Simultaneous point measurements of NO, the major species, mixture fraction, temperature, and OH are obtained in nonpremixed turbulent hydrogen jet flames, using the combination of spontaneous Raman scattering, Rayleigh scattering, and laser-induced fluorescence. Results are presented for an undiluted hydrogen flame at Reynolds number I0,000 and for flames with 20 percent and 40 percent helium dilution. The radial dependence of the conditional mean NO mole fraction (conditional on mixture fraction) is shown to be small at upstream locations and negligible at the downstream locations that contribute most to the overall NO emission. Near the base of the flame, where NO formation rates and concentrations are sensitive to local strain, fluctuations of the NO mole ! fraction conditional on mixture fraction are 40 to 50 percent of the conditional mean. When average NO levels are calculated conditional on both mixture fraction and temperature, a significant temperature dependence is found. However, this double conditioning does not substantially reduce NO fluctuations relative to the mean values. These results combined with previously reported data on the present hydrogen flames provide a detailed basis for evaluation and refinement of turbulent combustion models for thermal NOx formation in jet flames. DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United State, s Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Refer-¢noe herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommcndation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
