Sound propagation within a chemically reacting ideal gas

The propagation of a one-dimensional sound wave within a nondiffusive, chemically reacting, ideal gas is considered. The particular case of a dissociating diatomic gas is analyzed, though the general procedure may be applied to more complex gas mixtures. The appropriate dispersion equation is derived from fundamental considerations and expressions for the sound speed and the absorption coefficient as a function of frequency are presented. The low-frequency (equilibrium) and high-frequency (frozen) limits are evaluated. Results are presented for oxygen for temperatures of 2000–6000 K and pressures of 10, 100, and 1000 kPa. The calculations for oxygen indicate that absorption due to chemical reaction can be quite strong, particularly in the high-frequency limit at high temperatures and pressures.