Cavity Flow Modeling in an Industrial Centrifugal Compressor Stage at Design and Off-Design Conditions

Abstract

Numerical tools and test equipments used in the design and validation of modern centrifugal compressor stages need to be at the state-of-the-art. In particular, a big effort is currently made to correctly model secondary flows that play a relevant role in the accuracy of the performance prediction. This paper presents the flow analysis of a high efficiency centrifugal compressor stage using high accurate computational fluid dynamics with a particular attention to the cavity flows modeling. Experimental data were also available and used to validate the numerical results. The key experimental data coming from an advanced FRAPP (Fast Response Aerodynamic Pressure Probe) and traditional probes are presented in the study as overall performance and flow features details. Test data are in fact necessary to validate and continuously improve the numerical techniques.The geometry of the stage including full modeling of the secondary flows cavities were faithfully reproduced in the computational model. The availability of new in-house automated tools for cavity meshing allow compressor aero-designers to ac- * Reference author. curately resolve leakage flows with a reasonable increase in computational and user time.The results of the computational model were in excellent agreement with the experimental data both in terms of overall performance and main flow field structures. Also details of the flow features inside the cavities matched the test data very well. Only using high accurate geometry modeling including leakage flows was possible to capture important flow features that instead were not correctly simulated with simplified computational models.

Effect of the hub cavity leakage on the aerodynamic performance and strength characteristics of the 150 kW SCO2 centrifugal compressor

“…The suction mode was beneficial to the mainstream flow, while the injection mode was harmful. Guidotti et al 20 numerically and experimentally investigated the effects of the cavity flow on the compressor performance. It was found that the three-dimensional numerical simulation including full cavity structure was excellent in predicting the overall performance and flow features details for the compressor.…”

Conjugate Heat Transfer Study of a Centrifugal Compressor with Impeller Cavities

“…Literature shows that the inclusion of rotor-stator cavities is crucial to the correct reproduction of stage characteristics: (Hu et al, 2017) and (Sun et al, 2009), amongst others, research centripetal flow through rotor-stator cavities and show how axial thrust and disk torque are affected. (Guidotti et al, 2012) show the influence of cavity modelling on the efficiency and pressure ratio. (Mischo et al, 2009) find that the shroud cavity leakage can induce flow separation and thereby severely influence compressor performance.…”