Based on the two-dimensional numerical simulation of continuously rotating detonations in an annular chamber, the paths of flow particles burned by three different processes are tracked and analyzed in detail. The detonation wave, the deflagration wave, the oblique shock wave, and the contact surface have a small influence on the paths of flow particles. The fluctuation of paths in the azimuthal direction is less than 12% of the circumference of the combustion chamber. The path will deflect when the flow particle encounters the detonation wave or the oblique shock wave, and it will not deflect when encounters the deflagration wave or the contact surface. About 23.6% fuel is burned by deflagration, and the left is burned by rotating detonation wave. The thermodynamic performance of continuously rotating detonations is then discussed. The p-v and T-s diagrams obtained by numerical simulation are qualitatively consistent with the ideal ZND model. The average thermal efficiency of the detonation combustion in 2D RDE is 31%, and its average net mechanical work is 1.3 MJ/kg. The thermal efficiency of the entire RDE is 26.4%, and its net mechanical work is 30% of the ideal ZND model. The superior performance of continuously rotating detonations is determined. Crown Copyright (C) 2012 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.