Experimental And Simulation Study On Flow Characteristics Of Rotating Stainless Steel Wire Mesh Impacted By Liquid Jet

Enhancing chemical processes to reduce energy consumption has always been the goal of engineers and scientists.Rotating Packed Bed(RPB)was one of the most important technologies to strengthen chemical process,which can effectively save energy and reduce consumption.Packing,the core component of rotating packed bed,cuts liquid into micro-elements and greatly increases the surface area of liquid,which effectively improves the gas-liquid contact area to enhance mass transfer and mixing performance.However,due to the complexity of packing structure and liquid flow,the liquid flow patterns in packing zone and the interaction between liquid and wire mesh are still not clear,which seriously affect the structure optimization and application of RPBIn this work,liquid impaction on the single-layer rotating wire mesh was studied,in order to reveal the interaction between packing and liquid in packing zone of RPB.Firstly,the macro liquid behaviors about the liquid impaction on the rotating wire mesh were studied by using the high-speed camera.It mainly included the effects of rotational speed,wire mesh number,liquid initial velocity,liquid surface tension and liquid viscosity on liquid flow pattern,liquid disintegration mode,liquid dispersion angle and droplet diameter.Empirical correlations of liquid disintegration mode transition,liquid dispersion angle and droplet diameter were given.The numerical simulation,as an assistant tool,is helpful to obtain the micro characteristics that are difficult to obtain in experiments,such as the dynamic change process of liquid film on wire mesh.It mainly involves dynamic behaviors of liquid film on the wire mesh surface and the change of liquid film thickness with time,wire mesh number,rotating speed and liquid initial velocity were carried out.The main conclusions are as follows:(1)Visualization technology was used to analyze the flow pattern of the liquid column impacting on the single-layer rotating stainless steel wire mesh at different positions(horizontal wires and vertical wires).It was found that the interaction between the wire mesh and liquid could be divided into carrying action of the horizontal wire and shearing action of the vertical wire.The carrying effect can make the liquid distribute uniformly in the circumferential direction,while the shearing action can break up the liquid.The flow characteristics of the liquid elements in the packing zone are determined by the complementarity of the two.(2)The visualization results showed that the liquid impacts on the rotating single-layer stainless steel wire mesh,and then mainly exists in the form of liquid sheet,ligament and droplet.There were two kinds of liquid disintegration modes:sheet-droplet disintegrating mode and ligament-droplet disintegrating mode.With the increase of mesh number,rotational speed,liquid initial velocity and the liquid viscosity,the liquid disintegration mode transited from ligament-droplet disintegrating mode to sheet-droplet disintegrating mode,and the transition criteria of liquid disintegration mode was obtained.Liquid dispersion cone angle increased with the increase of mesh number,rotational speed and liquid initial velocity,and decreased with the increase of liquid surface tension and liquid viscosity.Liquid dispersion shift angle increased with the increase of mesh number,rotational speed and surface tension,and decreased with the increase of liquid velocity and viscosity.The average diameter of droplets decreased with the increase of mesh number,rotational speed,and increased slightly with the increase of liquid initial velocity,viscosity and surface tension.(3)The results of CFD simulation and visualization are consistent in liquid flow patterns and dispersion,which shows the feasibility of the simulation method.CFD simulation method was used to study the liquid film on wire mesh.The liquid adhering to the wire mesh would go through three stages:spreading stage,shrinking stage and disappearance stage.There were two characteristics about the Dynamic liquid film thickness on wire mesh:minimum liquid film thickness and duration of the liquid film.The minimum liquid film thickness decreased with the increase of mesh number,while the rotational speed and liquid initial velocity had almost no effect on the minimum liquid film thickness.Duration of the liquid film decreases significantly with the increase of mesh number and liquid initial velocity,and the liquid film duration increased with the increase of rotational speed.The average liquid film thickness on the wire was between 20 and 40 ?m.