Preliminary experimental investigation of the pressure evolution in detonation cells

Recently two types of three-dimensional (3D) structure of gaseous detonation have been documented: rectangular and diagonal modes, easily distinguishable from soot records. This paper presents pressure measurements recorded along the central axis of the cellular structure. The pressure records are achieved by using piezoelectric gauges flush-mounted with respect to the surface of the soot-covered plate located in the detonation tube. The low pressure reactive mixture used (H₂, O₂, Ar; Equivalence ratio = 1) is ignited in a square cross-section tube. The detonation tube is operated in the shock tube mode. The time evolution of the local pressure exhibits several pressure peaks depending on the type of 3D structure and on the position in the detonation cell. The first peak characterizes the leading shock and the subsequent pulses correspond to the elaborate shock structure. The influence of the slapping waves (SW) is documented. The pressure profiles throughout the whole length of the detonation cell are reported for the individual types of 3D structure. The second pressure jumps can be rationalized in terms of the classical transverse wave structure. (C) 2000 Elsevier Science Inc. All rights reserved.