湍流能量耗散率标度律实验研究

应用粒子图像测速(PIV)系统对平板湍流边界层内流向和法向的瞬时速度进行了测量。湍流的能量耗散率由轴对称假设得到,同时在研究湍流动能耗散率标度律的过程中采用传统的统计学方法。实验结果显示,对于不同尺度上和不同法向位置湍流耗散率标度律来说,湍流耗散主要发生在小尺度上,也就是说湍动能耗散率标度律在小尺度上具有普适性。另外,根据层次结构理论假设,通过PIV实验数据对最高激发态的标度指数进行了研究,结果发现,最高激发态存在绝对标度指数,并且绝对标度律是由信号中最强耗散涨落的局部结构产生的。

Experimental Study of Energy Dissipation Rate Scaling Law in Turbulent Boundary Layer

Particle-image Velocimetry (PIV) system was used to measure the instantaneous streamwise velocity and longitudinal velocity in turbulent boundary layer on a flat plate. The turbulent energy dissipation rate was obtained by axisymmetric homogeneous hypothesis.In order to study turbulent energy dissipation rate scaling law, traditional statistics method was used to analyze experimental data. For different scales and different wall distances, experimental investigation indicates that turbulent energy dissipation rate scaling law is universal at small scale, in other words, turbulent energy is dissipated in small scale in turbulent boundary layer. In addition, the most intensive structure is proposed in further study based on Hierarchical-Structure model hypothesis. It is concluded that there exists an absolute scaling exponent for this most intensive structure in turbulent boundary layer, and the statistical absolute scaling behavior only produced the local and strong intermittence structure.