• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1322-1325
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• 2009

The impeller and vane diffuser for the mixed flow pump(NS550) was designed by using meridional selection program and inverse design method. We decided the meridional shape of the impeller from the meridional design parameter, such as the specific speed and maximum diameter at the impeller exit. The meridional shape of vane diffuser was set from the impeller shape, distribution of cross sectional area and maximum diffuser diameter. The angle of impeller blade and diffuser vane was designed by using inverse design method. The predicted overall performance by using commercial CFD code(ANSYS CFX-11) shown good agreement with design goals.

• 센서학회지
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• 제10권4호
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• pp.232-238
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• 2001

본 논문에서는 Stereolithography 기술을 이용하여 마이크로 펌프를 제작했다. 펌프는 구동에 PZT를 사용하고, diffuser/nozzle 개념의 non-movable 밸브를 사용하여 제작했다. 펌프의 크기는 챔버$14mm{\psi}$, diffuser/nozzle의 크기는 좁은 쪽의 구멍은 $0.5mm{\psi}$, 넓은 쪽의 구멍은 $1mm{\psi}$로 제작하고, 챔버의 깊이는 1.2mm이다. 펌프는 주파수 100Hz, 인가 전압 $90{\sim}250Vp-p$ 사이에서 구동시켜, 그 동작을 확인했다. 측정 결과, 펌핑 용액이 에탄올 일 때, 인가 전압 200V, 100Hz로 구동했을 때, 53mm의 수두차를 나타냈다.

• International Journal of Fluid Machinery and Systems
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• 제8권3호
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• pp.193-201
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• 2015

This paper deals with the influence of leakage flow existing in SHF pump model on the analysis of internal flow behaviour inside the vane diffuser of the pump model performance using both experiments and calculations. PIV measurements have been performed at different hub to shroud planes inside one diffuser channel passage for a given speed of rotation and various flow rates. For each operating condition, the PIV measurements have been trigged with different angular impeller positions. The performances and the static pressure rise of the diffuser were also measured using a three-hole probe. The numerical simulations were carried out with Star CCM+ 9.06 code (RANS frozen and unsteady calculations). Some results were already presented at the XXth IAHR Symposium for three flowrates for RANS frozen and URANS calculations. In the present paper, comparisons between URANS calculations with and without leakages and experimental results are presented and discussed for these flow rates. The performances of the diffuser obtained by numerical calculations are compared to those obtained by the three-holes probe measurements. The comparisons show the influence of fluid leakages on global performances and a real improvement concerning the efficiency of the diffuser, the pump and the velocity distributions. These results show that leakage is an important parameter that has to be taken into account in order to make improved comparisons between numerical approaches and experiments in such a specific model set up.

• International Journal of Fluid Machinery and Systems
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• 제8권4호
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• pp.274-282
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• 2015

This paper deals with the influence of leakage flow existing in SHF pump model on the analysis of internal flow behaviour inside the vane diffuser of the pump model performance using both experiments and calculations. PIV measurements have been performed at different hub to shroud planes inside one diffuser channel passage for a given speed of rotation and various flow rates. For each operating condition, the PIV measurements have been trigged with different angular impeller positions. The performances and the static pressure rise of the diffuser were also measured using a three-hole probe. The numerical simulations were carried out with Star CCM+ 9.06 code (RANS frozen and unsteady calculations). Some results were already presented at the XXth IAHR Symposium for three flowrates for RANS frozen and URANS calculations. In the present paper, comparisons between URANS calculations with and without leakages and experimental results are presented and discussed for these flow rates. The performances of the diffuser obtained by numerical calculations are compared to those obtained by the three-holes probe measurements. The comparisons show the influence of fluid leakages on global performances and a real improvement concerning the efficiency of the diffuser, the pump and the velocity distributions. These results show that leakage is an important parameter that has to be taken into account in order to make improved comparisons between numerical approaches and experiments in such a specific model set up.

