Spray Characteristics of Heavy Fuel Oil (HFO) in Air Assisted Atomizer
Combustion performance of the air-assisted atomizers depend strongly on the fluid flow and spray behaviour. The atomization processes control the fuel air mixing, which is important criteria for the combustion process. The liquid fuel properties play the major roles in spray and atomization of the atomizer. This research aims to investigate the effects of using heavy fuel oil (HFO) on the fluid flow and spray characteristics in an air-assisted atomizers. Further analysis was carried out to compare between HFO and diesel fuel. The effect of fuel properties and jet-hole angle on spray characteristics of internal mixing air-assisted atomizer was investigated using Computational Fluid Dynamics (CFD). The investigated parameters including fluid flow such as velocity streamline, velocity profile, turbulence kinetic energy, volume fraction and spray characteristics such as Sauter mean diameter (SMD) and spray droplets density. The investigation involves three different fuel flow rates of 4.941 kg/hr, 6.175 kg/hr and 7.411 kg/hr to generate the fuel sprays. The results show that the fuel flow rates and jet-hole angle are effective influencing the fluid behaviour in the mixing chamber. Results indicated that MCJ plates create flow recirculation along the chamber and it reveals that the air flow recirculation by the inclined jet-hole could produce better atomization. Comparison between HFO and diesel indicates that there are differences in flow behaviour and spray characteristics of fuel with different properties. It can be concluded that the liquid fuel properties and geometry of air inlet in air assisted atomizer greatly influence the fuel air mixing process and atomization quality.