Abstract The walls of combustion systems are usually assumed to be black or gray in radiative calculations, which may cause large errors. The Planck-function-weighted emissivity is usually used as the gray-wall emissivity when using the Wide-Band Correlated K-distribution method. This approach can demonstrate good accuracy when coupled with the emissivity-based optimized band interval approach proposed by Solovjov et al., 2013. To improve computational efficiency without losing accuracy, a nongray-wall emissivity model and an absorption-coefficient-based method for determining the band interval are proposed. The accuracy of nongray-wall and gray-wall emissivity models along with different approaches to determine the band intervals is evaluated in three 1D isothermal and homogeneous cases bounded by fly-ash deposit, a high-temperature alloy, and soot deposit and a 3D fuel-air flame bounded by fly-ash deposit. The results show that the nongray-wall emissivity model is much more accurate than the gray-wall one when the number of bands is greater than 1. Coupled with the absorption-coefficient-based band interval approach, the nongray-wall emissivity model becomes more accurate when the number of bands is larger than 2, especially for low-temperature walls. It is sufficient to divide the entire spectrum into 4 bands for the cases tested here.

中文翻译：

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宽带相关 K 分布方法的非灰墙发射率模型

摘要 在辐射计算中，燃烧系统的壁面通常假设为黑色或灰色，这可能会导致较大的误差。当使用宽带相关 K 分布方法时，普朗克函数加权发射率通常用作灰墙发射率。这种方法与 Solovjov 等人在 2013 年提出的基于发射率的优化频带间隔方法结合使用时可以表现出良好的精度。为了提高计算效率而不损失精度，非灰壁发射率模型和基于吸收系数的方法用于确定建议波段间隔。非灰壁和灰壁发射率模型以及确定波段间隔的不同方法的准确性在三个以粉煤灰沉积物为界的一维等温均匀情况下进行评估，一种高温合金，和烟灰沉积物以及以粉煤灰沉积物为边界的 3D 燃料-空气火焰。结果表明，当波段数大于 1 时，非灰墙发射率模型比灰墙模型准确得多。再加上基于吸收系数的波段间隔方法，非灰墙发射率模型变得更加准确。当波段数大于 2 时准确，特别是对于低温壁。对于此处测试的情况，将整个频谱划分为 4 个频段就足够了。当波段数大于 2 时，非灰墙发射率模型变得更加准确，特别是对于低温墙。对于此处测试的情况，将整个频谱划分为 4 个频段就足够了。当波段数大于 2 时，非灰墙发射率模型变得更加准确，特别是对于低温墙。对于此处测试的情况，将整个频谱划分为 4 个频段就足够了。