The Fatigue Life Study Of Centrifugal Compressors Blade Based On The Fracture Mechanics

Centrifugal compressor plays an important role in natural gas transport and the design and manufacturing level of compressor marks the level of the country significant manufacturing equipment industry. Manufacture of compressor blade represents the highest level of compressor technology. Impeller blade is the main failure parts of a compressor. The main fault form of the blade is crack. Fatigue life of compressor needs to be resolved in design process.This paper studies for a large centrifugal compressor impeller blade. The load distribution of compressor blade is emulated using FLUENT. And the obtained results coupled with the impeller model in ANSYS. Analysis of impeller blade stress distribution in different conditions of is developed. Normal condition, stall and surge stresses of blade is also analyzed and the basic stress situation of blade is obtained, and find that the stress on joint of blade and sepal/cover plate is larger, these areas belong to the dangerous areas.The main factor of blade fatigue crack extension is the field distribution of the crack tip, including stress and displacement field. Stress intensity factor is the important factor of crack tip fields and it is the main factor determining crack initiation and cessation. In this paper, the distribution of impeller blade crack tip field is analyzed and distribution of edge and internal crack tip field is obtained, and find that the internal crack tip field is similar to the edge crack, and the value decreases30%-45%than the edge.On the basis of fracture mechanics, through the analysis of the blade section image, the position and fracture characteristics of fatigue crack initiation are concluded in the fourth chapter of this article. For PCL81compressor blade, S-N curve is obtained through the experimental method. Through the establishment of the crack growth rate model, crack growth rate, fatigue life and residual fatigue strength of different stress ratio are analyzed. And find that crack growth is slower under normal working condition, but he crack propagation is faster under the stall and surge condition.Results of this study not only obtain the crack growth rate in different conditions, but also have some reference value to the design and manufacturing of the compressor.