نمونه ترجمه تخصصی مکانیک سیالات درباره مطالعه عددی بر روی انتشار گذرای شعله نوسانی ابر ذرات کربن

numerical study on oscillating transient flame propagation of carbon particles cloud

Transient flame propagation in carbon spherical dust cloud was numerically examined. Unstable conservation equations for gas and particle phases in a spherical coordinate system, thermodynamic specifications, and gaseous phase reactions with multi-factor transfer specifications were written. Particle phase equations including two-phase interactions in momentum equations were solved by taking into account buoyancy, gravity, Stocks, drag, and thermophoretic (obtained from gas phase temperature gradient) forces. To improve the results and analyze more accurately, the particles porosity and heat losses, that have a notable effect on other parameters like carbon particle and gas temperature and propagation velocity, were taken into account. Eventually, one of the most complicated and delicate phenomena in particle combustion -i.e. oscillation of flame propagation velocity (oscillation mode)- in two-phase system combustion was examined. The key findings are: • Different velocities of gas and particles create oscillation. It causes sequential changes in density number of particles at reaction, changes the balance ratio, and creates oscillation in flame velocity. • Flame oscillations grow stronger with an increase in oxygen concentration as the reaction rate and generated heat increase with an increase in oxygen density, which leads to a higher velocity difference. • Flame propagation velocity is independent from temperature. This is more evident at bigger radiuses. • Severity of oscillation in combustion system decreases with an increase in carbon particles porosity. • With an increase in heat losses, velocity difference grows between the carbon particle and gas and this increase is a cause of intensification of oscillations.