The detonation processes occuring in a variable cross-section combustion chamber have been simulated for a hydrogen-air reacting flow. The chamber consists of a large diameter tube and two small identical tubes connected on each side through frustums. The channel is closed to the left and open to the right. A 2D, time-accurate, finite-volume-based method is used for the computations. Two cases are simulated, corresponding to initiation from the open and closed ends. Click here for a more detailed research paper.

When the incoming Mach number is high enough, a standing detonation wave can be initiated after multiple shock reflections in the wedge or afterbody area (Type 3) or directly at the wedge tip fromt the bow shock (Type 3'). If standing in the aft-body area, the wave is normal with interference by the shock or expansion before it. If it is standing in the wedge area, the wave is oblique. See the PDW Type 1 and 1' introduction for the computational parameters. For the Type 3 case, the Mach number is 5 and the wedge angle is 5 degrees. For the Type 3' case, the Mach number is 6 and the wedge angle is 15 degrees. Click here for a more detailed research paper.

For a small wedge angle, a steady shock system can form ove the wedge with no induced combustion. The simulation results show that the final thermodynamic parameters of the flow behind the last shock are lower than the CJ state. See the PDW Type 1 and 1' introduction for the computational parameters. Click here for a more detailed research paper.

A propagating detonation wave can be initiated after multiple shock reflections in the wedge or afterbody area. The Type 1 video shows the pressure contours created from this type of detonation wave. The upstream Mach number is 3, the wedge angle is 5 degrees and the reactive flow is a uniform mixture of hydrogen and oxygen. In the Type 1' model, detonation is induced from a bow shock at the tip of the wedge. For that simulation, the Mach number is 5 and the wedge angle is 15 degrees. Time-dependent, 2D Euler equations of an inviscid, non-heat-conducting, reacting gas flow were used. A finite volume algorithm was used with up to 25x150 cells, a 10e-7 second time step, a two-temperature non-equilibrium model and a Rogers-Chinitz two step hydrogen/oxygen reaction with five species. Click here for a more detailed research paper.

Below, two videos are shown of the pressure and temperature changes after detonation of a hydrogen-air mixture by Mach reflection waves over a 2D wedge.