IGNITION DELAY TIME MEASUREMENT OF A REDUCED SMOKE COMPOSITE SOLID PROPELLANT

Ballistic properties of solid propellants play an important role in the performance of the solid propellant rocket motors. Since the solid propellant rocket motors are generally used for military purposes, detailed characterization of the propellant ignition and combustion behavior has to be conducted in the development of a solid propellant. In this study, a specific Ammonium Perchlorate/Hydroxyl Terminated Polybutadiene (AP/HTPB) composite solid propellant was examined to obtain the ignition delay times as a function of heat flux and pressure. This study is a part of some experiments which were conducted to investigate the ballistic properties of propellants such as steady-state linear burning rates, temperature sensitivity, and pressure deflagration limit. Ignition tests were conducted at three different average laser energy fluxes of 40, 80, and 120 W/cm2. The laser produces a beam profile with a diameter of around 3.5 mm at the propellant surface. An LED light operated by the signal from the shutter was superimposed adjacent to the image of the propellant sample to indicate the onset and the duration of the laser energy input. Three parameters were deduced from the video camera records such as initial gas evolution time (tGE), first light emission time (tLE), and onset of self-sustained combustion (tIGN). Go/no-go criterion of the propellant was also extracted.