Abstract
One-dimensional simultaneous measurements of the species mass fractions of O2, H2 H2O, N2 and OH radical as well as flame temperature have been carried out in hydrogen jet diffusion flames diluted with Ar using the line-Raman/Rayleigh/LIPF-OH technique. Statistical information about the mixture fraction Z and scalar dissipation rate x can be obtained for evaluation of current finite-chemistry combustion models for the turbulent nonpremixed flames. At an upstream position of x/d = 8, the flamelet approach is found to be qualitatively valid, in agreement with a larger Favre mixture fraction fluctuation than the reaction zone thickness in the Z-space. Transient effect, however, can be important in view of H2 and O2 superequilibrium. Preferential diffusion effects are negligible due to a relatively large Peclet number. Joint correlations between a reactive scalar T with δ and the conserved scalar Z with γ are found to be different from those reported in nonreacting flows. The observed distinct features can be explained based on the flamelet concept so that statistical independence is argued to be a good approximation. There is evidence showing that large-scale turbulent motion dominates scalar transport in the connected reaction zone regime. Thus, flamelet approach is also favored. Some modeling assumptions used in the flamelet model and the CMC method are discussed. Model refinements based on the present experimental data are suggested as well.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.