In the ASME 2020 TURBO-EXPO Virtual conference, the National Technical University of Athens (NTUA) presented a modelling approach of Boundary Layer Ingesting (BLI) propulsion systems for future aircrafts. A distorted compressor model was created first in PROOSIS utilizing the parallel compressor theory in order to estimate the impact of inlet distortion on fan performance. A BLI propulsor component model was then developed in PROOSIS considering both distortion effects and reduced inlet momentum drag caused from boundary layer ingestion.
A Turbo-electric Distributed Propulsion (TeDP) model based on NASA’s N3-X aircraft concept (Hybrid Wing Body) was eventually set up, consisting of the BLI propulsor model, the associated turboshaft engine model and a representation of the relevant electrical system.
All models were validated through comparison with numerical and/or experimental data. A design point calculation was carried out initially to establish propulsor key dimensions for a specified number of propulsors and assuming common inlet conditions. Parametric design point analyses were then carried out to study the influence of propulsors number and location under different inlet conditions, by varying fan design pressure ratio between 1.15 and 1.5. BLI and non BLI configurations were compared at propulsion system level to assess the BLI benefits.
The results show that maximum BLI gains of 9.3% in TSFC and 4.7% in propulsive efficiency can be achieved with 16 propulsors and FPR=1.5, compared to podded propulsors, while further benefits can be achieved by moving the propulsor array backwards in the airframe.