The extinction process of three kinds of aluminized composite propellants by liquid injection has been experimentally investigated

according to the liquid quench model of solid propellant proposed by the authors.The experimental results indicate that(1)The liquid quantity requirment(LQR in g/cm 2)for reliable extinction varies significantly with the energy of propellant in the relationship of LQR ∝ 0 1Q f(Q f〔kJ/g〕the heat relased by the propellan at constant volume);(2)The extinction speed increases and LQR decreases with increasing liquid injection pressure drop;(3)LQR increases with increasing combustion chamber pressure for propellants having positive pressure exponents.In addition to LQR

there exists a non-dimensional parameter which summarizes the effects of energy and burning rate characteritics of propellants

liquid injection pressure drop

liquid properties and combustion chamber pressure on the liquid uqench process.If the parameter is less than a critical value

the extinction of propellant by liquid injection is not obtainable.The examination by means of the scanning electron microscopy demonstrates that the appearance of the burning surface quenched by liquid are different from those by extinguished by rapid depressurization.The surface profile is porous and a lot of oxidizer particles are dissolved during liquid quenching.This fact exerts an influence on the reignition of the quenched burning surface for stop/restart solid rocket motors.