• Journal of Power System Engineering
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• v.3 no.2
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• pp.13-19
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• 1999

The purpose of the present experimental study is to apply multi-point simultaneous measurement by PIV(Particle Image Velocimetry) to high-speed flow region within a domestic boiler circulation pump. Two different kinds of flow rate($27{\ell}/min,\;19{\ell}/min$)are selected as experimental condition. A volute casing and Impeller made of transparent Polycarbonate were made for the easy access of the illumination laser via fiber optical line and cylinder lens assembly to the measuring region. A CCD camera is syncronized with AOM to acquire clear original particle images. Optimized cross correlation identification to obtain velocity vectors is implemented by direct calculation of correlation coefficients. The instantaneous and time-mean velocity distribution, velocity profile and kinetic energy are represented quantitatively at the full-scale region for the deeper understanding of the unsteady flow characteristics in a commercial circulation pump.

• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 1989.10a
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• pp.1.3-25
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• 1989

This paper describes procedures and the results of mineralogical, fabric and pore sixte analyses perforied on four shales to understand time-dependent deforiation behav iour of swell ins shales better. Mineralogical compositions of theme shales are eBtablished froi the results of X-ray diffraction snalysis and chemical analyses. The importance of the fabric in the understanding of swelling behaviour of shales is demonstrated using Scanning Electron Microscope (SRI). The change in pore sixte distribution during the process of swelling is investigated by measuring pore size distribution before and after free swell test. The results Of the Present study imply that the swelling of Shales studied is not attributed to minerals like pyritei anhydrite or swelling clay minerals. The anisotropic swelling behaviour of shales studied ray be explained by fabrics of theme shales and the difference in them. The swelling of theme shales is found to be accoipanied by increase in the volute of pores.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.280-283
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• 2008

This study is concerned with development of air supply system in 250kW MCFC fuel cell system. The turbo blower is decided as an air supply system to increase the efficiency of fuel cell system. The turbo blower consists of an impeller, two vaneless diffuser, a vaned diffuser and a volute. The cascade diffuser is used to raise the efficiency of turbo blower. An aerodynamic design was done by applying the repeating design procedure including a meanline design, a 3D geometry generation and fluid dynamic calculation. It is confirmed from meanline and 3D flow analysis results that the operating range is enough and design requirements are successfully achieved. The performance test results were also included in this paper.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.8
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• pp.1035-1041
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• 2007

An improvement of driving motor burning damages on a couplingless type warship fire pump is studied. The pump consists of an induction motor a pump-motor shaft and a volute type impeller. The burning damage had occured by changing the material of the pump-motor shaft from carbon steel(SM 45C) to stainless steel(STS 316) for improving anti-corrision properity in sea water. It is shown that a material change on the pump-motor shaft can reduce the efficiency of driving motor and may cause motor burning in the process of pump development stage. This kind of motor burning problem can be solved by increasing the efficiency of the motor and changing the geometry of the inner parts.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.354-358
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• 2005

The magnitude of the axial force acting on turbopump bearings has a great influence on the operational reliability and service life of a turbopump. In the turbopump under current investigation the cavity vanes are introduced to the pump shroud casing to control the axial thrust of the turbopump. To investigate the effect of the cavity vanes, 3D computational flow analyses for a propellant pump stage including an inducer, impeller, volute and secondary flow passages are performed with and without the vanes. The results show that the cavity vanes are very effective in reducing the magnitude of axial thrust without notable changes on the overall performance of the turbopump.

• International Journal of Fluid Machinery and Systems
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• v.3 no.1
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• pp.29-38
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• 2010

This paper presents a procedure for the design optimization of a centrifugal compressor. The centrifugal compressor consists of a centrifugal impeller, vaneless diffuser and volute. And, optimization techniques based on the radial basis neural network method are used to optimize the impeller of a centrifugal compressor. The Latin-hypercube sampling of design-of-experiments is used to generate the thirty design points within design spaces. Three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model are discretized by using finite volume approximations and solved on hexahedral grids to evaluate the objective function of the total-to-total pressure ratio. Four variables defining the impeller hub and shroud contours are selected as design variables in this optimization. The results of optimization show that the total-to-total pressure ratio of the optimized shape at the design flow coefficient is enhanced by 2.46% and the total-to-total pressure ratios at the off-design points are also improved significantly by the design optimization.

• The KSFM Journal of Fluid Machinery
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• v.14 no.4
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• pp.5-11
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• 2011

This study investigated on details of flow characteristics in a vaneless diffuser of a compressor with 2-dimensional impeller at various flow rates. Experiment for a low speed compressor model in a water reservoir was performed to analyze the flow field in the vaneless diffuser and volute casing, which was done by PIV measurement. It was also focused on the periodic flow patterns occurring at low flow rate near unstable operating region of the compressor. At low flow rate condition, the flow visualization clearly shows that the flow energy from impeller is highly accumulated at the compressor exit by the blockage effect of a flow damper and consequently the reverse flow occurs in the diffuser.

• The KSFM Journal of Fluid Machinery
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• v.16 no.4
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• pp.28-34
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• 2013

Centrifugal pump consists of a axis, a impeller and a spiral casing. The impeller is the most important component in centrifugal pump. But to minimize flow loss in discharge passage including spiral casing, the shape of spiral casing is very important also. So, to investigate the effect of shape of the spiral casing on performance curve of pump, the characteristics of spiral casing were studied through numerical analysis for centrifugal pump used on industry field. From the results the rectangular model was showed more loss than the others because of asymmetric flow field.

• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.555-565
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• 2021

The goal of this study is to improve flow and noise performances of existing backward-curved blade centrifugal fan system used for circulating cold air in a refrigerator freezer by optimally designing airfoil shape. The unique characteristics of the system is to drive cold airflow with two volute tongues in combination with duct system in a back side of a refrigerator without scroll housing generally used in a typical centrifugal fan system. First, flow and noise performances of existing fan system were evaluated experimentally. A P-Q curve was obtained using a fan performance tester in the flow experiment, and noise spectrum was measured in an anechoic chamber in the noise experiment. Then, flow characteristics were numerically analyzed by solving the three-dimensional unsteady Navier-Stokes equations and noise analysis was performed by solving the Ffowcs Williams and Hawkins equation with input from the flow simulation results. The validity of numerical results was confirmed by comparing them with the measured ones. Based on the verified numerical method, blade inlet and outlet angles were optimized for maximum flow rate using the two-factor central composite design of the response surface method. Finally, the flow and noise performances of a prototype manufactured with the optimum design were experimentally evaluated, which showed the improvement in flow and noise performance.