ID#: 75
Abstract Title: Numerical Study of Detonation Instability for a Two-Step Kinetics Model
Session Title: Poster Session I
Session Date: 7/31/01
Session Start Time: 2:50 PM
Contributing Author: Mazaheri, K.
Organization: Tarbiat Modarres University
Country: Iran
Authors: K. Mazaheri, S.A. Hashemi, J.H.Lee
Short Abstract: In parallel with linear stability analyses, there have been numerous studies concerned with the numerical simulation of the pulsating detonation instability with Arrhenius one-step reaction kinetics. In one-dimensional calculations, the detonation instability appears as oscillatory behavior of detonation front. Using advanced numerical techniques, simulations of reactive Euler equations were able to obtain numerical results in close agreement with the theoretical predictions. Previous research have shown that for one-step Arrhenius kinetic model the activation energy is the main parameter, which determine the instability of CJ detonation. In one-step model, for a mixture with Q/RTo=50 and gamma (the specific heat ratio)=1.2 the ZND structure is unstable for Ea/RTo higher than 25. In this paper a two-step reaction model is used to study the stability of detonation. The first step is a non-heat release induction step and the second one is an exothermic reaction. The effect of activation energy on the detonation front behavior has been studied in this work. In our calculations, Q/RTo=50 and gamma=1.2 are used. It is observed that increasing activation energy of induction step (Ea1), destabilizes a detonation, the same behavior as one-step model. Increasing Ea2 (i.e. the activation energy of the heat release step), has a stabilizing effect for Ea2<25, that is the stability limit of one-step reaction model. Increasing Ea2 to value higher than 25, has a destabilizing effect. It seems that increasing the difference of two activation energies, (i.e., Ea1-Ea2), tends to destabilize the front propagation for Ea2<25. The same result was reported by Sharp for pathological detonations regardless the value of Ea1 or Ea2.