Fatigue Life Prediction Of Centrifugal Compressor Blades Under Complex Loads

The centrifugal compressors play an important role in every field of the national economy,such as aerospace, petroleum and chemical industry, power plants and metallurgy industry. The smooth operations of the centrifugal compressors are vital to the production lines. In recent years, a big challenge to the design and research of the domestic compressors with large capacity is posed, especially in the large air separation unit and megaton ethylene project. In practical running, the fracture problem of impeller blade happens occasionally, which threatens the smooth running of the compressor and the safety of the staff. It turns out that fracture of the impeller blades is most likely caused by fatigue. Therefore, further research on the principle of blades' fatigue and reasonable life prediction of the blades are very valuable for the quality and reliability of the compressors.Concerning about blades' fatigue problem, this article firstly divides the compressor's working conditions into start/stop, normal working and rotating stall by analyzing the operational working profiles of the compressor and the sorts of loads on blades in different working phases. Secondly, simulate the flow fields and analyze the fluid-structure interaction in different conditions respectively with the commercial software, ANSYS-CFX and ANSYS-Static Structural. Joining the results with the structure's S-N curve, calculate the damage in different working conditions. According to the research, initial unsteady flow in normal working phase will not result in blades' fatigue. While, start/stop and rotating stall are reasons of the blades' damage. Especially for its high frequency, rotating stall works much more obviously. Therefore, it is necessary to consider the influence of start/stop and rotating together, when predicting the life of blades. This article provide a reference for the research of blades' fatigue and life prediction of blades.