Experimental investigation on combustion of aluminum in the AP/HTPB composite propellent

The purpose of the experiment is to investigate the combustion process of aluminum of the ammonium perchlorate/hydroxyl- Terminated polybutadiene (AP/HTPB) propellent. It is know that AlO is the intermediate of gas- phase aluminum oxidation, and evidence of the AlO would be an indication that either gas -phase reactions were occurring or that temperatures were high enough such that some AlO was dissociating. The AlO emission is 486nm wavelength. In this paper, a spectrometer was used to measure light emission of the burning propellent in the combustion chamber. The AP/HTPB propellents used in experiment contains 17% mass percent of aluminum. The combustion chamber filled with nitrogen, so as to guarantee a certain pressure. Experiments were performed both with and without a 486nm bandpass filter in front of the spectrometer to isolate the Δv=10nm band sequence in the transition of AlO. The size of propellents was 8mm*8mm* 100mm. Measurements were at IMPa, 2MPa and 2.5MPa. The observed trends are that with increasing pressure, the intensity of 486nm light increased gradually. From the experiments without the filter at IMPa, it was found that in the 580-600nm and 750-780nm range, spectrum appears two peaks. This phenomenon in all experiments without the filter have emerged.