In the first part of the present paper the result of an experimental analysis of common rail high pressure Diesel spray evolving in high counter pressure conditions is reported. The global spray momentum and momentum flux measurement can be strongly useful in determining the jet to jet non-uniformities in engine typical injection conditions. The jet to jet uniformities analysis can assist in the matching process between the injection system and the combustion chamber geometric characteristic. Furthermore the knowledge of spray momentum spatial distribution allows to optimize fuel air mixing and then the combustion efficiency that is fundamental in order to fulfill the new emission rules EURO 6. The potential of spray momentum measurement technique is showed. The internal spray structure analysis by means of local spray momentum flux distribution investigation is showed too. Results are discussed in terms of spray distribution characteristic, momentum profiles and differences in the spray structure obtained for the same nozzle jets. In the second part the results of GDI gasoline injector spray evolving in counter pressure is reported. An evaluation to use the same experimental approach for testing the internal spray structure is reported for multi-holes GDI injectors.
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