The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Daisaku Sakaguchi - One of the best experts on this subject based on the ideXlab platform.
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Effect of Guide Vane in Ring Groove Arrangement for a Small Turbocharger
2010Co-Authors: Daisaku Sakaguchi, Keiichi Nagoshi, Motoki Tanimura, Masahiro Ishida, Hironobu UekiAbstract:A high‐pressure ratio and a wide operating range are highly required for a turbocharger in diesel engines. Ring Groove arrangement is effective for flow range enhancement of centrifugal compressors. Two Ring Grooves on the suction pipe and the shroud casing wall are connected by means of the annular passage, and the stable recirculation flow is formed at small flow rates from the downstream Groove toward the upstream Groove through the annular bypass. It is well known that the Ring Groove arrangement shows the following two merits; (1) the formation of recirculation flow removes the low energy fluid around the downstream Groove located near the splitter blade leading edge, (2) the flow incidence can be reduced because the recirculation flow merges again with the incoming main flow upstream of the impeller inlet. In the present study, the Ring Groove arrangement was applied to the high speed centrifugal compressor, in addition, in order to suppress too large pre‐whirl due to the recirculation flow, the eff...
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Effect of Pre-Whirl on Unstable Flow Suppression in a Centrifugal Impeller With Ring Groove Arrangement
Volume 6: Turbomachinery Parts A and B, 2006Co-Authors: Masahiro Ishida, Daisaku Sakaguchi, Hironobu UekiAbstract:In order to obtain a wider operating range in a centrifugal impeller with inducer, the effect of the pre-whirl induced by the inlet recirculation flow on the flow incidence and the impeller characteristics were analyzed numerically and compared with the experimental results. In order to control the swirl intensity of the recirculation flow, guide vanes were installed circumferentially in the annular bypass of the Ring Groove arrangement, and the setting angle of the guide vane was changed. The fundamental concept for surge suppression is to achieve the flow incidence less than or close to the critical one. A too large-positive flow incidence can be reduced by increasing the recirculation flow rate determined by the pressure difference between the two Ring Groove positions, on the other hand, a higher pressure rise in the inducer can be obtained at the flow incidence close to the critical one by suppressing the pre-whirl induced by the recirculation flow. It is clearly shown that the better impeller characteristics and the large recirculation flow rate can be achieved by giving a suitable setting angle of the guide vane. The unstable flow rate range of the tested impeller was reduced by about 53% almost without deterioration of the impeller efficiency in the whole flow rate range.Copyright © 2006 by ASME
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optimization of inlet Ring Groove arrangement for suppression of unstable flow in a centrifugal impeller
ASME Turbo Expo 2005: Power for Land Sea and Air, 2005Co-Authors: Masahiro Ishida, Daisaku Sakaguchi, Hironobu UekiAbstract:An optimization of the inlet Ring Groove arrangement has been pursued in the present study for obtaining better impeller characteristics and a wider operation range at both small and large flow rates in a high specific speed type centrifugal impeller with inducer. The effects of the shape parameters with respect to the inlet Ring Groove on the impeller characteristic and the flow incidence were analyzed mainly based on numerical simulations, but also compared to the experimental results. At small flow rates, a significant improvement in the impeller characteristic is achieved due to reduction in the excessive-positive flow incidence by optimizing both location and width of the rear Groove near the inducer tip throat. On the other hand, the impeller characteristic is improved at large flow rates by implementing the corner radius at the rear Groove edge and by placing another front Ring Groove in the suction pipe. As a result, by the optimized configuration of the front and rear Ring Grooves, the unstable flow range of the test impeller can be reduced by about 50% without deterioration of the impeller characteristic even at the 125% flow rate.Copyright © 2005 by ASME
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Suppression of Unstable Flow at Small Flow Rates in a Centrifugal Blower by Controlling Tip Leakage Flow and Reverse Flow
Journal of Turbomachinery-transactions of The Asme, 2005Co-Authors: Masahiro Ishida, Hironobu Ueki, Taufan Surana, Daisaku SakaguchiAbstract:The effects of the inlet recirculation arrangement on inducer stall and the diffuser width on diffuser stall in a high-specific-speed-type centrifugal impeller with inducer were analyzed by numerical simulation and also verified experimentally. It was found that the incipient unstable flow occurs due to a rolling-up vortex flow, resulting from an interaction between the tip leakage flow and the reverse flow accumulated at the pressure side immediately downstream of the inducer tip throat, in which a strong streamwise component of vorticity is included. By forming the inlet recirculation flow the tip leakage vortex is effectively sucked into the suction Ring Groove, and the flow incidence is decreased simultaneously. The unstable flow range of the test blower was reduced significantly by about 45% without deteriorating the impeller characteristics by implementing optimally both the Ring Groove arrangement and the narrowed diffuser width.
