As conventional aircraft designs approach their limits in terms of efficiency and emissions,a drastic change to the architecture of conventional platforms is required if the environmentaltargets of the next several decades are to be met. Boundary Layer Ingestion is one of industry’smost promising answers to the challenges of the future, identifying a potential step-change inperformance in more integrated propulsion and airframe systems. This paper investigates thebehaviour of a boundary layer ingesting solution of a closely embedded wing-electric ductedfan design, with focus on the implications of the aerodynamic coupling on the individualperformance of both the aerodynamic and propulsive elements as well as on the assessment ofthe reliability of a low order panel code method. Wind tunnel testing was undertaken tounderstand the flow physics at different combinations of airframe and propulsor operatingconditions; in addition, part of the data used for the experimental validation of a panel methodmodel for predicting the upstream inlet flow conditions. It was found that there were clear localand extended upstream effects of the propulsor on the performance of the aerodynamicsurface, resulting from the different combinations of suction strength and nacelle blockage.Similar trends were observed in the numerical code predictions, and identified limitations ofthe methodology in defining the experimental boundary conditions of the propulsor to beimposed in CFD. The study of the response of the propulsor to varying inlet boundaryconditions, created by varying wing angles of attack was also carried out, however, smallchanges in flow velocity combined with measurement errors of the current system, preventedany solid conclusions being drawn about the impact of distorted inlet flow on propulsorperformance.
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