Dual-pump coherent anti-Stokes Raman scattering technique for simultaneous measurement of pressure and temperature

Pressure, temperature, and density measurements using high-resolution N2 CARS

“…mm x mm, m < < which agrees with the shock location determined by Foglesong et al 8 (by shadowgraph photo and dual-pump CARS measurements) of x mm m ≈ 7…”

“…In addition, the agreement between experiment and theory increased as the low-pressure (0.13 atm) and temperature (98 K) regions upstream of the Mach disk were encountered. In comparison, the dual-pump CARS measurements of Foglesong et al 8 could not obtain the same level of agreement between experiment and theory at these conditions. The high-resolution N 2 CARS technique was also able to quantify the conditions found just downstream of the Mach disk, where the flow recompressed to 1.63 atm and 293 K. As expected, the density distribution, determined through the ideal gas equation-of-state, also generally followed the MOC prediction.…”

“…11 fail to consistently match the associated theoretical peaks. These discrepancies are primarily attributed to shot-to-shot variations 8,39,40 in the broadband dye laser profile. Notwithstanding these differences, CARSFIT still provides reasonable pressure and temperature values of 3.09 atm, 247 K and 3.81 atm, 256 K for Figs.…”

“…As a precursor to the current work, Foglesong et al 8 used a dual-pump CARS technique to measure the mean and fluctuating components of pressure, temperature, and density in a gas chamber and along the 2 centerline of an underexpanded jet. The technique provided accurate and repeatable results for P>1 atm and T=150-300 K. Unfortunately, the rotational and vibrational N 2 line structure displayed limited pressure sensitivity for P<1 atm.…”