Behavior of Charcoal in Black Powder on Burning Surface

Nomenclature Cp = specific heat of propellant Pg = pressure Qs = heat of reaction at the surface R = gas constant Tf = flame temperature Ts = surface temperature T0 = initial temperature ug = gas velocity δ = reaction length λg = heat conductivity in the gas phase ρg = gas density ρp = density of propellant τc = chemical ignition delay time τig = ignition delay time τp = physical ignition delay time Φs+ = temperature gradient near the burning surface in the gas phase