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您的检索式：作者名="Boukhalfa Abdelkrim"
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| 1 | A conditioned level-set method with block-division strategy to flame front extraction based on OH-PLIF measurements显示文摘A novel approach to extract flame fronts, which is called the conditioned level-set method with block division(CLSB),has been developed. Based on a two-phase level-set formulation, the conditioned initialization and region-lock optimization appear to be beneficial to improve the efficiency and accuracy of the flame contour identification. The original blockdivision strategy enables the approach to be unsupervised by calculating local self-adaptive threshold values autonomously before binarization. The CLSB approach has been applied to deal with a large set of experimental data involving swirlstabilized premixed combustion in diluted regimes operating at atmospheric pressures. The OH-PLIF measurements have been carried out in this framework. The resulting images are, thus, featured by lower signal-to-noise ratios(SNRs) than the ideal image; relatively complex flame structures lead to significant non-uniformity in the OH signal intensity; and, the magnitude of the maximum OH gradient observed along the flame front can also vary depending on flow or local stoichiometry.Compared with other conventional edge detection operators, the CLSB method demonstrates a good ability to deal with the OH-PLIF images at low SNR and with the presence of a multiple scales of both OH intensity and OH gradient. The robustness to noise sensitivity and intensity inhomogeneity has been evaluated throughout a range of experimental images of diluted flames, as well as against a circle test as Ground Truth(GT). | 韩乐 蔡国飙 徐旭 Renou Bruno Boukhalfa Abdelkrim | 2014 | Chinese Physics B2014，23，5： | 3 |
| 2 | Flow characterization and dilution effects of N_2 and CO_2 on premixed CH_4/air flames in a swirl-stabilized combustor显示文摘Numerically-aided experimental studies are conducted on a swirl-stabilized combustor to investigate the dilution effects on flame stability, flame structure, and pollutant emissions of premixed CH4/air flames. Our goal is to provide a systematic assessment on combustion characteristics in diluted regimes for its application to environmentally-friendly approaches such as biogas combustion and exhaust-gas recirculation technology. Two main diluting species, N2and CO2,are tested at various dilution rates. The results obtained by means of optical diagnostics show that five main flame regimes can be observed for N2-diluted flames by changing excess air and dilution rate. CO2-diluted flames follow the same pattern evolution except that all the domains are shifted to lower excess air. Both N2and CO2dilution affect the lean blowout(LBO) limits negatively. This behavior can be counter-balanced by reactant preheating which is able to broaden the flammability domain of the diluted flames. Flame reactivity is degraded by increasing dilution rate. Meanwhile, flames are thickened in the presence of both diluting species. NOx emissions are significantly reduced with dilution and proved to be relevant to flame stability diagrams: slight augmentation in NOx emission profiles is related to transitional flame states where instability occurs. Although dilution results in increase in CO emissions at certain levels, optimal dilution rates can still be proposed to achieve an ideal compromise. | 韩乐 蔡国飙 王海兴 Renou Bruno Boukhalfa Abdelkrim | 2014 | Chinese Physics B2014，23，3： | 1 |
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