Hot-wire anemometry system for studies of mixing in turbulent flows

在自然界和人造世界中，湍流都是常态，而层流则是例外。湍流的基础是它们快速混合质量、动量或能量的能力--这是*广泛过程的基础，包括空气动力学、气象学、燃烧和环境污染物扩散。目前的提案要求提供资金，以*翻新热线风速测量系统，这是我实验室中测量设备的核心部分，我在那里进行了湍流混合的研究。热线风速计是一种最先进的设备，它以非常高的空间和时间*分辨率测量流体流动的速度，并提供无与伦比的信噪比。当人们需要*测量湍流中的整个尺度范围时，它是可选的工具，它可以表现为：i)长度*尺度，范围从几米到亚毫米尺度，以及ii)时间尺度*跨度从几分钟到十分之一毫秒。*为了继续进行我的研究所需的这些精确的*测量，需要两个新的风速测量通道*来取代我系统中近*20年前购买的两个通道，因为一个失败了，另一个失败了。还需要正确使用风速计所需的探头、探头支架和其他附件，因为在我的实验室工作的学生在我的监督下使用了20年后，这些也需要更换。*要求的测量设备*将是我的研究计划的主要部分，该计划涉及一套与湍流中标量混合(例如，温度、化学物质*浓度)相关的补充*项目。具体地说，这项工作涉及以下四个研究项目：1)背景湍流对自由剪切流混合的影响的量化，2)湍流内多标量的同时混合，3)多孔表面/边界上的标量弥散，以及4)雪和冰表面上的湍流换热的影响。这项研究的结果将与燃烧、环境污染物扩散和气候模拟领域的工作人员直接相关。该研究计划*还将在湍流和一般热流体领域培训HQP，*为当地的航空航天、水电、汽车等行业提供熟练的专业人员。

****** In both nature and the man-made*world, turbulent flows are the norm, whereas laminar flows are the exception. Fundamental to turbulent flows is their*capacity to rapidly mix mass, momentum or energy – an attribute that underlies*a wide range of processes, including aerodynamics, meteorology, combustion, and*environmental pollutant dispersion. The present proposal requests funding to*refurbish a hot-wire anemometry system, which is the central piece of measurement*equipment in my laboratory, where my research on turbulent mixing is undertaken. A hot-wire anemometer is a state-of-the art*device that measures the velocity of fluid flows with very high spatial and temporal*resolutions, as well providing an unmatched signal-to-noise ratio. It is the tool of choice when one needs to*measure the entire range of scales in turbulent flows, which can exhibit i) length*scales ranging multiples of metres to submillimeter scales, and ii) time scales*spanning ranges from minutes to tenths of milliseconds. *** To continue to make these precise*measurements that are required for my research, two new anemometry channels are*requested to replace the two channels in my system that were purchased nearly*20 years ago, as one has failed and the other is failing. Probes, probe supports, and other accessories*required for proper use of the anemometer are also requested, as these too are*in need of replacement after two decades of use by students working in my*laboratory, under my supervision. *** This requested measurement equipment*will be the workhorse of my research program, which involves a complementary*set of projects relevant to the mixing of scalars (e.g., temperature, chemical*species concentration) in turbulent flows. Specifically, this work involves*four research projects pertaining to: 1) quantification of the effect of*background turbulence on the mixing within free-shear flows, 2) simultaneous*mixing of multiple scalars within turbulent flows, 3) scalar dispersion over a*porous surface/boundary, and 4) effect of turbulent heat transfer above snow*and ice surfaces. The results of this*research will be of immediate relevance to workers in the fields of combustion,*environmental pollutant dispersion, and climate modelling. The research program*will also train HQP in the fields turbulent flows, and thermofluids in general,*supplying skilled professionals to the local aerospace, hydropower, automotive,*etc. industries.