Analysis of Effects of Various Burn Rate Evalution Techniques and Process Variability on Bem Burn Rate Measurement

The burn rate for composite propellant is an important parameter which is required to be measured accurately for mission success. Burn rates for composite propellant are evaluated from the static test of BEMs (Ballistic Evaluation Motors) using pressure-time trace. Process Variability in BEM manufacturing such as bore offset, thermal shrinkage etc. results in a change in blowdown characteristics during burning of BEMs resulting in high burn rate bias in traditional burn rate evaluation method. Advanced analytical techniques for burn rate evaluation such as Hessler Glick, R ¸ Brimhall, Brooks etc. are used to mitigate these effects of process variability and arrive at reliable burn rates. The effects of traditional and advanced methods of burn rate evaluation on BEMs having different blowdown characteristics are studied. The advanced methods of burn rate evaluation are also compared to the traditional method and how the burn rate varies in these methods on BEMs having different blowdown characteristics.