Prediction of mean radical concentrations in lean hydrogen-air turbulent flames at different Karlovitz numbers adopting a newly extended flamelet-based presumed PDF

摘要: A recent analysis (Lipatnikov et al., 2020) of complex-chemistry direct numerical simulation (DNS) data obtained from lean hydrogen-air flames associated with corrugated-flame (case A), thin-reaction-zone B), and broken-reaction-zone C) regimes turbulent burning has shown that the flamelet concept (i) can predict mean concentrations various species in those if probability density function (PDF) for fuel-based combustion progress variable c is extracted DNS data, but (ii) poorly performs rate W¯c of product creation. These results suggest applying to evaluation concentration (but not rate) combination another closure relation W¯c whose predictive capabilities are better. This proposal developed present paper whose focus placed on studying a new flamelet-based presumed PDF P(c) predictions radicals engineering computational fluid dynamics (CFD) applications. Analysis shows well at intermediate values cases B, should be truncated small large c, modeling radical recombination zone (i.e., c) importance predicting H,O, OH. Accordingly, combined uniform c. Moreover, W¯c extracted used calibrate (the considered given by model). Assessment approach against it predicts density, temperature, reactants, product, aforementioned B. In case C, worse OandOH c¯ moderately underestimates H entire flame brush.