The influence of blade loading on tip clearance sensitivity in centrifugal compressor
In order to study the mechanism of the effect of blade load distribution of the compressor on tip clearance sensitivity,the flow structure and irreversible loss source of two types of blade shapes under different clearances were analyzed.The results show that mid-loaded impeller can reduce the sensitivity of impeller efficiency to clearance,the efficiency deterioration slope will decrease with back shift of design load with the magnitude of 14%.The mixing loss between the clearance leakage flow and the mainstream dominates the increase of impeller loss caused by clearance variation,accounting for nearly 70%.For fore-loaded impeller,secondary leakage was observed at 25%normalized streamwise distance.When tip clearance increases,this secondary leakage flow grows stronger,causing tertiary leakage.Whereas no such phenomenon was observed in the mid-loaded impeller.The main mechanism of the effect of the blade loading mode on the clearance sensitivity is that the fore-loaded blade has a stronger channel secondary flow and leakage vortex structure when the clearance increases,which will bring higher entropy production rate and loss,and cause the compressor efficiency to decrease faster and increase the clearance sensitivity.By optimizing the secondary flow and leakage vortex structure in the channel,it is beneficial to obtain an aerodynamic design with lower clearance sensitivity.These research results can provide a reference for the development of high-performance compressors with low clearance sensitivity.
centrifugal compressorblade tip clearancesensitivityentropy production ratemixing loss
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