Study of Viscous and Frictional Losses in Pressure Swirl Atomizers

In this work energy losses occurring inside pressure swirl atomizers due to viscosity and friction have been analyzed. Theoretical developments show that the liquid losses its energy and momentum as it passes through different components of the atomizer. The losses mainly occur due to length of swirl chamber, length of discharge orifice and due to reduction in area between swirl chamber and discharge orifice. These energy losses affect spray characteristics for instance spray cone angle, liquid film thickness and sauter mean diameter (SMD). Experimental studies conducted so far validate the analytical analysis carried out on viscous and frictional losses. Experimental observations reveal that increase in geometric ratios e.g. swirl chamber length to its diameter (L-k/D-k), discharge orifice length to its diameter (L-o/D-o) and swirl chamber diameter to discharge orifice diameter (D-k/D-o) increases frictional losses in pressure swirl atomizers and thus lowers spray quality by decreasing spray cone angle and increasing SMD. Similarly increase in viscosity of liquids increases energy losses inside atomizers and thus lower spray cone angle and increase SMD. The study concludes that energy losses due to viscosity and friction should be considered for accurate determination of spray characteristics.