Une entree d'air optimisee avec debit moteur ajuste sous la contrainte d'ingestion de couche limite.

摘要

The concept of the Blended-Wing-Body (BWB) offers the possibility of placing the engines at the rear of the plane. Two configurations are possible: one in which the configuration is considered as classical (Pod & Pylon) and a configuration in which the pylon is removed. This configuration has several benefits and could increase the propulsive efficiency of the engines. However, the Boundary Layer Ingestion (BLI) configuration has severe drawbacks, such as the non-uniformity of the flow developing inside the diffuser. The integration of the engines is thus complex due to the tight coupling between the aircraft aerodynamic and the propulsion system.;The main objective of this study is to investigate the impact of the boundary layer ingestion on the propulsion system. This is done by conducting a parametric study on the geometric variables in order to look for an inlet which reduces the distortion of total pressure at the fan face and the fuel consumption. These are the main factors retained for this study and their evaluation requires high-fidelity analyses. A parametric study is conducted on the geometric variables of the diffuser in order to reach this objective. This study is conducted first on a pod configuration (without the pylon) in order to compare the pressure recovery, the distortion and the ram drag for both configurations.;The present study is conducted on a constant section wing, thus ignoring the 3D effects of the Blended-Wing-Body. A parameterization of the inlet is done in order to analyse the influence of some parameters on the distortion and the fuel consumption. An analysis loop is then created, based on the Design of Experiment methodology together with Response Surfaces. A thermodynamic module is directly integrated into the solver (through the UDF – User Defined Functions) for calculating the fuel consumption.;The analysis of the results showed that long diffusers which ingest less boundary layer have better characteristics in terms of distortion and fuel consumption. The present study also shows the large effect of the shape of the inlet on the distortion. A variation of 36% was noticed inside the design space. The variation is smaller for the pressure recovery, the ram drag and the fuel consumption (between 0.75% to 1.2%). The distortion inside the design space is still too high and an acceptable level of distortion can't be reached only by modifying the shape of the diffuser.