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ISSN Печать: 2150-766X
ISSN Онлайн: 2150-7678
Indexed in
COMPOSITE PROPELLANT EXTINCTION BY LASER ENERGY PULSE
Краткое описание
Knowledge of the dynamic response characteristics of burning propellants to the variation of external parameters permits an evaluation of their capability to reach, through a combustion transient, the steady-state burning regime. In this experimental study, a transient combustion event is induced by employing externally incident laser radiation. The objective is to determine propellant extinction characteristics and its dependency on the working pressure. Fast deradiation of the burning propellant surface is utilized to achieve propellant extinction, because only the combustion process itself is perturbed; the flow field in the combustion chamber is unaffected. Tests were carried out using an AP/HTPB (86/14) propellant and a CO2 laser system, whereas laser Doppler velocimetry was used to measure the velocity of product gases from the burning propellant. Further qualitative information was obtained by a photodiode which collected light emitted by the burning surface and flame. Results of tests performed over pressures ranging from 12 to 50 kPa indicate that the transient propellant behavior upon deradiation depends on the laser pulse duration and that burning propellant extinction was achieved only if the form of the laser pulse was properly chosen. Two final solutions were found after laser cut off: continuous burning or extinction defining, for any working pressure, the curves separating the distinct burning propellant response. These boundary limits were drawn for different pressure values: 12, 15, 20 and 30 kPa.