Spray characterization of high pressure water mist injectors: Experimental and theoretical analysis

This study is focused on characterizing the spray released by a water mist injector at high pressure. To this end, an experimental campaign has been performed employing non intrusive techniques to investigate both drop size and initial velocity over a prescribed range of operative pressure. In particular, a laser-diffraction-based instrument (Malvern Spraytec) has been used to determine the characteristic diameter. An alternative method has been developed to reconstruct the drop-size trend in respect to fluid fraction: drop-size data have been averaged through mass flux distribution. This latter parameter has been measured by a mechanical patternator ad hoc built. Moreover a classic predictive formula for Sauter Mean Diameter has been validated through a physical analysis based on inviscid-fluid assumption. Velocity field has been studied by PIV technique. The proposed measurement methodology has been discussed and both maps and values have been finally stressed out. An experimental evaluation of the spray cone angle has been realized as an additional result of the PIV tests.