Abstract: It is essential to consider fluid–structure interaction an‎d stability analysis in blade design in order to improve the performance of compressors. In this study, the aeroelasticity of a centrifugal compressor blade under a specific operating condition is investigated. In the structural analysis section, the free vibrations of a rotating bladed disk were examined, an‎d its natural frequencies an‎d vibration mode shapes were determined. According to the results, by considering the stiffness effect induced by centrifugal force, the frequency increased by 26% compared to the unstressed state. Additionally, the von Mises stress an‎d displacement distribution in the bladed disk were analyzed, an‎d critical points were identified. The highest von Mises stress occurs at the blade–disk junction an‎d the inner radius of the disk. Subsequently, by applying deformation of the blade in its first mode an‎d a specific harmonic, a fluid–structure interaction (FSI) analysis was performed for the blade an‎d the surrounding fluid to eva‎luate the fluidʹs role in the stability of the blade in the considered vibration mode. To achieve better convergence, results from a steady-state analysis were used as initial conditions for the transient analysis. Moreover, to reduce computational cost, a Fourier transformation was employed to account for the effects of adjacent blades, an‎d therefore only two passages were analyzed. In the steady-state analysis, the total pressure an‎d temperature decrease in the hub near the regions where the blades connect to the disk an‎d the temperature increases near the shroud. According to the Mach number contours, the highest flow velocity occurs at the compressor inlet, an‎d as the flow moves toward the compressor outlet, the velocity gradually decreases. Variations in aerodynamic damping during the FSI analysis play a critical role in the instability of compressor blades. In transient analysis, these variations were computed as a result of work done by the fluid around the blades during their vibration in the first bending mode. According to the results, the maximum aerodynamic work occurs at the blade tip, which is the maximum blade displacement. the integral of the aerodynamic work on the fluid–structure interface over a vibration cycle is negative, indicating that the blade motion is unstable. Identifying blade instability through FSI simulation is an important step toward the optimal design of the considered centrifugal compressors.

زماني، زهرا

بهمن اسدي , هادي صفائي