Nozzle Geometry Size Influence on Reactive Spray Development: From Spray B to Heavy Duty Applications 2017-01-0846

In the present work a constant-pressure flow facility able to reach 15 MPa ambient pressure and 1000 K ambient temperature has been employed to carry out experimental studies of the combustion process at Diesel engine like conditions. The objective is to study the effect of orifice diameter on combustion parameters as lift-off length, ignition delay and flame penetration, assessing if the processing methodologies used for a reference nozzle are suitable in heavy duty applications. Accordingly, three orifice diameter were studied: a spray B nozzle, with a nominal diameter of 90 μm, and two heavy duty application nozzles (diameter of 194 μm and 228 μm respectively). Results showed that nozzle size has a substantial impact on the ignition event, affecting the premixed phase of the combustion and the ignition location. On the lift-off length, increasing the nozzle size affected the combustion morphology, thus the processing methodology had to be modified from the ECN standard methodology. Consequently, a fixed threshold criteria was used. An empirical correlation that allows to further understand the relation between conditions and lift-off length is also presented. Additionally, it was observed that for bigger nozzles, there is a liquid-vapor-flame interaction that can promote soot production, which is an important fact that should be taken into account for the understanding of combustion process and further Computational Fluid Dynamics models implementation.