超弹性球体入水过程空泡演化及球体变形实验  

Experimental study of cavity evolution and deformation during water entering into hyperelastic sphere

作　　者：杨柳 孙铁志 魏英杰[1] 王聪[1] 李佳川 夏维学[1] Yang Liu;Sun Tie-Zhi;Wei Ying-Jie;Wang Cong;Li Jia-Chuan;Xia Wei-Xue(School of Astronautics,Harbin Institute of Technology,Harbin 150001,China;School of Naval Architecture,Dalian University of Technology,Dalian 116024,China;Tianjin Navigation Instrument Research Institute,Tianjin 300131,China)

机构地区：[1]哈尔滨工业大学航天学院,哈尔滨150001 [2]大连理工大学船舶工程学院,大连116024 [3]天津航海仪器研究所,天津300131

出　　处：《物理学报》2021年第8期195-203,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11972138,11672094)资助的课题。

摘　　要：超弹性材料是工程实际中常用的材料,具有很强的非线性力学性能.将超弹性材料应用于入水问题是一个新的跨学科研究方向.与传统的刚性球体入水现象不同,超弹性球体入水后极易发生变形.为了探究该大变形的入水流固耦合问题,本文采用高速摄像方法,对超弹性球体垂直入水问题开展实验研究.基于实验结果,对比分析了球体材料属性和入水冲击条件对入水空泡流动及球体变形行为的影响.实验结果表明,超弹性球体入水后产生嵌套空泡现象的条件是需要足够大的入水冲击条件和小的材料剪切模量.嵌套空泡产生和保持的时间与球体的剪切模量和直径有关.超弹性球体的入水位移及其形成空泡的长度随入水冲击速度和剪切模量的增大而增大,却随球体直径的增大而减小.入水冲击速度的增加只会加剧球体的变形程度,而不影响嵌套空泡的产生时刻.同时,本文对球体的变形行为随弗劳德数和剪切模量与水动力之比的变化特性进行了描述与研究.Hyperelastic materials,which have strong nonlinear mechanical properties,are commonly used in the engineering field.The application of hyperelastic materials to the water entry problem is a new interdisciplinary research topic.Unlike the water entering into a traditional rigid sphere,the hyperelastic sphere is very easy to deform during water entry.In order to explore the fluid-structure coupling problem with large deformations during water entry,a high-speed camera is used to study the problem of vertical water entering into hyperelastic sphere in this paper.Based on the experimental results,the effects of the material properties and impacting conditions on the cavity flow and sphere deformation behaviors during water entry are compared and analyzed.The experimental results show that the formation of the nested cavity after impacting a free surface of the hyperelastic sphere needs large enough impact conditions and small material shear modulus.The time for the nested cavity to be formed and retained during water entry is related to the material shear modulus and sphere diameter.The sphere displacement and length of cavity formed by the hyperelastic sphere increase with the increase of the impact velocity and material shear modulus,but decrease with the increase of the diameter of the sphere.The increase of the impacting velocity can only aggravate the deformation behaviors of the hyperelastic sphere,but does not affect the formation moment of the nested cavity.In addition,the characteristics for the deformation behaviors of the hyperelastic sphere to vary with the Froude number and the dimensionless ratio of material shear modulus to impacting hydrodynamic pressure are described and studied.

关 键 词：超弹性球体 入水实验 嵌套空泡 变形 

分 类 号：TB34[一般工业技术—材料科学与工程] O353.4[理学—流体力学]