Study of internal flame front structure of accelerating hydrogen/oxygen flames with detailed chemical kinetics and diffusion models

Abstract

The problem of Detonation to Deflagration (DDT) is revisited. A stoichiometric hydrogen/oxygen combustion system is considered. The study focuses on the investigation of the system solution in the thermo-chemical state space of the system. The Σ model is implemented to study the flame acceleration and DDT in 1D formulation. The model was suggested to take into account wrinkling of the flame surface. In this way, the problem becomes treatable numerically even with the detailed mechanism of chemical kinetics and with detailed models for molecular diffusion. In order to treat and integrate the model a recently developed numerical scheme to deal with very stiff systems both in time and in space is introduced and applied. Typical system solution profiles of the ignition, quasi-deflagration, flame acceleration, DDT and detonation stages are considered to study the structure of the flame front in the system thermo-chemical state space. The results of computations show that at the stages of the ignition, deflagration and acceleration the flame structure in the state/composition space moderately depends on Σ, however, significant influence shows up during later stages of the flame acceleration and DDT. Moreover, the path of the solution in the detonation regime significantly deviates from that of deflagration. This means that accurate and quantitative study of the DDT is not possible without reliable mechanisms of chemical kinetics able to describe the system state space during the transient.

Multiobjective Optimization of a Metal Complex Catalytic Reaction Based on a Detailed Kinetic Model with Parallelization of Calculations

“…The development of mathematical optimization methods in chemical technology has been carried out and is being carried out by many authors: M. G. Slinko [1], V. I. Bykov [2], R. Aris [3], V. V. Kafarov [4], etc. These researchers use the following optimization methods: (1) classical analysis of the study of functions; (2) calculus of variations; (3) Pontryagin's maximum principle; (4) dynamic programming and linear programming; (5) nonlinear programming; (6) methods of global optimization, etc.…”

“…The limitations for the vector of the control can be written as (2), where D U represents a function space.…”

“…Thus, the problem of optimal control for chemical kinetics is to find the vector control, U(t), satisfying condition (2), in which a system of nonlinear ordinary differential equation (SNODE) solutions provides the optimality criterion extremum (3).…”