Effect of rotor axial blade loading distribution on compressor stability

Three compressors with fore-loaded, uniformly loaded and aft-loaded rotor blades are designed via streamline curvature method coupled with blade generation that uses arbitrary camber lines so as to study the effect mechanism of rotor axial blade loading distributions on compressor performance. The rotor blade loading design is achieved by modifying the flow circulation in the rotor region on the basis of ensuring the total rotor work unchanged during the through-flow solving. Based on global linear stability analysis, a stall inception prediction model is established and integrated into the compressor design process as an assessment tool of flow stability. The predicted stall inception of the fore-loaded compressor validates the model precision by comparing with experimental measurements. Steady numerical simulations show that the pressure rise and efficiency of aft-loaded compressor are the best at the mass flow rates less than design point, followed by the uniformly loaded compressor, and those of the fore-loaded compressor are the worst. Steady blade loading analysis indicates that the peak loading positions of the three types of rotors move towards the leading edge accompanying with the throttling process. The comparison of predicted stall inception points among the three compressors presents that the fore-loaded compressor is the first to enter instability state, followed by the uniformly loaded compressor, while the aft-loaded compressor is the last. The steady and unsteady flow fields show that the maximum tip loading of rotor and stator blades becomes larger at the near-stall point as the rotor becomes more fore-loaded. This finding combined with the unsteady tip clearance flow explains the flow stability distinction of the three compressors to some extent.