Simple Surface-Tracking Methods for Grain Burnback Analysis

Practical surface-tracking methods are successfully developed to simulate the evolution of the grain geometry, which is dynamically regressing during the combustion of the solid propellant. Three methods, namely the front-tracking, emanating-ray, and least-distance methods, are proposed. The front-tracking method is based on the Lagrangian approach, whereas both the emanating-ray and the least-distance methods are formulated from the Eulerian viewpoint. Three two-dimensional test cases have been examined to compare the programming complexity, simulation accuracy, and computational efficiency of the proposed methods. It is found that the least-distance method performs superior to the other two methods in many numerical respects. The least-distance method is implemented on the tetrahedron grid system to track the outwardly regressing surface of a three-dimensional cubical propellant. Comparison between the predicted erosive volume and burning surface area with the theoretical results yields satisfactory agreement. A grain design similar to one of the Falcon Launch V cases has been employed to demonstrate the usefulness of the proposed methodology in application to a practical three-dimensional grain burnback analysis.