Stability issues are often restricting the design space of axial-flow compressors. Casing treatments have shown the ability to enhance stability on existing designs in a late design phase. Prior studies have identified the positioning of the casing treatment as an important parameter for both stability and overall efficiency. Particularly for axial casing treatments, the downstream position of the fluid removal was found to be relevant. Within the present study the focus is put on a tip blowing casing treatment consisting of an axially and circumferentially discrete bleed port connected to an upstream injection port. For this kind of casing treatment, an accurate positioning of the fluid removal has high importance. Therefore, in the present study a parametric variation of the bleed port's axial position is carried out at design speed. Minimizing losses at sufficient stall margin improvement requires recirculation mass flows dependent on operating point. In support of that goal of mass flow self-regulation criteria for the fluid removal port position are derived. The analysis of the flow field, of the pressure distribution and of the shock-vortex-interaction help to identify an ideal position. The study is carried out on the isolated rotor of a 1.5 stage research compressor arrangement.
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