Effects of nozzle orifice shape on jet breakup and splashing during liquid jet impact onto a horizontal plate

In some accident situations in nuclear power plants, liquid coolant is discharged from a non-circular rupture hole. Thus, to improve the understanding on the effects of nozzle orifice shape on the jet behavior, experiments were carried out on the liquid jet ejected from oval nozzles. In the experiments, water was used as the test liquid, the area-equivalent nozzle diameter was within 1.8-2.9 mm, the aspect ratio of the nozzle hole was within 2.64.8, and the jet velocity was varied within 0.25-11.3 m/s. At low and high liquid flow rates, the liquid jet behaved similarly to the circular jet; the jet breakup lengths and the size of the droplets formed after the jet breakup were expressed by similar dimensionless correlations as those for the circular jet. At the intermediate liquid flow rate, a bamboo leaf-like structure formed on the liquid jet dominated the jet breakup. The jet breakup length was therefore correlated using a theory for the surface tension-induced shape oscillation of elliptical fluid. These correlations enabled to estimate the liquid jet state at any distance from the nozzle. It was also confirmed that if the state of the liquid jet at the impact point is known, the splash rate and the size of the splashed droplets can be predicted satisfactorily using the available correlations based on the experimental data for the circular jet. Therefore, the present work extended the available knowledge on the liquid jet discharged from a circular nozzle to enable the prediction of the behavior of the liquid jet and the characteristics of the secondary droplets produced during liquid jet impact onto a solid surface for the oval nozzles.

Automated summary

Experiments were conducted on liquid jets ejected from oval nozzles to investigate the effects of nozzle orifice shape on jet behavior. The study found that the liquid jet exhibited different characteristics at different liquid flow rates. Correlations were established to predict the liquid jet state and characteristics of the secondary droplets produced during jet impact onto a solid surface. This research extended the available knowledge on liquid jet behavior.