Influence Of Viscoelasticity On Liquid Air-Blast Atomization

The influence of viscoelasticity on air-blast atomization characteristics of different liquids and air were investigated by a high-speed camera, related tests and analysis methods. The main contents and results were summarized as follows:For primary atomization, the effects of viscoelasticity on unstable wave length, jet core length and oscillating frequency in primary atomization were discussed. Correlations for K-H instability wavelength and jet core length of coal-water slurry (CWS) were obtained based on instability theory, and oscillating frequency was obtained on the basis of boundary-layer theory. The results showed that the K-H wave length and jet core length increased with relative elasticity, so the elasticity of viscoelastic liquid increased the breakup difficulty; The elasticity of liquids had little influence on the oscillating frequency, the determine factors were Weber number and the momentum flux ratio.For secondary atomization, the impacts of viscoelasticity on deformation characteristics, time characteristics and drop size dimensions of CWS were investigated. The breakup time, deformation time and Sauter diameter (SMD) of fragments were obtained. The results showed that deformation ratio of drops was constant, but the deformation time increased with both viscosity and elasticity. Besides, the variation of CWS non-dimension breakup time depended on the breakup regimes. The dimensionless SMD of drop fragments increased with the viscosity and the elasticity, causing adverse impacts on the secondary atomization, and the effect of the viscosity is more significant.