Critical Analysis of Simplified Volute Models for Single-Stage Centrifugal Compressors

Optimization of centrifugal compressor stages with CFD-based surrogate models has become a common practice in the industrial scenario. However, effort and time required for such optimizations are linked to the complexity of the computational domain. Therefore, it is crucial for designers to maintain robustness and accuracy while reducing computational costs. Concerning single-stage compressors, discharge volutes are pivotal for performance evaluation, but full stage CFD analyses can be resource-intensive. Moreover, their non-axisymmetric shape exacerbates the effort involved during stage parameterization, jeopardizing robustness of the optimization chain. Although excluding volute can save resources, not considering its behavior can lead to incorrect results. Indeed, alternative geometries with similar total-to-total efficiencies at diffuser outlet could exhibit different dynamic pressures, and thus different losses across the volute. To mitigate this, introducing 1D volute loss models could potentially offer a compromise, preserving volute behavior without full-stage simulations. In this perspective, the theoretical contribution of the research is a critical analysis on 1D volute models based on CFD results and experimental measurement. Practically, the research provides practitioners with insights on joint adoption of CFD simulations and 1D models during optimization. The study lays the foundation for future works aiming to increase business sustainability of centrifugal compressor optimizations.