倾斜射流撞壁形成液膜的铺展形态及波动特征  

SPREADING MORPHOLOGIES AND FLUCTUATION CHARACTERISTICS OF LIQUID FILM FORMED BY OBLIQUE IMPINGEMENT OF LIQUID JETS ON WALL

作　　者：陈晓东 蔡国辉 吴二军 王博[2] 苏煜[1] Chen Xiaodong;Cai Guohui;Wu Erjun;Wang Bo;Su Yu(School of Aerospace Engineering,Beijing Institute of Technology,Beijing 100081,China;School of Medical Technology,Beijing Institute of Technology,Beijing 100081,China)

机构地区：[1]北京理工大学宇航学院,北京100081 [2]北京理工大学医学技术学院,北京100081

出　　处：《力学学报》2024年第7期1992-2003,共12页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金资助项目(U23B6009,12272050)。

摘　　要：为了深入理解倾斜射流撞壁液膜表面波的形成演变机理和液膜不同的铺展形态,开展了倾斜射流撞壁的实验观测和数值模拟.使用高速相机记录了不同射流速度和倾角的液膜铺展形态,并通过数值模拟结合实验观测揭示了液膜表面波的形成和演变过程.结果表明随着射流速度的增加,液膜的铺展形态将经历平滑液膜-闭合边缘、波动液膜-闭合边缘和波动液膜-开放边缘3种状态.液膜的铺展高度和宽度与射流速度近似正比关系,但随着液膜边缘的破碎,将会体现非线性变化.随着射流倾角的增加,液膜铺展将从窄变宽,并且液膜边缘形态可由闭合变为开放.射流速度和射流倾角的增加,都会使撞击点上方的区域趋向失稳破碎,导致液膜边缘出现指状结构.射流内的湍流扰动会在撞击壁面后激励起液膜的二维表面波,撞击点附近初始的表面波在下游发展过程中会发生展向演变,出现三维特征.射流速度越快,射流表面扰动越强,液膜表面形成的表面波也越复杂,三维表面波与撞击点越接近.表面波的形成会影响液膜的流动和厚度分布,在波峰处,液膜的流动速度较快,随着下游的发展,波峰的速度将会逐渐减小,在液膜表面还会出现两个波之间追赶的现象.To deeply understand the formation and evolution mechanism of surface waves on obliquely impinging wall jets and the different spreading morphologies of liquid films,experimental observations and numerical simulations of oblique impingement of jets on walls are carried out.High-speed cameras record the spreading morphologies of liquid films under different jet velocities and impingement angles,and numerical simulations combined with experimental observations revealed the formation and evolution process of surface waves on the liquid film.The results show that with increasing jet velocity,the spreading morphology of the liquid film will undergo three flow patterns:smooth liquid film with a closed rim,fluctuating liquid film with a closed rim,and fluctuating liquid film with an open rim.The spreading height and width of the film are approximately proportional to the jet velocity,but non-linear changes occur when the liquid film edge breaks up.As the jet impingement angle increases,the spreading of the liquid film changes from narrow to wide,and the rim morphology of the liquid film can change from closed to open.Increasing jet velocity and impingement angle destabilize and break up the region above the impingement point,leading to finger-like structures appearing at the rim of the liquid film.Turbulent disturbances in the liquid jet excite two-dimensional surface waves on the liquid film after impinging on the wall.The initial surface waves near the impingement point undergo spanwise evolution during downstream development,exhibiting three-dimensional characteristics.Faster jet velocities lead to stronger disturbances on the jet surface,resulting in more complex surface waves on the liquid film surface,while threedimensional surface waves are closer to the impingement point.The formation of surface waves affects the flow and thickness distribution of the liquid film.At the wave crests,the flow velocity of the liquid film is faster.As the waves develop downstream,the velocity at wave crests will gradually decrease.A

关 键 词：倾斜射流 撞壁液膜 铺展形态 表面波动 实验观测 数值模拟 

分 类 号：O358[理学—流体力学]