1987 Fiscal Year Final Research Report Summary
STUDY OF THREE-DIMENSIONAL EFFECTS ON AEROELASTIC CHARACTERISTICS OF CASCADE
| Project/Area Number |
61550048
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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 |
Aerospace engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
NAMBA Masanobu PROFESSOR, DEPARTMENT OF AERONAUTICAL ENGINEERING, KYUSHU UNIVERSITY, 工学部, 教授 (50037735)
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| Co-Investigator(Kenkyū-buntansha) |
TOSHIMITSU Kazuhiko RESEARCH ASSOCIATE, ibid., 工学部, 助手 (10180150)
NOTOMI Tetsuo RESEARCH ASSOCIATE, ibid., 工学部, 助手 (20037914)
YAMASAKI Nobuhiko ASSOCIATE PROFESSOR, ibid., 工学部, 助教授 (70166635)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Unsteady Cascade / Subsonic Cascade / Supersonic Cascade / Three-Dimensional Unsteady Flow / Sound Absorbing Wall Effect / Steady Loading Effect / フラッター / 空力弾性 |
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| Research Abstract |
1. Effects of sound absorbing wall linings Computer programs have been developed for the prediction of unsteady aerodynamic forces on vibrating stator and rotor cascades in subsonic and supersonic flows. Effects of sound absorbing side walls upon unsteady aerodynamic forces are much more significant for supersonic cascades than for subsonic ones. If the acoustic admittance of the wall is dependent on sound frequency as is usually the case, the wall effects on rotor cascades are much different from those on stator cascades, because a rotor cascade in simple harmonic vibration generates a multi-frequency sound field.
2. Aerodynamic characteristics of cascade vibrating with nonuniform steady loading
Computer programs for 2-dimensional subsonic and supersonic cascades and 3-dimensional subsonic cascades have been developed for the prediction of unsteady aerodynamic forces on vibrating blades with steady loadings, using the double linearization theory. The validity of the double linearization theory has been confirmed by comparison of the results with those by more accurate numerical field methods (FEM and a successive approximation method). Effects of incidence, camber and blade thickness and their spanwise nonuniformity have been made cleary by extensive numerical studies.
The critical incidence angles on the bending flutter boundary for supersonic cascades are much smaller than those for subsonic cascades. In the case of subsonic cascades a spanwise distribution of steady loading increasing from hub to tip is favourable for attaining stable (free from bending flutter) operation with large total steady loadings.
Extension of the double linearization theory to 3-dimensional supersonic cascade and rotating annular cascade models is being developed. Application of a finite element method to 3-dimensional oscillating cascades is also being conducted.
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