Flow fields with vortex in a small semi-open axial fan

Shiomi, Norimasa; Kinoue, Yoichi; Jin, Ying Zi; Setoguchi, Toshiaki; Kaneko, Kenji

doi:10.1007/s11630-009-0294-z

Cited by 8 publications

(4 citation statements)

References 5 publications

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“…The test result showed that the short intake has a flutter bite at 80% speed whereas there were no flutter bites for the long intake. Shiomi et al 8 clarified the performance and the flow fields with vortex in semi-open type fan by measuring the three-dimensional velocity fields at rotor outlet using a slant hot-wire probe, and to clarify the effect of tip clearance size on fan performance and vortex behaviors. Salunkhe and Pradeep 9 carried out experiments for a fan with and without inflow distortion and found that stall occurs in long and short-scale disturbances under the same direction and reverse rotating inflow distortion, respectively.…”

Section: Introductionmentioning

confidence: 99%

Flow instability in a volute-free centrifugal fan subjected to non-axisymmetric pre-swirl flow from upstream bended inflow tube

Liu

Yang

He³

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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The characteristics of internal flow and performance of a centrifugal fan is greatly dependent on the inflow pattern. As the fan is subjected to incoming flow from an upstream tube, the size and geometry of the tube affect the three-dimensional motion of local flow and possibly degrades the aerodynamic performance of the fan. In this work, we performed a numerical investigation on the internal flow in a centrifugal fan subjected to incoming flow from an upstream bended inflow tube of various radii using the steady and unsteady Reynolds-averaged Navier-Stokes (RANS and URANS) simulation approaches. The effects of the non-axisymmetric pre-swirl flow generated due to the curvature of the bended inflow tube are demonstrated by analyzing the internal flow characteristics of the fan, including the spatial distributions and temporal variations of pressure field and streamlines, pressure fluctuations in the upstream tube, the inflow and outflow sections of the impeller, and the circumferential distributions of velocity and pressure in the impeller. The numerical results reveal that as the inflow tube is curved with larger curvature (smaller radius of the bended section), the pre-swirl inflow is strong and deteriorates the static pressure rise and static pressure efficiency of the centrifugal fan more remarkably, and the circumferential non-uniformity of pressure and velocity distributions appears inside of the channels of the fan. As the radius of the bended section increases, the instability of the internal flow gets more pronounced, as represented by the stronger pressure fluctuations at the inflow and outflow sections. The prediction capabilities of RANS and URANS approaches are also analyzed based on the numerical data and we found that the latter is more reliable in predicting the performance of the fan.

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Section: Introductionmentioning

confidence: 99%

Flow instability in a volute-free centrifugal fan subjected to non-axisymmetric pre-swirl flow from upstream bended inflow tube

Liu

Yang

He³

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…Second, the modifications on the blade shapes can improve the aerodynamic and aeroacoustic performance of a fan. Generally, modification of conventional axial fan blades can help to improve the internal flow conditions; 7 smooth airfoils and irregular airfoil can change vortex distribution; 8 and hollow blade root can improve the highest efficiency and reduce the value of noise. 9 Meanwhile, modifications on blade-tip geometry will affect the multiple vortex behaviors of leakage flow; and addition of end-plates will change the tip-leakage-flow behavior, which can reduce the broadband noise.…”

Section: Introductionmentioning

confidence: 99%

“…13,14 Third, optimum tip clearance can help to decrease noise and improve performance. 7,15,16 For the backward-skewed blade, the tip leakage vortex moves towards the leading edge in the chordwise direction and towards the hub in the spanwise direction, which is less significant for the forward-skewed blade. 17 Besides, accessories of the fan also have great impact on its aerodynamic and aeroacoustic performances.…”

Section: Introductionmentioning

confidence: 99%

Investigation of aerodynamic performance of small axial flow fan coupled with deflecting ring

Huang

Zheng

Liu

2015

Proceedings of the Institution of Mechanical Engineers, Part C:

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Experimental and numerical investigations on the effect of deflecting rings featuring different axial lengths on aerodynamic performance of the small axial flow fan were conducted under the condition of maximum flow rate. Two deflecting rings, the semi-open type and closed type, were investigated. Aerodynamic and aeroacoustic performances have been measured in experiment, and key analysis of flow was based on computational fluid dynamics results. The numerical and experimental results show that the deflecting ring has great influence on the performance of an axial flow fan. For the semi-open-type deflecting ring, the fan has better P-Q performance and higher efficiency; pressure, vorticity, and vorticity gradient distributions on the blade surface are more uniform; and noise level of the fan is lower at wider frequency bands. For the closed-type deflecting ring, the performance curve has a convex feature; blade pressure difference between the pressure surface and the suction surface is much bigger. The result shows that better aerodynamic and aeroacoustic performances of the axial flow fan can be acquired when the semi-open-type deflecting ring is adopted.

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“…Recently, from the viewpoint of energy saving and quiet surrounding in house, it has been strongly desired to be high performance and low noise level also about these fans. Therefore, the researches for these fans are gradually increasing [1]- [6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Inlet Geometry on Fan Performance and Inlet Flow Fields in a Semi-opened Axial Fan

Shiomi

Kinoue

et al. 2014

International Journal of Fluid Machinery and Systems

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In order to clarify the effect of inlet bellmouth size of semi-opened type axial fan on its performance and flow fields around rotor, fan test and flow field measurements using hotwire anemometer were carried out for 6 kinds of bellmouth size. As results of fan test, the shaft power curve hardly changed, even if the bellmouth size changed. On the other hand, the pressure-rise near best efficiency point became small with the bellmouth size decreasing. Therefore, the value of maximum efficiency became small as the bellmouth size decreased. As results of flow field measurements at fan inlet, the main flow region with large meridional velocity existed ne ar blade tip when the bellmouth size was large. As bellmouth size became smaller, the meridional velocity at fan inlet became smaller and the one at outside of blade tip became larger. As results of flow field measurem ents at fan outlet, the main flow region existed near rotor hub side.

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Flow fields with vortex in a small semi-open axial fan

Cited by 8 publications

References 5 publications

Flow instability in a volute-free centrifugal fan subjected to non-axisymmetric pre-swirl flow from upstream bended inflow tube

Flow instability in a volute-free centrifugal fan subjected to non-axisymmetric pre-swirl flow from upstream bended inflow tube

Investigation of aerodynamic performance of small axial flow fan coupled with deflecting ring

Effect of Inlet Geometry on Fan Performance and Inlet Flow Fields in a Semi-opened Axial Fan

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