Influence of Nozzle Parameters on Single Jet Flow Quantities of Multi-Hose Diesel Injection Nozzles

摘要

A separate measurement of these single jet flow injection quantities is absolutely necessary for the evaluation of the injection nozzles. However, so far this has not been possible in a satisfying way [7, 9]. A measuring adapter for determination of the injection quantities for individual spray hole was developed here. With measuring adapter the influence of variation in shape and geometry of the individual nozzle components on single jet flow injection quantities can be determined. The measurements are supported by simulation results. The spray hole shape is crucial for flow coefficient and cavitation in the spray hole. During fuel atomization the diameter and shape of the injecting holes and the pattern realized by the nozzle needle in addition to the injection pressure play a substantial role. Here was asserted that the smaller the spray hole diameter, the larger the mass flow difference between the individual spray holes due to the increase in variation is the manufacturing process. Macro- and micro-geometrical structure of the spray hole surface and the transient areas of the nozzle interior into the spray hole has a strong influence on the flow conditions within the range (area) of the nozzle needle seat and within the spray holes and thus on flow values, flow symmetry and cavitation. E.g. the cavitation starts earlier at higher inclination angles (that means the flow is deflected more) and lower pressure differences. Design parameters like the angle in which the individual spray hole comes off the nozzle tip (inclination-angle), as well as manufacturing process driven parameters, such as the shape of the spray hole inlet edge (grinding radius) influence the quantity of fuel flowing through the individual spray hole. The mass flow variability was reduced by grinding the spray hole either for nozzle to nozzle or for spray hole to spray hole.