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二通量模型是计算气体-颗粒平板内辐射热通量的简化方法.在最初的二通量模型中,辐射场被假设成在半球方向的各向同性.但是对于燃烧领域的气体-颗粒混合介质,颗粒的散射通常都是各向异性的,这样,原有的二通量模型就会由于忽略各向异性而产生严重的误差.文中一个多层四通量模型被运用到包含气体-颗粒混合物的辐射热通量的计算.给出了模型的解析求解过程,定义了等价的平均交叉系数η和前向散射率ζ来描述整个平板散射的各向异性.为了验证模型的准确性,计算了一个无限大平板内的辐射传递过程,并与解析结果进行了比较.结果表明提出的模型能够得到准确的结果,对原有的二通量模型具有较好的改进作用.运用本模型计算含有飞灰/CO2/H2O的燃烧产物的辐射传递,所得到的平板发射率与Goodwin的经典结果相吻合.
The two-flux model is a simplified method for calculating the radiative heat flux in a gas-particle plate In the first two-flux model, the radiation field was assumed to be isotropic in the hemisphere but for gas-particle mixing in the combustion area Medium and particle scattering are usually anisotropic, so that the original two-flux model will have serious errors due to omitting anisotropy.In this paper, a multi-layer four-flux model is applied to the gas-particle The radiative heat flux of the mixture is calculated. The analytical solution of the model is given and the equivalent mean cross coefficient η and forward scatter ζ are defined to describe the anisotropy of the entire scattering plate.In order to verify the accuracy of the model, The radiation transfer process in an infinite plate is calculated and compared with the analytical results.The results show that the proposed model can get accurate results and improve the original two-flux model.Using this model to calculate The radiative transfer of combustion products containing fly ash / CO2 / H2O resulted in plate emissivity consistent with Goodwin’s classical results.