| Summary: | An effective method for handling turbulent fluctuations in temperature and in partial pressure of infrared-active gas is proposed in order to make a fairly accurate simulation within feasible calculation load in relation to radiative heat transfer in the large-scale hydrocarbon flame formed in industrial furnaces. As for the case of large-scale turbulent hydrogen flame in industrial furnace, an effective method for handling turbulent fluctuations has been proposed and verified in our previous papers. And yet, it’s applicability to large-scale turbulent hydrocarbon flames has not been confirmed. In this paper, the abovementioned method is examined as to the applicability to hydrocarbon flames, and then, an improved method is proposed. In regard to the method proposed in our previous papers to reduce the enormous calculation load contingent on detailed non-gray analysis like line-by-line analysis, it’s validity is easily confirmed not only for hydrogen flames but also for hydrocarbon flames. On the other hand, the method proposed in our previous paper for reducing the calculation load required for tracing turbulent fluctuation in temperature in great detail cannot give satisfactory results in relation to the large-scale hydrocarbon flame. So, in this paper, major attention is concentrated on the improvement of our method for reducing the calculation load associated with detailed trace of turbulent fluctuation. The assumption that temperature fluctuations of arbitrary two positions are independent from each other and the treatment of energy radiation associated with turbulent fluctuation are maintained also for hydrocarbon flames. In contrast, the treatment of fluctuating absorption is changed from the case of hydrogen flames. While the temporal mean amount of absorption is evaluated using the absorption coefficient at temporal mean temperature in the case of hydrogen flames, such value is evaluated using the temporal mean value of instantaneous absorptance. Validity of the improved method is examined on a model optical path imaging the typical course of radiative energy in large-scale industrial furnaces fueled by propane. It is indicated by examination that the error caused by improved method is satisfactorily smaller than that caused by entire disregard of turbulent fluctuation of temperature and gas composition. Moreover, this improvement related to the treatment of turbulent fluctuation is satisfactorily valid even if coupled with our efficient method for treating complicated spectrum of absorption coefficient.
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