Study of Flow around a Trapezoidal Model of a Small-Sized UAV into Turbulent Wake

Read more Abstract
Investigations of the structure of the flow near the surface of a trapezoidal model of a small unmanned aerial vehicle were carried out when it enters a narrow turbulent wake. All experimental data were obtained in a wind tunnel at subsonic flow velocities. A feature of the work was that the study of the flow around the model was carried out at fullscale (flight) Reynolds numbers. Using the soot-oily visualization method, data on the features of the flow around the model were obtained, taking into account such factors as the angle of attack, the presence and absence of a source of external disturbances that generated a turbulent wake. The experiments were carried out in two flow regimes: at a zero angle of attack, when there are local separation bubbles on the wing, and at a large (supercritical) angle of attack of 18 degrees, when there is a global stall of the flow from the leading edge. It was shown that the turbulent wake has a significant effect on the nature of the flow near the model surface in both cases. Local separation bubbles gradually decrease in size with a decrease in the distance between the sources of disturbances and the wing. Large-scale vortices significantly decrease in geometrical dimensions and shift towards the side edges in the event of a global stall of the flow, thereby increasing the region of the attached flow on the model surface.

Keywords
global flow stall, local separation bubble, turbulent wake, free stream disturbances, three-dimensional boundary layer, trapezoidal flying wing, UAV, natural Reynolds number
Funding
This work was carried out within the framework of the Program of Fundamental Scientific Research of State Academies of Science for 2021–2023 (project no. 121030500149-8)
УДК 532.526

Study of Flow around a Trapezoidal Model of a Small-Sized UAV into Turbulent Wake