Clarification of turbulent fine-scale structure in a stable stratified flow

稳定分层流中湍流细尺度结构的澄清

• 批准号: 10650180
• 负责人: SASSA Koji
• 金额: $ 2.3万
• 依托单位: Kochi University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650180/
• 关键词: Stable stratification; High Reynolds number; Active turbulence generation; Digital thermo-anemometer; Universal turbulence structure; Fine-scale coherent vortex; Multi-channel measurement; Heat transfer; 構造関数; 間欠構造; 条件付き計測; フルード数; 微細渦; 温度成層形成

A stably-stratified and high Reynolds number turbulence field was tried to realize in a small wind tunnel by using an active turbulence grid and a thermal stratification generator. A digital thermo-anemometer, ar I-X probe and a multi-sensor probe were also developed and examined in order to investigate the characteristics of the stratified turbulence field. The results of the measurements using these instruments are as follows ;(1) A high Reynolds number turbulence field (R_λ>300, R_λ denotes turbulence Reynolds number) was generated under the stable stratification in which the gradient of its stable linear temperature profile was 30 K/m. Such field has the turbulence characteristics and the stratification similar to those of a nocturnal surface layer.(2) The wide inertial subrange existed in the temperature and velocity spectra. The peak of heat flux located in the inertial subrange of the co-spectrum.(3) The normal component of large-scale velocity fluctuation was effectively suppressed by the buoyancy effect in the strongly stable stratification, though the disturbance Froude number showed that the stratification was weakly stable.(4) The relation between the power index and the order of the velocity structure function of the neutral turbulence field supported the results of the other works, whereas that of the stably-stratified turbulence field showed that the field was more intermittent than the neutral field.(5) The fine-scale coherent vortices were detected by the multi-points and conditioned measurements. Their mean diameter was about 10η, which is same with the results of DNS.Only small ones of such coherent vortices contributed to energy dissipation, but the large-scale vortices in inertial subrange transferred heat effectively.

尝试利用主动湍流网格和热分层发生器在小型风洞中实现稳定分层的高雷诺数湍流场。还开发并测试了数字热风速计、ar I-X 探头和多传感器探头，以研究分层湍流场的特征。利用这些仪器的测量结果如下：(1)在稳定层结下产生高雷诺数湍流场(R_λ>300，R_λ表示湍流雷诺数)，其稳定线性温度剖面的梯度为30 K/m。该场具有与夜间表层类似的湍流特征和层结特征。(2)温度谱和速度谱存在较宽的惯性子范围。热流峰值位于共谱的惯性子域。(3)强稳定层结中的浮力效应有效抑制了大尺度速度脉动的法向分量，尽管扰动弗劳德数表明层结是弱稳定的。(4)功率指数与中性湍流场速度结构函数阶数的关系支持了其他结果的支持。 有效，而稳定分层湍流场的结果表明，该场比中性场更具间歇性。(5)通过多点和条件测量检测到细尺度相干涡旋。它们的平均直径约为10η，与DNS的结果相同。这种相干涡旋中只有较小的涡旋有助于能量耗散，但惯性子范围内的大尺度涡旋可以有效地传递热量。

项目成果

佐々浩司,松永修二,蒔田秀治: "普遍構造解明のための安定成層乱流の実現"九州大学応用力学研究所研究集会報告. 11ME-S3. 45-50 (2000)

Koji Sasa、Shuji Matsunaga、Hideharu Makita：“用于阐明通用结构的稳定分层湍流的实现”九州大学应用力学研究所研究会议报告11ME-S3（2000）。

佐々浩司,松永修二,蒔田秀治: "レイノルズ数の高い安定成層乱流の特性"航空宇宙技術研究所特別資料. SP-47. 13-16 (2001)

Koji Sasa、Shuji Matsunaga、Hideharu Makita：“高雷诺数稳定分层湍流的特性”航天技术研究所专用材料 SP-47。

K.Sassa and S.Matsunaga: "Detection of fine-scale turbulent eddies by a multi-sensor probe."RIMS Kokyuroku. No.1121. 47-54 (2000)

K.Sassa 和 S.Matsunaga：“通过多传感器探头检测细尺度湍流涡流。”RIMS Kokyuroku。

K.Sassa,S.Matsunaga and H.Makita: "Buoyancy effect and universal structure of a stably stratified turbulence field"Advances in Turbulence VIII (Ed.C.Dopazo) CIMNE, Barcelona, Spain. 291-294 (2000)

K.Sassa、S.Matsunaga 和 H.Makita：“稳定分层湍流场的浮力效应和通用结构”Advances in Turbulence VIII (Ed.C.Dopazo) CIMNE，西班牙巴塞罗那。

K.Sassa, S.Matsunaga and H.Makita: "Characteristics of stably-stratified turbulence at a high Reynolds number"Special Publication of National Aerospace Laboratory. SP-47. 13-16 (2001)

K.Sassa、S.Matsunaga 和 H.Makita：“高雷诺数稳定分层湍流的特征”国家航空航天实验室特别出版物。