Spectroscopic measurements of combustion gas composition in supersonic flow.
A spectroscopic technique for measuring the composition of combustion gases in supersonic flow is described, and the difference between thermal equilibrium and chemical kinetic conditions is demonstrated. The gas flows were generated by an end-burning, double-base solid propellant and expanded through a conical nozzle. The physical chemistry involved was the water-gas reaction, the kinetics of which have been treated in the literature. Temperature and gas composition determinations were made by using the nozzle during flow as an infrared absorption or emission cell. The principle bands of H^O, CO, and CC>2 in the 4-6 H, spectral region were recorded at selected stations along the axis. Calibration of the spectrometer was done with gas samples heated to elevated temperatures and pressures in an electric furnace. Spectral measurements of CC>2 using the 4.25-^ band indicated that the gas composition followed the chemical kinetic calculation.