Atomization and spray characteristics of gelled-propellant simulants formed by two impinging jets

Near- and far-field atomization processes of impinging doublets are experimentally characterized using non-gelled and gelled water as fluids. Main emphasis is on the effect of nozzle geometry such as orifice inlet shape and aspect ratio on jet stream surface dynamics and break up process before and after jet impingement, respectively. Gelled-water jets, due to increased viscosity, display less disturbed surface than non-gelled water jets. As a result, for given flow rate the sheet formed by impinging jets is much more stable and the sheet break up length is much greater for gelled-water than non-gelled water jets. The nozzle aspect ratio has more noticeable effects on the near-field jet stream characteristics for both fluids than the orifice inlet shape. The longer nozzle (l/d=20) forms more stable jet stream and delays break up of sheets, leading to greater break up length than the shorter nozzle (l/d=5). For similar Reynolds number, droplet size for gelled water is much smaller than that for non-gelled water. Also, impinging jets employing gelled-water produce spray distributed over wider space and in wider range of sizes than the non-gelled water.