Analysis And Study On Static And Dynamic Load For The Impeller Of A Centrifugal Compressor

With the strengthening of industrialization, the demand of industrial gas such as oxygen, nitrogen and argon is increasing so rapidly that the air separation equipment is becoming large-scale. As the core part of the large separation equipment, the large centrifugal compressor plays an important role of the reliability of the separation equipment. So it is significant to do some research on the key component impeller. The loads on impellers include centrifugal force, shaft system vibration and aerodynamic load. The blades have a large static stress under action of centrifugal force, while shaft system and aerodynamic loads may cause the vibration of blades, which can results in fatigue fracture. Therefore, the calculation of the blade loads becomes a key problem for the design of an impeller.Based upon the background of 973 Project, this paper focuses on the centrifugal compressor in the oxygen system. The effect of the centrifugal force and the aerodynamic load on the modal parameters of an impeller had been analyzed by using the method of one way fluid-structure pre-stress modal analysis. The influence on aerodynamic loads in different working conditions has been analyzed; an unsteady calculating of the flow field has been made. The main contents of this paper are as follows:Firstly, using CFX to get the aerodynamic loads on the surface of the impeller, applying the results on the impeller surface, a pre-stressed modal has been analyzed. The results show that the effect of pre-stress is greater in high frequency than that in low frequency. The centrifugal force has a greater influence than aerodynamic load.Secondly, an analysis has been made to study the influence on aerodynamic loads with different input air temperature and different relative humidity (RH) by adjusting the proportion of ideal air and ideal vapor in CFX. The aerodynamic load increases 200Pa when RH increases 10%, and it increases 2000Pa when input temperature increases 10?.Thirdly, numeric simulation of the unsteady flow in an IGV-impeller is performed to analyze the variation of aerodynamic load with time for the impeller with a uniform stators and explore the mechanism of the IGV-impeller interaction. The effect of an asymmetry stator mistuned on the unsteady flow in the IGV-impeller has been analyzed to investigate the effect of the asymmetry stator on the aerodynamic load of IGV-impeller. The results show that the pressure pulsation frequency is related with the number of IGV and the rotational speed. An aerodynamic mistuned design stator can reduce the amplitude of the aerodynamic load that the frequency is equal to the multiplication of number of the IGV and rotational speed, but increase the amplitude of the low frequency aerodynamic load.