Stability Analysis and Measurement of Flow-induced Vibration of a Parallel-plate Structure

摘要

A model consisting of multi-parallel-beam joined with single-beam is adopted in a theoretical study on the natural vibration characteristics of the parallel-plate assembly. In the theoretical analysis and numerical computation of 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 stability evaluation of the parallel-plate assembly, its critical flow velocity and destabilizing deflection are analyzed and calculated by both direct method and variational method, and the results of the two methods agree reasonably well with each other. Furthermore, to secure the strength, rigidity, stability and reliability of the parallel-plate assembly, the natural vibration characteristics are measured and analyzed in the flow field, which is important for the design and safe operation of new type fuel elements in nuclear reactors. A new electromagnetic method is introduced for measuring flow-induced vibration in small space. The sensor is small in size, light in weight and easy in fixation. Experimental results show that (1) the natural frequencies decrease as the flow velocity increases; (2) flow-induced vibration is of complex-modal characteristics; (3) the electromagnetic method has high reliability and precision, and therefore it is suitable and effective for the measurement on flow-induced vibration.