A Study on the Relationship between ECN Spray D and Marine-Sized Nozzles Using FGM Combustion Model

Present work investigates the relationship between the combustion parameters of a well-known ECN heavy-duty nozzle called Spray D and marine-size nozzles. The study is carried out in OpenFOAM software within the framework of RANS turbulence modelling, using a flamelet based tabulation technique known as FGM to model the combustion. The large nozzles are tested in a constant volume chamber representative of marine engines, for which a CFD setup is validated against inert data in literature. The reacting results have been validated first with experimental data, initializing the domain with a highly reactive environment (23% oxygen) and engine-like swirl. Then, a less reactive initial condition was set up in the domain (15% oxygen) without swirl, to achieve a Spray D-like environment. The main goal is to study the variation of the combustion parameters Ignition Delay Time (IDT) and Lift-Off Length (LOL) as function of nozzle diameter, leading to a mathematical correlation to estimate the IDT and the LOL for different nozzle sizes from the well-known Spray D. The resulting dependency was well captured by a polynomial relationship y(x) = ax^b + c. Only the smaller nozzle of 300μm, does not follow this trend, possibly confining its validity to a range of diameters larger than two times the Spray D nozzle.