It is known that increasing the injection pressure reduces the breakup length and the droplet size. Adding pulses

on the other hand

helps to atomize the liquid into finer droplets

similar to air-assisted injectors but without altering the air-to-fuel concentration. To further reduce the droplet size and breakup length

a novel injector type

called "Pulsed Pressure-Swirl" (PPS)

is introduced in this work

which is a combination of pressure-swirl and ultrasonic pulsed injectors. A pressure-swirl atomizer was designed and fabricated specifically for Mazut HFO (Heavy Fuel Oil). The droplet formation process and droplet size distribution have been studied experimentally (by shadowgraphy high speed imaging) and numerically (with the open-source Volume-of-Fluid code

Gerris

). Changing liquid injection pressure effect on the spray angle and film thickness has been quantified. These simulations have been used to study the primary breakup process and quantify the droplet size distributions

using different injection pulse frequencies and pressures. The numerical results have revealed that the new injector concept successfully produces finer droplets and results in a decrease in the breakup

length

especially when applying high pulse frequencies

with no significant changes in the spray angle.