Pure Rotational CARS Thermometry Studies of Low Temperature Oxidation Kinetics in Air and Ethene-Air Nanosecond Pulse Discharge Plasmas
OHIO STATE UNIV COLUMBUS DEPT OF MECHANICAL ENGINEERING
Pagination or Media Count:
Pure rotational CARS thermometry is used to study low-temperature plasma assisted fuel oxidation kinetics in a repetitive nanosecond pulse discharge in ethene-air at stoichiometric and fuel lean conditions at 40 Torr pressure. Air and fuel-air mixtures are excited by a burst of high-voltage nanosecond pulses peak voltage 20 kV, pulse duration 25 nanosecond at a 40 kHz pulse repetition rate and burst repetition rate of 10 Hz. The number of pulses in the burst is varied from a few pulses to a few hundred pulses. The results are compared to the previously developed hydrocarbon-air plasma chemistry model, modified to incorporate non-empirical scaling of the nanosecond discharge pulse energy coupled to the plasma with the number density, as well as one-dimensional conduction heat transfer. Experimental time-resolved temperature, determined as a function of number of pulses in the burst, is found to agree well with the model predictions. The results demonstrate that the heating rate in fuel-air plasmas is much faster compared to air plasmas, primarily due to energy release in exothermic reactions of fuel with O atoms generated by the plasma. It is found that the initial heating rate in fuel-air plasmas is controlled by the rate of radical primarily O atoms generation and is nearly independent of the equivalence ratio. At long burst durations, heating rate in lean fuel air-mixtures is significantly reduced when all fuel is oxidized.
- Inorganic Chemistry