Multidisciplinary Design Optimization for a Blended Wing Body Transport Aircraft with Distributed Propulsion.

摘要

A distributed propulsion concept for aircraft is considered. The concept involves replacing a small number of large engines with a moderate number of small engines and ducting part of the engine exhaust to exit out along the trailing edge of the wing. Models to describe the effects of this distributed propulsion concept were formulated and integrated into an MDO formulation. The most important effect modeled is the impact on the propulsive dynamic/propulsion system, resulting in an increased propulsive efficiency. Other models formulated include the effect of the trailing edge jet on the induced drag, longitudinal control through thrust vectoring of the trailing edge jet, increased weight due to the ducts, and thrust losses within the ducts. The Blended Wing Body (BWB) aircraft was used as a testbed to study the distributed propulsion concept. Two different BWB configurations were optimized. A conventional propulsion BWB with four pylon mounted engines and a distributed propulsion BWB with eight boundary layer ingestion inlet engines. The results show that significant weight penalty is associated with the distributed propulsion system that realistically cannot be overcome by the potential savings by effects on the induced drag, elimination of trailing edge flaps, and by filling in the wake.