Influence of Marangoni Effect on heated falling liquid films

摘要

An experimental research on the temperature field and flow pattern of a falling liquid film flowing over a uniformly heated or cooled vertical plate has been made. It is found that the lateral temperature gradient up to 6.2K/mm exists in falling liquid films, resulting in the contraction/expansion of the heated/cooled film. And the degree of the contraction or expansion is concerned with temperature difference between the film and the heater. Such abnormal properties of flow and boundaries of the heated films, prove that Marangoni Effect due to the surface tension gradient in the transverse direction of the film has significant influence on film movement. Then, the influence of Marangoni Effect on heated film flow is verified in this work. By considering transverse surface tension gradient and shrinkage characteristics in the brim of the heated film, a shrinkage model that satisfactorily describes shrinkage characteristics of the heated film is derived.