• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.464-468
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• 2003

A general program of three dimensional profile design of impellers for centrifugal/fixed-flow compressors is successfully commercialized using Bezier curves and quasi-3D flow analysis methods. Control points for meridional hub and shroud contours and blade camberline angles are arbitrarily changed to give smooth Bezier curves. With specified blade normal thicknesses, contructed geometry is instantly analyzed using flow analysis methods to be checked.

• Journal of KSNVE
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• v.14 no.1
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• pp.18-23
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• 2004

균열 현상은 모든 필터에서 발생하였다. 1997년 9월 원심 압축기 B에서 발생한 지나친 진동현상으로 여러 필터 중 한 필터가 부서져 임펠러 흡입부로 빨려 들어갔다. 1997년 10월 기동중에 선회실속 문제가 임펠러에서 발생하였고, 이 원인은 임펠러 eye가 부분적으로 막혔기 때문이었다. 압축기 입구와 출구의 전체 유량과 압력 상태는 정상이었기 때문에 어떠한 서지현상도 anti-surge 시스템에 의해서 감지되지 않았다. 고장상태를 진단함으로써 압축기의 재가동을 방지하여 필터들이 부서졌다는 것을 확인하게 되었다. 이번 기계 점검과정을 통하여 원격진단의 중요성을 확인하였으며, 이에 회사는 원격서비스(remote service) 계약을 체결하여 현재 원격 진단 서비스 점검이 계약 기간에 따라 정기적으로 이루어지고 있다. 이와 같이 기계에 대한 정기적인 점검을 실시하는 목적은 기계의 결함이나 고장문제를 조기에 발견함으로써 중대한 고장으로의 진행을 사전에 예방하거나 또는 최소화하는데 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1503-1510
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• 2012

In this research, various cases of centrifugal impeller for HVAC system have been numerically analyzed by changing center angle of blades and length of outlet. Commercial CFD code, FLUENT has been used to calculate velocity, pressure, turbulence intensity, and temperature that can lead numerous results. Regardless of warming up, when the heater power level was increased, the temperature inside surrounding impeller also increased due to flowing outer air, but the temperature decreased because of flowing inner air. Consequently, the variation of central angle of blades and length of outlet led difference of velocity and flow rate which can reduce $CO_2$ in gas emission.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.248-254
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• 2015

There has been no previous study on technology development of large capacity drainage pump for rescue sinking ship in the country. The agricultural drainage pump was widely used for rescue sinking ship but this pump has several problems such as efficiency, low displacement and malfunction in winter. Therefore, this paper proposes to solve the problems for swiftly rescue sinking ship and develops the drainage pump system that has $20m^3/min$ mass flow rate specification at suction head 8 m. The centrifugal pump type the most commonly used in the field of naval architecture and ocean engineering was selected and designed based on the requirement specification. The blade design of impeller was derived from the Stepanoff coefficient and requirement specification and used computational fluid dynamics to review the target mass flow rate according to the impeller RPM at design operating conditions. We also performed structure analysis of the impeller to find structurally vulnerable points for the pump in service and completed the theoretical design of drainage pump system.

• The KSFM Journal of Fluid Machinery
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• v.4 no.1 s.10
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• pp.22-29
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• 2001

Centrifugal fans are widely used in industrial practices but the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the easing. However, only a few researches have been carried out on predicting the noise because of the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan, and to calculate the effects of small vanes that are attached in original impeller - Splitter impeller. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated by the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The splitter impeller changes the acoustic characteristics as well as performance. Two-splitter type impeller and splitter impeller which splitter locates in jet region are good for acoustic characteristics.

