ID#: 156
Abstract Title: On the Location of the Chapman-Jouguet Surface in Gaseous Detonations Close to the Limit of Propagation
Session Title: Detonation Structure
Session Date: 7/30/01
Session Start Time: 2:00 PM
Contributing Author: Weber, M.
Organization: Shock Wave Laboratory, Univ. of Technology Aachen
Country: Germany
Authors: Michael Weber, Herbert Olivier, Hans Gr–nig, J–rg Biegling
Short Abstract: The location of the sonic surface xS in a cellular detonation is measured by the use of time-resolved schlieren photography for stoichiometric oxy-hydrogen mixture (diluted with 40 % argon and pure) and for stoichiometric oxy-acetylen. This is done by fixing a thin blade in the middle of a detonation tube, whose edge faces the incoming detonation front. A weak shock wave forms at the edge of the blade as soon as it is engulfed by the front. This weak shock separates from the edge when the absolute gas velocity has decreased from its highly supersonic value (directly behind the front) to the speed of sound. After separation the absolute velocity of the shock is low and becomes nearly constant. This is explained as an indication of the proximity of the sonic surface and the CJ-surface. Furthermore it is shown, that the ratio of xS and the cell size l rises with pressure, and the influence of the proximity of l to the tube diameter is small. In addition a diagonal-mode detonation was observed with l equal to the diagonal D of the utilised tube with square cross-section. This mode was defined by Hanana et al. (1999). I pasted in a Word-text, and some formats are lost: Please reconvert single l and D to lambda and capital Delta, and convert xS to x subscribt S. Thanks a lot