| The Navier-Stokes equation is discretized in the moving-grid system. By adopting the explicit four-stage Runge-Kutta Jameson finite volume scheme, and under the sustainment of acceleration algorithms such as dual-time stepping method, the multi-grid strategy and implicit smoothing of the residuals, a two dimensional unsteady viscous flow in vibrating cascades is simulated.First, a 2-D unsteady viscous flow in a vibrating cascade is investigated under flow-structure uncoupled conditions. Assuming the blades conduct a planar simple harmonic motion, the flows in vibrating cascades in the case of different oscillating amplitudes, different reduced frequencies and different torsional centers are computed respectively for two blade profiles. According to comparing flow calculations at different oscillation modes, the influence of the oscillation parameters' selection on aeroelastic performances of cascades is analyzed.Second, the structural dynamic equations for blades are introduced in this paper. Through numerically solving the aerodynamics-structure coupled equations, a 2-D unsteady viscous flow in a single cascade is investigated under flow-structure coupled conditions, and a preliminary analysis of the cascade flutter is prosecuted. The flows in the case of different reduced frequencies are computed respectively for two blade profiles. By comparing the time curves of relative parameters in oscillating cascades and the flow field contours under different conditions, it is indicated that the reduced frequency is an important factor to determine whether the blade flutter happens or not.In the end, the situations of work done by aerodynamic forces on blade surfaces when flow-structure is coupled and isn't coupled under the same conditions are compared, the result indicates that the work done by aerodynamic forces after the coupling restraint is unloaded has a distinct change. In order to deeply study the flows in cascades, the structure dynamic factors must be included. |
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