Analysis of Hybrid Air Vehicles Using Computational Fluid Dynamics

Abstract

This paper presents an aerodynamic study of bodies related to lighter than air vehicles, using Computational Fluid Dynamics. The work begins with the validation of the CFD method using a 6:1 prolate spheroid. The validated method is then employed for the study of the flow around a shape similar to the Airlander aircraft of Hybrid Air Vehicles Ltd. An overview of the flow around is presented, supported by pressure survey, flow visualisation and transitional flow effects. The sensitivity of the transition location to the Reynolds number is also demonstrated, and the role of each component of the vehicle is analysed in terms of its effect on the flow-field, the lift and drag, and stability in pitch. It was found that the fins contributed the most to increase the lift and drag coefficients.

Study of Hybrid Air Vehicle Stability Using Computational Fluid Dynamics

“…Nevertheless, an improvement was obtained by including the tail aerodynamic surfaces, as C α My dropped by about 50% both at small and high pitch angles. These results are in good agreement with earlier works for the same vehicle [9]. It should be mentioned that in the present study the front and rear thrusters, that may affect the stability of the vehicle, were not accounted for in the simulations.…”

“…Note that a grid refinement study was performed for this multi-lobe body in Ref. [9]. The length L of the multi-lobe body is representative of a large-scale vehicle and is approximately 120 m, the total width is 60 m and the three spheroids occupy a volume of 100, 000 m 3 .…”

“…In addition, CFD has been hardly used in the literature in the analysis of this type of aircraft [9] and this is also the case for stability studies using CFD instead of simpler aerodynamic models.…”

“…The first two approaches are costly and difficult to perform accurately. In addition, the flows around airships are highly vortical [9] and these large vortical structures need to be accounted for. This is possible with potential flow theory, but it requires extensive corrections and geometry simplifications.…”

A study on the aerodynamic characteristics of a stratospheric airship in its entire flight envelope

“…Dumas et al 16 and Kaluvan et al 17 conducted CFD simulation of an unconventional high altitude airship, which belongs to the MAAT project (Multibody Advanced Airship for Transport). Carrio´n et al 18,19 addressed an overview of the flow around a hybrid air vehicles based on the CFD analysis and evaluated the contribution of each component (hull and fins).…”