Three-dimensional simulations of detonation propagation in circular tubes: Effects of jet initiation and wall reflection

Abstract

In the present work, using a high-resolution three-dimensional numerical analysis the initiation and propagation mechanism of a detonation wave is studied in a circular tube with a hot jet initiation. The reactive Euler equations with a one-step two-species chemistry model are solved based on the structured adaptive mesh refinement technique. Influences of both a single hot jet and impinging double hot jets on the formation of the detonation wave are studied. For each case, the objective is to investigate the role of the tube wall on the initiation and propagation of the detonation wave. The result for both cases shows that the hot jet-induced bow shock forms a complex reflection structure in the circular tube. The reflection effect of the circular wall strengthens the shock and facilitates the formation of the Mach stem, which leads to the formation of the detonation wave. However, when the hot jet condition and the total area of jet hole remain the same, for the case of initiation using double hot jets, the reflection strength of the bow shocks weakens when the diameters of the hot jets become smaller. When using a single hot jet, the initiated detonation is overdriven and propagates in the twoheaded mode. In this initiation mode, by increasing the inflow Mach number, a four-headed mode detonation front is formed. While in the case of impinging double hot jets, a four-headed mode detonation front is initiated directly.

Numerical Investigation on Detonation Initiation and Propagation with a Symmetric-Jet in Supersonic Combustible Gas

“…The details of the chemical reaction model and the corresponding selection of thermodynamic parameters can also be found in studies by Ziegler [31]. Chen et al [32] conducted numerical simulations of three-dimensional detonation waves with this reaction mechanism, and verified the reliability of the mechanism by comparing the numerical simulation results with the available experimental results. It should be noted that the weakness of this chemistry model is that it is unable to capture the chain-branching characteristics of the reactions and the corresponding crossover effects [33], and only the state parameters before and after the detonation wave are considered.…”