design of Centrifugal Compressor which is used in sizes 50 horse power has 8 pressure ratio and numerical analysis of the flow within compressor varying tip clearance length are performed. To get high pressure ratio with low power the exit height of impellers is low but compressor has very high speed of revolution. So compressor has high specific speed although mass flow rate is very small. The shape of impellers at the first stage is carried out. Flow and performance characteristics of impellers has been analyzed by using a commercial CFD program, $Fine^{TM}$/turbo. The result shows that loss coefficient is affected by tip clearance length and compressor has proper tip clearance length. It is possible to decrease loss by selecting apt tip clearance length.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.568-573
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• 2000

In this study, experimental and numerical analyses are carried out to investigate the performance of centrifugal pump with various air admitting conditions. Experiments on pump performance under air-water two-phase flow n accomplished using a centrifugal pump with semi-open type impeller having three, five and seven blades, respectively. Also, the numerical analysis of turbulent air-water two-phase flow using finite volume method has been carried out to obtain the pressure, velocities and void fraction on the basis of a so-called bubbly flow model with the constant size and shape of cavity. The results obtained through this study show the reasonable agreements within the range of bubbly flow regime. There are promising developments concerning application of the present study for the flow in a centrifugal pump with two-phase flow conditions and efforts must be followed to improve the turbulence model and two-phase flow model for turbomachinery.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.491-496
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• 2005

A pump design system was constructed by several integrating in-house programs and commercial softwares to design and evaluate centrifugal pumps. An agent-based prototype framework has been developed for collaborative design and optimization of a centrifugal pump. This paper introduces the feasible technology needed to construct a pump design system based on software agents. The integrated design system, developed in the present study, was used in designing a centrifugal pump and modifying its impeller shape by using optimization processes to increase the pump performance.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.583-589
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• 2004

One of noticeable features in the cross flow fan is that a working fluid passes through impeller blade twice without distinction between the inlet and exit angles. Also, it does produce higher circumferential velocity than other types of blade at the same flow rate in accordance with the application of the forward curved shape. However, a design theory for the cross-flow fan has not yet been formed owing to an eccentric vortex, which is the remarkable characteristics, occurred in a cross-flow fan. Furthermore, the eccentric vortex, which is difficult to control of the size and position, is the important cause of performance decrease. In this study, experiments are carried out to estimate the similarity of the cross-flow fan with various scales and rotational velocity changes. Pressure coefficients to flow coefficients with various scales of the cross-flow fan are plotted to research the application of the general similarity law of the turbomachinery in the cross-flow fan with Archimedes spital, which is the important factor haying an effect on it.

• The KSFM Journal of Fluid Machinery
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• v.12 no.6
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• pp.7-12
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• 2009

This paper presents a numerical study on the design of side-suction inlet geometry which is used for multi stage centrifugal pumps or inline centrifugal pumps. In order to achieve an optimum inlet geometry and to explain the interactions between the different geometric configurations, the three dimensional computational fluid dynamics and the design of experiment methods have been applied. Geometric design variables describing the cross sectional area distribution through the inlet were selected. The objective functions are defined as the non-uniformity of the velocity distribution at the passage exit which is just in front of the impeller eyes. From the 2k factorial design results, the most important design variable was found and the performance of the side suction inlet was improved compared to the base line shape.

• Journal of ILASS-Korea
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• v.9 no.4
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• pp.77-82
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• 2004

This paper describes the improvement of engine cooling system. To improve engine cooling performance, the authors approached in two ways. One is to increase water pump performance, changing of impeller shape and lightening of material were carried out. The second one is cooling efficiency rise, which were investigated with head gasket coolant flow passage optimization with flow visualization technique. The test results show that water pump performance was increased effectively, reduction of pump drive torque, and increase of pump flow-rate and pressure rise. Gasket hole pattern optimization test results represent an optimized head coolant flow which stands cross flow from exhaust to intake port side and small vortex were removed.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.6
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• pp.787-791
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• 2010

This paper describes the performance of small waterjet propulsion system and show the influence of performance for nozzle shape and area. The installed engine sets a limit on maximum power in below 1800 rpm for fuel saving. Our designated target is reached by redesign of the impeller considering engine characteristics and extention of nozzle pararell part. The results of the full-scale ships are compared with thoes of the model test. In the future, those experimental data will be applied to the relation study between engine characteristics and powering performance prediction.