Direct numerical investigation of detonation waves using a Monte Carlo method

Open Access
Author:
O'Connor, Patrick Dennis
Graduate Program:
Chemistry
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
April 24, 2008
Committee Members:
  • James Bernhard Anderson, Committee Chair
  • Lyle Norman Long, Committee Member
  • Albert Welford Castleman Jr., Committee Member
  • Mark Maroncelli, Committee Member
Keywords:
  • DSMC
  • Monte Carlo
  • detonation
Abstract:
A detonation wave describes a shock that propagates at supersonic velocity through a chemically unstable gas medium and is driven by the energy released by the chemical reactions within the wave. A Monte Carlo algorithm has been developed to directly model the physics and chemistry of detonations to a level of detail never before accomplished. The direct simulation Monte Carlo method is used to accurately model the coupled gas dynamic-chemical kinetic behavior found in detonation waves generated in high velocity flows with sharp gradients of velocity, temperature, density, composition, etc. Direct simulation Monte Carlo is a stochastic, particle-based method capable of simulating the full microscopic details of rarefied gas flows. Previous work with this algorithm was found to be in excellent agreement with the Chapman-Jouguet and Zeldovich-von Neumann-Doring theoretically predicted temperatures and detonation velocities for detonation waves in which the shock region precedes the reaction region. In order to extend from simple one-step reaction driven detonation waves to more realistic systems such as the 34-reaction, 5-step hydrogen-chlorine reaction, several modifications have been made to the Monte Carlo algorithm. The addition of phenomenological energy models has allowed particles to exhibit the behavior of diatomic and polyatomic molecules. Several reaction models have been investigated in order to accurately calculate reaction rates drawn from experimental mechanisms. In addition, several reactions types have been added including bimolecular, dissociation and recombination interactions. Modifications have also been made to model mixtures containing particles with realistic molecular properties such as mass, diameter, internal degrees of freedom, and rates of exchange of internal energy. The direct simulation Monte Carlo method has been used to investigate the hydrogen-chlorine mechanism in systems with and without flow. Detonation profiles have been examined in detail in order to study initiation sources, boundary effects, the interaction between shock and reaction regions, and reaction sensitivity. Detonation velocities, peak detonation temperatures and particle distributions across the detonation front have also been studied. The results obtained are promising and indicate that calculations using this Monte Carlo method are feasible for other complex reaction systems.