The Study on the Development of Resonance Avoidance Design for Axial Compressor Blades using the Stepwise Regression Method

The flow generated from the inlet to the outlet by the rotation of the compressor rotor and blades induces vibrations as it passes through the stationary vanes.The rotation of the rotor and the number of vanes and their difference are the sources of excitation that induce the vibration of the blades.Resonance avoidance design is the process of adjusting the mass and stiffness to prevent the natural frequencies of the excitation sources and the blade from intersecting.It is generally performed after evaluating aerodynamic performance.Therefore, design variables that can change the natural frequency of the blade while minimizing changes in aerodynamic performance are utilized, and the most representative is the thickness distribution ratio of the blade cross-section.In this study, Static structure and modal analysis were performed on blade shapes with various thickness-to-chord length ratio in each section in the span direction of the blade.The influence of the thickness over chord length ratio on each major vibration mode was analyzed by applying the stepwise regression analysis method, and the linear regression equation for predicting the frequency of each major mode was derived and applied to the resonance avoidance design.In addition, the frequency using the regression equation and the frequency of the modal analysis results were compared to validate the proposed resonance avoidance design method.