| The conventional surface treatment technology on casting,steel products,large oil tank,the plane surface of anticorrosive paint there are still some problems to be solved,such as poor working environment,high labor intensity of workers,difficulties in mechanization and automation,etc.Compared with other surface treatment technologies,ice particle air jet has more prominent advantages.Compared with traditional pneumatic sand blasting,ice jet paint stripping will not produce dust,which greatly reduces the negative impact of paint stripping operation on the working environment and avoids the harm of paint stripping operation to the health of operators.However,the technology has not been popularized and applied on a large scale.The key reason is that there are still many key problems to be solved in the preparation,storage and transportation of ice particles.On the basis of realizing the real-time preparation of ice particles,the corresponding real-time utilization device of ice particles is designed to form an air jet of ice particles,which can avoid the problems caused by the storage and transportation of ice particles.In order to realize the even utilization of ice particles and improve the erosion effect of ice particles,an ice particle instant utilization device combined with the ice particle preparation device is designed based on the ejector principle,and its key parameters are optimized in order to further improve the surface treatment effect of ice particle air jet.The main conclusions of this paper are as follows:（1）the position of the working nozzle affects the flow field structure of the air jet by affecting the distribution of the core area of the air jet.With the increase of the diameter ratio between the stable section of the mixing chamber and the nozzle,the injection coefficient increases and the length of the jet core section decreases.When the ratio is lower than 3.5,the contraction section of the mixing chamber of the ejector will produce reverse air flow along the wall,resulting in poor ejector ejection performance.At the same time,when the ratio is large,the jet core area cannot occupy the whole stable section of the mixing chamber,resulting in a shorter jet core area and affecting the gas acceleration effect.The working nozzle with different expansion ratio can not improve the ejection performance and acceleration effect at the same time.（2）The effect of ice particles on gas velocity mainly occurs in the stable section of the mixing chamber.By comparing the velocity,mass flow and kinetic energy of ice particles at different positions inside and outside the ejector,it is concluded that the optimal ejector structure is that the nozzle position is 0mm away from the inlet of the convergence section of the mixing chamber,the ratio of the diameter of the stable section of the mixing chamber to the diameter of the nozzle throat is 4.0,the length diameter ratio of the stable section of the mixing chamber is 4,the expansion ratio of the working nozzle is 1.5,and the inlet pressure is 2MPa,The ice particle impact kinetic energy of ice particle gas jet reaches the maximum at the target distance of 75mm,which is 1.56×10-3J.（3）Under the inlet pressure of 2MPa,the nozzle with expansion ratio of 1.5 is adopted.When the diameter ratio of mixing chamber is 4.0,the length diameter ratio is4 and the throat nozzle distance is 0mm,the maximum paint removal radius is 22mm.Under the inlet pressure of 1MPa,the nozzle with expansion ratio of 1.5 still has the best paint removal effect,and its paint removal radius is 12mm.The influence of working nozzle expansion ratio on ejector performance is independent of working pressure. |
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