Influence of the rotation characteristics of the controllable speed casing on the flow stability of a high-load compressor stage

The controllable speed casing (CSC) has been confirmed as a novel type of casing treatment technology that is capable of designing the original fully fixed casing structure into two parts, i.e., the rotatable ring section and the stationary ring section. A range of circumferential additional forces will be imposed on the tip region of the rotor by regulating the rotation direction and rotation speed of the rotatable ring section, such that different effects will be exerted on the aerodynamic performance and flow stability at the compressor stage. As indicated by the results of this study, when the rotation direction of the CSC was opposite to that of the rotor, the relative increase of the stable operating margin changed from positive to negative when the casing rotation speed was increased and accounted for 60% of the rotor speed. When the CSC exhibited the identical rotation direction to the rotor, the stability turned out to be more significantly increased. With the decrease of circumferential pressure gradient in the tip region, the original driving force of the tip leakage flow reduces, and the flow capacity was increased. The stable operating margin was increased with the rise of the rotation speed of the CSC, and the stable operating margin was increased by up to 45.44% at casing rotation speed accounting for 100% of the rotor speed.& COPY; 2023 Elsevier Masson SAS. All rights reserved.