A hybrid method for the interior and exterior design of blended-wing-body cabins

Considering the fact that all large commercial aircraft have not changed significantly in their tube–and–wing shape during the past few decades, one would suggest that a completely different configuration is necessary to facilitate a new leap forward in aircraft performance. The blended–wing–body is potentially such an alternative configuration. Existing conceptual design methodologies do not always apply to these configurations since they are often based on empirical relations for, or intensively tailored towards, tube–and–wing configurations. Developing new conceptual design methodologies for the interior and exterior design and analysis of these blended–wing–body configurations forms the main objective of this study. An automatic, fast–turnaround, non–empirical aircraft cabin sizing method, hereafter called Cabin Configurator, has been developed that places all the required elements within aircraft cabins. The dimensions in which the elements are fitted can be sized automatically by the method itself (inside–out approach) but can also be pre–defined by the designer (outside–in approach). Other key differences with existing design methods are the ability to cope with arbitrary cabin shapes such as the trapezium–like blended–wing–body cabin and to exchange seats for galleys and lavatories. The Cabin Configurator has been extensively validated against a large amount of existing tube–and–wing cabins. The average underestimation of the cabin length and cabin width for widebody configurations is found to be 7.8% and 4.4% respectively. For narrowbody configurations, the overestimation of the cabin length is found to be 5.2% where the cabin width is underestimated by 1.9%. No conclusions could be derived about the feasibility of Cabin Configurator results for blended–wing–body cabins due to the lack of well–documented cabin designs in the research field. A fast–turnaround aerodynamic analysis method, hereafter called BWB–Q3D, has also been developed that analyses the wing and fuselage exterior of a blended–wing–body configuration from an aerodynamic perspective. The three–dimensional lift and drag coefficients are estimated by the combination of a vortex lattice method with a two–dimensional airfoil analysis method. An important consideration in the BWB–Q3D methodology is setting the sectional sweep angles of the fuselage to zero, leading to conservative estimations of the drag coefficients. BWB–Q3D has been validated with high–fidelity computational fluid dynamics based on the Reynolds–averaged Navier–Stokes equations. Firm conclusions on the magnitude of the results could not be given. However, a good correlation in global design trends of lift–over–drag ratios has been observed between the results of BWB–Q3D and the high–fidelity computational fluid dynamics. Computations were performed in cruise conditions (Mach 0.7, Mach 0.75 and Mach 0.8) on two different geometries. An extensive analysis of blended–wing–body cabin–sizing approaches has been performed in order to determine the differences in accuracy in a worst-case scenario. The inside–out approach of the Cabin Configurator has been compared with the tube–and–wing–tailored outside–in approach, often pursued in the research field. In analyzing several thousands of cabins, it has been shown that an average overestimation between 7% and 22% in cabin capacity results from following the outside–in design approach. Finally, a new aircraft cabin sizing method has been outlined, the hybrid approach, based on combining cabin width dimensioning with pre–defined cabin length determination. An average decrease of more than 50% in cabin area sizing error is obtained when following this method instead of outside-in. No dedicated interior–sizing tool such as the Cabin Configurator is required, making this method easily applicable within the blended–wing–body research field.Flight Performance and PropulsionAerospace Engineerin