ID 179

Combustion of fuel droplets without and with addition of nanoparticles in turbulent atmosphere

 

Abstract:

This paper intends to study the effect of air turbulence on the burning characteristics of fiber suspended n-heptane droplets without and with addition of nanoparticles. Dilute concentration of Alumina nanoparticles (mass loading 0.1% to 1%) in conjunction with the oleic acid (as surfactant) are added to the base fuel followed by ultra-sonication such that a stable suspension of the nanofuel is obtained. Time resolved images of the burning droplets are captured using a high speed camera. In order to study the effect of turbulence alone (in absence of mean flow) on droplet burning, the experiments are conducted in a so called ‘box of turbulence’, where zero-mean isotropic turbulence is achieved at the central region of the box. The turbulence is characterized by the application of LDV/PIV technique. The burning of pure heptane and heptane plus surfactant droplets (without nanoparticles) are also studied in the absence/presence of air turbulence. Interestingly, for pure heptane the burning rate was found to decrease for higher turbulent intensity, which is in contrast to the effect of addition of nanoparticles. Because of the difference in the boiling point of the surfactant and base fuel, low intensity explosions were observed at the end of droplet burning. However, in case of nanofuel droplet burning (in absence of turbulence) three distinctive stages (classical combustion following d2-law, bulging of droplet followed by explosion, fragmented droplet flame) are observed. Preliminary results on the influence of increasing air turbulent intensity on the nanofuel droplet burning process and flame characteristics are presented