Parametric investigation of entire annular recess casing treatment on compressor stable operation

Application of casing treatment in compressor has been found to give substantial improvement in compressor stable operating range. An experimental investigation has been carried out with one variant of casing treatment, an entire annular recess (EAR) over the compressor rotor blades. Various tip clearances and two groups of annular recesses (without and with penetration of rotor blade tips into casing) were used. The results for 20 such configurations are presented in the proposed paper, analyzed with respect to relative tip clearance and recess relative volume influence on compressor stable operating range.