Inhibitory Effects of Convergent Annular Nozzles on the Primary Breakup of Discontinuous Shear-Thickening Suspensions

Annular air nozzles with different geometrical properties are used to investigate their influence on the primary breakup of discontinuous shear-thickening suspensions. By the use of a high-speed camera, the primary breakup process is visualized. Contrary to conventional fluids, no improvement in the atomization performance of discontinuous shear-thickening suspensions is achieved by using convergent annular air nozzles. Compared to a uniform sectional nozzle, the suspension jet exhibits shattering breakup at a higher critical Weber number when using convergent nozzles. In the shattering breakup mode, the breakup occurs close to the exit, while the cross-section is flat, which may be due to being stretched. Based on the discussion of the experimental results, this phenomenon is found to be connected to the anisotropic microstructure of the discontinuous shear-thickening suspension and the geometrical properties of the convergent nozzle.