Dynamic Response Analysis Of Compressor Impeller Subjected To Turbulent Airflow

Centrifugal compressor is a kind of large rotating mechanical equipment widely used in important production industries of the national economy such as machinery,chemical industry,aerospace,etc.It has the characteristics of high speed,high power,and high manufacturing precision.The impeller is the core component of the centrifugal compressor,which bears turbulent aerodynamic loads during work.So the safety of the impeller is an important indicator to ensure the normal operation of the compressor.With the development of compressors in the direction of large-scale,high-speed,large flow,and high power,in order to ensure the safe and reliable operation of the impeller,it is necessary to consider the dynamic response of the impeller under the action of turbulent airflow.Due to the randomness of the aerodynamic load,the aerodynamic load of the fluid structure coupling surface in the solid region of the centrifugal compressor is extracted by the partition solution method,which is regarded as the random vibration excitation.By studying the relevant statistical characteristics of the unsteady aerodynamic load,the fluctuating pressure part is transformed from the time domain to the frequency domain.Using the transient analysis module and the harmonious response analysis module of the large-scale finite element analysis software ANSYS,based on the pseudo excitation method,the secondary development of ANSYS APDL was carried out,and the efficient algorithm of displacement response analysis of impeller under the action of turbulent airflow with different characteristics was written to realize the application of random vibration pseudo excitation in ANSYS.Then obtained the statistical characteristics of displacement response vibration amplitude of impeller.Promoted the application of pseudo excitation method,and provided the corresponding reference basis for the reliability design and fatigue analysis of the related fields in the future.This paper focuses on the following work:Firstly,the basic knowledge of signal analysis theory is introduced.Taking the measured pressure fluctuation data and strain data of a large centrifugal compressor as an example,the statistical characteristics are calculated.Secondly,the multi-dimensional multi-point vibration analysis method,virtual excitation method,which is excited by random vibration with different statistical characteristics,is deduced.The realization process of the method in ANSYS is described in detail.Through several examples,different random vibration excitation is constructed,and the accuracy of response displacement power spectrum calculated by PEM is compared with that of analytical solution and time-domain transient analysis.The results fit well and accord with the actual demand of the project.Aiming at the partial coherent stationary random vibration excitation of multi-degree-of-freedom system,the algorithm is optimized from the perspective of extracting the frequency points with large amplitude of the excitation power spectrum and the structure natural frequency points.The algorithm is optimized to reduce the calculation time and improve the calculation efficiency.Finally,the blade of a centrifugal compressor was modeled and a finite element model was built.The unsteady aerodynamic load of the impeller fluid domain generated by CFD software was extracted and its statistical characteristics were analyzed.The pressure pulsation value of the impeller solid domain on the fluid-structure coupling interface was obtained by triangular fast mapping method.By using the efficiency optimization method,the multi-dimensional and multi-point partially coherent stationary random vibration of the impeller is analyzed,and the statistical characteristics of the displacement response power spectrum of the concerned nodes are obtained.