Inhibition of the wall-attached fuel combustion and the formation of aerosol particle

The wall-attached fuel layer of the combustor usually leads to an unstable combustion and produces an unexpected emission, such as aerosol particles and unburn hydrocarbons. In this study, the impaction of ethanol droplet on a heated liquid surface was examined for investigating the factors those could effectively control the fuel atomization and avoided the formation of wall-attached fuel layer. We accelerated the volatilization of ethanol droplets after contacting the liquid surface and even achieved the flash evaporation condition to burst the oil layer, which was conducive to cleaning the inner wall of the combustors and reducing emissions. A 3.12-mm ethanol droplet was used to impact a glycerol pool. The Weber number (WE, 303–1343) and pool temperature (T, 50–260°C) were two controlled parameters to explore the impaction characteristics. There were four typical phenomena observed, including surface dissolving, penetrating dissolution, vapor explosions, and nucleate boiling. Results showed that the maximum volume and surface area of the crater increased with the WE and the liquid pool temperature during impaction. Meanwhile, the boundary temperatures between the penetrating dissolution and the vapor explosion decreased. Additionally, the vapor explosion time increased with the WE but negatively correlated to the liquid pool temperature. The entire vapor explosion process was very short, lasting about 200 milliseconds. Furthermore, the increasing WE had a negative effect on the nucleate boiling intensity when the liquid pool temperature significantly enhanced it. Consequently, the fuel droplet atomization and explosion could be sensitively controlled by varying the WE and the temperature of impaction surface. This finding provides valuable information to the designer of combustor control unit to inhibit and destroy the wall-attached fuel layer during the spry combustion and further inhibit the formation of combustion aerosol particles.