The aviation sector is experiencing an increasing pressure to reduce emissions via long-term strategies for a ceaselessly growing number of flight passengers. Aircraft currently in operation have typically been designed by considering the airframe somewhat separately from the propulsion system. In doing so, conventional aero-engine architectures are approaching their limits in terms of propulsive efficiency, with technological advancements yielding diminishing returns. A promising alternative architecture for improving the overall performance of the next generation of commercial aircraft relies upon boundary layer ingestion (BLI). This technology aerodynamically couples the airframe with a strategically positioned propulsion system to purposely ingest the airframe’s boundary layer flow. Nonetheless, there is a lack in consensus surrounding the interpretation and quantification of BLI benefits. This is primarily because conventional performance accounting methods breakdown in scenarios of strong aerodynamic coupling. Subsequently, there is a major challenge in defining appropriate performance metrics to provide a consistent measurement and comparison of the potential benefits. This review examines the various accounting methods and metrics that have been applied in evaluating BLI performance. These are discussed and critiqued in the context of both numerical and experimental models. Numerically, the geometric, aerodynamic and propulsive models are sorted by their orders of fidelity along with the plenitude of methods used for flow feature identification enabling a phenomenological understanding of BLI. Particular attention is then given to experimental BLI models with their different set-ups, methods and associated limitations and uncertainties. Finally, the numerous unconventional BLI aircraft concepts are categorised, compared and critiqued with reference to their associated design exploration and optimisation studies.

航空业正面临越来越大的压力，需要通过长期战略为不断增长的飞行乘客减少排放。目前运行中的飞机通常在设计时将机身与推进系统分开考虑。在这样做的过程中，传统的航空发动机架构在推进效率方面正接近其极限，技术进步产生的收益递减。用于提高下一代商用飞机整体性能的有前途的替代架构依赖于边界层摄取 (BLI)。该技术将机身与战略定位的推进系统进行空气动力学耦合，以有目的地吸收机身的边界层气流。尽管如此，围绕 BLI 益处的解释和量化缺乏共识。这主要是因为传统的性能核算方法在强空气动力耦合的情况下会失效。随后，在定义适当的性能指标以提供一致的测量和潜在收益比较方面存在重大挑战。本次审查检查了用于评估 BLI 绩效的各种会计方法和指标。这些在数值和实验模型的背景下进行了讨论和批评。在数值上，几何模型、空气动力学模型和推进模型按其保真度顺序以及用于流动特征识别的大量方法进行排序，从而能够对 BLI 进行现象学理解。然后特别注意具有不同设置、方法和相关限制和不确定性的实验 BLI 模型。最后，参考相关的设计探索和优化研究，对众多非常规 BLI 飞机概念进行分类、比较和批评。