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根据现场煤层厚度的多样性,构建关于煤体、岩体及煤岩体(煤岩高度比为1∶2,1∶1,2∶1)的热-流耦合传热的数学模型;考虑测得孔隙度、颗粒直径、阻力影响及温度加载方式,引入局部热平衡假设和Brinkman-Darcy-Forchheimer建立守恒方程组,进行数值求解,将计算结果与实验进行对比。研究表明:煤岩体中央处对流作用最弱,近壁面处流体对流作用最强,流体经过煤岩接触面处速度发生突变;随煤岩体中煤层增厚,流函数最大值|ψ|_(max)减小,对流换热能力减弱;在传热过程中,流场与温度场的规律相对应,随瑞利数Ra增大,Nu呈指数增加趋势。通过验证,地温与暴露立侧面风流温差在10~30℃时,该模拟能很好的预测煤层厚度对热流耦合传热规律产生的影响。为有效预防煤层自燃、岩体损伤力学分析及煤矿能源合理露采等提供科学依据。
According to the diversity of on-site coal seam thickness, a mathematical model of heat-flow coupling heat transfer of coal, rock mass and coal rock mass (coal height ratio of 1: 2, 1: 1, 2: 1) Porosity, particle diameter, drag effect and temperature loading method, the local heat balance hypothesis and the Brinkman-Darcy-Forchheimer equation were introduced and numerically solved. The calculated results were compared with the experimental results. The results show that the convection is the weakest in the center of the coal and rock mass, the convection is the strongest at the near wall and the velocity of the fluid at the contact surface of the coal and rock changes suddenly. With the thickening of the coal seam in the coal and rock mass, the maximum of the flow function | ψ | (max) decreases, and the convective heat transfer decreases. In the process of heat transfer, the flow field and the temperature field correspond to each other. As the Rayleigh number Ra increases, Nu increases exponentially. Through the verification, when the temperature difference between the ground temperature and the exposed vertical air flow is between 10 and 30 ℃, the simulation can well predict the influence of coal seam thickness on the heat and fluid coupling heat transfer law. In order to provide a scientific basis for the effective prevention of spontaneous combustion of coal seam, damage mechanics analysis of rock mass and reasonable dew extraction of coal mine energy.