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Vortex Features in a Half-ducted Axial Fan with Large Bellmouth (Effect of Tip Clearance)
Shiomi, Norimasa,Kinoue, Yoichi,Setoguchi, Toshiaki,Kaneko, Kenji Korean Society for Fluid machinery 2011 International journal of fluid machinery and syste Vol.4 No.3
In order to clarify the features of tip leakage vortex near blade tip region in a half-ducted axial fan with large bellmouth, the experimental investigation was carried out using a 2-dimensional LDV system. Three sizes of tip clearance (TC) were tested: those sizes were 1mm (0.55% of blade chord length at blade tip), 2mm (1.11% of blade chord length at blade tip) and 4mm (2.22% of blade chord length at blade tip), and those were shown as TC=1mm, TC=2mm and TC=4mm, respectively. Fan characteristic tests and the velocity field measurements were done for each TC. Pressure - flow-rate characteristics and two-dimensional velocity vector maps were shown. The vortex trace and the vortex intensity distribution were also illustrated. As a result, a large difference on the pressure - flow-rate characteristics did not exist for three tip clearance sizes. In case of TC=4mm, the tip leakage vortex was outflow to downstream of rotor was not confirmed at the small and reference flow-rate conditions. Only at the large flow-rate condition, its outflow to downstream of rotor existed. In case of TC=2mm, overall vortex behaviors were almost the same ones in case of TC=4mm. However, the vortex trace inclined toward more tangential direction. In case of TC=1mm, the clear vortex was not observed for all flow-rate conditions.
Behavior of Rotating Stall Cell in a High Specific-Speed Diagonal Flow Fan
Shiomi, Norimasa,Cai, W.X.,Muraoka, A.,Kaneko, K.,Setoguchi, T. The Korean Society of Mechanical Engineers 2001 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.15 No.12
An experimental investigation was carried out to clarify unsteady flow fields with rotating stall cell, especially behavior of stall cell, in a high specific-speed diagonal flow fan. As its specific-speed is vary high for a diagonal flow fan, its pressure-flow rate curve tends to indicate unstable characteristics caused by rotating stall similar to axial flow fan. Although for an axial flow fan many researchers have investigated such the flow field, for a diagonal flow fan tittle study has been done. In this study, velocity fields at rotor Inlet in a high specific-speed diagonal flow fan were measured by use of a single slant hot-wire probe. These data were processed by using the "Double Phase-Locked Averaging"(DPLA) technique, i. e. phases of both the rotor blade and the stall cell were taken into account. The behaviors of stall cell at rotor inlet were visualized for the meridional, tangential and radial velocity.
Vortices within a Three-Dimensional Separation in an Axial Flow Stator of a Diagonal Flow Fan
Kinoue, Yoichi,Shiomi, Norimasa,Setoguchi, Toshiaki Korean Society for Fluid machinery 2011 International journal of fluid machinery and syste Vol.4 No.2
Experimental and numerical investigations were conducted for an internal flow in an axial flow stator of a diagonal flow fan. A corner separation near the hub surface and the suction surface of a stator blade was focused on, and further, three-dimensional vortices in separated flow were investigated by the numerical analysis. At low flow rate of 80% of the design flow rate, a corner separation of the stator between the suction surface and the hub surface can be found in both experimental and calculated results. Separation vortices are observed in the limiting streamline patterns both on the blade suction and on the hub surfaces at 80% of the design flow rate in the calculated results. It also can be observed in the streamline pattern that both vortices from the blade suction surface and from the hub surface keep vortex structures up to far locations from these wall surfaces. An attempt to explain the vortices within a three-dimensional separation is introduced by using vortex filaments.
Effect of Inlet Geometry on Fan Performance and Inlet Flow Fields in a Semi-opened Axial Fan
Liu, Pin,Shiomi, Norimasa,Kinoue, Yoichi,Setoguchi, Toshiaki,Jin, Ying-Zi Korean Society for Fluid machinery 2014 International journal of fluid machinery and syste Vol.7 No.2
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 near 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 measurements at fan outlet, the main flow region existed near rotor hub side.