• 한국초전도ㆍ저온공학회논문지
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• 제18권1호
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• pp.64-68
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• 2016

High Temperature Superconductor power cable systems are being developed actively to solve the problem of increasing power demand. With increases in the unit length of the High Temperature Superconductor power cable, it is necessary to develop highly efficient and reliable cryogenic pumps to transport the coolant over long distances. Generally, to obtain a high degree of efficiency, the cryogenic pump requires a high pressure rise with a low flow rate, and a partial emission type pump is appropriate considering its low specific speed, which is different from the conventional centrifugal type, full emission type. This paper describes the design of a partial emission pump to circulate subcooled liquid nitrogen. It consists of an impeller, a circular case and a diffuser. The conventional pump and the partial emission pump have different features in the impeller and the discharge flow passage. The partial emission pump uses an impeller with straight radial blades. The emission of working fluid does not occur continuously from all of the impeller channels, and the diffuser allows the flow only from a part of the impeller channels. As the area of the diffuser increases gradually, it converts the dynamic pressure into static pressure while minimizing the loss of total pressure. We used the known numerical method for the optimum design process and made a CFD analysis to verify the theoretical performance.

• International Journal of Fluid Machinery and Systems
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• 제4권1호
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• pp.14-24
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• 2011

In this paper, design optimization for mixed-flow pump impellers and diffusers has been studied using a commercial computational fluid dynamics (CFD) code and DOE (design of experiments). We also discussed how to improve the performance of the mixed-flow pump by designing the impeller and diffuser. Geometric design variables were defined by the vane plane development, which indicates the blade-angle distributions and length of the impeller and diffusers. The vane plane development was controlled using the blade-angle in a fixed meridional shape. First, the design optimization of the defined impeller geometric variables was achieved, and then the flow characteristics were analyzed in the point of incidence angle at the diffuser leading edge for the optimized impeller. Next, design optimizations of the defined diffuser shape variables were performed. The importance of the geometric design variables was analyzed using $2^k$ factorial designs, and the design optimization of the geometric variables was determined using the response surface method (RSM). The objective functions were defined as the total head and the total efficiency at the design flow rate. Based on the comparison of CFD results between the optimized pump and base design models, the reason for the performance improvement was discussed.

• Nuclear Engineering and Technology
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• 제50권3호
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• pp.368-378
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• 2018

Understanding of turbulent flow in the reactor coolant pump (RCP) is a premise of the optimal design of the RCP. Flow structures in the RCP, in view of the specially devised spherical casing, are more complicated than those associated with conventional pumps. Hitherto, knowledge of the flow characteristics of the RCP has been far from sufficient. Research into the nonintrusive measurement of the internal flow of the RCP has rarely been reported. In the present study, flow measurement using particle image velocimetry is implemented to reveal flow features of the RCP model. Velocity and vorticity distributions in the diffuser and spherical casing are obtained. The results illuminate the complexity of the flows in the RCP. Near the lower end of the discharge nozzle, three-dimensional swirling flows and flow separation are evident. In the diffuser, the imparity of the velocity profile with respect to different axial cross sections is verified, and the velocity increases gradually from the shroud to the hub. In the casing, velocity distribution is nonuniform over the circumferential direction. Vortices shed consistently from the diffuser blade trailing edge. The experimental results lend sound support for the optimal design of the RCP and provide validation of relevant numerical algorithms.

• Journal of Advanced Marine Engineering and Technology
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• 제27권5호
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• pp.633-640
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• 2003

The present experimental study is focused on the application of multi-point simultaneous measurement by PIV(Particle Image Velocimetry) to guide vane region within diffuser pump. Various different kinds of rotational velocity were selected as experimental condition. Optimized cross correlation Identification to obtain velocity vectors is implemented with direct calculation of correlation coefficients. Fine optical setup concerned with PIV performance is arranged for the accurate PIV measurement of high-speed complex flow. Variable flow pattern are represented quantitatively at the stator region.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1395-1400
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• 2004

A centrifugal compressor for geothermal heat pump system using R134a as working fluid has been developed. The centrifugal compressor consists of an impeller with splitters, two vaneless diffuser, a low solidity vaned diffuser and a volute. In this compressor, diffuser blade angles are controlled to satisfy both heating and cooling conditions. A aerodynamic design was done by applying the repeating design procedure including a meanline design, a 3D geometry generation and fluid dynamic calculation. In this paper, design and performance prediction results of the compressor are presented.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.29-35
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• 2000

The present experimental study is focused on the application of multi-point simultaneous measurement by PIV(Particle Image Velocimetry) to guide vane region within diffuser pump. Various different kinds of rotational velocity were selected as experimental condition. Optimized cross correlation identification to obtain velocity vectors is implemented with direct calculation of correlation coefficients. Fine optical setup concerned with PIV performance is arranged for the accurate PIV measurement of high-speed complex flow. Variable flow pattern are represented quantitatively at the stator region.