The weighted-sum-of-gray-gas(WSGG)model and Mie theory are applied to study the influents of particle size on the radiative transfer in high temperature homogeneous gas-particle mixtures,such as the flame in aero-engi...The weighted-sum-of-gray-gas(WSGG)model and Mie theory are applied to study the influents of particle size on the radiative transfer in high temperature homogeneous gas-particle mixtures,such as the flame in aero-engine combustor.The radiative transfer equation is solved by the finite volume method.The particle size is assumed to obey uniform distribution and logarithmic normal(L-N)distribution,respectively.Results reveal that when particle size obeys uniform distribution,increasing particle size with total particle volume fraction fvunchanged will result in the decreasing of the absolute value of radiative heat transfer properties,and the effect of ignoring particle scattering will also be weakened.Opposite conclusions can be obtained when total particle number concentration N0 is unchanged.Moreover,if particle size obeys L-N distribution,increasing the narrowness indexσor decreasing the characteristic diameter Dˉwith the total particle volume fraction fvunchanged will increase the absolute value of radiative heat transfer properties.With total particle number concentration N0 unchanged,opposite conclusions for radiative heat source and incident radiation terms can be obtained except for radiative heat flux term.As a whole,the effects of particle size on the radiative heat transfer in the high-temperature homogeneous gas-particle mixtures are complicated,and the particle scattering cannot be ignoring just according to the particle size.展开更多
碳黑颗粒是燃烧不足的产物,通常以聚集体的形式存在。碳黑分形聚集体的多次散射特性已被证明在研究烟灰辐射特性方面起着重要作用,但在预测燃烧火焰中的辐射传热时很少考虑这一点。本文基于用于预测湍流扩散火焰中温度场和碳黑聚集体的...碳黑颗粒是燃烧不足的产物,通常以聚集体的形式存在。碳黑分形聚集体的多次散射特性已被证明在研究烟灰辐射特性方面起着重要作用,但在预测燃烧火焰中的辐射传热时很少考虑这一点。本文基于用于预测湍流扩散火焰中温度场和碳黑聚集体的灰体分形聚集体加权和(Weighted sum of gray soot fractal aggregate,WSGSA)模型,分别计算了模型不考虑辐射、Fluent软件默认辐射模型和WSGSA模型条件下的火焰温度分布和烟尘体积分数分布。结果表明,不考虑辐射会较大程度地高估火焰温度,火焰中心线温度的最大相对偏差约为64.5%。Fluent软件中的默认辐射模型将提高精度,但火焰温度仍然偏高,火焰中心线温度的最大相对偏差约为42.1%。然而,WSGSA模型获得的结果更加精确,火焰中心线温度的最大相对偏差不超过15.3%。在研究沿不同火焰高度的温度分布时也可以得到类似的结论。此外,应用WSGSA模型还可以更准确地预测烟尘体积分数。不考虑辐射以及使用Fluent软件中默认的辐射模型都会导致碳黑体积分数偏低。所有结果显示,WSGSA模型可用于有效预测CH/空气湍流扩散火焰中的温度和碳黑聚集体分布。展开更多
基金supported by the National Natural Science Foundation of China (No: 51806103)Jiangsu Provincial Natural Science Foundation(No: BK20170800)Open Funds of Aero-engine Thermal Environment and Structure Key Laboratory of Ministry of Industry and Information Technology (No. CEPE2018005)
文摘The weighted-sum-of-gray-gas(WSGG)model and Mie theory are applied to study the influents of particle size on the radiative transfer in high temperature homogeneous gas-particle mixtures,such as the flame in aero-engine combustor.The radiative transfer equation is solved by the finite volume method.The particle size is assumed to obey uniform distribution and logarithmic normal(L-N)distribution,respectively.Results reveal that when particle size obeys uniform distribution,increasing particle size with total particle volume fraction fvunchanged will result in the decreasing of the absolute value of radiative heat transfer properties,and the effect of ignoring particle scattering will also be weakened.Opposite conclusions can be obtained when total particle number concentration N0 is unchanged.Moreover,if particle size obeys L-N distribution,increasing the narrowness indexσor decreasing the characteristic diameter Dˉwith the total particle volume fraction fvunchanged will increase the absolute value of radiative heat transfer properties.With total particle number concentration N0 unchanged,opposite conclusions for radiative heat source and incident radiation terms can be obtained except for radiative heat flux term.As a whole,the effects of particle size on the radiative heat transfer in the high-temperature homogeneous gas-particle mixtures are complicated,and the particle scattering cannot be ignoring just according to the particle size.
基金supported by the National Natural Science Foundation of China(No.51806103)the Natural Science Foundation of Jiangsu Province(No.BK20231445)the Fundamental Research Funds for the Central Universities(No.501XTCX2023146001)。
基金supported by the National Natural Science Foundation of China (No. 51806103)the Aeronautical Science Foundation of China (No.201928052002)the Fundamental Research Funds for the Central Universities(No.NT2021007)。
文摘碳黑颗粒是燃烧不足的产物,通常以聚集体的形式存在。碳黑分形聚集体的多次散射特性已被证明在研究烟灰辐射特性方面起着重要作用,但在预测燃烧火焰中的辐射传热时很少考虑这一点。本文基于用于预测湍流扩散火焰中温度场和碳黑聚集体的灰体分形聚集体加权和(Weighted sum of gray soot fractal aggregate,WSGSA)模型,分别计算了模型不考虑辐射、Fluent软件默认辐射模型和WSGSA模型条件下的火焰温度分布和烟尘体积分数分布。结果表明,不考虑辐射会较大程度地高估火焰温度,火焰中心线温度的最大相对偏差约为64.5%。Fluent软件中的默认辐射模型将提高精度,但火焰温度仍然偏高,火焰中心线温度的最大相对偏差约为42.1%。然而,WSGSA模型获得的结果更加精确,火焰中心线温度的最大相对偏差不超过15.3%。在研究沿不同火焰高度的温度分布时也可以得到类似的结论。此外,应用WSGSA模型还可以更准确地预测烟尘体积分数。不考虑辐射以及使用Fluent软件中默认的辐射模型都会导致碳黑体积分数偏低。所有结果显示,WSGSA模型可用于有效预测CH/空气湍流扩散火焰中的温度和碳黑聚集体分布。
基金supported by the National Natural Science Foundation of China(No.51806103)the Natural Science Foundation of Jiangsu Province(No.BK20170800)Aeronautical Science Foundation of China(No.201928052002)。