Surge Detection of Centrifugal Compressor Using CFD Results

In this study, a method has been proposed to generate surge lines based on the high-fidelity numerical simulation conducted for a refrigerant centrifugal compressor and later the results are compared against the experimental results. Surge, a violent flow instability at low mass flow rates, is often accompanied by severe detrimental effects including reduced efficiency, safety concerns, noise, and vibration on both the compressor itself and the overall system in which it operates. Conducting experiments for mapping a surge line often requires an extensive amount of time. In this paper, a surge line is mapped for a centrifugal compressor for a wide range of rotational speeds. The behavior of aerodynamically induced radial force and torque are used as the primary criteria for predicting the surge of the compressor. In this study, the pressure ratio and isentropic efficiency of the simulation results closely align with experimental results. Later, the radial displacement of the rotating shaft, a key indicator to identify surge, is obtained in the experiments for an oil-free magnetic bearing compressor. Finally, the surge line based on test data is used for evaluating the accuracy of the proposed method based on simulation results.