Innovative Propulsion Systems and CFD Simulation for Fixed Wings UAVs

Abstract

Nowadays, mobile applications demand, in large extent, an improvement in the overall efficiency of systems, in order to diversify the number of applications. For unmanned aerial vehicles (UAVs), an enhancement in their performance translates into larger payloads and range. These factors encourage the search for novel propulsion architectures, which present high synergy with the airframe and remaining components and subsystems, to enable a better UAV performance. In this context, technologies broadly examined are distributed propulsion (DP), thrust split (TS), and boundary layer ingestion (BLI), which have shown potential opportunities to achieve ambitious performance targets (ACARE 2020, NASA N+3). The present work briefly describes these technologies and shows preliminary results for a conceptual propulsion configuration using a set number of propulsors. Furthermore, the simulation process for a blended wing body (BWB) airframe using computational fluid dynamics (CFD) OpenFOAM software is described. The latter is examined due to its advantages in terms of versatility and cost, compared with licensed CFD software. This work does not intend to give a broad explanation of each of the topics, but rather to give an insight into the state of the art in modeling of distributed propulsion systems and CFD simulation using open-source software implemented in UAVs.

Design and Determination of Aerodynamic Coefficients of a Tail-Sitter Aircraft by Means of CFD Numerical Simulation

“…The geometric model for the numerical simulation as shown in Figure 11a is composed of two domains: the tail-sitter domain and the air enclosure domain. This model was carried out using the CAD ANSYS DesignModeler, in which, the domain of the tail-sitter was exported from the prototype built in CAD ANSYS SpaceClaim and the air enclosure domain was drawn based on [22,48]; the dimensions are described in Table 5. The computational domain shown in Figure 11b surrounded the tail-sitter aircraft, which has the same dimensions as the design stage.…”

“…The rear wall was considered as the outlet boundary, with a gauge pressure outlet condition of 0 [Pa] (since the absolute pressure is equal to the atmospheric pressure). The other walls (upper, lower, right, and left sides) were considered as symmetry boundary conditions in a similar way to that of [22,48]. This allowed the air velocity to be maintained above zero in the area close to the walls to avoid the hydrodynamic boundary layer effect.…”