Particle Transport and Losses in Sampling Aircraft Gas Turbine Engine Combustion Emissions

飞机燃气轮机燃烧排放采样中的颗粒传输和损失

• 批准号: 2440391
• 金额: --
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2440391
• 关键词: Particle; Transport; Losses; Sampling; Aircraft

Aircraft gas turbine engine produce soot emissions through combustion. Soot is considered to have negative impacts on both public health and the environment. To combat the impacts, regulations have been introduced by the ICOA and enforced by international regulators, such as EASA. The regulations - specifically APR6320 - stipulates how to sample and measure the soot particles, and this has led to collaborations between engine manufacturers, regulators, and universities to develop a sampling system. Currently, the sampling system uses aerosol instrumentation to measure the number and the mass of soot particles at the exit plane of the engine. However, the sampling of soot is still largely unquantified due to losses witnessed throughout the system - especially at the probe. Penetration curves indicate that smaller particles are not sampled as they do not penetrate far enough through the sample system. Although there has been various loss models developed (LLCA, UTRC, etc..), small soot particle (below 15 nm in diameter) loss remains uncertain, as the models extrapolate for particles below 15 nm. Due to the size of the soot particles being lost and the temperature gradients between the hot emissions and the sampling system, it is speculated that the losses are mostly due to diffusion and thermophoretic loss mechanism. To fully study small soot particle loss, the sampling point will need to be moved to just outside the combustion chamber. Sampling from this point will isolate small soot particles before they agglomerates and coagulates to form long chains (larger than 15 nm in diameter) and allow a better understanding of soot particle formation processes near the combustion chamber. As sampling from this area has not been done before, there will be several challenges, mainly developing a probe that can withstand the harsh environment (temperatures of 1100 K). This project will be split into two main objectives; experimentally quantifying the soot losses and transport when sampling close to the combustion zone and the development of an 2020/2021 Fergus Lidstone-Lane effective model to account for small soot particles. The experimentation will be conducted using various aerosol instrumentation - CPC for number concentrations, LII and MSS for mass measurements, and DMA and ACC for size measurements. Experimentation will mostly be conducted on various combustion test rigs, where it is easier to isolate specific combustion conditions and allows direct access to the combustion zone. For the modelling, there will be both development of current loss models to account for small soot losses and more advanced 3D CFD models. The first steps of the modelling process will be to challenge current assumptions - such as, assuming all soot has a density of 1 g/cm3 - with theory and experimental results to check the models validity when considering small soot particles. This process will become iterative as new experimental results are obtained and feed into the models. Due to the concerns around emissions, it is key that throughout this project responsible innovation needs to be considered. The main concern is that the unquantified amount of small soot particles being emitted is significantly larger than expected. Resulting in policy change which could be potentially damaging for engine manufacturers, or more likely result in design change for more efficient engines.

飞机燃气涡轮机发动机通过燃烧产生烟尘排放。烟尘被认为对公众健康和环境都有负面影响。为了应对这些影响，ICOA制定了相关法规，并由EASA等国际监管机构强制执行。该法规-特别是APR 6320-规定了如何采样和测量烟尘颗粒，这导致发动机制造商，监管机构和大学之间的合作，以开发一个采样系统。目前，采样系统使用气溶胶仪器来测量发动机出口平面处的烟尘颗粒的数量和质量。然而，由于整个系统中的损失，特别是在探头处的损失，烟尘的采样在很大程度上仍然没有量化。穿透曲线表明，较小的颗粒没有被采样，因为它们没有穿透样品系统足够远。虽然已经开发了各种损失模型（LLCA、UTRC等），小的烟灰颗粒（直径小于15 nm）损失仍然不确定，因为模型外推小于15 nm的颗粒。由于碳烟颗粒的尺寸损失和热排放和采样系统之间的温度梯度，据推测，损失主要是由于扩散和热泳损失机制。为了充分研究小的碳烟颗粒损失，采样点将需要移动到燃烧室的外面。从该点取样将在小烟灰颗粒聚集和凝结形成长链（直径大于15 nm）之前分离它们，并允许更好地理解燃烧室附近的烟灰颗粒形成过程。由于以前从未在该地区进行过采样，因此将面临几项挑战，主要是开发一种能够承受恶劣环境（1100 K的温度）的探头。该项目将分为两个主要目标;实验量化烟尘损失和运输时，采样接近燃烧区和2020/2021年的费尔格斯Lidstone-Lane有效模型的发展，以考虑小烟尘颗粒。将使用各种气溶胶仪器进行实验- CPC用于数浓度，LII和MSS用于质量测量，DMA和ACC用于尺寸测量。实验将主要在各种燃烧试验台上进行，在那里更容易隔离特定的燃烧条件，并允许直接进入燃烧区。对于建模，将开发当前的损失模型以考虑小的烟尘损失和更先进的3D CFD模型。建模过程的第一步将是挑战当前的假设-例如，假设所有烟灰的密度为1 g/cm 3-用理论和实验结果来检查模型在考虑小烟灰颗粒时的有效性。随着新的实验结果的获得和输入模型，这个过程将变得迭代。由于对排放的担忧，在整个项目中，需要考虑负责任的创新是关键。主要的问题是，未量化的小烟尘颗粒排放量明显大于预期。导致政策变化，这可能对发动机制造商造成潜在损害，或者更可能导致更高效发动机的设计变化。