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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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International Journal of Fluid Machinery and Systems
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Korean Fluid Machinery Association
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Volume & Issues
Volume 2, Issue 4 - Dec 2009
Volume 2, Issue 3 - Sep 2009
Volume 2, Issue 2 - Jun 2009
Volume 2, Issue 1 - Mar 2009
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Design Optimization of a High Specific Speed Francis Turbine Using Multi-Objective Genetic Algorithm
Nakamura, Kazuyuki ; Kurosawa, Sadao ;
International Journal of Fluid Machinery and Systems, volume 2, issue 2, 2009, Pages 102~109
DOI : 10.5293/IJFMS.2009.2.2.102
A design optimization system for Francis turbine was developed. The system consists of design program and CFD solver. Flow passage shapes are optimized automatically by using the system with Multi-Objective Genetic Algorithm (MOGA). In this study, the system was applied to a high specific speed Francis turbine (nSP = 250m-kW). The runner profile and the draft tube shape were optimized to decrease hydraulic losses. As the results, it was shown that the turbine efficiency was improved in wide operating range, furthermore, the height of draft tube was reduced with the hydraulic performance kept.
Numerical Analysis of the Whole Field Flow in a Centrifugal Fan for Performance Enhancement - The Effect of Boundary Layer Fences of Different Configurations
Karanth, K. Vasudeva ; Sharma, N. Yagnesh ;
International Journal of Fluid Machinery and Systems, volume 2, issue 2, 2009, Pages 110~120
DOI : 10.5293/IJFMS.2009.2.2.110
Generally the fluid flows within the centrifugal impeller passage as a decelerating flow with an adverse pressure gradient along the stream wise path. This flow tends to be in a state of instability with flow separation zones on the suction surface and on the front shroud. Hence several experimental attempts were earlier made to assess the efficacy of using boundary layer fences to trip the flow in the regions of separation and to make the flow align itself into stream wise direction so that the losses could be minimized and overall efficiency of the diffusion process in the fan could be increased. With the development of CFD, an extensive numerical whole field analysis of the effect of boundary layer fences in discrete regions of suspected separation points is possible. But it is found from the literature that there have been no significant attempts to use this tool to explore numerically the utility of the fences on the flow field. This paper attempts to explore the effect of boundary layer fences corresponding to various geometrical configurations on the impeller as well as on the diffuser. It is shown from the analysis that the fences located on the impellers near the trailing edge on pressure side and suction side improves the static pressure recovery across the fan. Fences provided at the radial mid-span on the pressure side of the diffuser vane and near the leading edge and trailing edge of the suction side of diffuser vanes also improve the static pressure recovery across the fan.
Experimental Study on Internal Flow of a Mini Centrifugal Pump by PIV Measurement
Wu, Yulin ; Yuan, Huijing ; Shao, Jie ; Liu, Shuhong ;
International Journal of Fluid Machinery and Systems, volume 2, issue 2, 2009, Pages 121~126
DOI : 10.5293/IJFMS.2009.2.2.121
The internal flow field in a centrifugal pump working at the several flow conditions has been measured by using the particle image velocimetry (PIV) technique with the laser induced fluorescence (LIF) particles and the refractive index matched (RIM) facilities. The impeller of the centrifugal pump has an outlet diameter in 100mm, and consists of six two-dimensional curvature backward swept blades of constant thickness. Measured results give reliable flow patterns in the pump. It is obvious that application of LIF particle and RIM are the key methods to obtain the right PIV measured results in pump internal flow.
Study on Design of Air-water Two-phase Flow Centrifugal Pump Based on Similarity Law
Matsushita, Naoki ; Furukawa, Akinori ; Watanabe, Satoshi ; Okuma, Kusuo ;
International Journal of Fluid Machinery and Systems, volume 2, issue 2, 2009, Pages 127~135
DOI : 10.5293/IJFMS.2009.2.2.127
A conventional centrifugal pump causes a drastic deterioration of air-water two-phase flow performances even at an air-water two-phase flow condition of inlet void fraction less than 10% in the range of relatively low water flow rate. Then we have developed a two-phase flow centrifugal pump which consists of a tandem arrangement of double rotating cascades and blades of outer cascade have higher outlet angle more than
. In design of the two-phase flow pump for various sized and operating conditions, similarity relations of geometric dimensions to hydraulic performances is very useful. The similarity relations of rotational speed, impeller diameter and blade height are investigated for the developed impeller in the present paper. As the results, the similarity law of rotational speed and impeller diameter is clarified experimentally even in two-phase flow condition. In addition, influences of blade height on air-water two-phase flow performances indicate a little difference from the similarity relations.
Experimental Research for Performance and Noise of Small Axial Fan
Ito, Takahiro ; Minorikawa, Gaku ; Fan, Qinyin ;
International Journal of Fluid Machinery and Systems, volume 2, issue 2, 2009, Pages 136~146
DOI : 10.5293/IJFMS.2009.2.2.136
Small axial fans have become widely used as cooling devices in recent years. Because of their increasing importance, studies have been conducted on ways to improve the performance and reduce the noise of such fans. In this report, a small axial fan with a diameter of 85 mm (a type popularity used in personal computer or workstation) was selected for further examination. The influence on aerodynamic performance and noise of such frame design parameters as blade tip clearance results in a decrease of discrete frequency noise and an increase of broad-spectrum noise. As for the most suitable design refinement in terms of fan efficiency, we found that the treatment of outlet corner roundness and altering spoke skew to the direction counter to that of fan rotation was effective.
