Solid Rocket Motor Internal Ballistics Using a Vortex Particle Method

A vortex particle method is developed to efficiently and accurately solve the internal flowfield of solid rocket motors modeled with the surface-vorticity approach. The goal of such is to produce a tool suitable for conceptual and preliminary design of solid rocket motors. The current work concerns a two-dimensional implementation of the method. Surface vorticity is shed from the model surface panels, which represent the exposed surfaces in a solid rocket motor combustion chamber, into discrete vortex particles that flow through the domain freely. The inclusion of vortex particles leads to a large improvement in the internal ballistics solutions, as the rotationality of the internal flowfield is adequately captured with the proposed method, where the surface- vorticity method alone was only able to produce irrotational internal flowfields. Results are given for 2D planar solid rocket motor models with tapered sidewalls and headwall injection, and the solutions from the vortex method are compared with analytical models. Good agreement is observed between the vortex method and analytical models for the cases considered. Similar errors are observed between the studied cases, primarily consisting of inaccuracies near the headwalls and outlets of the models. The error near the outlet was expected as the surface panels are unbounded here. Future work will involve three- dimensional geometries. More work is needed regarding a generalized timestep rule for the method, as the timestep is seen to have a considerable effect on the solutions.