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强吸气旋转圆筒壁面湍流边界层建模及计算

MODELLING AND CALCULATION OF THE TURBULENT BOUNDARY LAYER ON A ROTATING CYLINDER SURFACE WITH STRONG SUCTION

  • 摘要: 提出了湍流边界层的一种简单、快速计算方法, 用以求解强吸气作用下旋转圆筒表面边界层流动. 首先, 理论分析了同心圆筒间的旋转流体运动, 外筒静止、内筒旋转且为多孔吸气条件. 强吸气情况下旋转流动主要表现为内筒壁面附近的边界层流动, 基于这一事实得到了周向速度分布的解析表达式. 其次, 通过引入新参数扩展Cebeci-Smith代数湍流模型, 使其能考虑流线曲率、壁面吸气、低Reynolds数效应等因素. 针对这些因素的综合影响, 采用解析修正和经验参数对模型进行调整. 同时, 基于Reynolds应力湍流模型的仿真结果, 校准代数湍流模型中的经验参数. 最后, 给出基于广义Cebeci-Smith湍流模型的旋转壁面边界层流动的迭代算法, 该算法适用于需要特殊迭代过程的轴向及周向流动均匀情况. 计算了不同旋转速度和吸气强度组合工况下的边界层流动, 其周向速度和湍流强度分布与基于Reynolds应力湍流模型的计算结果非常接近. 并且表明, 当Reynolds应力湍流模型数值模拟预测内筒边界层为稳定层流时, 该方法也再现了相同初始条件下的层流边界层.

     

    Abstract: A simple, fast and adequate approach to the turbulent boundary layer calculation on the surface of a rotating permeable cylinder has been elaborated for the case of a strong suction through the cylinder surface. Firstly, the rotational gap flow between two concentric cylinders was analyzed theoretically; the outer cylinder is stationary, and the inner porous cylinder is rotating with suction condition. Based on the fact that the stationary outer cylinder does not influence the flow near the rotating inner one, it can be treated as a boundary layer on the surface of rotating permeable cylinder, and an analytical expression for the circumferential velocity distribution is obtained. Secondly, the Cebeci-Smith two-layer algebraic turbulence model has been adjusted to account for centrifugal force field (streamlines curvature), wall suction, and low-Reynolds-number effects. Analytical corrections and empirical coefficients are used to tune the model for the specific conditions of coupled influence of the factors mentioned above. The calibration database was used which has been obtained by detailed numerical simulation based on the Reynolds stress turbulent model. The numerical simulation approach has been comprehensively verified in the known study for the specific flow conditions under consideration. Finally, the solution algorithm based on generalized Cebeci-Smith two-layer algebraic turbulence model was offered to solve the boundary layer flow over the rotating porous cylinder surface. The algorithm is suited for the situation of flow uniformity in the azimuthal and axial directions that required a special iterative procedure to be elaborated. The results of the algebraic turbulence model with different combinations of the rotational speed and the suction velocity agree well with the simulation results of the Reynolds stress turbulent model. It is demonstrated that the method developed reproduces also the laminar boundary layer at the same initial conditions when the detailed numerical simulation predicts the stable laminar flow in the inner cylinder boundary layer.

     

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