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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The KSFM Journal of Fluid Machinery
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Journal DOI :
Korean Fluid Machinery Association
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Volume & Issues
Volume 2, Issue 4 - Dec 1999
Volume 2, Issue 3 - Sep 1999
Volume 2, Issue 2 - Jun 1999
Volume 2, Issue 1 - Mar 1999
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Flow Characteristics of Centrifugal Impeller Exit under Rotating Stall
Shin, You-Hwan ; Kim, Kwang-Ho ;
The KSFM Journal of Fluid Machinery, volume 2, issue 2, 1999, Pages 5~12
This study presents the measured unsteady flctuation of impeller discharge flow for a centrifugal compressor in an unstable operating region. The characteristics of the blade-to-blade flow at rotating stall onset were investigated by measuring unsteady velocity fluctuations at several different diffuser axial distances using a hot wire anemometer. The flow characteristics in terms of the radial and tangential velocity components and the flow angle distribution at the impeller exit were analyzed using phase-locked ensemble averaging techniques. As a result, increase or decrease of the radial velocity component during the rotating stall is dominated by that of the suction side. The radial velocity distributions show the opposite trends in the regions where the radial velocity during rotating stall onset increases and decreases.
A Study on the Seismic Analysis of Nuclear Power Plant Pumps
Seo, Young-Soo ; Son, Hyo-Sok ; Chun, Hyong-Sik ; Chung, Hee-Taeg ;
The KSFM Journal of Fluid Machinery, volume 2, issue 2, 1999, Pages 13~18
The pump safety related to the functions in nuclear power plants must be designed to meet load conditions considering seismic requirements. In order to satisfy both structural integrity and operability of these pumps, the initial step in the seismic qualification is to establish the resonant frequencies of the structure. Applications we made to the design of the vertical and horizontal type pump. Computational results are analyzed with respect to the dynamic characteristics and are compared to the expected design requirements.
Measurement of Water Flow in Closed Conduits by Chemical Tracer Method
Lee, Sun-Ki ; Chung, Bag-Soon ; Kim, Chang-Ho ;
The KSFM Journal of Fluid Machinery, volume 2, issue 2, 1999, Pages 19~26
Thermal output in a nuclear power plant is verified with calorimetric heat balance on the secondary plant. The calorimetry involves the precise measurement of the feedwater flow rate. However, the correct indication of feedwater flow rate obtained by a pressure-difference measurement across a venturi can be affected by instrument errors, fouling or a poorly developed velocity profile. This can result in an inaccurate mass flow rate and consequently an inaccurate estimate of power. The purpose of this study is to develop verification methods with accuracy better than
for high precision flow measurement to be used for measuring feedwater flow rate. This chemical tracer method is a testing process that uses tracers which can be applied to quantify losses in electrical output due to the incorrect measurements of feedwater flow rate. And this system has good response to the variation of the flow rate. Accuracy of better than 0.5 percent can be expected for feedwater flow measurement, providing that the system can be stabilized during the test. This methodology is applicable to other flow systems well.
Characteristics of the Shaft Vibration in a High Head Pump-Turbine
Ha, Hyun-Cheon ; Choi, Seong-Pil ;
The KSFM Journal of Fluid Machinery, volume 2, issue 2, 1999, Pages 27~31
This paper describes the shaft vibration phenomena measured on a pump-turbine of a pumped storage power plant. The pump-turbine runs at a rotational speed of 450 rpm (7.5 Hz). The power output (load) of the pump-turbine is varied from 100 to 300 MW in the generating mode. The magnitude of the shaft vibration highly depends on the power load. The vibration magnitude of the shaft is very high in the middle load zone from 170 to 210 MW, elsewhere the vibration is low. From nitration spectra, it is shown that the frequency of major nitration in that load zone is 2.5 Hz which is approximately
of the shaft rotating speed in Hz. This frequency component does not occur below and above that load zone. This subsynchronous vibration is caused by the flow induced disturbance due to spiral vortex flow downstream of the pump-turbine runner. Furthermore, the shaft vibration is highly decreased due to an increased bearing preload.
Experimental Study on the Stiffness and Damping Coefficients of a Tilting Pad Journal Bearing
Ha, Hyun-Cheon ; Yang, Seong-Heon ;
The KSFM Journal of Fluid Machinery, volume 2, issue 2, 1999, Pages 32~38
An experimental study is performed to investigate the frequency effects of the excitation force on the linear stiffness and damping coefficients of a LOP (load on pad) type five-pad tilting pad journal bearing with the diameter of 300.91 mm and the length of 149.80 mm. The main parameter of interest in the present work is excitation frequency to shake the test bearing. The excitation frequency is controlled independently, using orthogonally mounted hydraulic exciters. The relative movement between the bearing and shaft, and the acceleration of the bearing casing are measured as a function of excitation frequency using the different values of bearing load and shaft speed. Measurements show that the variation of excitation frequency has quite a little effect on both stiffness and damping coefficients. Both direct stiffness and damping coefficients in the direction of bearing load decrease by the increase of shaft speed, but increase with the bearing load.
