Vibrating Cascade Unsteady Flow Numerical Simulation And Blade Flutter Analysis

The flutter is one of the main obstacles in the development of turbomachinery. Because of the flutter of blade, lots of breakdown occurred in turbomachine. So, the correct prediction of the blade flutter is very important in the design and modification of the turbomachine. Based on the Computational Fluid Dynamics and Structural Dynamics methods, a numerical analysis system for the blade flutter in turbomachinery was established.By using a finite volume method to solve the Navier-Stokes equations, two-dimensional vibrating cascade flow was computed. The numerical results are in well accord with the published data. There were some intensively nonlinear features in the vibrating cascade flow. The frequency of the separated vortex's propagation was not equal to the vibrating frequency of the blade.High-resolution NND scheme and fully implicit dual-time stepping method were adopted in the three-dimensional vibrating cascade flow calculation. Thus, the correct simulation of the shock in transonic flow and the efficiency of calculation were both taken into consideration. The results are in good agreement with the semi-analytical solution.The numerical flutter analysis system was formed by the three-dimensional numerical simulation of the vibrating cascade flow combined with the structural dynamics analysis of vibrating blade. Two kinds of actual blade were tested with this system. The analysis results are just the same as the practical operation. This shows that the numerical flutter analysis system is effective and can be used in the practical engineering problem.Furthermore, the generation of moving grid, Dual-Time Stepping method and the disposal of phase-difference periodic boundary condition were also been studied. It indicates that the moving grid generation method used in this paper is simple, fast and easy to deal with the boundary conditions of the upstream and downstream. The use of the fully implicit Dual-Time Stepping method in this paper can greatly decrease the calculating time of the three-dimensional unsteady flow in vibrating cascades to satisfy the engineering practice requirement. The efficiency of this acceleration method is very high. Finally, multi-passage method was adopted to deal with the phase-difference periodic boundary condition. When the frequency of separated vortex propagating is not the same as the vibrating frequency of blade, this method is much more reasonable than those simple phase-shifted periodic condition in single passage.