Simulation of Detonation Initiation in Straight and Baffled Channels


Department of Aerospace Engineering,Sharif University of Technology


Euler conservation equations, ideal gas state equations and simplified chemical kinetics models were used to simulate two-dimensional straight and baffled shock tubes. In a straight channel, detonation waves were initiated by a strong shock wave and allowed to travel down the channel to reach a CJ wave condition. It has been shown that a two-step reaction, kinetics model with an induction time delay, resulted in a physically plausible transient solution. The one-step kinetics model solution is only valid at the limit of a steady state CJ wave condition and should not be used for transient problems. The two-step kinetics model was then used to simulate a detonation initiation in a baffled shock tube. It was shown that the presence of multiple baffles in a channel could result in an initiation of detonation, in cases where the temperature jump across the traveling initial compression wave and the presence of a single baffle are not sufficient to initiate a detonation. Furthermore, it is shown that in the absence of any viscous mechanisms, shock reflection from the second baffle created a moving Mach stem between the baffles. The coalescence and focusing of pressure waves behind this Mach stem resulted in the creation of a hot spot leading to a detonation wave.