【作者】 李朗； 万建龙；

【Author】 Li Lang;Wang Jianlong;School of Energy and Power Engineering,Huazhong University of Science and Technology;

【机构】 华中科技大学,能源与动力工程学院；

【摘要】 燃气热水器行业中,提高热效率并减少污染物排放是行业研究的重要课题。为进一步提高火排热效率并降低燃气热水器污染物排放,本文通过采用CFD软件FLUENT和GRI-Mesh 3.0详细反应机理的FGM扩散小火焰模型对燃气热水器用火排进行了多工况数值模拟,揭示了入口钝体对火排混合性能及其燃烧特性的影响。模拟结果表明FGM扩散小火焰模型的数值模拟结果与实验数据吻合较好,且相对冷态组分输运模型准确性更高。低负荷下的火焰锚定能力强,而高负荷下的火焰抗回火能力强。最后阐明了V形入口钝体高度对混合性能和火焰均匀性的影响:对于不同入口钝体高度火排火孔均匀性而言,随着入口钝体高度的增加,火孔分布速度的均匀性明显提升,其浓度均匀性略微降低,但影响不大,并且存在使得火孔速度偏差和浓度偏差最小的入口钝体高度h=4.0mm和4.4mm;对于单火排火孔速度浓度分布而言,此火排从左至右火孔速度先降低再升高,而一次空气系数相反一先增大再降低,且增大入口钝体高度并不会改变不同点位火孔速度以及浓度的变化趋势。更多还原

【Abstract】 In the gas water heater industry,improving thermal efficiency and reducing pollutant emissions are significant research topics.To further enhance the thermal efficiency of the burner and lower pollutant emissions from gas water heaters,this study employs the FGM(Flamelet Generated Manifolds) model with detailed reaction mechanismsGRI-Mesh 3.0,using the CFD software.A multi-condition numerical simulations of the burner was conducted to reveal the impact of the inlet bluff-body on the mixing performance and combustion characteristics of the burner.The simulation results show that the numerical results obtained from the FGM model agree well with experimental data and exhibit higher accuracy compared to the cold-state species transport models.Low-load flames exhibit strong anchoring capability,while high-load flames exhibit strong flashback resistance.Additionally,the study elucidates the effects of the V-shaped inlet bluff-body height on mixing performance and flame uniformity.It is found that as the height of the inlet bluff-body increases,the speed uniformity of the flame hole improves significantly,while the concentration uniformity slightly decreases,but the impact is minimal.Furthermore,there exists an optimal inlet bluff body height of h=4.0 mm and 4.4 mm that minimizes the speed and concentration deviations of the flame holes.For the flame hole velocity and concentration distribution,the burner exhibits a trend where the velocity of the flame holes decreases then increases from left to right,while the air-fuel ratio exhibits the opposite trend,first increasing then decreasing.The increase in the height of inlet bluff-body does not alter the general trend of velocity and concentration variations at different positions of the flame holes.更多还原