水平烧结椭圆管蒸发器管外降膜流动性能研究OA

To investigate the falling film flow characteristics outside sintered elliptical tubes,the research group prepared sintered elliptical tubes using copper-nickel alloy powder,and adopted the FLUENT software to conduct numerical simulation on the falling film flow process outside sintered elliptical tubes and smooth elliptical tubes under columnar flow conditions.The effects of the cross-sectional shape of sintered tubes,spray flow rate,outer cross-sectional perimeter of sintered elliptical tubes and particle diameter of the sintered layer on the external liquid film distribution were studied.The results show that the porous structure of the sintered layer can enhance the disturbance and mixing of the fluid.At a spray flow rate of 200 L/h,the sintered elliptical tube exhibited an average liquid film thickness of 0.217 5 mm,which was 0.243 9 mm for the sintered circular tube.It featured a lower thinning rate,thus enabling the formation of a thinner and more uniform liquid film.The liquid film thickness at both the wave peak and liquid column cross-sections outside the sintered elliptical tube increased with the increase in spray flow rate and outer cross-sectional perimeter of the tube,with a more remarkable increase observed at the wave peak cross-sections.When the particle diameters of the sintered layer were 20 μm and 200 μm respectively,the average liquid film thickness at the wave peak cross-sections was reduced by 9.9％and 4.8％compared with that of the smooth elliptical tube.In addition,the thinning rate of the average liquid film thickness at the liquid column cross-sections relative to the wave peak cross-sections is lower than that of the smooth elliptical tube in both cases,resulting in a more uniform liquid film distribution.