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Suppression of Unstable Flow at Small Flow Rates in a Centrifugal Blower by Controlling Tip Leakage Flow and Reverse Flow
Volume 5: Turbo Expo 2004 Parts A and B, 2004Co-Authors: Masahiro Ishida, Hironobu Ueki, Taufan Surana, Daisaku SakaguchiAbstract:The effects of the inlet recirculation arrangement on inducer stall and the diffuser width on diffuser stall in a high specific speed type centrifugal impeller with inducer were analyzed by a numerical simulation and also verified experimentally. It is found that the incipient unstable flow occurs due to a rolling-up vortex flow resulting from an interaction between the tip leakage flow and the reverse flow accumulated at the pressure side immediately downstream of the inducer tip throat in which a strong streamwise component of vorticity is included. By forming the inlet recirculation flow, the tip leakage vortex is effectively sucked into the suction Ring Groove, and the flow incidence is decreased simultaneously. The unstable flow range of the test blower was reduced significantly by about 45% without deteriorating the impeller characteristics by implementing optimally both the Ring Groove arrangement and the narrowed diffuser width.Copyright © 2004 by ASME
Hironobu Ueki - One of the best experts on this subject based on the ideXlab platform.
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Effect of Guide Vane in Ring Groove Arrangement for a Small Turbocharger
2010Co-Authors: Daisaku Sakaguchi, Keiichi Nagoshi, Motoki Tanimura, Masahiro Ishida, Hironobu UekiAbstract:A high‐pressure ratio and a wide operating range are highly required for a turbocharger in diesel engines. Ring Groove arrangement is effective for flow range enhancement of centrifugal compressors. Two Ring Grooves on the suction pipe and the shroud casing wall are connected by means of the annular passage, and the stable recirculation flow is formed at small flow rates from the downstream Groove toward the upstream Groove through the annular bypass. It is well known that the Ring Groove arrangement shows the following two merits; (1) the formation of recirculation flow removes the low energy fluid around the downstream Groove located near the splitter blade leading edge, (2) the flow incidence can be reduced because the recirculation flow merges again with the incoming main flow upstream of the impeller inlet. In the present study, the Ring Groove arrangement was applied to the high speed centrifugal compressor, in addition, in order to suppress too large pre‐whirl due to the recirculation flow, the eff...
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Effect of Pre-Whirl on Unstable Flow Suppression in a Centrifugal Impeller With Ring Groove Arrangement
Volume 6: Turbomachinery Parts A and B, 2006Co-Authors: Masahiro Ishida, Daisaku Sakaguchi, Hironobu UekiAbstract:In order to obtain a wider operating range in a centrifugal impeller with inducer, the effect of the pre-whirl induced by the inlet recirculation flow on the flow incidence and the impeller characteristics were analyzed numerically and compared with the experimental results. In order to control the swirl intensity of the recirculation flow, guide vanes were installed circumferentially in the annular bypass of the Ring Groove arrangement, and the setting angle of the guide vane was changed. The fundamental concept for surge suppression is to achieve the flow incidence less than or close to the critical one. A too large-positive flow incidence can be reduced by increasing the recirculation flow rate determined by the pressure difference between the two Ring Groove positions, on the other hand, a higher pressure rise in the inducer can be obtained at the flow incidence close to the critical one by suppressing the pre-whirl induced by the recirculation flow. It is clearly shown that the better impeller characteristics and the large recirculation flow rate can be achieved by giving a suitable setting angle of the guide vane. The unstable flow rate range of the tested impeller was reduced by about 53% almost without deterioration of the impeller efficiency in the whole flow rate range.Copyright © 2006 by ASME
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optimization of inlet Ring Groove arrangement for suppression of unstable flow in a centrifugal impeller
