ID 213

Dynamics of intersecting pressure swirl sprays

 

Abstract:

Intersecting sprays are important to several practical applications, from rocket combustion to spray painting. Characteristics of these sprays are examined using diesel and water as working fluids. Three types of pressure swirl atomizer configurations are used: (i) single spray (ii) double spray- two identical atomizers, separated by a distance in the exit orifice plane and (iii) triple spray- three identical atomizers, placed at the corners of an equilateral triangle. Sauter mean diameter, joint velocity and diameter distributions, as well as the radial and circumferential liquid surface area distributions are experimentally measured using phase Doppler interferometry (PDI) and high speed imaging techniques. At low injection pressures, it is observed that liquid sheets emerge from exit orifices and the sprays remain separated. As the injection pressure is increased, the breakup length tends to decrease and a regime is identified where the liquid sheets interfere. In this regime, drop clouds formed from different sheets collide with each other, resulting in further break up into finer drops. As a result, the hollow cone nature of the overall spray is transformed into solid cone spray of almost even mean drop size distribution downstream of the spray intersection region. This study demonstrates that the dynamics of wave propagation on the liquid sheets in intersecting sprays is markedly different from the non-intersecting counterparts. In conclusion, we show that mere superposition of diameter and velocity distribution of two or more single sprays is not sufficient to predict the performance of an intersecting spray.