• The KSFM Journal of Fluid Machinery
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• v.16 no.1
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• pp.11-16
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• 2013

A numerical study was conducted to improve the performance of an impeller of centrifugal compressor. Nine design variables were chosen with constraints. Only meridional contours and blade profile were adjusted. ANN (Artificial Neural Net) was adopted as a main optimization algorithm with PSO (Particle Swarm Optimization) in order to reduce the optimization time. At first, ANN was learned and trained with the design variable sets which were obtained using DOE (Design of Experiment). This ANN was continuously improved its accuracy for each generation of which population was one hundred. New design variable set in each generation was selected using a non-gradient based method of PSO in order to obtain the global optimized result. After $7^{th}$ generation, the prediction difference of efficiency and pressure ratio between ANN and CFD was less than 0.6%. From more than 1,200 design variable sets, a pareto of efficiency versus pressure ratio was obtained and an optimized result was selected based on the multi-objective function. On this optimized impeller, the efficiency and pressure ratio were improved by 1% and 9.3%, respectively.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.129-136
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• 2000

Centrifugal fans are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few researches have been carried out on predicting the noise because of the difficulty in obtaining detailed Information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan, and to calculate the effects of small vanes that are attached in original impeller - Splitter impeller. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated by the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The splitter impeller changes the acoustic characteristics as well as performance. Two-splitter type impeller and splitter impeller which splitter locates in jet region are good for acoustic characteristics.

• Journal of computational fluids engineering
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• v.21 no.1
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• pp.58-63
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• 2016

This research is to investigate the performance analysis for efficient design with four different inlet angles of the centrifugal pump impeller. Assuming that the rotation speed and exit angle are fixed, Four cases of the centrifugal pumps were numerically analyzed using ANSYS FLUENT. According to the numerical results, head and pump efficiency at inlet angle of 20 degrees was highest. There is no big difference of efficiency at inlet angle of 20 degrees compared to the inlet angle 30 degrees. About 15% of efficiency at inlet angle of 20 degrees is higher than inlet angle of 40 degrees and 31% higher than inlet angle oof 50 degrees. Because there is liner functional relationship between speed and flow rate, suction flow rate at inlet angle of 20 degrees is superior to the inlet angle of 30 degrees as much as 0.89%, inlet angle of 40 degrees as 13%, inlet angle of 50 as 28.4%. Head at inlet angle of 20 degrees is superior to the inlet angle of 30 degrees as much as 0.4%, inlet angle of 40 degrees as 2.7%, inlet angle of 50 degrees as 3.2%. There should exist highest efficiency and also optimal design shape at inlet angle of 20 degrees.

• The KSFM Journal of Fluid Machinery
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• v.19 no.2
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• pp.21-26
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• 2016

The objective of present study is to assess the performance of the first stage compressor in a total 3-stage 5000 HP-level turbo compressor. CFD commercial code, CFX has been used to predict three-dimensional flow characteristics inside of the impeller. Shear Stress Transport (SST) model has been used to simulate turbulent flows through Reynolds-averaged Navier-Stokes (RANS) equations. Grid dependency has been also checked to get optimal grid distribution. Numerical results have been compared with the experimental test results to elucidate performance characteristics of the present compressor. In addition, flow characteristics of the impeller only have been studied for various blade configurations. Angular offset in leading edge of the blade has been selected for the optimal blade design. Performance characteristics in region of low mass flow rate and high pressure ratio between the impeller entrance and exit have been investigated for the selection of optimal blade design. Also, flow instability such as stall phenomena has been studied and anti-stall characteristics have been checked for various blade configurations in the operational window.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.170-178
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• 1999

In general, an impeller of centrifugal turbomachinery is designed at isolated condition without considering the presence of a volute, but when the impeller is operating with its volute, the performance of impeller can be different. This is largely caused by the interaction between the impeller and volute flow fields. The magnitude of distortion is increased as the operating point is away from the design point and, as a result, the interaction between the impeller and volute is stronger. In the present calculation, the flow through the impeller is simulated using coarse grids. The flow within the impeller and the volute is naturally unsteady, but the flow is assumed to be steady across the interface between the volute and impeller flow fields. Under the assumption of steady three-dimensional incompressible turbulent flow, the time averaged N-S equations involving standard k-$\epsilon$ turbulent model was solved by the F.V.M. The calculation results are compared with the experimental results obtained for an industrial fan by Sakai etc. and the Hood agreement is demonstrated. And the effects of the impeller-volute interaction are studied.