Effects of activation energy on the instability of oblique detonation surfaces with a one-step chemistry model

Abstract

A numerical study was performed to investigate the detailed effects of activation energy E a on the oblique detonation wave surface instability. Numerical simulations were performed using an ideal reactive flow model given by the inviscid Euler equations with one-step irreversible Arrhenius reaction kinetics. The numerical results demonstrate two types of unstable structures following the initial smooth surface after detonation initiation. One exhibits by a "saw-tooth" reactive front and the other exhibits by a "keystone" feature. To quantify the destabilization processes, two characteristic length scales, L 1 and L 2 , are defined statistically to be the length of the smooth detonation surface before the appearance of instabilities and the length of the unstable surface before the first cellular structure with the onset of right-running transverse waves, respectively. Their dependence on E a was simulated and analyzed. In general, both lengths decrease with increasing E a , making the surface more unstable. However, with increasing E a , the high temperature sensitivity of the mixture causes an abrupt explosion in the initiation region, introducing a high overdriven surface and suppressing the instability. With the balance between the destabilizing effect of E a and the stabilizing effect of increasing overdrive factor, both L 1 and L 2 are found to approach a near-constant value in the high E a limit.

A reconstruction method of detonation wave surface based on convolutional neural network

“…The half-reaction zone length L1/2, i.e. the distance required for half the reactant to be consumed in the steady ZND detonation wave, is scaled to unit length, which is controlled by pre-exponential factor k with the different Ea [32]. Ea and corresponding k are shown in Table . 1.…”

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

“…However, it can visually reveal the physical nature of the detonation, which helps to qualitatively analyze the structure of the detonation and the effect of the jet parameters on the state of the detonation. Additionally, Arrhenius' law, which relates chemical reaction rates to temperature changes, is also widely used as the simplest model for the detonation simulation [34][35][36]. The two-species one-step reaction model is set using the ideal thermal cycle condition, as follows:…”

Linear stability analysis of one-dimensional detonation coupled with vibrational relaxation

“…The importance of understanding the stability behavior of a detonation wave is thus addressed. These studies are crucial in many engineering applications involving the transfer rate of energy in a detonation, particularly in the design of an oblique detonation engine [5][6][7] and rotating detonation engine. 8 An overview of the detonation stability theory on the application in propulsion can be found in the work of Stewart and Kasimov.…”