The estimated scalar dissipation rate in gas‐phase turbulent jets
The estimated scalar dissipation rate in gas‐phase turbulent jets
复制标题
气相湍流射流中估计的标量耗散率
DOI：
10.1063/1.857904
复制
发表时间：
1991
影响因子：
4.6
通讯作者：
D. Dowling
中科院分区：
文献类型：
--
作者：
D. Dowling
本文研究了由圆形、气相、动量驱动的湍流射流的喷嘴流体和夹带的油藏流体之间形成的湍流浓度场中标量耗散率的估计。结果基于雷诺数为5000、16000和40000时在射流自相似远场中进行的高分辨率单点测量的浓度时间导数的平方。估计标量耗散率的时间行为，平均值和统计特性的结果报告。估计标量耗散率的瞬时值的峰值被发现产生一个显着的，但不占主导地位，对射流中心线上的平均耗散率的贡献。这些峰的发生统计被确定为泊松分布以外的分布。峰值的平均宽度被发现物理上对应于与标量耗散相关的泰勒尺度，并取决于射流雷诺数的平方根倒数。平均估计标量耗散率被认为是独立的雷诺数，自相似的方式是一致的湍流射流的相似定律。估计的标量耗散率的概率密度函数（pdf）也被发现是自相似的。编制的分布，这是基于只有一个平方场梯度，偏离显着的对数正态性在小值。这一结果表明，不排除对数正态分布的真实标量耗散率。
An estimate for the scalar dissipation rate in the turbulent concentration field formed between the nozzle fluid from a round, gas‐phase, momentum‐driven, turbulent jet and the entrained reservoir fluid is studied. The results are based on the square of the concentration time derivative from high‐resolution, single‐point measurements made in the self‐similar far field of the jet at Reynolds numbers of 5000, 16 000, and 40 000. Results for the temporal behavior, mean value, and statistical properties of the estimated scalar dissipation rate are reported. Peaks in the instantaneous value of the estimated scalar dissipation rate are found to produce a significant, but not dominant, contribution to the average dissipation rate on the jet centerline. The occurrence statistics of these peaks are determined to be other than Poisson distributed. The mean width of the peaks is found to physically correspond to the Taylor scale associated with scalar dissipation, and depend on the inverse square root of the jet Reynolds number. The average estimated scalar dissipation rate is found to be independent of Reynolds number, and self‐similar in a manner that is consistent with similarity laws for the turbulent jet. The probability density function (pdf) of the estimated scalar dissipation rate is also found to be self‐similar. The compiled distributions, which are based on only one squared field gradient, deviate significantly from lognormality at small values. This result is shown to not preclude the lognormality of the distribution of the true scalar dissipation rate.