PIV Measurements in a Planar Two-Phase Countercurrent Shear Layer

Efficient atomization of viscous liquids has widespread applications in different industries. Numerous research articles have focused on trying to make the atomization process more efficient and less energy consuming. While conventional atomizers have struggled with the efficiency of the atomization of highly viscous liquids, a counterflowing nozzle recently developed at the University of Minnesota has shown remarkable results in spraying liquids ranging in viscosity from 54 cP to over 1000 cP and producing sauter mean diameters of less than 50 microns at Air to Liquid Ratios ranging from 0.1 to 0.5. Upon closer investigation, it is assumed that extremely thin shear layers might be formed on liquid and air streams leading to interfacial instabilities of very short wavelength. The work presented here is an attempt to look deeper into the physics at work by studying the dynamics and spatiotemporal evolution of interfacial instabilities in a planar two-phase countercurrent mixing layer. The counterflowing shear layer was set up by two opposing momentum-driven streams, water and air. High speed imaging and Particle Image Velocimetry (PIV) were used to investigate the governing flow physics. Finally, a parametric study was also performed by varying the flow rates and velocities in the streams to gain a better understanding.