Experimental and Numerical Evaluation of a Highly-Loaded Multistage Low-Speed Axial Compressor Featuring Tandem Stator Vanes: Part 1 — Operational Behavior and Steady-State Flow Field

Abstract The loading limit of an axial compressor stage can be increased by introducing tandem stator vanes. Although many design studies show the potential of this concept, there is a lack of multistage investigations in a representative environment. Furthermore, existing theoretical and simulative studies are rarely validated with experimental data. The present paper series investigates a highly-loaded low-speed 3.5-stage axial compressor featuring tandem stator vanes both experimentally and numerically. Focus is set on understanding the multistage behavior of the configuration and validating the numerical studies. The present part 1 of the series shows that a high aerodynamic loading with a good overall efficiency and a wide operating range is possible with tandem stators. Detailed flow field investigations show how the complex secondary flow structure evolves through the three stages for different operating conditions. Furthermore, it is shown that 3D numerical simulations are capable of resolving the flow structures and operating behavior obtained from the experiment properly, but some misalignment remains. Part 2 investigates the detailed flow field of the highly-loaded rotor and the interaction with the stator. Part 3 investigates the overall performance, losses, and the blockage development for different inlet conditions.