Effect of a fuselage boundary layer ingesting propulsor on airframe forces and moments

The aim of this research project was to investigate the benefits of hybrid-distributed propulsion and boundary layer ingestion applied to an airliner similar in size, range and cruise velocity to an Airbus A320. The power system selected consisted of two under-wing mounted conventional turbofans and an electrically driven boundary layer ingesting fan, located at the rear fuselage. The power required to drive the fan is extracted from both turbofans. The worked carried out and presented in this paper offers a new approach to modelling boundary layer ingestion configurations, consisting of using the sliding mesh method to simulate the rotation of the blades within an airflow. The simulations were performed in two phases. The first stage corresponded to the analysis of an isolated configuration, where fuselage and electric fan were considered to be far away from each other such that there is no aerodynamic interference between the fuselage and the electric fan. During the second phase, the simulations were conducted with the electric fan integrated with the airframe, ingesting the boundary layer around the fuselage. The simulations indicate that ingesting the boundary layer results in remarkable improvements reducing drag and increasing propulsive force, reaffirming the potential of this technology to reduce fuel consumption. However, the results also registered a substantial increment in the pitching, rolling and yawing moments in the integrated configuration with respect to the isolated arrangement. This gain needs to be accounted for during early stages of the design process to maintain the stability and control of the aircraft within acceptable margins.