热毛细对流模式转换及温度振荡特征

Characteristics of temperature oscillation inthermocapillary convection in rectangular pool

研究了矩形液池中由于两端温差引起的热毛细对流的温度振荡临界条件.在实验室中,设计了一个高分辨率的温度测量系统,用于实时观测并记录流体的温度.该系统主要由热电偶温度传感器、纳伏表和数据采集电脑3部分组成.得到了各种实验条件下温度振荡的临界条件,并且讨论了它与Prandtl数和Bond数之间的关系.利用flow3d软件数值模拟了微重力条件下的热毛细对流,发现了一种由于自由面变形和液层流场相互作用导致的晃荡的现象.

Experimental and numerical results on characteristics of temperature oscillation in a rectangular pool of silicone oil were presented.A thermocapillary-convection controlling system was established in laboratory to study the critical condition and characteristics of temperature oscillation.The applied temperature gradient along the fluid-gas interface drived shear flow along the free surface from hot to cold and a back flow in the underlying layer.When the temperature gradient increases to a critical value,the original steady flow will become unstable to oscillatory flow.And with the deeply increasement of the temperature gradient,the flow will finally transit to the state of chaos.A temperature measurement system,which consists of thermocouple,nano-voltmeter and data-acquiring computer,was used to record the temperature of the liquid dynamically.Critical conditions for different experimental parameters were obtained,and its relationship with Prandtl number and Bond number was discussed in details.In addition,thermocapillary convection in microgravity was simulated;Sloshing of free surface was observed,which is thought to be produced by the interaction between deformation of free surface and flow field.