【摘要】 为了准确地数值预报煤粉旋流火焰特征和主要烟气成分,比较扩展的涡耗散模型在多湍流模型下的预测性和影响,针对IFRF(国际火焰研究基地)2.5MW煤粉氧燃烧和空气燃烧实验,利用组分输运方程,结合7步改进的总包反应,对炉内煤粉氧燃烧进行数值计算,并与实验结果和空气燃烧基况对比.结果表明:氧扩散率、发射率和比热容等物性参数修正后,湿循环、氧预混二次流的煤粉氧燃烧扩散火焰温度场与空气燃烧总体一致,火焰稳定且为Ⅱ型火焰结构;EDC模型(涡耗散概念模型)对组分预测更为准确,尤在可实现k-ε模型下的缓慢反应CO生成和IRZ(中心内回流区)高温预测;而FRED模型(有限速率涡耗散模型)在多湍流模型下对炉内温度、组分、火焰结构预测亦较准确.更多还原

【Abstract】 To predict the oxy-coal swirling flame characteristics and main produces,the effects on these predictions by the extended eddy-dissipation models with different turbulent models was discussed.The oxy-coal combustion characteristics were numerically investigated and compared with experimental results and air-fired mode with a consistent thermal load of 2.5 MW at IFRF(International Flame Research Foundation).The wet-recycled oxy-coal combustion with pure oxygen premixed in secondary stream was dealt with and contrasted to the modified physical parameters,including oxygen mass diffusivity,emissivity,specific heat capacity,etc.The results show that the oxy-fired swirling flame temperature is similar with air-fired mode,and the stabilized flame is a flame type-Ⅱ.The EDC(eddy dissipation concept) model gives better predictions of products,especially for CO and high temperature in IRZ(internal recirculation zone) with realized k-ε model.However,the FRED(finite rate and eddy dissipation) model with two turbulent models also gives good predictions of temperature,products and flame structure.更多还原