圆形湍流射流中的Taylor假设

On Taylor's Hypothesis in a Turbulent Round Jet

在一湍流射流自模区的中心线上,沿流向的温度空间相关和差分量的统计关系由两种方法获得。一是用两根平行并在流向上分离的冷丝直接测量;另一方法是通过计算关于时间的相关和差分(根据来自下游位置的冷线信号),以及Taylor假设去获得关于空间的对应量。本文对有关的时、空量,如相关系数,均方根值,偏斜和平坦因子以及谱密度函数,作了对比和讨论。可以认为,Taylor假设在所测量的流动中是相当合理和有用的。

Statistic of the streamwise correlation and difference of temperature fluctuations on the centerline and at one streamwise station in the self-preserving region of a turbulent round jet have been obtained by two techniques. In one, the streamwise correlation and difference are directly measured by two parallel cold-wires separated in the streamwise direction. In the other, they are inferred from the temporal counterparts, of the temperature signals from one (downstream) of the above two wires, and Taylor's hypothesis. Comparisons have been done between the spatial and temporal quatities. i. e. , the correlation and the rms value, the skewnesses and flatnesses, and the spectral density functions of the temperature differences. Taylor's hypothesis is quite reasonable and helpful in the measured flow.