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8167148 
Meetings & Symposia 
Casting process effect on composite solid propellant burning rate 
Ribéreau, D; Le Breton, P; Ballereau, S 
2001 
English 
This work is a synthesis carried out by SNPE propulsion to investigate full scale solid rocket motor (SRM) ballistics response, on basis of sub-scale analysis 1. It has been organized with following guideline: Ballistics analysis use sub-scale characterization to determine full scale prediction. The parameters of this transformation are determined: Grain deformation, erosive burning, manufacturing process effects. Processing effects at firing are analyzed in a major laboratory study performed by SNPE and CELERG on a composite HTPB nozzleless solid rocket booster. Ammonium Perchlorate (AP) segregation is identified as a potential candidate to hump factor modification. Then an experimental study is performed to construct local burning rate model and to validate it. The particles segregation during the filling of SRM induces propellant heterogeneity which leads to local anisotropy of burning rate and to operating particularities known as hump effect and scale factor. A 2D study performed on a small scale SRM is presented. Several grains were manufactured using the same propellant batch and with three different filling processes. For each process, two grains were casted, one grain was fired, and the other one was cut in samples for local burning rate measurements The numerical model is finally presented. This model computes local burning rate using 3D propellant grain filling simulation. A 3D varying burning rate surface burnback code has been developed at SNPE Propulsion to take into account those casting process effects in performance predictions of large SRM. The performance of large SRM has been computed using this new 3D surface burnback simulation based on a 3D filling simulation results. Simulation results are compared to experimental results deduced from firing tests results analysis (hump effect and scale factor), and to local burning rate measurements. The numerical model gives a fairly good prediction of both global and local behavior.