ID#: 159
Abstract Title: On the Origin of the Double Cellular Structure of Detonation in Gaseous Nitromethane
Session Title: Cellular Structure I
Session Date: 7/30/01
Session Start Time: 8:55 AM
Contributing Author: Presles, H.
Organization: Laboratoire de Combustion et de Detonique, CNRS
Country: France
Authors: N. Lamoureux, C. Matignon, M.-O. Sturtzer, D. Desbordes, H.-N. Presles
Short Abstract: An experimental study of the detonation in pure gaseous nitromethane (NM) or mixed with oxygen has exhibited unambiguously the existence of a double cellular structure in the range of equivalence ratio F from 1.3 to 1.75 (pure NM). Calculations of the reaction zone of the detonation in the same range of equivalence ratio, using a detailed chemical kinetics scheme in the ZND frame, demonstrate that the chemical energy is released in two main successive reaction steps characterized by their own induction length. This work shows that these two main exothermic reaction steps, through their induction length, justify the two levels of cellular structure. To our knowledge, this work is the first which deals with the problem of non monotonous chemical energy release behind the leading shock of a detonation wave. Results obtained strengthen the idea that the cellular detonation structure find its origin in instabilities amplified by the high energy release rate inside the reaction zone.