细颈容器倾角对瓶颈效应影响的实验研究

Experimental Study on the Influence of the Incline Angle of Narrow-Necked Container on Bottleneck Effect

细颈容器向外倾倒液体时,在颈部会产生周期性间歇振荡的"瓶颈效应"。本实验设计了转角、转速、瓶口大小、转轴位置均可调的有机玻璃容器,采用高速摄影仪对这一现象进行了观察。研究了瓶颈效应产生的基本原理,并探究了容器倾倒角度对瓶颈处气泡产生和生长、液体倾倒平均流量的影响。研究发现,瓶颈效应在倾倒角度不小于某一临界角度时产生,本实验中该临界角度为86°;随倾倒角度增大,气泡在产生和发展过程中稳定性下降,振动愈发剧烈,表面皱褶程度增强;在同一实验条件下,平均流量随着倾倒角度的增加,呈现出先增大后减小的趋势,本实验中平均流量最大值所对应的角度为160°。

Periodical oscillatory flow typically occurs at bottleneck when liquid is poured out of a narrow-necked container.This unsteady flow phenomenon is defined as Bottleneck Effect.In this experimental study,a synthetic glass container with adjustable incline angle,rotation speed,bottleneck sizes and location of rotation axis was designed.A high speed camera was employed to record the flow phenomena of bottleneck effect.The fundamental of bottleneck effect was investigated,and the influence of incline angle on bubble generating,growing and the average flow rate were carefully studied.The result shows that bottleneck effect occurs only when the incline angle is no less than a critical angle which is 86° in this experiment.As the incline angle increases,the stability of bubbles decreases during the process of generation,coalescence and breakup,furthermore,the average flow rate goes up in the beginning and then drops down.In this experiment,the inclination angle for the maximum average flow rate of pouring water was 160°.