ASME Turbo Expo 2005: Power for Land Sea and Air, 2005Co-Authors: Masahiro Ishida, Daisaku Sakaguchi, Hironobu UekiAbstract:An optimization of the inlet Ring Groove arrangement has been pursued in the present study for obtaining better impeller characteristics and a wider operation range at both small and large flow rates in a high specific speed type centrifugal impeller with inducer. The effects of the shape parameters with respect to the inlet Ring Groove on the impeller characteristic and the flow incidence were analyzed mainly based on numerical simulations, but also compared to the experimental results. At small flow rates, a significant improvement in the impeller characteristic is achieved due to reduction in the excessive-positive flow incidence by optimizing both location and width of the rear Groove near the inducer tip throat. On the other hand, the impeller characteristic is improved at large flow rates by implementing the corner radius at the rear Groove edge and by placing another front Ring Groove in the suction pipe. As a result, by the optimized configuration of the front and rear Ring Grooves, the unstable flow range of the test impeller can be reduced by about 50% without deterioration of the impeller characteristic even at the 125% flow rate.Copyright © 2005 by ASME
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Suppression of Unstable Flow at Small Flow Rates in a Centrifugal Blower by Controlling Tip Leakage Flow and Reverse Flow
Journal of Turbomachinery-transactions of The Asme, 2005Co-Authors: Masahiro Ishida, Hironobu Ueki, Taufan Surana, Daisaku SakaguchiAbstract:The effects of the inlet recirculation arrangement on inducer stall and the diffuser width on diffuser stall in a high-specific-speed-type centrifugal impeller with inducer were analyzed by numerical simulation and also verified experimentally. It was found that the incipient unstable flow occurs due to a rolling-up vortex flow, resulting from an interaction between the tip leakage flow and the reverse flow accumulated at the pressure side immediately downstream of the inducer tip throat, in which a strong streamwise component of vorticity is included. By forming the inlet recirculation flow the tip leakage vortex is effectively sucked into the suction Ring Groove, and the flow incidence is decreased simultaneously. The unstable flow range of the test blower was reduced significantly by about 45% without deteriorating the impeller characteristics by implementing optimally both the Ring Groove arrangement and the narrowed diffuser width.
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Suppression of Unstable Flow at Small Flow Rates in a Centrifugal Blower by Controlling Tip Leakage Flow and Reverse Flow
Volume 5: Turbo Expo 2004 Parts A and B, 2004Co-Authors: Masahiro Ishida, Hironobu Ueki, Taufan Surana, Daisaku SakaguchiAbstract:The effects of the inlet recirculation arrangement on inducer stall and the diffuser width on diffuser stall in a high specific speed type centrifugal impeller with inducer were analyzed by a numerical simulation and also verified experimentally. It is found that the incipient unstable flow occurs due to a rolling-up vortex flow resulting from an interaction between the tip leakage flow and the reverse flow accumulated at the pressure side immediately downstream of the inducer tip throat in which a strong streamwise component of vorticity is included. By forming the inlet recirculation flow, the tip leakage vortex is effectively sucked into the suction Ring Groove, and the flow incidence is decreased simultaneously. The unstable flow range of the test blower was reduced significantly by about 45% without deteriorating the impeller characteristics by implementing optimally both the Ring Groove arrangement and the narrowed diffuser width.Copyright © 2004 by ASME
Masahiro Ishida - One of the best experts on this subject based on the ideXlab platform.
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Effect of Guide Vane in Ring Groove Arrangement for a Small Turbocharger
2010Co-Authors: Daisaku Sakaguchi, Keiichi Nagoshi, Motoki Tanimura, Masahiro Ishida, Hironobu UekiAbstract:A high‐pressure ratio and a wide operating range are highly required for a turbocharger in diesel engines. Ring Groove arrangement is effective for flow range enhancement of centrifugal compressors. Two Ring Grooves on the suction pipe and the shroud casing wall are connected by means of the annular passage, and the stable recirculation flow is formed at small flow rates from the downstream Groove toward the upstream Groove through the annular bypass. It is well known that the Ring Groove arrangement shows the following two merits; (1) the formation of recirculation flow removes the low energy fluid around the downstream Groove located near the splitter blade leading edge, (2) the flow incidence can be reduced because the recirculation flow merges again with the incoming main flow upstream of the impeller inlet. In the present study, the Ring Groove arrangement was applied to the high speed centrifugal compressor, in addition, in order to suppress too large pre‐whirl due to the recirculation flow, the eff...
