Solid Propellant Grain Design and Burnback Simulation Using a Minimum Distance Function

DOI: 10.2514/1.22937 A fast computational method for simulating the evolution of the burning surface of a complex, three-dimensional solid rocket motor propellant grain has been developed using a signed minimum distance function. The minimum distance function is calculated using stereo-lithography surface information from a computer-aided-design file and propellant surface burnback is simulated by manipulation of the initial minimum distance function. Variable time steppingandmultiplespatialgridsfurtherreducecomputationtimerequirements. Resultsindicatethatthismethod gives adequate accuracy with acceptable computation time for time scales of the full motor burn. The resulting code (Rocgrain) allows for motor grain design by user-friendly commercial computer-aided-design programs and for coupling with internal flow codes. This enables a single geometric tool to be used for describing the propellant grain geometry for both grain design and internal flowfield analysis. The Rocgrain code can be coupled with a variety of flowfield codes ranging in complexity from simple zero-dimensional to more sophisticated computational fluid dynamics analysis (e.g., nonlinear acoustic instability).