EAPSI: Using Tomographic Reconstruction of Liquid-Phase Extinction Measurements to Assess Fuel Spray Breakup Outcomes in Internal Combustion Engines

已知雾化和燃料喷雾过程在很大程度上影响直喷式发动机中的燃烧和排放物形成。为了加速清洁燃烧和燃油效率燃烧技术的开发，必须开发基于物理的预测喷雾模型。在这个项目中，我们计划通过比较计算流体动力学（CFD）模型预测的喷雾破碎结果，如液滴大小和数量密度，与定量喷雾测量，以评估液体燃料喷雾在发动机相关条件下破碎成较小液滴的物理机制。拟议的工作将促进目前和未来的合作与博士迈克尔Brear？澳大利亚墨尔本大学的热力学实验室。布里奥博士的实验室是唯一的定位与我们合作，因为他们专门从事燃烧诊断，并已应用层析重建的光学发射测量层流flames.The拟议的工作的目标是评估流体动力学不稳定性和液体湍流的相对重要性，在直接喷射式内燃机的液体燃料喷雾的破碎使用定量喷雾测量。据推测，在缸内条件下，在完全压缩，空气动力学引起的不稳定性管理喷雾破碎和随后的液滴尺寸。然而，对于早期或晚期注射，我们预计液体顺磁性诱导的分裂在喷雾分裂和液滴形成中发挥更主导的作用。以前，采用CFD喷雾模拟来评估和比较这些喷雾破碎机制中的每一个的预测喷雾形态。因此，需要一种可以量化喷雾破碎结果的测量方法，如液滴尺寸和数密度的联合分布，以评估这些破碎理论的物理有效性。在以前的工作中已经表明，液相激光消光和喷雾形态的预测之间有直接的相关性，并已证明，这种测量技术显示出评估初级喷雾破碎模型的希望。在这个建议中，断层重建2-D激光消光测量将产生3-D空间信息，局部喷雾结构和不对称性的强大的模型验证。这个NSF EAPSI奖是与澳大利亚科学院合作资助的。

Atomization and fuel spray processes are known to largely impact combustion and emissions formation in direct injection engines. In order to accelerate the development of clean-combusting and fuel-efficient combustion technologies, physically-based and predictive spray models must be developed. In this project, we plan to assess the physical mechanism by which a liquid fuel spray breaks up into smaller droplets under engine-relevant conditions by comparing computational fluid dynamics (CFD) model predictions of spray breakup outcomes, such as droplet size and number density, with quantitative spray measurements. The proposed work will foster current and future collaboration with Dr. Michael Brear?s Thermodynamics Laboratory at the University of Melbourne, Australia. Dr. Brear?s lab is uniquely positioned to collaborate with us on this proposal as they specialize in combustion diagnostics and have applied tomographic reconstruction to optical emission measurements of laminar flames.The goal of the proposed work is to assess the relative importance of hydrodynamic instabilities and liquid turbulence on the breakup of a liquid fuel spray in direct injection internal combustion engines using quantitative spray measurements. It is hypothesized that under in-cylinder conditions at full compression, aerodynamically-induced instabilities govern spray breakup and subsequent droplet sizes. However, for early or late injections, we expect liquid turbulence-induced breakup to play a more dominant role in spray breakup and droplet formation. Previously, CFD spray simulations were employed to evaluate and compare the predicted spray morphology for each of these spray breakup mechanisms in isolation. A measurement that can quantify spray breakup outcomes, such as joint distributions of droplet size and number density, is therefore needed to assess the physical validity of these breakup theories. It has been shown in previous work that there is a direct correlation between predictions in liquid-phase laser extinction and spray morphology, and have demonstrated that this measurement technique shows promise of assessing primary spray breakup models. In this proposal, tomographic reconstruction to 2-D laser extinction measurements will be employed to yield 3-D spatial information regarding local spray structure and asymmetry for robust model validation. This NSF EAPSI award is funded in collaboration with the Australian Academy of Science.