The reduction of blade-tip induced instabilities in transonic as well as in subsonic compressors can be reached with Casing Treatments. In this thesis, Casing Treatments are designed for a transonic and for a subsonic axial compressor stage. Special focus has been put on the improvement of the efficiency when applying such passive Casing Treatments. In the transonic stage, the loss-producing flow mechanisms were identified and reduced by modifying the geometry of the Casing Treatments. Furthermore, the prevailing flow mechanisms in circumferential grooves on a subsonic stage were identified and used for an improved design with lower efficiency losses. Finally, a new numerical method called non-linear Harmonics Method has been tested and validated in order to be able to perform unsteady computations of multi-stage compressor for further designs of Casing Treatments.
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The reduction of blade-tip induced instabilities in transonic as well as in subsonic compressors can be reached with Casing Treatments. In this thesis, Casing Treatments are designed for a transonic and for a subsonic axial compressor stage. Special focus has been put on the improvement of the efficiency when applying such passive Casing Treatments. In the transonic stage, the loss-producing flow mechanisms were identified and reduced by modifying the geometry of the Casing Treatments. Furthermo...
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