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Effect of Pre-Whirl on Unstable Flow Suppression in a Centrifugal Impeller With Ring Groove Arrangement
Volume 6: Turbomachinery Parts A and B, 2006Co-Authors: Masahiro Ishida, Daisaku Sakaguchi, Hironobu UekiAbstract:In order to obtain a wider operating range in a centrifugal impeller with inducer, the effect of the pre-whirl induced by the inlet recirculation flow on the flow incidence and the impeller characteristics were analyzed numerically and compared with the experimental results. In order to control the swirl intensity of the recirculation flow, guide vanes were installed circumferentially in the annular bypass of the Ring Groove arrangement, and the setting angle of the guide vane was changed. The fundamental concept for surge suppression is to achieve the flow incidence less than or close to the critical one. A too large-positive flow incidence can be reduced by increasing the recirculation flow rate determined by the pressure difference between the two Ring Groove positions, on the other hand, a higher pressure rise in the inducer can be obtained at the flow incidence close to the critical one by suppressing the pre-whirl induced by the recirculation flow. It is clearly shown that the better impeller characteristics and the large recirculation flow rate can be achieved by giving a suitable setting angle of the guide vane. The unstable flow rate range of the tested impeller was reduced by about 53% almost without deterioration of the impeller efficiency in the whole flow rate range.Copyright © 2006 by ASME
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optimization of inlet Ring Groove arrangement for suppression of unstable flow in a centrifugal impeller
ASME Turbo Expo 2005: Power for Land Sea and Air, 2005Co-Authors: Masahiro Ishida, Daisaku Sakaguchi, Hironobu UekiAbstract:An optimization of the inlet Ring Groove arrangement has been pursued in the present study for obtaining better impeller characteristics and a wider operation range at both small and large flow rates in a high specific speed type centrifugal impeller with inducer. The effects of the shape parameters with respect to the inlet Ring Groove on the impeller characteristic and the flow incidence were analyzed mainly based on numerical simulations, but also compared to the experimental results. At small flow rates, a significant improvement in the impeller characteristic is achieved due to reduction in the excessive-positive flow incidence by optimizing both location and width of the rear Groove near the inducer tip throat. On the other hand, the impeller characteristic is improved at large flow rates by implementing the corner radius at the rear Groove edge and by placing another front Ring Groove in the suction pipe. As a result, by the optimized configuration of the front and rear Ring Grooves, the unstable flow range of the test impeller can be reduced by about 50% without deterioration of the impeller characteristic even at the 125% flow rate.Copyright © 2005 by ASME
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Suppression of Unstable Flow at Small Flow Rates in a Centrifugal Blower by Controlling Tip Leakage Flow and Reverse Flow
Journal of Turbomachinery-transactions of The Asme, 2005Co-Authors: Masahiro Ishida, Hironobu Ueki, Taufan Surana, Daisaku SakaguchiAbstract:The effects of the inlet recirculation arrangement on inducer stall and the diffuser width on diffuser stall in a high-specific-speed-type centrifugal impeller with inducer were analyzed by numerical simulation and also verified experimentally. It was found that the incipient unstable flow occurs due to a rolling-up vortex flow, resulting from an interaction between the tip leakage flow and the reverse flow accumulated at the pressure side immediately downstream of the inducer tip throat, in which a strong streamwise component of vorticity is included. By forming the inlet recirculation flow the tip leakage vortex is effectively sucked into the suction Ring Groove, and the flow incidence is decreased simultaneously. The unstable flow range of the test blower was reduced significantly by about 45% without deteriorating the impeller characteristics by implementing optimally both the Ring Groove arrangement and the narrowed diffuser width.
