A new type of elastic wall distributor of outer annular falling film was developed.This method could create a uniform annular channel for the micron-size ultra-thin falling film flow

which could be precisely controlled.This distributor had homogeneity and stability of internal mechanism due to the axisymmetrical deformation coordination characteristics of elastic wall and it could generate negative feedback responses to fluid pressure changes sensitively.According to the theory of thin shell and Amonton law of friction

the linear relationship between initial film thickness and liquid height was given.Also

the equation of falling film flow was established.Experiments were performed using water and 30% glycerol aqueous solutions at lower flow rates.The results indicated that the two equations obtained were in good agreement with experimental data and could be used as the design equations for engineering applications. The experiments also revealed that the vertical tube with a length of 0.6 m and a diameter of 14 mm could be completely wetted by the ultra-thin falling film 0.157 mm thick using the elastic wall distributor.And the wetting performance of the distributor reached the dimensionless minimum wetting rate

which was dependent on the properties of the solid-liquid interface.Compared with other liquid distributors

the elastic wall distributor gave the best performance of hydrodynamics.