Laser Doppler Anemometer (LDA) replacement

特伦特大学边界层环境风洞(TEWT)是为模拟颗粒物在风中的传输而设计建造的。该设施已投入使用近30年，在风沙输送研究方面处于国际领先地位。它是世界上唯一一家配备了完全气候控制、气温(-10摄氏度至35摄氏度)和相对湿度(3%至85%)变化的同类设施。例如，它能够模拟干旱期间莱斯布里奇一个农场的风蚀；北极零下温度下尾矿池和堆积物的颗粒排放；以及加拿大各地废物管理设施周围空气微塑料运输的季节性变化。我们目前面临的障碍是，我们的LDA处理器在过去13年的风洞操作期间几乎连续运行，出现故障，无法由制造商进行维修。它迫切需要被取代，以便我们能够履行我们的直接义务，维持研究生培训；作为NERC资助的英国同事的项目合作伙伴，在大气中进行微塑料运输实验；并在获得与行业和各种公共机构的合同工作以评估排放率和控制方面保持竞争力。自从2009年通过CFI拨款获得LDA以来，我们每天都使用这台仪器进行研究，NSERC发现拨款资助740,000美元。我们实验室正在研究的颗粒可能包括悬浮状态下长距离(Km)飞行的气溶胶，或者质量足以将其运动限制在低弹道跳跃(Cm)和/或在短距离(Mm)上爬行的较大颗粒。这些污染物可能来自矿物、有机或人为来源，但众所周知，它们都会影响空气质量和人类健康。在我们的日常操作中，我们需要激光多普勒风速仪(LDA)来测量携带和推动目标颗粒的湍流结构以及颗粒云的动力学。与老式技术相比，非接触式2D LDA具有许多优势，因为它快速准确地采样，而不会因为直接在流动中插入钝体仪器而引起流动扰动，特别是可以被颗粒撞击摧毁的仪器。使用这台仪器，我们的实验室第一次捕捉到了直接同步测量，表明被颗粒物饱和的气流增加了湍流强度。我们在未来工作中的首要目标是评估气候变化对加拿大特有的高纬度、寒冷气候地区的风沙输送系统动力学的影响。这项工作将建立在TEWT实验室对基本了解大气边界层流动中粒子传输的关键贡献的基础上。

The boundary-layer environmental wind tunnel at Trent University (TEWT) was designed and constructed for simulating the transport of particulate matter by wind. Nearing three decades in operation, this facility is a well-established international leader in aeolian transport research. It is the only facility of its type in the world that is equipped to run under full climate control with varied air temperature (-10 deg C to 35 deg C) and relative humidity (3% to 85%). It is capable of simulating, for example, wind erosion on a farm in Lethbridge during a drought; particle emissions from tailings ponds and stockpiles in the arctic at subfreezing temperatures; and seasonal variation in airborne microplastics transport surrounding waste management facilities throughout Canada. The barrier that we currently face is that our LDA processor, which has run almost continuously during operation of the wind tunnel over the last 13 years, is malfunctioning and cannot be repaired by the manufacturer. It urgently needs to be replaced so that we can fulfill our immediate obligations to sustain graduate student training; conduct experiments on microplastics transport in the atmosphere as a Project Partner with NERC funded colleagues in the UK; and remain competitive in obtaining contract work with industry and various public agencies to assess emission rates and controls. Since acquiring the LDA through a CFI grant awarded in 2009, we have used this instrument daily to carry out research supported by $740K in NSERC Discovery Grant funding. Particles under investigation in our lab may include either aerosols that travel over long distances (km) while in suspension, or larger particles with sufficient mass to constrain their motion to low ballistic hops (cm), and/or creep over short distances (mm). These may originate from sources that are either mineral, organic or anthropogenic, but all are well known to influence air quality and human health. In our daily operations we require a Laser Doppler Anemometer (LDA) to measure the kinetics of both the turbulent airflow structure, which entrains and propels the particles of interest, as well as the particle cloud. A non-contact 2D LDA offers many advantages over older technologies in that it samples rapidly and accurately without inducing flow perturbation caused by inserting a bluff body instrument directly in the flow, particularly one that can be destroyed by particle impact. Using this instrument, our lab was first to capture direct synchronous measurements showing that airflows saturated with particulate matter have increased turbulence intensity. Our overarching aim in future work is to assess the effects of a changing climate on the kinetics of aeolian transport systems that exist throughout high latitude, cold climate regions characteristic of Canada. Such work will build on the pivotal contributions of the TEWT lab toward fundamental understanding of particle transport in atmospheric boundary-layer flows.