Development of a new facility for the study of low-density chemically reacting hypersonic flows

A facility has been developed to investigate the hypersonic low-density flows of chemically reacting gases. Originally developed to study vibrational excitation kinetics, the experimental apparatus is appficable to general studies of transitional shock-layer flows. A gaseous rocket-engine is operated in a large vacuum chamber to generate a highly expanded beam from the exhaust products. A shock-holder is located in the beam in order to produce a shock- induced relaxation zone. Electron beam measurements of shock-structure in a water vapor/nitrogen beam produced by combusting stoichiometric mixtures of H₂/O₂ in a N₂ diluent are presented. The measured shock-wave density profile is compared to Direct-Simulation Monte Carlo computations and measurements in pure N₂. The measurements of the 2.7 mm emission from H₂O and the translational-rotational-vibrational shock structure are discussed. The extension of the measurements to other combustible gas mixtures is suggested. The application of the facility to study kinetics effects such as rotational- vibrational or vibrational-dissociation coupling in low density flows is examined. Experiments are proposed to support the development of models such as DSMC for reacting low density flows.