Aerodynamic Force of Coandà Jet on a Curved Surface with Tilted Profile

Abstract

The potential of UAVs to serve as an alternative solution for performing inspection and surveillance is of greater interest when considering lower workforce and operating costs. Coanda effect-based UAV is one of the options. However, the present knowledge on this type of UAV is yet fully explored, such as the profile of the curved surface to harness the utmost lift force augmentation. This paper presents an experimental evaluation of the static lift force due to the changes in the curved surface tilting profile angle subjected to the Coanda jet flow. Two test models (axisymmetric 2D half-hemispherical curved surfaces) are considered in this study; semi-circular surface (Rx/Ry = 1) and semi-ellipse surface (Rx/Ry = 2). The static lift force is quantified through static pressure measurement from 13 pressure tapping points located at the centerline of the test models that are connected to a manometer. From the acquired measurements, the static pressure coefficient and lift coefficient distributions are plotted. The result has shown that altering the tilting angle of the test models has yielded additional static lift, up to about 30%; due to the translation of the concentrated pressure region on the curved surface. It was also shown that the semi-circular surface provides a higher lift output compared to the semi-ellipse surface.