N₂/O₂/H₂ dual-pump cars: Validation experiments

Abstract

The dual-pump coherent anti-Stokes Raman spectroscopy (CARS) method is used to measure temperature and the relative species densities of N 2, O2 and H2 in two experiments. Average values and root-mean-square (RMS) deviations are determined. Mean temperature measurements in a furnace containing air between 300 and 1800 K agreed with thermocouple measurements within 26 K on average, while mean mole fractions agree to within 1.6 % of the expected value. The temperature measurement standard deviation averaged 64 K while the standard deviation of the species mole fractions averaged 7.8% for O2 and 3.8% for N2, based on 200 single-shot measurements. Measurements have been performed in a hydrogen-air flat-flame burner for fuel-lean and fuel-rich conditions. A preliminary comparison is shown between the fitted data and an adiabatic, equilibrium computation. For fuel-lean conditions, good agreement was found for temperature. Temperatures measured under fuel-rich conditions were about 50 K higher than the computation. Mole-fractions for N2 agreed with the computation to within 3%. Measured O2 mole fractions were systematically high while measured H2 mole fractions were systematically low by 10-15% compared to the computation. For an equivalence ratio of 2.8, the standard deviation of 58 single-shot temperature measurements was 108 K, or 5.8%, and the standard deviations of H2 and N 2 mole fractions were 9.8% and 3.8% of the measured values, respectively.