Ballistic imaging in the near-field of an effervescent spray

We have investigated liquid breakup mechanisms in the near nozzle region of a high-pressure effervescent atomizer using ballistic imaging. This technique has revealed various breakup regimes depending upon total flow rate and the gas-to-liquid ratio (GLR). At low total speeds, the jet does not exhibit the wide spread angle and rapid breakup for which effervescent sprays are known, even at high GLR. Above a distinct threshold value for total flow rate, the jet passes through several recognizable flow regimes depending on GLR and it does achieve the expected wide spread angle and rapid breakup. Intermediate GLR's produce interesting flow patterns that seem to be generated by surging at the nozzle exit, and this surging can probably be attributed to the flow pattern just at the nozzle exit. Indeed, specific interior flows seem to generate the most rapid breakup and should be investigated further.