Development of Combined Dual-Pump Vibrational and Pure- Rotational Coherent Anti-Stokes Raman Scattering (DPVCARS and PRCARS) System

Coherent anti-Stokes Raman scattering (CARS) [1,2] is a spatially-resolved, time-resolved spectroscopic technique for quantitative measurements in reacting flows [3 – 6]. This work demonstrates a combination of N2/O2/CO2 dual-pump vibrational coherent anti-Stokes Raman scattering (DPVCARS) system and two-beam pure-rotational coherent anti-Stokes Raman scattering (PRCARS) system. It is based on the previous development of combined VCARS and PRCARS system which was used to obtain temperature measurements in non-premixed H2-air flames. The new combined system will be used to measure the temperature profiles and major species concentrations such as N2/O2/CO2 in laminar counter-flow non-premixed (CH4/Air) and partially-premixed (CH4/H2/Air) flames. The new system is being characterized in H2/Air diffusion flames stabilized over a Hencken burner. CO2 will be added to the oxidizer stream for the system to assess the precision of the system while performing concentration measurements. The new combined system has shown good precision temperature using PRCARS (better than 3%) and N2/O2 mole-fraction ratio (better than 5%) using DPVCARS