温度边界层对壁湍流多尺度相干结构的影响

用热线风速仪以高于对应最小湍流时间尺度的分辨率精细测量了风洞中壁面加热平板湍流边界层不同法向位置流向速度分量的时间序列信号, 与常温情况相比, 热对流加速了壁湍流中流体的动量、质量和能量的交换, 加快了湍流边界层的发展;用子波分析方法研究了壁面加热对壁湍流多尺度相干结构喷射和扫掠条件相位平均波形的影响, 显示热对流明显增大了缓冲层相干结构扫掠过程和喷射过程的强度, 是增强壁湍流中流体的动量、质量和能量交换的根本原因. 

Experimental investigation of effects of temperature boundary layer on multi-scale coherent structures in wall turbulence

The velocity time sequence at different vertical locations of turbulent boundary layer in wind tunnel was finely measured using a hot-wire anemometer,at a resolution higher than the corresponding minimum turbulence time scale.As compared with normal temperature,the heat convection could accelerate the exchanges of momentum,mass and energy in wall turbulence,and also facilitate the development process of turbulent boundary layer.Wavelet analysis method was employed to study the effects of temperature boundary layer on phase-averaged waveforms of multi-scale coherent structures during ejection and sweep process in wall turbulence.The research reveals that heat convection enhances dramatically the strength of coherent structures,contributing much to the exchange of momentum,mass and energy in wall turbulence.