Streamwise Interface of an Isolated Turbulent Region in a Laminar Flat-Plate Boundary Layer
Streamwise Interface of an Isolated Turbulent Region in a Laminar Flat-Plate Boundary Layer
复制标题
层流平板边界层中孤立湍流区域的流向界面
DOI：
10.1299/kikaib.77.56
复制
发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Y. Fukunishi
中科院分区：
文献类型：
--
作者：
O. Terashima;S. Izawa;A. Inasawa;Y. Fukunishi
通过风洞实验研究了层流平板边界层中孤立湍流区的流向界面。在实验中，双压电晶片型压电陶瓷致动器被用来产生一个椭圆形的湍流区域，在展向方向上有一个宽的界面。采用压电陶瓷作动器，消除了湍流区展向界面与流向界面的干扰。因此，流向界面可以看作是一个独立的界面。实验结果表明，在湍流区的前缘，速度脉动和湍流脉动的均方根值变化迅速。另一方面，在湍流区的后缘处，湍流脉动消失后，速度脉动的均方根值仍然很高。湍流区尾缘的运动速度大于湍流区尾缘近壁处的整体平均流向速度（η≤1.3）。此外，湍流区后缘的速度分布表明湍流流体在壁面附近存在加速。由以上结果发现，由于湍流流体的加速作用，在近壁湍流区的后缘处发生了逆转捩。
The streamwise interface of an isolated turbulent region in a laminar flat plate boundary layer is investigated by performing a wind tunnel experiment. In the experiment, bimorph-type piezoceramic actuators are used to generate a trapezoidal-shaped turbulent region that has a wide interface in the spanwise direction. With the use of the piezoceramic actuators, the interference of the spanwise interface with the streamwise interface of the turbulent region is eliminated. Therefore, the streamwise interface can be considered as an independent interface. The experimental results show that the rms value of the velocity fluctuation and the turbulent fluctuation rapidly changes at the leading edge of the turbulent region. On the other hand, the rms value of the velocity fluctuation remains high after the turbulent fluctuation disappears at the trailing edge of the turbulent region. It is also shown that the traveling speed of the trailing edge of the turbulent region is faster than the ensemble-averaged streamwise velocity at the trailing edge of the turbulent region near the wall (η≤1.3). In addition, the velocity profile at the trailing edge of the turbulent region indicates the existence of the acceleration of the turbulent fluid near the wall. From the above results, it is found that the inverse transition occurs at the trailing edge of the turbulent region near the wall due to the acceleration of the turbulent fluid.