The Rotating Stall Analysis Of The First Stage In A Centrifugal Compressor

Centrifugal compressors play an important role in national economy construction for its broad usage in many important industries, such as the petrochemical industry, metallurgy, etc. In many cases, centrifugal compressors are the key equipments in the whole cooperation. The smooth operations of the centrifugal compressors are vital to the production lines. One particular phenomenon that threatens the safe running of the compressor is the rotating stall in the compressor. In many cases, rotating stall had caused great damages with serious consequence. The study of the rotating stall is of great importance for the prevention of the rotating stall in the design stage or the control of the rotating stall during the operation.The fracture problem of the first stage impeller blades in one centrifugal compressor was studied in this thesis by analysis the flow field in the inlet camber and the first stage. The numerical analytic platform was based on the CFD commercial software NUMECA and the real 3-D geometry model of the compressor. The boundary condition was specified by the actual operating parameters. Simulation results indicate that the flow distortion at the impeller inlet is induced by the poor design of the inlet camber and the inlet guide vane. The flow distortion upstream of the impeller inlet excitateds the rotating stall so that the pressure field oscillated violently. Based on the simulation results of the pressure field, further mechanic analysis proved that the vibration and fracture failure of the impeller blades is most likely caused by this pressure fluctuation. Unsteady flow simulation was carried out and the propagation and development of the rotating stall cell was observed clearly. The actual pressure fluctuation on the blade surface was obtained for accurate mechanic analysis. The study may provide a guideline in solving the fracture problem of the impeller blades.