地表非均匀加热条件下边界层湍流特征的实验研究

A laboratory study on the turbulent characteristics of convective boundary layer driven by heterogeneous surface heating

在下垫面非均匀加热条件下进行对流边界层的水槽模拟实验，并与下垫面均匀加热条件下的情形对比，研究地表热力非均匀性对边界层湍流特征的影响．结果表明，地表的非均匀加热使得混合层湍流的组织性得到加强，湍流涡旋结构的空间分布比较稳定，湍流强度也有明显的增强．进一步分析表明，对流边界层的发展受到下垫面热力非均匀尺度的影响，在对流边界层的发展过程中，当边界层高度为下垫面非均匀尺度的1．3～1．4倍时，夹卷速度（即边界层高度的抬升速度）最小．

The convective boundary layer driven by heterogeneous surface heating is modeled in water tank. The turbulent characteristics in it are studied and compared with those in the convective boundary layer driven by homogeneous surface heating. The measurement results indicate that the organized turbulent motions are enhanced by the heterogeneous surface heating and the strength of turbulent energy is enlarged. Further analyses show that the development of the convective boundary layer is influenced by the heterogeneous scale of surface heating. When the convective boundary layer is 1.3 - 1.4 times the height of the heterogeneous scale, the entrainment rate has the minimum value.