UAV Air Intakes

Improved aerodynamic design


In the present work the second stage of design and improvement of the prototype of the white plane developed from the Department of Thermal Engines of the UPV is shown. Project focused on the remodeling of the central area of ​​the aircraft based on the new propulsive system and the external aerodynamic improvement.

The design of the air intakes, according to flight specifications, has been one of the main tasks carried out during this stage. The objective, the proposal and study of a first design version of the diffuser. The behavior and conditions of the air at the inlet of the engines have been calculated through numerical simulation.

The study cases used for the geometric specification of the external fuselage and the air intakes are two, cruise flight and takeoff. Critical flight conditions due to their relevance regarding the efficiency and behavior of the aircraft.

The results obtained will serve as validation of the external aerodynamic improvement, as well as the basis for a final design proposal for the air intakes. This task, as well as the rest of the pending future work, will be carried out during future design stages.

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As the first phase of this second design stage, the aerodynamic remodeling of the entire central area has been carried out, respecting the wing floor, due to the implementation of a new propulsive system. Both engines are placed one above the other and in the plane of symmetry of the aircraft.

The design process has followed two lines of action. The redesign of the external fuselage and the specification of the nozzles, as well as the air intakes, to adapt the chosen engines to the modified prototype. To ensure the correct operation of the propulsion plant, the air intakes must be validated from the aerodynamic point of view together with the rest of the aircraft.


Through fluid simulation it is possible to characterize the behavior of air under different flight conditions. In this way, and through an iterative process, it is possible to adapt the geometry to obtain the desired results during the design phase. Despite not being a good initial design proposal, thanks to these results and the fluid simulation, design flaws have been detected, as well as improvement actions.


On the one hand, the results obtained show the improvement of the external aerodynamic behavior. The new design for the central fuselage is capable of perfectly adapting the passage of air, thus improving the aerodynamic efficiency of the aircraft. However, the design proposal for the air intakes needs to be improved. In this case, there is a detachment of the flow, just at the entrance of the diffuser, which causes the generation of vortices. This phenomenon must be avoided to ensure the correct intake of air to the motors.


Vortex generation occurs under all flight conditions. This phenomenon affects the advance of the air flow inside the ducts, deflecting it and causing a turbulent behavior. To ensure the correct operation of the engines, the geometry of the air intakes must be modified.

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