Experiments in a constant pressure combustion chamber at room temperature and elevated pressures using schlieren system were conducted to investigate the cellular instabilities in hydrogen/carbon monoxide/methane (or propane)–air premixed flames. In the present study, hydrodynamic and diffusional-thermal instabilities were evaluated to elucidate their effects to flame instabilities. Effective Lewis numbers of premixed flames with methane addition decrease for all of the cases. Meanwhile, the effective Lewis numbers with propane addition increase for lean and stoichiometric conditions, but they increase for rich and stoichiometric cases for hydrogen-enriched flames. With propane addition, the propensity for cells formation is significantly diminished whereas the cellular instabilities for hydrogen enriched flames are promoted. With methane addition, the similar behavior of cellularity is obtained, indicating that methane is not a candidate for suppressing cells formation in hydrogen/carbon monoxide/methane–air premixed flames.
Relative line intensities in the 2 → 0 sequence of bands of carbon monoxide observed in emission from a radio-frequency discharge have been measured. An enhancement of the R branch lines and a diminution of the P branch lines due to vibration–rotation interaction has been observed in agreement with theoretical predictions. Vibrational and rotational temperatures have been calculated and when allowance is made for the vibration–rotation interaction these prove to be equal within experimental error indicating the existence of thermal equilibrium in the discharge.
Output Characteristics of a Radio Frequency Discharge Excited Carbon Monoxide Laser Operated at Room Temperature.