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Suppression of Unstable Flow at Small Flow Rates in a Centrifugal Blower by Controlling Tip Leakage Flow and Reverse Flow
Volume 5: Turbo Expo 2004 Parts A and B, 2004Co-Authors: Masahiro Ishida, Hironobu Ueki, Taufan Surana, Daisaku SakaguchiAbstract:The effects of the inlet recirculation arrangement on inducer stall and the diffuser width on diffuser stall in a high specific speed type centrifugal impeller with inducer were analyzed by a numerical simulation and also verified experimentally. It is found that the incipient unstable flow occurs due to a rolling-up vortex flow resulting from an interaction between the tip leakage flow and the reverse flow accumulated at the pressure side immediately downstream of the inducer tip throat in which a strong streamwise component of vorticity is included. By forming the inlet recirculation flow, the tip leakage vortex is effectively sucked into the suction Ring Groove, and the flow incidence is decreased simultaneously. The unstable flow range of the test blower was reduced significantly by about 45% without deteriorating the impeller characteristics by implementing optimally both the Ring Groove arrangement and the narrowed diffuser width.Copyright © 2004 by ASME
Taufan Surana - One of the best experts on this subject based on the ideXlab platform.
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Suppression of Unstable Flow at Small Flow Rates in a Centrifugal Blower by Controlling Tip Leakage Flow and Reverse Flow
Journal of Turbomachinery-transactions of The Asme, 2005Co-Authors: Masahiro Ishida, Hironobu Ueki, Taufan Surana, Daisaku SakaguchiAbstract:The effects of the inlet recirculation arrangement on inducer stall and the diffuser width on diffuser stall in a high-specific-speed-type centrifugal impeller with inducer were analyzed by numerical simulation and also verified experimentally. It was found that the incipient unstable flow occurs due to a rolling-up vortex flow, resulting from an interaction between the tip leakage flow and the reverse flow accumulated at the pressure side immediately downstream of the inducer tip throat, in which a strong streamwise component of vorticity is included. By forming the inlet recirculation flow the tip leakage vortex is effectively sucked into the suction Ring Groove, and the flow incidence is decreased simultaneously. The unstable flow range of the test blower was reduced significantly by about 45% without deteriorating the impeller characteristics by implementing optimally both the Ring Groove arrangement and the narrowed diffuser width.
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Suppression of Unstable Flow at Small Flow Rates in a Centrifugal Blower by Controlling Tip Leakage Flow and Reverse Flow
Volume 5: Turbo Expo 2004 Parts A and B, 2004Co-Authors: Masahiro Ishida, Hironobu Ueki, Taufan Surana, Daisaku SakaguchiAbstract:The effects of the inlet recirculation arrangement on inducer stall and the diffuser width on diffuser stall in a high specific speed type centrifugal impeller with inducer were analyzed by a numerical simulation and also verified experimentally. It is found that the incipient unstable flow occurs due to a rolling-up vortex flow resulting from an interaction between the tip leakage flow and the reverse flow accumulated at the pressure side immediately downstream of the inducer tip throat in which a strong streamwise component of vorticity is included. By forming the inlet recirculation flow, the tip leakage vortex is effectively sucked into the suction Ring Groove, and the flow incidence is decreased simultaneously. The unstable flow range of the test blower was reduced significantly by about 45% without deteriorating the impeller characteristics by implementing optimally both the Ring Groove arrangement and the narrowed diffuser width.Copyright © 2004 by ASME
Bi Zhi-wei - One of the best experts on this subject based on the ideXlab platform.
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Thermal Analysis of Susceptor Structure with Ring Groove in Vertical MOCVD Reactor
Journal of Synthetic Crystals, 2010Co-Authors: Bi Zhi-weiAbstract:A susceptor structure with a Ring Groove was proposed in the vertical nitride MOCVD reactor by induction heating. Using finite element method,the location and size of the Groove in the susceptor which made the temperature distribution in the wafer uniform was obtanied. Compared with the conventional susceptor,the temperature distribution in the wafer on this susceptor is improved obviously. In addition,The law of heat transfer in this susceptor was discorved by the analysis of the temperature in it changing with the heating time. Namely,the Groove changes the directions of the thermal transport in the susceptor. The heat in the wafer is conducted from the regions on and under the Groove of the susceptor. With time increasing,the temperature in the susceptor approaches constant and that in the wafer becomes uniform,which contributes to improve the quality of the film growth.
