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.

飞机燃气轮机发动机通过燃烧产生烟灰排放。烟灰被认为对公共卫生和环境都有负面影响。为了打击影响，ICOA引入了法规，并由国际监管机构（例如Easa）执行。该法规 - 特别是APR6320-规定了如何采样和测量烟灰颗粒，这导致了发动机制造商，调节器和大学之间的合作，以开发采样系统。当前，采样系统使用气溶胶仪器来测量发动机出口平面处的烟灰颗粒的数量和质量。但是，由于整个系统中看到的损失，尤其是在探针下，烟灰的采样仍然很大程度上是未量化的。穿透曲线表明，较小的颗粒没有采样，因为它们在样品系统中的穿透不足。尽管开发了各种损失模型（LLCA，UTRC等），但由于模型推断出低于15 nm的颗粒的模型外推，小烟灰颗粒（直径低于15 nm）仍然不确定。由于烟灰颗粒的尺寸正在丢失以及热排放和采样系统之间的温度梯度，因此据推测损失主要是由于扩散和嗜热损失机制造成的。为了完全研究小烟灰颗粒损失，需要将采样点移至燃烧室外。从这点采样将在团聚并凝结以形成长链（直径大于15 nm）之前隔离小烟灰颗粒，并可以更好地了解燃烧室附近的烟灰颗粒形成过程。由于以前没有从该区域进行采样，因此将面临一些挑战，主要是开发一种可以承受严酷环境的探测器（温度为1100 K）。该项目将分为两个主要目标。在接近燃烧区的采样以及2020/2021 Fergus Lidstone-Lane有效模型的开发时，通过实验量化了烟灰损失和运输，以说明小烟灰颗粒。该实验将使用各种气溶胶仪器-CPC进行数量浓度，LII和MSS进行质量测量，DMA和ACC进行尺寸测量。实验将主要是在各种燃烧测试钻机上进行的，在这种燃烧测试台上，可以更容易隔离特定的燃烧条件并直接进入燃烧区。对于建模，将既开发当前的损失模型，以说明小烟灰损失和更高级的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均为1 g/cm3，则具有理论和实验结果，以在考虑小烟灰颗粒时检查模型有效性。随着获得新的实验结果并进食模型，此过程将变得迭代。由于对排放的担忧，需要考虑负责任创新的关键。主要问题是，发射的未量化小烟灰颗粒的数量明显大于预期。导致政策变化可能对发动机制造商有可能损害，或者更有可能导致更有效的发动机的设计变化。