Numerical investigation of detonation initiation by a focusing shock wave

• Published in: Shock waves 2021-10, Vol.31 (7), p.777-788
• Main Authors: Bengoechea, S., Reiss, J., Lemke, M., Sesterhenn, J.
• Format: Article
• Language: English
• Subjects: Acoustics; Combustion chambers; Condensed Matter Physics; Configuration management; Deflagration; Detonation; Engineering; Engineering Fluid Dynamics; Engineering Thermodynamics; Fluid- and Aerodynamics; Heat and Mass Transfer; Mathematical models; Original Article; Thermodynamics
• ISSN: 0938-1287; 1432-2153
• DOI: 10.1007/s00193-020-00962-z

This work presents a numerical study of detonation initiation by means of a focusing shock wave. The investigated geometry is a part of a pulsed detonation combustion chamber, consisting of a circular pipe in which the flow is obstructed by a single convergent–divergent axisymmetric nozzle. This obstacle acts as a focusing device for an incoming shock wave, serving as a low-energy detonation initiator. The chamber is filled with stoichiometric premixed hydrogen-enriched air. The simulation uses a one-step chemical model with variable parameters optimized by the adjoint approach in terms of the induction time τ c . The model reproduces τ c of a complex kinetics model in the range of pressures and temperatures appearing at the focusing point. The results give a comprehensive description of the shock-induced detonation initiation, which is the mechanism for the deflagration-to-detonation transition in this type of configurations. Potential geometry design improvements for technical applications are discussed. The first attempt to parameterize the transition process is also undertaken.