Vibration Analysis of Pump/Turbine and Generator/Motor Rotor System for Pumped Storage Power Stations
Yang, Bo-Suk ; Choi, Byung-Gun ; Kim, Young-Han ; Ha, Hyun-Cheon ;
The KSFM Journal of Fluid Machinery, volume 2, issue 2, 1999, Pages 39~45
Pumped-storage power plants pumps the water from the lower reservoir to the upper reservoir using the extra electric power at night and generates electric power in the daytime. Currently it tends to be a high-head large-capacity machine. In this paper, we developed the computer programs for vibration analysis of the pump/turbine and generator/motor rotor system considering electromagnetic force, hydrodynamic unbalance force, dynamic characteristics of guide bearings and add mass of water. This program was verified by applying it to the real model and calculating the critical speed, natural mode and unbalance response.
A study on Low-Noise and High-Efficiency Sirocco Fan Development
Park, Kwang-Jin ; Lee, Sang-Hwan ; Son, Byung-Jin ;
The KSFM Journal of Fluid Machinery, volume 2, issue 2, 1999, Pages 46~56
This study is on the performance prediction and design of a sirocco fan. Slip coefficient is very important factor for the performance analysis of a centrifugal-type fan. Because generally used slip coefficient equations of backward curved centrifugal fan are not appropriate for forward curved sirocco fan, in this study a proper slip coefficient equation for a sirocco fan is suggested. Using this equation performance prediction program for sirocco fan is composed of and also included the total noise prediction that include the turbulent noise at the fan inlet and boundary layer noise. A comparison between the values obtained from performance prediction program and experimental values shows that the program predicts the sirocco fan performance in a practical rate.
Development of a Computational Method of 3-D Unsteady Incompressible Flow in Turbomachinery
Kim, Bbong-Kyun ; Park, Jae-In ; Joo, Won-Gu ; Cho, Kang-Rae ;
The KSFM Journal of Fluid Machinery, volume 2, issue 2, 1999, Pages 57~63
The flow through multistage turbomachinery is affected by the interaction between a rotor and a stator. The interaction is due to the inviscid potential effect and viscous effect between closely spaced rotor and stator airfoils. Three-dimensional, unsteady, incompressible Navier-Stokes equations with a standard
model are solved using a non-staggered grid system. This method is applied to the flow through a multistage compressor measured by Stauter et al. The results have shown strong interaction between the rotating and stationary flow field. The decay of rotor wake and the pressure profiles agree very well with experimental data. The wake produced by rotor causes unsteady pressure on the surface of a stator. The rotor/stator interaction produces the unsteady pressure force on the rotor and stator blades.
Numerical Analysis of Flow Field and Performance of Water Jet Pump
Cho, Jang-keun ; Park, Warn-gyu ;
The KSFM Journal of Fluid Machinery, volume 2, issue 2, 1999, Pages 64~73
The three-dimensional numerical study of a water jet pump was carried out to investigate the relationship between performance and the geometric variables of nozzle space, area ratio, and throat length. Because of the complex geometry, the multiblock technique was adopted for numerical analysis and a special treatment for transferring data from each of the block interfaces was implemented in order to maintain the conserved properties. To validate the present code, flow passing through a square duct with a 90-deg bend was computed, our results show good accordance with other experimental and computational results. The numerical simulation was done with the flow of the water jet pump having a 180-deg bend in order to calculate the performance at different operating conditions. The performance of the water jet pump can be improved by study of parameters which clarify the relations between the geometric variables and the flow characteristics of vortex strength and location.
Experimental Study on the Performance Characteristics of the Diffuser as a Relation of the Variation of Vane Turning Angle
Cho, Sung-Kook ; Kang, Shin-Hyoung ;
The KSFM Journal of Fluid Machinery, volume 2, issue 2, 1999, Pages 74~80
Recently, impressive gains of performance and efficiency with apparently little or no loss in flow range have been seen with the use of LSVD(Low Solidity Vaned Diffuser) over vaneless diffuser. Experiments of the effects of the vane turning angle variations(positive, negative, zero), with the other design parameters fixed, on the performance and flow range were carried out. Diffusers with a zero turning angle have the best characteristics in terms of performance and efficiency and the FFT results show different frequency characteristics due to vane turning angles in low flow range.