Papers by Keyword: Pressure Exponent

Abstract: In this paper, experimental investigation of pressure exponent in burning rate of composite propellant was conducted. Four sets of different propellant compositions had been prepared with the combination of Ammonium Perchlorate (AP) as an oxidizer, Aluminum (Al) as fuel and Hydroxy-Terminated Polybutadiene (HTPB) as fuel and binder. For each mixture, HTPB binder was fixed at 15% and cured with isophorone diisocyanate (IPDI). By varying AP and Al, the effect of oxidizer-fuel mixture ratio (O/F) on the whole propellant can be determined. The propellant strands were manufactured using compression molded method and burnt in a strand burner using wire technique over a range of pressure from 1atm to 31atm. The results obtained shows that the pressure exponent n, increases with increasing O/F. The highest pressure exponent achieved was 0.561 for propellant p80 which has O/F ratio of 80/20.

Abstract: There were very limited number of references published discussing the burning characteristic of aluminized propellant without any additive substance. This paper describes the performance characteristics of basic formulations of aluminized ammonium perchlorate based propellant. Four sets of propellant formulations namely by p60, p66, p74 and p80 had been formulated and manually prepared without adding any additives. The propellant consists of ammonium perchlorate (AP) as an oxidizer, aluminum (Al) as fuel and hydroxy-terminated polybutadiene (HTPB) as fuel/binder. For each mixture, HTPB binder composition was fixed at 15% per-weight. By varying AP and Al, the effect of oxidizer-fuel (O/F) ratio on the whole propellant can be determined. The propellant strands were manufactured using press-molding method and burnt in a strand burner over a range of chamber pressure from 6 atm to 31 atm. Based on theoretical evaluation using NASA CEC71 program, p66 has been selected for testing in ballistic evaluation motor (BEM) to ascertain its characteristics performance. The results from burning rate test shows that the increasing of O/F ratio and combustion pressure lead to the increase in burning rate. The highest burning rate achieved was 12mm/sec at combustion pressure of 31atm for propellant p80 which has O/F ratio of 4.0. While for the BEM, the propellant efficiency obtained for p66 was 95.44%.