Aerodynamic study of the high-pressure collector in a compressor test bench. BeCover

Abstract

The BeCOVER test bench is a strategic infrastructure designed for the validation of next-generation aviation compressors. A critical component of this facility is the high-pressure collector, which regulates mass flow through calibrated multi-hole diaphragm restrictors and manages high-temperature exhaust via an annular ejector. However, spatial constraints dictate the installation of an elbow immediately upstream of the restrictors, violating standard analytical norms. Furthermore, to support the facility's high-pressure upgrade, the system must safely dilute hot primary air with ambient secondary air before atmospheric discharge.This thesis presents a comprehensive Computational Fluid Dynamics (CFD) analysis using the SU2 solver to characterize the aerodynamic penalties of the installation and evaluate the thermal mixing efficiency across various operating points. The investigation is divided into two phases. First, the upstream elbow is shown to generate strong Dean vortices and flow distortion, inducing a systematic reduction in the discharge coefficient across the choked operational range. By normalizing the data using the Saint-Venant reduced mass flow, this penalty is proven to be a purely geometric and inertial phenomenon, independent of thermal conditions.Second, the full system analysis reveals that the momentum-driven secondary suction forms a uniform protective fluid shield, isolating the divergent walls from the hot primary core. The ejector enters a stable, saturated regime at high inlet pressures. Under high-temperature conditions, a minor thermal degradation in corrected suction efficiency is observed due to severe density gradients. Nevertheless, the exhaust line secures high thermal homogenization, successfully dropping peak temperatures to structurally safe limits. Ultimately, the enthalpy balance demonstrates that the cooling process is pressure-independent on the saturated plateau. The system acts as a self-regulating mechanism, formalized through the development of continuous operational maps to provide operators with safe, real-time monitoring capabilities.