液态金属堆内小长径比同轴双层薄壁结构的流固耦合试验研究

The Experimental Study on the Fluid-structure Interaction of Coaxial Cylindrical Thin-walled Shells with Small Aspect Ratio in the Liquid Metal Reactor

池式液态金属堆的主容器与热屏之间具有狭窄的流体间隙,该结构属于含窄缝间隙的小长径比同轴双层柔性壳体。窄缝间隙中流体与结构之间相互作用产生的流固耦合效应在抗震分析时必须加以考虑。现有研究主要针对长径比较大和流体间隙相对较大的圆柱壳体,对于小长径比和极小流体间隙的同轴柔性壳体研究较为缺乏。本文参考液态金属反应堆的结构设计了三种不同尺寸的窄缝间隙,开展窄缝间隙条件小长径比同轴双层壳体模型的振动试验,测量结构在不同间隙尺寸下的加速度,得到模态频率和主要振型。然后,使用有限元法进行模态分析,通过与试验结果的对比,验证了有限元法的准确性。最后,计算出不同间隙尺寸下模型的附加质量;且随着间隙尺寸的减小,模型附加质量随之增大。本研究可为类似的含窄缝小长径比同轴双层柔性壳体结构的抗震设计提供数据支持,对于液态金属堆的抗震分析具有重要意义。

The liquid metal reactor has a narrow fluid gap between the reactor vessel and the thermal shield,which is a small aspect ratio coaxial flexible cylindrical shell containing a narrow gap.The fluid-structure interaction in the narrow gap produces fluid-structure interaction effects that must be considered in the seismic analysis.The study mainly focuses on cylindrical shells with relatively large aspect ratios and large fluid gaps,and there are few studies on coaxial flexible shells with small aspect ratios and very small fluid gaps.Three different sizes of narrow gaps were designed with reference to the structure of liquid metal reactor.The vibration experiment of small aspect ratio coaxial cylindrical shell model with narrow gap conditions was carried out.The modal frequencies and main vibration modes were obtained.Then,the modal analysis was performed using the finite element method,and the experimental and finite element results were compared.Finally,the added mass of the model at different gap sizes were calculated to verify the applicability of the added mass calculation method,and the effect of different gap sizes on the fluid-structure interaction characteristics was investigated.This study can provide input for the seismic design of the similar coaxial flexible cylindrical shell structure containing a narrow gap with a small aspect ratio,and is of great significance for the seismic analysis of liquid metal reactors.