Modelling and measurement of high pressure sprays, Ignition and combustion of Heavy Fuel Oil and Marine Diesel Oil

Measurements of spray angle, spray penetration, ignition delay, flame extent and flame temperature are made in an optically accessible, electrically heated constant volume chamber of relatively large dimensions. Both Marine Diesel Oil (MDO) and a poor quality Heavy Fuel Oil (BFO) are analysed and compared. Soot temperature is measured using the two-colour method. The measured data are compared with predictions using the CFD package StarCD. Fuel evaporation, ignition and combustion models developed specifically for heavy residual fuel oil are applied. Initial spray atomisation is modelled with the blob method as well as with the Max Plank Institute (MPI) model, which creates a denser spray core than the blob atomisation model, as well as child droplets from aerodynamic stripping and collision. The denser core results in increased droplet coalescence during the subsequent secondary breakup phase, resulting in greater droplet persistence and spray penetration during combustion. Droplet persistence and spray penetration is much greater for BFO than MDO. Higher chamber initial temperature significantly reduces ignition delay period and flame lift-off distance. Flame lift-off distance and ignition delay for MDO are less than for BFO. The models reproduce these trends.