<p>Rotating Detonation Engine (RDE) system has become popular due to its fuel efficiency. The present study focuses attention on the 2-dimensional modelling of an RDE using commercial ANSYS-Fluent software. A premixed hydrogen–air mixture at an equivalence ratio of unity is considered. A density based solver with Euler equation is solved with Roe-FDS implicit scheme to predict the flow field of the RDE combustor. A single wave and multi wave models are studied to understand the real time experimental phenomena of multiple rotating detonation waves. The effect of multiple ignitions and the effect of number of waves on the parameters like detonation wave velocity, detonation pressure, height of the wave, percentage opening of injectors and pressure gain in the combustor are studied. The numerical investigation provides the limit on the maximum number of waves that can be sustained for the chosen geometry, reactants and mixture ratio. The limit can be obtained by using the results of the single wave simulation itself.</p>