Sandpit: A Study of Practical Abatement Techniques for Exhaust Jets from Commercial Aircraft.

沙坑：商用飞机废气喷射实用减排技术的研究。

• 批准号: EP/H002987/1
• 负责人: Michael Bennett
• 金额: $ 52.57万
• 依托单位: Manchester Metropolitan University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FH002987%2F1
• 关键词: Sandpit; Study; Practical; Abatement; Techniques

We should like to maximize the utility of airports within their existing energy and land usage, but local air quality is often a constraining issue. We note, for example, that long-term mean concentrations of NO2 near Heathrow already attain the EU limit value of 40 ug/m3: this has serious implications for the operation of the proposed third runway. We note also, however, that the concentrations experienced locally from aircraft operations depend quite delicately on the balance between the advection of aircraft exhausts away from the airport and their buoyant rise away from the ground. The net result is that the highest surface concentrations occur for wind speeds of 6-8 m/s. Such a brisk wind is already rather infrequent (the mean wind speed at Heathrow is only ~4.4 m/s), so any enhancement to the buoyant rise of exhaust emissions would reduce disproportionately the impact of aircraft emissions on the local environment. The most significant part of the operational cycle from the point of view of local air quality is the start of the take-off run: the engines are on full power at this point, while the aircraft is only moving slowly. We have studied this part of the cycle in a series of field trials over the last few years (using a laser scanner - Lidar) and have observed the buoyant rise of the exhaust jet. We have also developed a theoretical model to describe our observations.It transpires that the time from the point of emission to the point at which buoyant rise becomes dominant may be scaled with the ratio of the engines' thrust to their thermal emission. To enhance plume lift-off, we should like this ratio to be as small as possible. Clearly, we can do nothing about the engines themselves, but we may be able to influence the jet that emerges from them, i.e. add heat or remove momentum. Adding a significant amount of heat is not a practical proposition (the thermal output from a commercial jet aircraft is of order 100 MW). Removing momentum, however, should be quite feasible: we merely have to aerodynamically roughen the airfield surface. It transpires that the runway surface is aerodynamically smooth at the Reynolds numbers typical of flow within the exhaust jet. Only 10-20% of the jet thrust is thus lost to the surface in the near field. We propose therefore to install an array of baffles or wind breaks in the runway strip behind the start of the runway. These will make the surface aerodynamically very rough and significantly enhance the loss of momentum from the plume to the ground.The project will comprise a series of stages. We will start with a theoretical analysis analysing the aerodynamics of the process and prescribing the aerodynamic parameters of an effective array of baffles; model arrays will then be tested in the wind tunnel at Cranfield. When we have a working model, we shall then devise an agreed design which can be installed temporarily at Cranfield Airfield. We will also assess the proposed array acoustically using the facilities at ISVR at Southampton.Once the certification process is complete, we will install the array on airfield at Cranfield and measure its effect on the exhaust plume from the FAAM aircraft. Field trials using Lidar will measure the dispersion parameters of the plume (height, spread) at the distance of the boundary fence. (From trials sponsored by the Omega consortium, we already have some base measurements of the exhaust plume in the absence of the arrays ). We shall also use the trials to test our acoustic modelling of the impact of the array.If the baffles are made of porous wind break material rather than being solid, then with suitable coatings they may be used to absorb pollutant species (PM and NOx) from the exhaust. We will model this effect as part of the project, recommending appropriate surface-active coatings and possibly observing their effectiveness on a small scale in the field.

我们希望在现有能源和土地使用的情况下，最大限度地发挥机场的效用，但当地的空气质量往往是一个制约因素。例如，我们注意到，希思罗机场附近二氧化氮的长期平均浓度已经达到了欧盟的限值40微克/立方米：这对拟建的第三条跑道的运行有严重影响。然而，我们也注意到，飞机运行在当地所经历的浓度，相当微妙地取决于飞机废气远离机场的平流和它们远离地面的浮力上升之间的平衡。净结果是，风速为6-8米/秒时，地表浓度最高。这样的大风已经相当罕见了（希思罗机场的平均风速只有~4.4米/秒），所以任何对废气排放的增强都将不成比例地减少飞机排放对当地环境的影响。从当地空气质量的角度来看，运营周期中最重要的部分是起飞运行的开始：此时发动机处于全功率状态，而飞机只是缓慢移动。在过去的几年里，我们在一系列的现场试验中（使用激光扫描仪-激光雷达）研究了这个循环的这一部分，并观察到了排气射流的浮力上升。我们还开发了一个理论模型来描述我们的观察结果。结果表明，从发射点到浮力上升占主导地位的时间可以按发动机推力与热辐射的比值进行缩放。为了提高羽流的升力，我们希望这个比值尽可能小。显然，我们对发动机本身无能为力，但我们也许能够影响从发动机中喷出的喷气，即增加热量或减少动量。增加大量的热量并不是一个实际的建议（一架商用喷气式飞机的热量输出约为100兆瓦）。然而，消除动量应该是相当可行的：我们只需要在空气动力学上使机场表面变得粗糙。结果表明，在典型的排气射流内流动雷诺数下，跑道表面在空气动力学上是光滑的。因此，只有10-20%的喷气推力在近场中损失到表面。因此，我们建议在跑道起点后面的跑道跑道上安装一系列挡板或挡风板。从空气动力学的角度来看，这将使表面变得非常粗糙，并大大增加了从羽流到地面的动量损失。该项目将包括一系列阶段。我们将从理论分析开始，分析过程的空气动力学并规定有效挡板阵列的空气动力学参数；然后，模型阵列将在克兰菲尔德的风洞中进行测试。当我们有一个工作模型时，我们将设计一个可以临时安装在克兰菲尔德机场的商定设计。我们还将使用南安普顿ISVR的设施对拟议的阵列进行声学评估。一旦认证过程完成，我们将在克兰菲尔德机场安装阵列，并测量其对FAAM飞机排气羽流的影响。使用激光雷达的实地试验将测量在边界栅栏距离处羽流的色散参数（高度、扩散）。（从欧米茄联盟赞助的试验中，我们已经在没有阵列的情况下对排气羽流进行了一些基本测量）。我们还将使用这些试验来测试我们对阵列影响的声学建模。如果挡板是由多孔防风材料而不是固体材料制成的，那么在适当的涂层下，它们可以用来吸收废气中的污染物（PM和NOx）。作为项目的一部分，我们将对这种效应进行建模，推荐合适的表面活性涂层，并可能在小规模的现场观察它们的有效性。

项目成果

Aviation operations and climate change impacts: the Airport Energies Technologies Network response

航空运营和气候变化影响：机场能源技术网络响应

• 作者: Tim Ryley (Author)

Large Eddy Simulations of Turbofan Engine Exhaust Plume Dispersion on Take-Off Runway

涡扇发动机起飞跑道排气烟流扩散的大涡模拟

• DOI: 10.1115/gt2013-95006
• 发表时间: 2013
• 作者: Spanelis A

Wind Tunnel Modelling of Aerodynamic Baffle Arrays for Aircraft Exhaust Plume Control

• 发表时间: 2014
• 作者: S. Velikov

Studies of urban air quality using electrochemical based sensor instruments

使用基于电化学的传感器仪器研究城市空气质量

• 发表时间: 2012
• 作者: Popoola Olalekan Abdul Muiz

The application of an aerofoil array to enhance the dispersion of an extended surface-based pollution source

应用机翼阵列增强大范围地表污染源的消散

• 发表时间: 2014
• 作者: Bennett M