Experimental and Analytical Study of the H2-Air Reaction Kinetics Using a Standing-Wave Normal Shock

摘要

An experimental method was devised whereby the macroscopic chemical reaction history can be traced from wall pressure measurements in a high speed reacting gas in a tube. The experiments were conducted with H2 and vitiated air, and the data were compared with calculated pressure profiles using recent reaction kinetic information obtained from shock tubes. Good agreement between experiment and calculation was found when the flow was steady and no oscillations were present, indicating that the kinetics which govern the chemical reactions in shock tube experiments can be reproduced with the standing-wave experiment. Wall effects are evaluated. In addition, a semi-empirical analysis was made of the ignition delay and recombination, with the assumption that the two-body reactions are essentially in equilibrium during the slower recombination period. The mathematics of this approach is simple and is potentially useful with machine computations involving chemistry and mixing, or chemistry and aerodynamics. Finally, a short experiment with methane combustion in the tube produced similar phenomena, indicating that the method may be useful for determining rates of heat release for gases where little is known of the kinetics. (Author)