• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.04a
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• pp.148-153
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• 1994

각종 산업 플랜트엣 입형펌프의 공진문제는 다른 기계에 비해 자주 발생한다. 이는 입형펌프가 구조 특성상 대개 지반에 비해 기초강성이 낮은 콘크리이트 슬래브(slab)위에 설치되는 경우가 많고, 외팔보 형태의 펌프 위에 무거운 전동기가 설치되어 무게 중심이 횡형펌프에 비해 높게 되기 때문에 대형 입형펌프 구조물의 고유진동수는 낮게 된다. 그리고, 일반 대형펌프의 회전주파수도 저속임에 따라 축계의 불평형가진력에 의한 공진문제가 빈번하게 발생된다. 대형 입형펌프가 설비가동에 있어서 최중요 기계(critical machine)인 경우가 대부분이므로 높은 진동을 유발시키는 공진은 공장 설비운전의 안정성에 큰 영향을 미친다. 입형펌프의 전동기가 아무리 밸런싱 상태가 좋고, 설치상태가 펌프 전동기제작사의 설치조건을 만족한다 하더라도 전도이가 펌프위에 설치되어 운전될 경우 공진이 발생하게 되면 과도한 진동이 일어나게 된다. 이때 전동기에 부하가 걸리지 않는 전동기 단독운전 상태에서도 높은 진동이 나타나기 때문에 운전자는 흔히 전동기자체의 문제로 판정하곤 한다. 이같은 현상은 보통 진동원인이 전동기에 있지 않고 펌프의 전동기대(motor stool)와 전동기 시스템의 리드 공진(reed resonance)에 의한 결과이다. 본 논문에서는 입형 펌프에서 리드공진의 확인방법과 대책작업에 대해 실제 사례를 통하여 논한다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.1
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• pp.57-64
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• 1990

It is important in design of vertical pumps to consider arbitrary foundation excitation in addition to rotor vibration due to unbalance. In this study, a model of a vertical pump was developed for the analysis of its dynamic response. The vertical pump was modeled with lumped masses and springs which represent mult-cylinderical and rotor structure. A dynamic simulation program was developed and numerical calculation on the above mentioned problems were carried out.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.362-372
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• 1989

It is important in design of vertical pumps to consider external excitation in addition to rotor vibration due to unbalance. In this study, a model of a vertical pump was developed for the analysis of its dynamic response. The vertical pump was modeled with lumped masses and springs which represent multi-cylindrical and rotor structure. A dynamic simulation program was developed and numerical calculation on the above mentioned problems were carried out.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.543-547
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• 2002

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.458-463
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• 2012

This case study refers to resonance with vertical pumps. Vibration problem occurring after the inverter was installed for speed control. Its problem was appeared any revolution under rated speed. Vibration data was acquired during normal operation and transient state. We examined FRF on its resonance in field and also analyzed a result by finite element method. There was carried out the retrofit in field which was based on these results for solving problem.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.402-407
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• 2002

A commercial CFD code is applied to analyze the 3-D viscous flow field within vertical multi-stage centrifugal pimp including impeller with 6 blades and guide vane with 11 blades and is performed by changing flow rate from 10 to $26\;m^3/h$ at the constant 3500rpm. The purpose of this 3-D numerical simulation is to confirm how much the effect of blade inlet angle of guide vane has an influence on the performance of vertical multi-stage centrifugal pimp. these results performed by $20^{\circ},\;30^{\circ}$ inlet angle of guide vane are compared with grundfos performance data. The vertical multi-stage pump consist of the impeller, guide vane, and cylinder. The characteristics such as total pressure coefficient total heat shaft horse power, power efficiency, discharge coefficient are represented according to flow rate changing.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.589-592
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• 2002

A commercial CFD code is applied to analyze the 3-D viscous flow field within vertical multi-stage centrifugal pump including impeller of centrifugal pump with 6 blades and guide vain with 11 blades. The numerical analysis of vertical multi-stage centrifugal pump is performed by changing flow rate from $8\;to\;26\;m^{3}/h$ at the constant 3500rpm. The characteristics such as total pressure coefficient, total head, water horse power, power efficiency are represented according to flow rate changing. In the future, we will need to perform flow calculation of vertical multi-stage centrifugal pump by considering meridional shape of impeller.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.1
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• pp.65-72
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• 2013

This case study presents a practical method to reduce resonant vibration of large vertical pumps. The pumps are driven at 400 rpm rated speed by induction motor. The vibration was not significantly large when operated at this rated speed. Large vibration was occurred when the pump was operated below the rated speed for flow control. Due to the large vibration resonance, variable speed operation of the pump was not possible for several months at worst cases. To find an efficient vibration control method, the flexural responses of pumps for both normal and transient operations were measured. The measured modal characteristics were compared with those of finite element analysis. When the pump was operated at a specific rpm, the natural mode whose resonance frequency is twice the rotating angular speed induced the large vibration. The retrofit utilizing stiffeners to reduce this resonant vibration were performed. Effects of designed stiffeners on reducing vibration were validated through tests after actual installation.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.71-77
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• 2006

This study introduces the seismic qualification of safety related equipments for nuclear power plants to verify the possibility of resonance in regard to the operating speed and the structural integrity due to external piping nozzle loads as well as seismic dynamic loads using El-Centro earthquake, which was occurred in the 1940's previously. As a first step, it is necessary to investigate the natural frequency of the vertical mixed flow pump in order to determine whether static or dynamic equipment comparing with seismic cut-off frequency, 33hz. Also the normal mode analysis was carried out with the introduction of seismic redesign straint at the middle of vertical pump to increase the natural frequency. In terms of structural integrity, the application of static analysis with normal, upset and faulted nozzle loads event was presented for the comparison of material allowable stress. Also the dynamic analysis was performed to show the design adequacy through the application to the case of El-Centro earthquake.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.698-702
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• 2013

This paper considers the vertical pumps resonance and soundness. Normally large vertical pump's rotating speed is low, so the low natural mode can make a resonance on the motor and motor stand assembly. The pump resonance makes a very high vibration and trouble on the pump systems. Thus to avoid pump resonance when the pump is on the resonance region, we give the added mass method and evaluate the structure soundness by computer simulation and test on the site. Furthermore we evaluate the modal sensitivity and expect running conditions by the using ISO10814.