In order to study differences between Diesel nozzle holes, four methodologies have been tested. The techniques compared in this paper are: the internal geometry determination, hole to hole mass flow measurement, spray momentum flux and macroscopic spray visualization. The first one is capable of obtaining the internal geometry of each of the orifice of the nozzle; the second one is capable of measuring the mass flow of each nozzle hole in both, continuous and real injections. The third one gives the momentum flux of each orifice, and finally, with the macroscopic spray visualization, the spray penetration and spray cone angle of each hole, are obtained. Generally, all these techniques can be used in order to determine the hole to hole dispersion due to different angle inclination of the holes, different internal geometry of orifices, deposits, nozzle needle off-center, needle deflection, etc. Moreover, the results obtained from theses techniques are a very useful tool in order to study the injection process.
Special attention deserves the new capability developed to carry out the hole to hole mass flow measurement. In fact, although Diesel nozzle mass flow measurement, either injection rate or continuous mass flow, is a technique widely used, it has the disadvantage that the complete nozzle mass flow is characterized without a distinction between the mass flow from each of the orifices. Here, a new test rig is presented in order to achieve this kind of measurements.