Analysis On The Effect Of The Key Parts Size On Fatigue Life For An Air Compressor

The characteristics of the air separation equipment in foreign countries is:large-scale, high reliability, low energy, etc. Compared with the level of development of air separation equipment abroad, the development of air separation equipment in our country is relatively late, smaller in the manufacturing scale, and higher energy consumption. There is an urgent need for large scale air separation equipment about the analysis of the system, especially the operation condition of the key components of air separation equipment, the loads and its influencing factors in-depth exploration, So as to the further establish prediction method of air separation equipment, the fatigue life of key components. it studied that the size of key parts influence on fatigue life of air compressor in this paper, All the research work was in the following.(1) In the static structure analysis result of the air compressor impeller, it found that the location of impeller was somewhere to occur yield failure in work. Compared the modal analysis of free state, the modal analysis of impeller under the state of rotating stress, the modal analysis of impeller under rotating impeller under the state of rotating stress and aerodynamic force, explored the effects of the aerodynamic force on natural frequency of impeller, analyzed the change of the modal frequency and modal form with the size of the impeller. The results showed that the impeller modal frequency increased slightly with the increase of the rotating centrifugal force. The impeller modal frequency decreased slightly, with the increase of the aerodynamic force. With the increase of size of the impeller, the impeller natural frequency had a decreasing trend, and the amplitude of the decrease decreased with increasing size.The maximum deformation, the equivalent stress and strain of the impeller increased with the increase of the size of the impeller.(2) By the direct transient analysis and the uniflow solid coupling method, studied the time course of the compressor impeller loads, based on ANSYS software environment. Compared the calculation results and program running time of two methods, the results showed that calculated results obtained by the two methods were close, but direct transient analysis calculation was more reduction than calculated results of solid coupling method uniflow. Therefore, could use direct transient analysis instead of uniflow solid coupling analysis to research the size effect of the impeller.(3) By the direct transient analysis method, calculated the load time histories of impeller with different dimensions. It defined the equivalent fatigue nominal stress of the impeller, with Crossland model and Matake model respectively. Using the MATLAB language to develop the rain flow count method for extracting two kinds of fatigue stress of impeller with different sizes, and build right load spectrum of the impeller with different size. Fatigue load spectrum was compiled impeller. It established fatigue life prediction mode based on fatigue cumulative damage theory. Separately used two equivalent nominal stress to predict the fatigue life of impellers of different sizes, Under the same conditions, it showed that, with the increase of size of the impeller, the impeller of the fatigue life decreased,. The predicted fatigue life of the impeller comes to the minimum. The fatigue life of two kinds of equivalent stress for different nominal size impeller were close, But the results based on the equivalent of Crossland model were more than Matake model for the life prediction results slightly larger.