Numerical Investigations of Aerodynamics in a Transonic Compressor Rig

Sammanfattning

The DARLING project offers a mixed experimental-virtual simulationapproach to understand better the aeromechanical behaviour ofdamaged compressor blades. The compressor rig built for the experiments allows for the use of gases other than air, namely the refrigerant R-134a, to achieve higher Mach numbers. This thesis aimsto investigate the behaviour of the compressor rig when the refrigerantis contaminated with small amounts of air. This is done throughsteady state CFD simulations performed using ANSYS CFX 2024 R1.Firstly, different models of the refrigerant were built and benchmarked. After that, different strategies using a multicomponent, single phaseand ideal mixture approach were compared. Finally, the performancemaps for different concentrations were computed, showing how the contamination with air drastically changes the operating point. It was found that higher air mass fractions move the speedlines towards lowermass flow rates and lower stage pressure ratios. It was also foundthat the mixture components need to have a high enough number of elements in the interpolation table, to avoid a shift of the speedlinetowards higher mass flow rates due to the mixture model