Research On Static And Dynamic Characteristic Of The Blade In Axial-Flowing Compressor

As one of the key parts of compressors, the blades play an important role in the working performance of the compressor, especially its' structural design rationality. While the static and dynamic characteristics are the main aspects in evaluating the performance of blades. In this thesis, one type of blade designed by an enterprise manufacturing the axial-flow compressors is used as the research object, and its characteristics in strength, natural frequency and mode shape are studied by combining the finite element analysis method and experiments method.First, considering the high skewness of blades and the problem of converting the CAD model into CAE model freely by general modeling methods, a new method is put forward for blade's solid model with more than one boundary curves by dividing the cross-sections of the blade into 4 parts. SolidWorks, a parametric software, is used to build up the three-dimensional CAD model and then the model for CAE analysis in the environment of ANSYS is obtained by converting from CAD model by virtue of the data interface.On the basis of successful establishing of the finite element model, the static characteristics of the blade subjected different loads and constraint conditions are analyzed by ANSYS software, and the distribution of stress and displacement are obtained. The results show that the high stress of the blade is mainly caused by centrifugal force, which primarily occurs on tenon-grooves of blade roots, while airflow pressure is more dominant factor affecting the deformation value of blades, deformation always reaches to the maximum on the top of blades. In addition, the crack phenomenon on the tenon-grooves of blade roots can be avoided to some extent if the forced location is ordered to offset the boundaries.Considering the research necessity of dynamic characteristics of blades, the natural frequency and mode shape are also calculated. The first 4 modes are shown as one bending mode,two bending mode,one twisting mode and bending-torsion . Then the Campbell diagram is drawn based on the dynamic frequency values, where two resonance points exist in the normal working conditions. It is necessary to carry out the frequency modulation. Constraint conditions have little effect on the static or dynamic frequency.Spectrum analysis is adopted to measure the natural frequency of the first stage blades and the numerical results are reasonably consistent with the experimental test, which shows the veracity of finite element analysis. In addition, the dispersities of a few blades are out of standard in from the tested natural frequency values of blades. So it is necessary to improve the accuracy of machining and the frequency of measurement and repairment.