| Project/Area Number |
02402023
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Aerospace engineering
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| Research Institution | University of Tokyo |
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Principal Investigator |
KAJI Shojiro University of Tokyo, Faculty of Engineering, Professor., 工学部, 教授 (80013704)
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| Co-Investigator(Kenkyū-buntansha) |
HANAMURA Yoji University of Tokyo, Faculty of Engineering, Sub Professor., 工学部, 助教授 (00013665)
WATANABE Toshinori University of Tokyo, Faculty of Engineering, Sub Professor., 工学部, 助教授 (10201211)
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| Project Period (FY) |
1990 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥21,700,000 (Direct Cost: ¥21,700,000)
Fiscal Year 1993: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1992: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1991: ¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1990: ¥15,700,000 (Direct Cost: ¥15,700,000)
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| Keywords | Supersonic cascade / Cascade flutter / Shock wave / Unstarted flutter / Detached shock / Shock oscillation / 不始動(アンスタート) / ファンエンジン / 曲げ振動 / 不始動(アンスタ-ト) |
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| Research Abstract |
In the supersonic cascades of modern aeroengines, bending mode flutter is experienced at high rpm. and at high back pressure i.e., at high loading conditions. During this type of flutter the compressor cascade operates undee an unstarted condition, and the blades are accompanied by detached shock waves, and hence it is called "unstarted flutter. " The present study is aimed at revealing the physical mechanism of the unstarted flutter.
The experiment was performed in a two-dimensional transonic cascade tunnel. The central bladd of the cascade was mechanically oscillated. The back pressure of the cascade was controlled by the change of the flow channel area at a downstream position. The shock waves in the cascade flow field ware visualized by schlieren technigue, and the pressure distributions on the side walls and blade surfaces were measured. The following conclusions were obtained from the results :
(1) When the back pressure is low, the shock waves are obligue attaching to the blade le
… More
ading edge and trailing edge. With the increase of the back pressure the shock wave changes to a passage shock, and finally becomes a detached bow shock.
(2) The movement of the shock waves on non-oscillatory blades are hardly influenced by the blade oscillation under the low back pressure condition. When the back pressure becomes high, on the other hand, the blade oscillation gives nonlinear effects on the shock movement of other blades.
The oscillating blades with detached bow shocks were theoretically analyzed by the semi-actuator-disk method. The results predict that the detached shocks make the blade oscillation more dangerous when the flow Mach number approaches to 1.0 in the supersonic flow regime.
An Euler code was developed to simulate the flow around a two-dimensional oscillating cascade. The computed results show that the cascade flutter can occur in the suction side traveling mode, and that the unstarted flow condition provides a more unstable situation than the started condition. Less
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