Book-keeping investigations for BLI aircraft

摘要

Due to the high coupling between airframe and engine aerodynamics, new metrics are required to analyse and design aircraft configurations with Boundary Layer Ingestion (BLI). The objective of this work is to evaluate different methods of analysing and quantifying the benefits of BLI and to investigate their applicability in a preliminary design phase. In this context, CFD calculations have been carried out for different propulsor operating points on a simple fuselage with an actuator disk on its trailing edge to model the propulsor. A comparison between different book-keeping methods was performed and focused on the physical analysis of the aerodynamic coupling between the propulsor and fuselage. The power balance approach allows an understanding of the phenomena related to boundary layer ingestion and can be used even at a preliminary design stage. Furthermore, it gives better insights and allows the quantification of the interaction effects between the propulsor and the airframe. The comparison between the isentropic expansion method and the rigorous power balance shows that the isentropic expansion approach gives reasonable results when the interaction effects are limited. The accuracy degrades if inappropriate averaging is applied.