Dynamic Characteristics of the Radial Clearance Flow between Axially Oscillating Rotational Disk and Stationary Disk
Horiguchi, Hironori ; Ueno, Yoshinori ; Takahashi, Koutaro ; Miyagawa, Kazuyoshi ; Tsujimoto, Yoshinobu ;
International Journal of Fluid Machinery and Systems, volume 2, issue 2, 2009, Pages 147~155
DOI : 10.5293/IJFMS.2009.2.2.147
Dynamic characteristics of the clearance flow between an axially oscillating rotational disk and a stationary disk were examined by experiments and computations based on a bulk flow model. In the case without pressure fluctuations at the inlet and outlet of the clearance, parallel and contracting flow paths had an effect to stabilize the axial oscillation of the rotating disk. The enlarged flow path had an effect to destabilize the axial oscillation due to the negative damping and stiffness for outward and inward flows, respectively. It was shown that the fluid force can be decomposed into the component caused by the inlet or outlet pressure fluctuation without the axial oscillation and that due to the axial oscillation without the inlet or outlet pressure fluctuation. A method to predict the stiffness and damping coefficients is proposed for general cases when the device is combined with an arbitrary flow system.
A Review of Ocean Wave Power Extraction; the primary interface
Nik, W.B. Wan ; Muzathik, A.M. ; Samo, K.B. ; Ibrahim, M.Z. ;
International Journal of Fluid Machinery and Systems, volume 2, issue 2, 2009, Pages 156~164
DOI : 10.5293/IJFMS.2009.2.2.156
This paper aims to describe the importance of data, data collection methods, parameters to estimate the potential of wave energy and environmental impacts. The technical and economical status in wave energy conversion is outlined. Power and energy efficiency relationships are discussed. Many different types of wave-energy converters have been detailed. The progress in wave energy conversion in Malaysia is reviewed.
Prediction of Cavitation Intensity in Pumps Based on Propagation Analysis of Bubble Collapse Pressure Using Multi-Point Vibration Acceleration Method
Fukaya, Masashi ; Ono, Shigeyoshi ; Udo, Ryujiro ;
International Journal of Fluid Machinery and Systems, volume 2, issue 2, 2009, Pages 165~171
DOI : 10.5293/IJFMS.2009.2.2.165
We developed a 'multi-point vibration acceleration method' for accurately predicting the cavitation intensity in pumps. Pressure wave generated by cavitation bubble collapse propagates and causes pump vibration. We measured vibration accelerations at several points on a casing, suction and discharge pipes of centrifugal and mixed-flow pumps. The measured vibration accelerations scattered because the pressure wave damped differently between the bubble collapse location and each sensor. In a conventional method, experimental constants are proposed without evaluating pressure propagation paths, then, the scattered vibration accelerations cause the inaccurate cavitation intensity. In our method, we formulated damping rate, transmittance of the pressure wave, and energy conversion from the pressure wave to the vibration along assumed pressure propagation paths. In the formulation, we theoretically defined a 'pressure propagation coefficient,' which is a correlation coefficient between the vibration acceleration and the bubble collapse pressure. With the pressure propagation coefficient, we can predict the cavitation intensity without experimental constants as proposed in a conventional method. The prediction accuracy of cavitation intensity is improved based on a statistical analysis of the multi-point vibration accelerations. The predicted cavitation intensity was verified with the plastic deformation rate of an aluminum sheet in the cavitation erosion area of the impeller blade. The cavitation intensities were proportional to the measured plastic deformation rates for three kinds of pumps. This suggests that our method is effective for estimating the cavitation intensity in pumps. We can make a cavitation intensity map by conducting this method and varying the flow rate and the net positive suction head (NPSH). The map is useful for avoiding the operating conditions having high risk of cavitation erosion.
Design Optimization of Centrifugal Pump Impellers in a Fixed Meridional Geometry using DOE
Kim, Sung ; Choi, Young-Seok ; Lee, Kyoung-Yong ; Yoon, Joon-Yong ;
International Journal of Fluid Machinery and Systems, volume 2, issue 2, 2009, Pages 172~178
DOI : 10.5293/IJFMS.2009.2.2.172
This paper reports on an investigation (using RSM with commercial CFD software) of the performance characteristics of the impeller in a centrifugal pump. Geometric parameters of vane plane development were defined with the meridional shape and frontal view of the impeller. The parameters are focused on the blade-angle distributions through the impeller in a fixed meridional geometry. For screening, a
factorial design has been used to identify the important design parameters. The objective functions are defined as the total head rise and the total efficiency at the design flow-rate. From the
factorial design results, it is found that the incidence angles and the exit blade angle are the most important parameters influencing the performance of the pump.
Surrogate Based Optimization Techniques for Aerodynamic Design of Turbomachinery
Samad, Abdus ; Kim, Kwang-Yong ;
International Journal of Fluid Machinery and Systems, volume 2, issue 2, 2009, Pages 179~188
DOI : 10.5293/IJFMS.2009.2.2.179
Recent development of high speed computers and use of optimization techniques have given a big momentum of turbomachinery design replacing expensive experimental cost as well as trial and error approaches. The surrogate based optimization techniques being used for aerodynamic turbomachinery designs coupled with Reynolds-averaged Navier-Stokes equations analysis involve single- and multi-objective optimization methods. The objectives commonly tried to improve were adiabatic efficiency, pressure ratio, weight etc. Presently coupling the fluid flow and structural analysis is being tried to find better design in terms of weight, flutter and vibration, and turbine life. The present article reviews the surrogate based optimization techniques used recently in turbomachinery shape optimizations.