水凝胶延迟水下回转体边界层自然转捩机理研究  

Mechanism of natural transition delay by hydrogel metamaterialover a body of revolution

作　　者：刘建华 张彬 徐良浩 张占阳[1] 潘翀[3,4] 张永明 朱文博[6] LIU Jianhua;ZHANG Bin;XU Lianghao;ZHANG Zhanyang;PAN Chong;ZHANG Yongming;ZHU Wenbo(China Ship Scientific Research Center,Taihu Laboratory of Deepsea Technological Science,Wuxi 214082,China;Department of Mechanics,Tianjin University,Tianjin 300072,China;Fluid Mechanics Key Laboratory of Ministry of Education,Institute of Fluid Mechanics,Beihang University,Beijing 100191,China;Aircraft and Propulsion Laboratory,Ningbo Institute of Technology,Beihang University,Ningbo 315800,China;Laboratory for High-speed Aerodynamics,Tianjin University,Tianjin 300072,China;School of Aerospace Engineering,Beijing Institute of Technology,Beijing 100081,China)

机构地区：[1]中国船舶科学研究中心深海技术科学太湖实验室,无锡214082 [2]天津大学机械工程学院,天津300072 [3]北京航空航天大学流体力学教育部重点实验室,北京100191 [4]北京航空航天大学宁波创新研究院先进飞行器与空天动力创新研究中心,宁波315800 [5]天津大学高速空气动力学研究室,天津300072 [6]北京理工大学宇航学院,北京100081

出　　处：《实验流体力学》2024年第2期1-13,共13页Journal of Experiments in Fluid Mechanics

基　　金：国家自然科学基金项目(91952301,91852101)。

摘　　要：水下航行体首部声纳探测能力与边界层转捩密切相关。本文开展了水凝胶超材料在延迟水下航行体边界层自然转捩方面的应用基础研究,并探究了其内在机理。在高速水洞中分别开展了刚性和水凝胶表面的SUBOFF模型总阻力系数与二维瞬时速度场大视场PIV实验测试,采用多路径积分算法对SUBOFF模型周围脉动压力场进行估算;结合刚性SUBOFF模型边界层流动线性稳定性分析与PIV流场测试结果,获得刚性SUBOFF模型边界层自然转捩特性;采用“比光强”算法,对低速水洞中水凝胶表面SUBOFF模型局部形变与近壁区速度场进行频谱分析,揭示水凝胶表面流−固耦合作用机制;基于法向瞬时速度分量的连续子波变换,对边界层瞬时流场间歇性进行分析,揭示水凝胶在流−固耦合作用下延迟SUBOFF模型边界层自然转捩的机理。Laminar-turbulence transition in a bow boundary layer is crucial for theperformance of the bow sonar of an underwater vehicle.An investigation on the application of thehydrogel metamaterial on natural transition delay is conducted and the underlying mechanism isanalyzed.The two-dimensional velocity fields around both rigid and hydrogel SUBOFF modelsare acquired by a long-distance PIV in a high-speed water tunnel,and drag coefficients are measured as well.Based on the velocity fields,the pressure fluctuations around the SUBOFFmodels are calculated through the multi-path integration algorithm.Combining the linearinstability analysis and PIV measurement,the characteristics of natural transition of theboundary layer over the rigid SUBOFF model are analyzed.The flow-hydrogel coupling is figuredout,according to the spectral analysis of local deformation of the hydrogel surface and thevelocity above the hydrogel SUBOFF model in a low-speed water tunnel.The intermittency ofthe instantaneous boundary layer flows are denoted by continuous wavelet transform of the wall-normal velocity components.Eventually,compared with the flow intermittency of the rigidSUBOFF model,the mechanisms of natural transition delay by the hydrogel metamaterial arediscussed,under the influence of the flow-hydrogel coupling.

关 键 词：水下航行体 自然转捩 流动稳定性 转捩延迟 水凝胶超材料 

分 类 号：O357.41[理学—流体力学]