Investigation Of Jet For Air-water Atomized Flow Characteristics During Secondary Cooling Of Continuous Casting

Spray cooling is an efficient method for high heat flux removal. With the advantages of strongly heat removing ability, low mass rate of working fluid,compact structure, and good adaptability for different environments, spray cooling can be used in almost any environments for high heat flux removal.The aim of this article was to compare with the characteristics of nozzles at spray-angle, water-impact flux, water flow density, droplet size, and impact-velocity. The test results showed that with nozzle. The method can be used to correctly water spraying system for the secondary cooling region of slab continuous casting of heat transfer,and secondary cooling scheme,and nozzle array arrangement.In the study on droplet size distribution, experiment used the oil film method for measuring the droplet size. Droplet size distribution obtained. By analysis, the droplet size distribution focused on the 0～240μm. In same air pressure, and hydraulic pressure,and spray distance condition, droplet size of the nozzle vertical region almost the same. And droplet size from the nozzle vertical region to both sides of the nozzle vertical region decreases.In velocity measurements of the jet, PIV has been applied. By PIV, velocity obtained different working conditions in air pressure 0.10~0.30MPa and hydraulic pressure 0.10~0.50MPa. The velocities of jet droplet increase with the water pressure and air pressure decrease from direct jet area to fringe jet area. When water and air pressure is constant, with the increase of spray distance, jet droplet velocity decrease in direct jet area, jet droplet velocity firstly increase and then decrease in the transition of direct jet area to its both sides. When reached the edge area of jet flow, the velocities of jet droplet increase.Discussion was to compare with the characteristics of nozzles at spray-angle, and water-impact flux, water flow density, droplet size, and impact-velocity. In air pressure 0.20MPa, hydraulic pressure 0.40MPa,and spray distance 285mm working conditions, NCJ fifth-generation nozzle has characteristics that spray droplet jet velocity evenly, a wide range of area for jet velocity evenly, water flow distribute uniformity, jet have good atomization, etc. Therefore, this working condition for NCJ fifth-generation nozzle is the best working conditions.