1988 Fiscal Year Final Research Report Summary
Structure of Three demensional Shock Wave and Stall Limits
| Project/Area Number |
62550134
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Fluid engineering
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| Research Institution | Kyushu University |
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Principal Investigator |
HAYAMI Hiroshi Institute of Advanced Material Study of Kyushu University, 機能物質科学研究所, 教授 (10038606)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Centrifugal Compressor / Supersonic Compressor / Shock Wave / Inducer / Laser Anemometry / Stall / サージ |
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| Research Abstract |
The flow field in the inducer of a supersonic centrifugal impeller has been measured with a laser-2-focus velocimeter (L2F) at three flow rates that were the peak efficiency, the stall limit and the choked condition at constant high speed. The L2F system was modified for practical use in velocity measurement in flows with shock waves between rotating blades by a multi-window data sampling system, by microcomputer aided automatic measurement system and by a hard disc unit. The various shapes of the joint probability distributions of the time-of-flight and the flow angle showed the complexity of the flow between blades. Each distribution had a predominant peak and this confirmed that the L2F system had a high S/N ratio. The distribution contained useful information on flow flucturation as well as mean flow. The relative flow angle changed smoothly between blades while the absolute flow angle changed abruptly between blades due to a shock wave. This fact demonstrated the high accuracy in the L2F measurements. Contour maps of mach number between blades were demonstrated at three depth ratios and the three dimensional structures of the shock waves were discussed. The structure and the intensity of shock waves were affected by the incidence angle and the camber angle of the blade as well as the inflow mach number. the behavior of shock waves with the change in flow rate were also discussed. It was demonstrated the shock wave at the peak efficiency was rather weak but the strong shock wave was generated on the suction surface of the blade near the stall limit, where the upstream mach number reached beyond 1.3.
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