Effect of Inlet Geometry on Fan Performance and Inlet Flow Fields in a Semi-opened Axial Fan
Pin Liu,Norimasa Shiomi,Yoichi Kinoue,瀨戶口俊明,Yingzi Jin 한국유체기계학회 2014 International journal of fluid machinery and syste Vol.7 No.2
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 near 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 measurements at fan outlet, the main flow region existed near rotor hub side.
Experimental Investigation on Separated Flows of Axial Flow Stator and Diagonal Flow Rotor
Kinoue, Yoichi,Shiomi, Norimasa,Setoguchi, Toshiaki,Jin, Yingzi Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.3
Experimental investigations were conducted for the internal flows of the axial flow stator and diagonal flow rotor. Corner separation near the hub surface and the suction surface of stator blade are mainly focused on. For the design flow rate, the values of the axial velocity and the total pressure at stator outlet decrease between near the suction surface and near the hub surface by the influence of corner wall. For the flow rate of 80-90% of the design flow rate, the corner separation of the stator between the suction surface and the hub surface is observed, which becomes widely spread for 80% of the design flow rate. At rotor outlet for 81% of the design flow rate, the low axial velocity region grows between near the suction surface of rotor and the casing surface because of the tip leakage flow of the rotor.
Design and Experimental Studies of Radial-Outflow Type Diagonal Flow Fan
Kinoue, Yoichi,Shiomi, Norimasa,Setoguchi, Toshiaki Korean Society for Fluid machinery 2013 International journal of fluid machinery and syste Vol.6 No.1
In order to apply the design method of diagonal flow fan based on axial flow design to the design of radial-outflow type diagonal flow fan which has lower specific speed of 600-700 [$min^{-1}$, $m^3/min$, m], radial-outflow type diagonal flow fan which specific speed was 670 [$min^{-1}$, $m^3/min$, m] was designed by a quasi three-dimensional design method. Experimental investigations were conducted by fan characteristics test, flow surveys by a five-hole probe and a hot wire probe. Fan characteristics test agreed well with the design values. In the flow survey at rotor outlet, the characteristic region was observed. Two flow phenomena are considered as the cause of the characteristic region, one is tip leakage vortex near rotor tip and another is pressure surface separation on the rotor blade.
Design and Experimental Studies of Radial-Outflow Type Diagonal Flow Fan
Yoichi Kinoue,Norimasa Shiomi,Toshiaki Setoguchi 한국유체기계학회 2013 International journal of fluid machinery and syste Vol.6 No.1
In order to apply the design method of diagonal flow fan based on axial flow design to the design of radial-outflow type diagonal flow fan which has lower specific speed of 600-700 [min-1, m3/min, m], radial-outflow type diagonal flow fan which specific speed was 670 [min-1, m3/min, m] was designed by a quasi three-dimensional design method. Experimental investigations were conducted by fan characteristics test, flow surveys by a five-hole probe and a hot wire probe. Fan characteristics test agreed well with the design values. In the flow survey at rotor outlet, the characteristic region was observed. Two flow phenomena are considered as the cause of the characteristic region, one is tip leakage vortex near rotor tip and another is pressure surface separation on the rotor blade.
Effect of Vortex Design on a Half-Ducted Axial Flow Fan (In the case of forced vortex design)
Kaji, Atsushi,Kinoue, Yoichi,Shiomi, Norimasa,Setoguchi, Toshiaki Korean Society for Fluid machinery 2018 International journal of fluid machinery and syste Vol.11 No.1
An improvement of the half-ducted axial flow fan design by applying the forced vortex design to the rotor blade was conducted by CFD. The quasi three-dimensional flow theory was applied for the half-ducted fan design, and the meridional flow was calculated by the method of streamline curvature. When the radial balance equations from hub to tip was solved, the vortex design was changed from the constant-whirl-velocity design to the forced vortex design in reference to our previous experimental results of the half-ducted fan's internal flow. The analysis of the three-dimensional internal flow fields of the half-ducted fan designed by adopting the forced vortex design was conducted. As a result of CFD, the efficiency ${\eta}$ of the fan was about 1-3 % larger at the flow rate coefficient ${\phi}$ of 0.158-0.343 than the constant-whirl-velocity design.