Stability of high-pressure gaseous detonation: impact of molecular volume and attraction forces

The dynamics of detonation is governed by intrinsic longitudinal and transverse instabilities. This work fills the research gap of detonation stability at elevated pressure as real gas effects, including the finite molecular volume and inter-molecular attraction forces, become non-negligible. The stability of one-dimensional pulsating and two-dimensional cellular detonations at elevated pressure was investigated using both linear stability analysis and high-fidelity numerical simulations. For pulsating detonations, the neutral stability boundaries derived from the linear stability analysis reveal that the impact of real gas effects on detonation stability depends on the heat content. Specifically, real gas effects stabilise pulsating detonation at high heat content, destabilise it at intermediate levels and exhibit competing influences, i.e. destabilisation from finite molecular volume and stabilisation from the inter-molecular attraction force, at low heat content. For cellular detonations, a stability map is proposed in the Mach number–reduced activation energy plane, demonstrating that real gas effects stabilise detonation and lead to more regular cellular structures or even fully planar detonations. Theoretical predictions show good agreement with numerical simulations. An oscillator model was used to elucidate the interplay between the heat release and shock dynamics. It shows that the stabilising effect of real gas is associated with reduced velocity oscillation amplitude, increased phase lag between heat release and shock speed variations and lower values of the coupling parameter. The comprehensive linear stability analysis with complete real gas models is an effective predictive tool for the detonation dynamics at elevated pressure.