Modeling Research And Verification On Liquid Breakup Process Of Internal-mixing Twin-fluid Atomization

The atomization process of the internal-mixing twin-fluid atomizer is very complicated,which include the movement of gas and liquid phase in the same flow channel.And it is difficult to obtain the first breakup process parameters directly without affecting the flow field.Therefore,there is no complete conclusion on the internal-mixing twin-fluid atomizer's atomization process.This paper mainly conduct the modeling analysis of the first breakup process,and the first breakup process is obtained from the internal-mixing twin-fluid atomizer,which is widely used in industrial field.Firstly,the advantages and disadvantages of the established models of annular sheet and the first breakup process are analyzed,and based on these models,the optimization models are taken by improving models which close to the actual atomization process.Then,the simulation method is used to study the second atomization process,and the input parameters of simulating are the calculation results from the optimization models.Finally,the results of the first breakup models' calculation and the secondary atomization process simulation are compared with the experimental results.In order to verify the validity of the modeling method and the simulation method,the experimental research is adopted.The liquid breakup pattern,the spray cone angle,the particle size and its distribution at the nozzle exit and a distance 15 cm are tested experimentally,and the test results have good regularity and repeatability.It is confirmed that with the increase of ALR,the length of liquid breakup is shorten,the spray cone angle first increases and then decreases,the droplet size of the spray decreases,and the atomization effect becomes better.Compared with the experimental results,it is found that the annular sheet model based on the isentropic process can better predict the liquid sheet thickness in the internal-mixing twin-fluid atomization process.The optimized surface wave model,braided model and Takeshi model can effectively predict the SMD value of the first breakup process.In the meantime,the surface wave model based on surface wave theory can predict the SMD value of the first breakup process more accurately than other models.By bring in the calculted SMD results under the operation condition of large ALR,the simulation results obtained from FLUENT can effectively predict the secordary atomization process.