Authors: C. J. Sung, J. G. Li, G. Yu, and C. K. Law
Direct link to the paper: DOI: 10.2514/2.715
Self-ignition tests of a model scramjet combustor were conducted by using parallel sonic injection of gaseous hydrogen from the base of a blade-like strut into a supersonic vitiated airstream. The range of stagnation pressure and temperature studied varied from 1.0 to 4.5 MPa and from 1300 to 2200 K, respectively. Experimental results show that the self-ignition limit, in terms of either global or local quantities of pressure and temperature, exhibits a nonmonotonic behavior resembling the classical homogeneous explosion limit of the hydrogen– oxygen system. Speci cally, for a given temperature, increasing pressure from a low value can render a nonignitable mixture torst become ignitable, then nonignitable again. This correspondence shows that, despite the globally supersonic nonpremixed con guration studied herein, ignition is strongly in uenced by the intricate chemical reaction mech-anism and thereby exhibits the homogeneous explosion character . Consequently, self-ignition criteria based on a global reaction rate approximating the complex chemistry are inadequate. An auxiliary computational study on counter ow ignition was also conducted to systematically investigate the contamination effects of vitiated air . Re-sults indicate that the net contamination effects for the present experimental data are expected to be substantially smaller than contributions from the individual contamination species because of the counterbalancing in uences of the H2 O-inhibition and NO-promotion reactions in effecting ignition.
Citation: C. J. Sung, J. G. Li, G. Yu, and C. K. Law, “Chemical Kinetics and Self-Ignition in A Model Supersonic Hydrogen-Air Combustor,” AIAA Journal 37 (2), 208-214 (1999).