Table 1. Eighteen cases tested with different device geometries.
| Case Number | Di (μm) | Df (μm) | L(μm) | Case Number | Di (μm) | Df (μm) | L(μm) |
|---|---|---|---|---|---|---|---|
| A | 86 | 258 | 97–714 | K | 147 | 242 | 806 |
| B | 186 | 258 | 197–1100 | L | 147 | 242 | 267 |
| C | 203 | 258 | 119–1136 | M | 147 | 242 | 570 |
| D | 217 | 258 | 130–1284 | N | 147 | 242 | 150 |
| E | 186 | 150 | 126–1166 | O | 147 | 176 | 272 |
| F | 186 | 210 | 146–1094 | P | 73 | 242 | 270 |
| G | 186 | 353 | 155–1038 | Q | 208 | 242 | 265 |
| H | 265 | 155 | 1208–1654 | L | 147 | 197 | 409 |
| I | 305 | 155 | 163–1410 | ||||
| J | 305 | 258 | 192–1263 |
Cases A–J, with various combinations of Di and Df, are conducted to investigate the condition for the location shift of droplet breakup from focusing orifice to injection nozzle. For each case from A to J, the orifice distance L is variable, starting from an initial value comparable to the diameter of injection nozzle Di, ending with the value when droplet breakup occurs at the injection nozzle. The range of L for each case from A to J can also be found in Fig. 3. Cases K–Q are used to characterize the influence of device geometry on tip-multi-breaking mode. Different combinations of Di, Df and L are studied. Case L is used to develop the correlation between the oscillation period T and the capillary number Cafocus in tip-multi-breaking mode. The capillary number Cafocus ranges from 0.15 to 0.45 in our experiments.