A nonlinear equation for extracting laminar burning velocity was deduced from a detailed theoretical model,and flame development history of methane/air,n-butane/air and hydrogen/air mixtures was obtained by using a constant-volume combustion bomb.Four linear and nonlinear extraction models form previous and present works were used to investigate the influence of nonlinear stretch on laminar burning velocity extraction for four typical flames.The results show that the influence of nonlinear stretch on flame increases with the increasing Markstein length,and consequently the difference in laminar burning velocity measured using four extraction methods increases.The nonlinear NLC model proposed in present work is in full best agreement with the experimental results,and thus it measures the most accurate laminar burning velocity.The performance of nonlinear LC and NLS models is good,while the linear LS model obviously over-estimates laminar burning velocity.In addition,a strategy of increasing initial flame radius properly and using a high-accuracy,nonlinear model can be applied to reduce the effect of nonlinear stretch on extraction and improve the accuracy in the measurements of laminar burning velocity.
维普
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