Hydrodynamic instabilities and transverse waves in propagation mechanism of gaseous detonations

• Published in: Acta astronautica Vol. 91; pp. 263 - 282
• Main Authors: Mahmoudi, Y., Mazaheri, K., Parvar, S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2013
• Subjects: Computer simulation; Detonation; Detonation structure; Hydrodynamics; Instability; Kelvin–Helmholtz instability; Keystone region; Navier-Stokes equations; Richtmyer–Meshkov instability; Stability; Transverse waves; Wave propagation; Kelvin–Helmholtz instability; Richtmyer–Meshkov instability; Transverse waves; Keystone region; Detonation structure
• ISSN: 0094-5765; 1879-2030
• DOI: 10.1016/j.actaastro.2013.06.009

The present study examines the role of transverse waves and hydrodynamic instabilities mainly, Richtmyer–Meshkov instability (RMI) and Kelvin–Helmholtz instability (KHI) in detonation structure using two-dimensional high-resolution numerical simulations of Euler equations. To compare the numerical results with those of experiments, Navier–Stokes simulations are also performed by utilizing the effect of diffusion in highly irregular detonations. Results for both moderate and low activation energy mixtures reveal that upon collision of two triple points a pair of forward and backward facing jets is formed. As the jets spread, they undergo Richtmyer–Meshkov instability. The drastic growth of the forward jet found to have profound role in re-acceleration of the detonation wave at the end of a detonation cell cycle. For irregular detonations, the transverse waves found to have substantial role in propagation mechanism of such detonations. In regular detonations, the lead shock ignites all the gases passing through it, hence, the transverse waves and hydrodynamic instabilities do not play crucial role in propagation mechanism of such regular detonations. In comparison with previous numerical simulations present simulation using single-step kinetics shows a distinct keystone-shaped region at the end of the detonation cell. •The role of hydrodynamic instabilities (i.e. Richtmyer–Meshkov instability and Kelvin–Helmholtz instability) in gaseous detonations is determined.•The role played by jet flows in consumption mechanisms of un-reacted gas pockets in detonations is studied.•The role of transverse waves in ignition and propagation mechanism of both regular and irregular detonations is clarified.•In comparison to the previous investigations the mechanism of formation of keystone-like unburnt region in regular detonations is also determined.