Maximum loading capacity of tandem blades in axial compressors

Tandem blades are widely reported to be superior to a single-blade configuration under the aerodynamic circumstance with a large flow turning in a stator or a high work input in a rotor. Aiming at the design of a highly loaded rear stage of a high pressure compressor with the advanced concept, the maximum loading capacity of a tandem-blade configuration, which is rarely described in open literature, is fundamentally necessary to be explicit in order to determine a stable operation range. A diffuser analogy is carefully carried out between the tandem-blade geometry and the diffuser passage using a reliable and robust numerical method. The analysis approach to effectively predicting the maximum static pressure rise is verified by the limited results of computational fluid dynamics (CFD) and experiments. In addition, the maximum loading capacity of the tandem-blade configuration is compared with that of the single-blade configuration to define a more favorable design range of meanline parameters. The results indicate that the tandem blade outperforms the conventional blade in a specific design space and the approach can be a potential design tool to guide the selection of one-dimensional parameters of tandem blades in a highly loaded axial compressor.