Study On Flow-induced Vibration And Stability Of The Parallel-plate Structure

Fluid-structure interaction dynamic problems in parallel-plate structures can be often met in many fields and it is a difficult problem that should be solved quickly. The parallel-plate assembly is a new type fuel element in nuclear reactors. Its flow-induced vibration and stability are studied in this thesis.A model of multi-parallel-beams joined with single-beam is adopted in the theoretical analysis of the natural vibration characteristics of the parallel-plate assembly. In the study of theoretical calculation and analysis on the wet-modal natural frequencies and modes, the dry-modal mode functions are used as trial functions to solve the complex-modal mode equation by variational method. In the study of stability of the parallel-plate assembly, its critical flow velocity and destabilizing deflection are analyzed and calculated by direct method and variational method, and the results of the two methods agree with each other. In the study of flow-induced vibration and stability of the parallel-plate assembly with nonlinear support, the stability of steady-state solution near the equilibrium points is analyzed by using the theory of stability. In the study of flow-induced vibration experiment on the parallel-plate structure, electric-magnetic method is used to measure the flow-induced vibration of the single plate and the parallel plate.Through theoretically analyzing, calculating and experimenting, some conclusions are drawn as follows. In the dry-modal, odd-order mode curves of the parallel-plate structure are symmetric modal, but even-order mode curves are asymmetric modal. Flow-induced vibration of the parallel-plate structure is of complex-modal characteristics. The natural frequency of any order decreases with increasing flow velocity. Symmetric modal and asymmetric modal are not strictly arranged alternatively. Critical velocity increases with increasing the plate length, the damp and liquid stickiness coefficient, decreasing the plate length, the channel height, liquid density and so on. The electromagnetic method has high...