Investigation of thermal radiation, atomization air, and fuel temperature effects on liquid fuel combustion

Abstract

The purpose of the present study is to investigate the effects of radiative heat transfer, atomization air temperature and mass flow rate, and fuel initial temperature on liquid diesel fuel (C16H34) combustion. Fuel is injected by an airblast atomizer inside a model cylindrical combustion chamber. Geometry of the airblast atomizer is modeled in detail so that its impacts on droplet breakup and flow formation are accurately considered. Evaporating fuel spray is simulated by the discrete phase model based on the Eulerian-Lagrangian approach. Turbulent viscosity is numerically computed by the realizable k-ε turbulence model while the discrete ordinates model and the steady flamelet model are applied for modeling the radiative heat transfer and combustion, respectively. NO species concentrations are achieved using post-processing. It turns out that neglecting thermal radiation in well-atomized spray combustion only affects high-temperature zones through increasing axial temperature values of the mixture by almost 8%. Thermal radiation has an imperative effect on producing NO species. Without considering thermal radiation, axial NO concentration becomes almost doubled. Augmentation in mass flow rate and temperature values of atomization air enhances spray formation and combustion efficiency by increasing the evaporation rate. Changing the fuel temperature from 300 K to 325 K rises the total temperature at the end of the center line of the model combustion chamber by 9.8%. It is shown that increasing the fuel initial temperature is not a suitable choice compared to enhancing the temperature and mass flow rate of the atomization air.