Monte Carlo method for uncertainty quantification of SRM internal ballistic model

Solid rocket motors are systems commonly adopted for launcher missions. Compactness, reliability, readiness, and construction simplicity make the technology very appealing for commercial service. The lack of mission flexibility makes reliability of predictions and reproducibility of performance a primary goal. Objective of this Thesis is the investigation of solid rocket motor uncertainties through the application of the Monte Carlo method to a dedicated model of internal ballistics. The engine investigated is the Baria, a small scale solid rocket motor used at Avio S.p.a. to test Ariane 5 propellant during production. The Monte Carlo method is a numerical approach to statistics requiring the creation of a numerical model for the analysis of rocket performances. In this work, the model was based on Shapiros’s equations and describes a quasi-one dimensional flow inside a propulsion unit. A quasi-steady approximation for time domain is used. Efficiencies, lateral burning, propellant axis offset, hump and erosive burning are considered to investigate sources of uncertainties. Moreover the model is able to treat different geometries for the propellant grain perforation. Comparison between numerical and experimental data from Baria engine was accomplished. Simulations studied the propagation of uncertainties towards performance parameters (burning time, pressure, specific impulse, etc.). Each parameter was analysed independently to verify its influence. Multivariate simulations with all uncertainties were done as well. A particular study was dedicated to the application of the aforementioned model simulating the propellant procedure for ballistic parameter characterisation, commonly adopted for data reduction of the Baria engine. Uncertainties propagation to calculate ballistic coefficients was highlighted.