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Effect of Turbulence Parameter on Heat and Particle Diffusion in a Atmospheric Turbulenc

大气湍流中湍流参数对热量和粒子扩散的影响

基本信息

批准号：
17560145
负责人：
MAKITA Hideharu
金额：
$ 2.24万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17560145/
关键词：
Fluid Engineering Atmospheric Turbulence Hear and Mass Transfer Turbulent Diffusion Meandering Motion Wind Tunnel Experiments Thermo Anemometer Flow Visualization

项目摘要

The present research aimed to examine the effect of turbulence parameter on heat and particle diffusion in a large-scale turbulence, R_λ=400 (Re_M =10^6〜10^7), generated by a turbulent shear flow generator. Its velocity and temperature fields were measured by a thermo-anemometer and a I-type cold-and X-type hot-wire probe. The streamwise evolution of thermal plume was obtained through statistical analysis on velocity and temperature fluctuations.(1) The meandering motion of thermal plume was observed in a wind tunnel. The variation of probability density function of mean temperature gave good agreement with the Taylor's diffusion theorem and short time diffusion process was realized.(2) The meandering motion was affected by the large-scale turbulent eddy. When the streamwise interval of thermal plume, LI, was almost same as the longitudinal integral scale, LI didn't change in the stremwise distance. When the spanwise length of the thermal plume equaled the lateral integral scale, its diffusion shifted to long time diffusion process.(3) Compared with thermal diffusion in a grid turbulence field, heat flux was extremely large and spanwise thermal transportation was very active in the large-scale turbulence. As a result, the diffusion coefficient was K=180cm2/s for Rλ=430.

本文研究了湍流参数对剪切流发生器产生的R_λ=400（Re_M =10^6 <$10^7）大尺度湍流中热量和颗粒扩散的影响。用热风速仪、I型冷丝探针和X型热线探针测量了其速度场和温度场。通过对速度和温度脉动的统计分析，得到了热羽流的流向演化规律。(1)在风洞中观测到热羽流的弯曲运动。平均温度概率密度函数的变化与泰勒扩散定理吻合较好，实现了短时扩散过程。(2)大尺度湍流涡旋影响了曲流运动。当热羽流的流向间隔LI与纵向积分尺度基本相同时，LI在流向距离上基本不变。当热羽流的展向长度等于横向积分尺度时，热羽流的扩散过程转变为长时间扩散过程。(3)与网格湍流场中的热扩散相比，大尺度湍流中的热通量非常大，展向热输运非常活跃。当Rλ=430时，扩散系数K= 180 cm ~ 2/s。