Propulsor models for computational analysis of aircraft aerodynamic performance with boundary layer ingestion

In this paper, we assess the effectiveness of different propulsor computational models for use in Reynolds-Averaged Navier-Stokes (RANS) calculations of aerodynamic performance of integrated aircraft configurations with boundary layer ingesting (BLI) propulsion. The range of propulsor models considered include inlet and outlet boundary conditions to produce the desired mass flow through the propulsor, actuator disks, and momentum and energy source distribution descriptions. Two integrated propulsor configurations with aft fuselage BLI are considered: the Aurora D8 “double bubble” configuration and a conventional fuselage with tailcone thruster. The effectiveness of the models is assessed on the basis of predicted inlet stagnation pressure, velocity, and swirl distortions at the fan face and nacelle surface pressure distributions. Numerical results show the importance of the upstream interaction of the fan with the non-uniform inlet flow. Of the propulsor models considered, only the source distribution description captures this effect, and the other more commonly used descriptions yield errors in predicted inlet swirl that can significantly impact BLI propulsor efficiency. From these results, we conclude that prediction of BLI propulsor inlet conditions from integrated configuration computations requires propulsor models that accurately describe the non-uniform response of the fan to the inlet distortion.