Turbulence Structure in a Turbulent Channel Flow with Injection

以完全发育的紊流通道为研究对象，以5种喷射速率均匀喷射通过多孔壁面。用热线风速仪测量了水流方向和横向速度的波动以及时间平均速度剖面。研究了其能谱、自相关和概率密度函数等统计特性。采用VITA技术和象限分析的条件抽样对组织结构进行了分析。喷射对湍流结构的主要影响可以概括如下。（1）. 湍流强度和雷诺剪切应力随注入速度的增加而增大。（2）. 一点双相关系数是恒定的，与注入速度无关。(3)。注入对能谱的影响仅限于近壁区。局部各向同性湍流假设可以应用于注射流动。(4)。爆破现象的波及事件和爆破频率注入的贡献。这就是注入后雷诺数剪应力增大的原因。

An experimental study was carried out on a fully developed turbulent channel flow with uniform injection through the porous wall at five injection rates. Measurement were made of fluctuations of stream-wise and transverse velocity as well as the time-averaged velocity profiles by mean of hot-wire anemometer. The statistical properties, which were included energy spectrum, auto-correlation and probability density function, were investigated. Organized structure was analyzed applying conditional sampling with VITA technique and quadrant analysis.The main effects of injection on the turbulence structure can be summarized as follows. (1). Turbulence intensities and Reynolds shear stress increase with increasing the injection rate. (2). One-point double correlation coefficient is constant and independent of the injection rate. (3). The effect of injection for energy spectrum is restricted in the near wall region. Local isotropy turbulence hypothesis can be applied to injection flow. (4). The contribution from sweep event of bursting phenomenon and bursting frequency injection. This is the reason why Reynolds shear stress increase by injection.