Uncertainty Propagation in Post-Firing Analysis of SRM Internal Ballistics

Post-firing analysis of solid rocket motors enables the identification of important propulsion parameters such as characteristic velocity, discharge coefficient, throat erosion, burning time, and other details, depending on the degree of complexity involved in the analysis. Firing data can have different sources. Test-bench firings are usually carried on for evaluation purposes during design processes, prototype evaluation, or routine quality check in propellant production. Mission-related data may be obtained from in-flight streaming. In this respect, some types of information are not always available for in-flight tests. Throat erosion measurements are not accessible or the propulsion unit might not be fully instrumented, in case of production flights. The accuracy featuring analysis results are influenced by both uncertainty of available data (e.g. random or systematic errors) and lack of knowledge for some parameters. The present work applies a methodology for uncertainty propagation to a simplified post-firing tool. The post-processing algorithm is based on a zero-dimensional framework capable of deriving characteristic velocity, thrust coefficient, throat erosion, and burning time. Code implementation and verification are presented. An example of uncertainty analysis is reported for a limited number of sources, both epistemic and aleatory. Propagation is traced using a Monte Carlo method and Latin hypercube sampling.