14th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
The aeronautical industry is facing stronger and stronger challenges to respect the legal constraint concerning the CO2 and pollutant emissions. To address these challenges, the well-known Boundary Layer Ingestion (BLI) method certainly holds a lot of potential to improve the engines propulsion efficiency. Nevertheless, one of the main limitation of this technic is that the fan and the first compression stages encounter highly distorted inlet flow conditions, which has a strong impact on the performance and the operability of the engine. The aim of this work is to propose a joined numerical and experimental analysis of the flow behavior in a single compressor stage under flow distortion. The test-bench, support of this work, is a single-stage axial compressor whose main parameters are given in Table 1. TABLE 1: COMPRESSOR PARAMETERS Rotational speed 3200 rpm Design mass flow rate at 3200rpm 5.3 kg/s Design total to static pressure ratio at 3200 rpm 1.03 Rotor blade number 30 Stator blade number 40 Casing diameter 550 mm Rotor tip chord 84 Mm Rotor tip stagger angle 54 ° Rotor tip gap 0.5 mm The compressor can be led to stall by throttling a valve located downstream to the machine. The distortions are generated by different grids which can be placed upstream to the rotor. Experimentally, the flow analysis is based measurements obtained by a series of unsteady pressure sensors flush mounted at the casing of the machine rotor. URANS computations are conducted using the elsA software. The flow distortion is simulated by a drop of stagnation pressure ratio at the inlet boundary condition. The outlet boundary condition is set with a radial equilibrium boundary condition following a throttle law so as to reproduce experimental behavior. Special care has been applied on the mesh and the numerical set-up so as to ensure good boundary layer discretization and wake propagation throughout the domain. A special attention is paid on the arising of rotating stall, from the very first inception of the instability to completely developed stall cells.