Implementing the equation of state to account for the density variation at the inlet boundaries for high velocity oxy gas fuel process

摘要

The gas dynamics of high velocity oxy fuel (HVOF) can be described by the conservative continuum equations of mass continuity, Navier-Stokes, a form of κ-ε model for turbulence and the equation of state, to account for the density variation in the flow field. Regarding combustion, a reduced kinetic (eddy-dissipation model) of onestep global reaction has been validated against measurements in previous work in the literature and good agreement was found. However, in all of the previous studies the inlet condition of the gases into the domain was considered to be of constant mass flow inlet without taking into account the variation of the densities of the gases. In this study, the equation of state is implemented into ANSYS FLUENT code to correlate the variation of density to the temperature and pressure as this may reveal more about the flow behaviour in the HVOF process. It was concluded that the pressure and temperature of the gases prior to entering the combustion chamber has a pronounce effect on the combustion pressure and the compressibility behaviour of the gases before expanding to the ambient pressure. For the velocity, the influence of pressure and temperature of the gases in the range considered has a marginal effect on the velocity behaviour except at the exit of the nozzle and the subsequent compressibility behaviour. As for the temperature, no considerable effect was observed for the range considered in this study.