The paper investigates the mean mass transfer/passive scalar spreading in turbulent submerged round jets. Two regions of flow are present in the jet evolution: the Near-Field Region (NFR) and the Fully Developed Region (FDR). This group of research investigates from some years the mean evolution of turbulent rectangular jets with the new physical finding that two sub-regions (not a single one) are present in the NFR. The first region of the two is the newly discovered Undisturbed Region of Flow (URF), while the second one is the known Potential Core Region (PCR). In a recent paper we showed that the flow evolution of turbulent round jets, as far as momentum spreading is concerned, is self-similar also in the NFR. Literature shows that mass transfer spreading is self-similar only in FDR. The present paper presents new mean mass transfer results of the numerical Large Eddy Simulation (LES) in turbulent round jets. Four Reynolds numbers, from 2492 to 19,988, and two laminar Schmidt numbers, 1 and 10, are investigated. The first novel result of this paper is that mass transfer is self-similar in the NFR. The second result is that two new analytical models describe the passive scalar spreading in the URF and PCR. The third result is that two new self-similar laws describe the passive scalar spreading in the FDR. The fourth result states that the well-known power-law relationship, between passive scalar and axial momentum in the FDR, holds regardless of the modeling of turbulent viscosity and turbulent Schmidt number.

本文研究了湍流淹没式圆形射流中的平均传质/被动标量扩展。射流演化中存在两个流动区域：近场区域（NFR）和完全发育区域（FDR）。这组研究几年来一直在研究湍流矩形射流的平均演变，这一新的物理发现是NFR中存在两个子区域（而不是一个子区域）。两者的第一个区域是新发现的无扰流区域（URF），而第二个区域是已知的潜在核心区域（PCR）。在最近的一篇论文中，我们表明，就动量扩散而言，湍流圆形射流的流动演化在NFR中也是自相似的。文献表明，传质扩散仅在FDR中是自相似的。本文提出了湍流圆形射流中数值大涡模拟（LES）的新平均传质结果。研究了从2492到19,988的四个雷诺数，以及两个1和10的层状Schmidt数。本文的第一个新颖的结果是传质在NFR中是自相似的。第二个结果是，两个新的分析模型描述了URF和PCR中的被动标量扩展。第三个结果是两个新的自相似定律描述了FDR中的被动标量扩展。第四个结果表明，FDR中被动标量和轴向动量之间的公知幂律关系保持不变，而与湍流粘度和施密特湍流数模型无关。研究了两个层状施密特数1和10。本文的第一个新颖的结果是传质在NFR中是自相似的。第二个结果是，两个新的分析模型描述了URF和PCR中的被动标量扩展。第三个结果是两个新的自相似定律描述了FDR中的被动标量扩展。第四个结果表明，FDR中被动标量和轴向动量之间的公知幂律关系保持不变，而与湍流粘度和施密特湍流数模型无关。并研究了两个层状施密特数1和10。本文的第一个新颖的结果是传质在NFR中是自相似的。第二个结果是，两个新的分析模型描述了URF和PCR中的被动标量扩展。第三个结果是两个新的自相似定律描述了FDR中的被动标量扩展。第四个结果表明，FDR中被动标量和轴向动量之间的公知幂律关系保持不变，而与湍流粘度和施密特湍流数模型无关。第三个结果是两个新的自相似定律描述了FDR中的被动标量扩展。第四个结果表明，FDR中被动标量和轴向动量之间的公知幂律关系保持不变，而与湍流粘度和施密特湍流数模型无关。第三个结果是两个新的自相似定律描述了FDR中的被动标量扩展。第四个结果表明，FDR中被动标量和轴向动量之间的公知幂律关系保持不变，而与湍流粘度和施密特湍流数模型无关。