Numerical Investigation of Detonation Wave Propagation in Pulse Detonation Engine with Obstacles

Abstract

The numerical investigation of Detonation wave propagation and Deflagration-to-Detonation transition is done in straight long tube of 1200 mm length and 60 mm internal circular diameter with stoichiometric (ϕ=1) mixture of hydrogen-air at ambient pressure and temperature of 0.1 MPa and 293 K respectively. The detonation tube contains obstacles having blockage ratio (BR) 0.5, 0.6 and 0.7, and having 60 mm gap among them. The computation analysis is performed firstly on simple straight tube having no obstacle (BR=0.0) and then obstructed channel. The combustion phenomena of fuel-air mixture are modeled by one-step irreversible chemical reaction model. Three-dimensional Navier-Stokes equations along with realizable k-ɛ turbulence model are solved by the commercial computation fluid dynamics software ANSYS Fluent-14 code. The performance of pulse detonation engine (PDE) depends on blockage ratio (BR) of obstacles. The simulation results show that the initiation and propagation of flame is due to exothermic expansion of hot combustion gases. The obstacles generated turbulence at obstacle wakes, which caused to increase flame surface area. Therefore, obstacles reduced the Deflagration-to-Detonation transition (DDT) run-up length. The perturbation inside the combustor increases as increased the blockage ratio of obstacle. The PDE Simulation results of with and without obstacles were analyzed and compared with adiabatic flame temperature.