Flow Field Of Composite Propellant Cracks And Ignition Combustion Characteristic Research

Experimental research of ignition process of AP/HTPB composite propellant was done, and then the fluid flow characteristic and ignition process of propellant crack was simulated in the paper.The ignition process of AP/HTPB composite propellant was investigated by CO2-laser radiation in air and ignition delay time for variable heat flux density was obtained using data collection system. A one-dimensional heat transfer model describing physical phenomenon occurring in solid propellant was developed to predict the ignition delay time for different heat flux. With ignition criterion selected, the experimental data was analyzed.The fluid flow of propellant crack was simulated when combustion chamber was in steady state or transient state. The pressure characteristics and ignition process were analyzed, and then influence of variable factors including crack width on fluid flow was studied.The experimental results showed that the prediction of the model was accurate when compared with the experimental data. With least square data fitting method, the melting layer thickness and surface ignition temperature were obtained. Simulation results indicated that shock waves in front of burning gas would have an impact on crack tip and flame propagation speed in propellant crack appears first quick back slow trend during ignition stage. Mass flow rate at inlet had little influence on fluid flow while crack width had great effect. When combustion chamber was in steady state, the burning gas penetrated into crack, and then pressure in propellant crack increased quickly. As pressurization in propellant crack began, shock wave would have an impact on crack tip which probably made propellant at crack tip ignite earlier. The pressure increase in combustion chamber made the impact stronger while crack width had little impact.