Don't forget you need a controlled high pressure fuel supply, and atomised fuel is extremely (as in extremely) combustable - so this can be a pretty hazardous experiment and a little 12v spark would make it even more exciting .
You can look on line for a given injectors flow rate characteristic ,which is easier. Some injectors ( usually diesel) have a coding for their individual performance ( often loaded into the ECU when an injector is changed)
If you don't use fuel remember a liquid of different density and viscosity will flow at a different rate
