Blended Wing Body Propulsion System Design

This research paper focuses on the optimization of the propulsion system of a blended wing body design. Two different aspects of the design, the engine placement and count, and the engine itself, are investigated. The preliminary wing of the BWB is created through aerodynamic analysis, and is kept as a constant over the different propulsion system configurations. The engine parameters are first investigated. Equations are derived to express takeoff distance and climb rate as a function of engine sea level thrust, cruise thrust, and the number of engines. Nearly 150 different engine models, in BWB configurations of 2, 3, 4, and 8 engines, are analyzed from these equations. Engines that satisfy the constraints of less than 3000 meters takeoff run at sea level and climb rates comparable to those of a large modern airliner are then shortlisted, after which the engine with a proper balance of excess thrust and SFC is selected for each case. Six different BWB models are then created in CAD software. Mathematical computations are conducted on each of the models to find maximum takeoff weight, drag coefficient, empty weight, and more. A relative comparison of the lift to drag ratios of the models is also conducted in SolidWorks CFD. The results showed that the 8 engine aft BWB model had the highest lift to drag ratio, but had slightly higher empty weight than four of the designs and a lower maximum takeoff weight and specific fuel consumption than all others