CFD has become an essential tool for researchers to analyze centrifugal compressors. Tip leakage flow is
usually considered one of the main mechanisms that dictate compressor flow field and stability. However,
it is a common practice to rely on CAD tip clearance, even though the gap between blades and
shroud changes when compressor is running. In this paper, sensitivity of centrifugal compressor flow
field and noise prediction to tip clearance ratio is investigated. 3D CFD simulations are performed with
three different tip clearance ratios in accordance to expected operating values, extracted from shaft
motion measurements and FEM predictions of temperature and rotational deformation. Near-surge operating
conditions are simulated with URANS and DES. DES shows superior performance for acoustic predictions.
Cases with reduced tip clearance present higher pressure ratio and isentropic efficiency, but no
significant changes in compressor acoustic signature are found when varying clearance. In this working
point, tip clearance is immersed in a region of strongly swirling backflow. Therefore, tip leakage cannot
establish any coherent noise source mechanism.The equipment used in this work has been partially supported by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)", framed in the operational program of unique scientific and technical infrastructure of the Ministry of Science and Innovation of Spain. The authors wish to thank Mr. Pau Raga for his worthy assistance during the meshing process.Galindo, J.; Tiseira Izaguirre, AO.; Navarro García, R.; López Hidalgo, MA. (2015). Influence of tip clearance on flow behavior and noise generation of centrifugal compressors in near-surge conditions. International Journal of Heat and Fluid Flow. 52:129-139. https://doi.org/10.1016/j.ijheatfluidflow.2014.12.004S1291395
