Numerical Simulation on Critical Initiation Conditions of Air-Breathing Pulse Detonation Combustor

In order to conduct accurate numerical simulations of the pulse detonation combustor using fewer computational resources, a three-step ethylene/air global reaction mechanism was established. Using this mechanism, the ignition delay times and detonation initiations can be accurately predicted. So as to reproduce the results of the detailed mechanism, the activation energy of the three-step mechanism is set as a key parameter that varies with the initial state of the reactants. A database of detonation simulation activation energy was established in a board range of equivalence ratio of 0.7-2.3, temperature, and pressure in front of the shock wave of 300 K and 0.2-2 atm. The developed mechanism was used to successfully predict the lean and rich limits of detonation initiation for simulation in an air-breathing pulse detonation combustor, as well as the initiation distances were obtained. The simulation results were consistent with the theoretical limits estimated by cell sizes. This indicates that the established three-step mechanism is appropriate for the simulations of detonation initiation.