Analysis of Changes in Burning Rate Coefficient (a) on The Burning Rate of Propellant Based on Particle Size Aluminum

Propellant made by LAPAN basically consists of raw materials HTPB (Hydroxy Terminated Polybutadiene) and TDI (toluene diisocyanate) as Binder and Curing Agent, Ammonium Perchlorate or AP as oxidizing agents and Aluminum Powder as additive. Aluminum powder in the form of fine powder which has a certain particle size. From propellant burning rate measurements, it was obtained that the aluminum particle size affects the burning rate coefficient value. Burning rate of propellant was measured using the Strand Burner instrument. Propellant burning rate was conducted with 3 different Aluminium Powder particle sizes 100, 30 and <30 microns. The principle works is to determine the propellant burning time with a certain distance on the three conditions of the combustion chamber pressure of 20 bar, 40 bar and 60 bar. The burning rate is then calculated using the formula r = apn where r is the burning rate, a is the burning rate coefficient, P is Pressure and n is the pressure exponent. From the comparison of the data it can be seen that the smaller the particle size of the aluminum used the burning rate coefficient. Aluminum functions acts as the propellant burning rate enhancer. So that the smaller the particle size, the surface area becomes larger and so the burning surface area. With a burning surface area becomes larger, the burning rate becomes higher. From the tests performed using the same amount of aluminum that is 7.5 persen of 100 persen of the materials used, the data obtained as follows: for a 100 micron aluminum obtained Coefficient of Burning Rate of about 0.02, 30 micron aluminum obtained Coefficient Burning Rate of about 0,06 and aluminum < 30 microns Burning Rate coefficient of about 0.09. Prosiding International Seminar on Aerospace Science and Technology II (ISAST II) 2015.