基于有限体积法的掘进工作面无因次围岩温度场

Research on temperature field of dimensionless surrounding rock at excavation roadway based on finite volume method

  • 摘要: 掘进工作面围岩散热属于轴对称散热问题,准确解算其围岩温度场并计算不稳定换热准数是风温预测的前提。以三角形单元重心圈划了有限体积法的控制体积,采用面积坐标函数准确离散了轴对称条件下围岩无因次导热积分方程,并基于Visual Studio编程平台自主开发了掘进工作面围岩温度场解算程序,分析了毕渥数(Bi)、贝克来数(Pe)对围岩温度场分布和不稳定换热准数的影响规律,构建了掘进工作面端面和周边巷道的不稳定换热准数数学模型。结果表明:掘进工作面端面区域的围岩冷却范围较小,远离工作面的周边巷道区域围岩冷却范围较大。随着毕渥数增加,巷道壁面附近围岩温度降低,围岩冷却范围增大。随着贝克来数增加,巷道壁面附近围岩温度升高,围岩冷却范围减小。掘进工作面端面和周边巷道的不稳定换热准数均随着毕渥数、贝克来数增加而增大,且周边巷道中靠近掘进工作面端面位置的不稳定换热准数最大,随着与掘进工作面端面的距离增加,不稳定换热准数逐渐减小,同时不稳定换热准数的变化程度也在逐渐减弱。基于掘进工作面端面和周边巷道的不稳定换热准数计算结果,构建了相应的不稳定换热准数数学模型,并给出了该模型的实际工程应用方法。带入一组工程实际参数的模型计算结果与数值模拟结果具有较高一致性,其中掘进工作面端面的相对误差为0.10%,周边巷道的平均相对误差为3.52%,验证了模型的准确性。此外,该模型形式简洁,计算准确高效,避免了查图、查表的繁琐性,便于进一步计算巷道风流温度。

     

    Abstract: Heat dissipation from the surrounding rock at excavation roadway is an axisymmetric heat transfer problem. Accurate determination of the rock temperature field and the unstable heat transfer number is a prerequisite for airflow temperature prediction. Control volumes for the finite volume method were constructed by centroid-based partitioning of triangular elements. The dimensionless axisymmetric heat conduction integral equation for the surrounding rock was discretized accurately using area coordinate functions. A dedicated solver for the rock temperature field at excavation roadway was developed on the Visual Studio platform. The effects of the Biot number and Peclet number on the temperature field distribution and unstable heat transfer number were investigated, and mathematical models for the unstable heat transfer number were established for both the heading face and the surrounding roadway. Results show that the cooling range is smaller near the heading face, whereas a larger cooling range develops in the surrounding roadway farther from the face. Increasing the Biot number reduces rock temperature near the wall and enlarges the cooling range; increasing the Peclet number raises rock temperature near the wall and shrinks the cooling range. The unstable heat transfer number for both the heading face and the surrounding roadway increase with increasing Biot and Peclet numbers. In the surrounding roadway, the unstable heat transfer number is maximal near the heading face and decreases with distance from the heading face, with progressively diminishing spatial variation. Based on the computed unstable heat transfer number, corresponding mathematical models were formulated and an engineering application procedure was provided. For a representative set of field parameters, the model predictions agree well with numerical simulations, with a relative error of 0.10% for the heading face and a mean relative error of 3.52% for the surrounding roadway, confirming the model accuracy. Moreover, the proposed models are concise and computationally efficient, eliminating cumbersome chart/table lookups and facilitating subsequent calculation of roadway airflow temperature.

     

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