借助Fluent软件模拟了甲烷–空气扩散燃烧过程,对燃烧过程进行了熵产分析。单位体积内由导热和对流、粘性耗散、质量扩散和化学反应过程的不可逆性产生的局部熵产率通过用户自定义函数(user defined function,UDF)求解,由辐射过程的不...借助Fluent软件模拟了甲烷–空气扩散燃烧过程,对燃烧过程进行了熵产分析。单位体积内由导热和对流、粘性耗散、质量扩散和化学反应过程的不可逆性产生的局部熵产率通过用户自定义函数(user defined function,UDF)求解,由辐射过程的不可逆性导致的局部熵产率则通过对已求解的温度场进行后处理得到。结果表明对含有辐射换热的传热过程进行热力学分析时,辐射熵产不能忽略。在燃料和空气入口温度及壁面温度不变时,总熵产数随燃料入口雷诺数和玻尔兹曼数的增大分别先减小后增大。因此可以选择适当的燃料入口雷诺数和玻尔兹曼数使系统的总熵产数最小,从而提高能量利用效率。展开更多
To research the characteristics of vented explosion of methane-air mixture in the pipeline,coal mine tunnel or other closed space,the experiments and numerical simulations were carried out.In this work,explosion chara...To research the characteristics of vented explosion of methane-air mixture in the pipeline,coal mine tunnel or other closed space,the experiments and numerical simulations were carried out.In this work,explosion characteristics and flame propagation characteristics of methane in pipeline and coal mine tunnel are studied by using an explosion test system,combined with FLACS software,under different vented conditions.The numerical simulation results of methane explosion are basically consistent with the physical experiment results,which indicates that the numerical simulation for methane explosion is reliable to be applied to the practice.The results show that explosion parameters(pressure,temperature and product concentration)of methane at five volume fractions have the same change trend.Nevertheless,the explosion intension of 10.0%methane is the largest and that of 9.5%methane is relatively weak,followed by 11.0%methane,8.0%methane and 7.0%methane respectively.Under different vented conditions,the pressure and temperature of methane explosion are the highest in the pipeline without a vent,followed by the pipeline where ignition or vent position is in each end,and those are the lowest in the pipeline with ignition and vent at the same end.There is no significant effect on final product concentration of methane explosion under three vented conditions.For coal mine tunnel,it is indicated that the maximum explosion pressure at the airproof wall in return airway with the branch roadway at 50 m from goaf is significantly decreased while that in intake airway does not change overwhelmingly.In addition,when the branch roadway is longer or its section is larger,the peak pressure of airproof wall reduces slightly.展开更多
文摘借助Fluent软件模拟了甲烷–空气扩散燃烧过程,对燃烧过程进行了熵产分析。单位体积内由导热和对流、粘性耗散、质量扩散和化学反应过程的不可逆性产生的局部熵产率通过用户自定义函数(user defined function,UDF)求解,由辐射过程的不可逆性导致的局部熵产率则通过对已求解的温度场进行后处理得到。结果表明对含有辐射换热的传热过程进行热力学分析时,辐射熵产不能忽略。在燃料和空气入口温度及壁面温度不变时,总熵产数随燃料入口雷诺数和玻尔兹曼数的增大分别先减小后增大。因此可以选择适当的燃料入口雷诺数和玻尔兹曼数使系统的总熵产数最小,从而提高能量利用效率。
基金Project(51674193)supported by the National Natural Science Foundation of ChinaProject(2019-JLM-9)supported by the Natural Science Foundation of Shaanxi Province,ChinaProject(2019-M-663780)supported by the Postdoctoral Science Foundation,China。
文摘To research the characteristics of vented explosion of methane-air mixture in the pipeline,coal mine tunnel or other closed space,the experiments and numerical simulations were carried out.In this work,explosion characteristics and flame propagation characteristics of methane in pipeline and coal mine tunnel are studied by using an explosion test system,combined with FLACS software,under different vented conditions.The numerical simulation results of methane explosion are basically consistent with the physical experiment results,which indicates that the numerical simulation for methane explosion is reliable to be applied to the practice.The results show that explosion parameters(pressure,temperature and product concentration)of methane at five volume fractions have the same change trend.Nevertheless,the explosion intension of 10.0%methane is the largest and that of 9.5%methane is relatively weak,followed by 11.0%methane,8.0%methane and 7.0%methane respectively.Under different vented conditions,the pressure and temperature of methane explosion are the highest in the pipeline without a vent,followed by the pipeline where ignition or vent position is in each end,and those are the lowest in the pipeline with ignition and vent at the same end.There is no significant effect on final product concentration of methane explosion under three vented conditions.For coal mine tunnel,it is indicated that the maximum explosion pressure at the airproof wall in return airway with the branch roadway at 50 m from goaf is significantly decreased while that in intake airway does not change overwhelmingly.In addition,when the branch roadway is longer or its section is larger,the peak pressure of airproof wall reduces slightly.
