中文摘要：

实验观察了加热基板上0.65cSt硅油液滴蒸发过程Marangoni对流失稳现象及其演变规律,测量了Marangoni对流失稳的临界条件,分析了润湿半径和Ma数对液滴内Marangoni对流稳定性的影响。结果发现：只有当液滴的接触角减小到某一临界值以下时,液滴内才产生Bénard-Marangoni对流涡胞,涡胞呈＂花瓣＂状,液滴顶点处较尖细,三相接触线附近为圆弧形,涡胞相互挤压处呈直线形。随着蒸发的进行,涡胞变短变粗。涡胞数随润湿半径、Ma数的增大而增多。产生Bénard-Marangoni对流涡胞的临界接触角θc随Ma数的增大而增大。液滴边缘处始终为热毛细对流,无Bénard-Marangoni对流涡胞。

英文摘要：

The phenomenon of Marangoni convection instability in an evaporating sessile droplet of 0.65cSt silicon oil on a heated substrate was observed by experiment. The critical condition for the incipience of the unstable Marangoni convection was measured and the influences of the wetting radius and Ma number on the Marangoni convection instability were investigated. The result found that the flower-like Benard-Marangoni convection cell would occur only if the contact angle was less than a critical value. At the apex of droplet the shape of the Benard-Marangoni convection cell is sharp and thin but it is circular arc near the contact line. With evaporating, the cells become short and wide. The cell number of the B6nard-Marangoni convection increases with increase of wetting radius and the Ma number. The critical contact angle for the incipience of the Benard-Marangoni convection increases with increasing the Ma number. Near the contact line, thermocapillary convection always exists there but without Benard-Marangoni convection cell.