Abstract
The present study focuses on producibility and surface roughness characteristics of airfoil geometries and their effect on aerodynamic performance for different velocities, surface roughness values and angles of attack. Two different tray orientations (along X and Y axis), two different build directions (vertical and horizontal) and two different surface finish settings (matte and glossy) were used to evaluate the effect of these parameters on the surface roughness of both up- and down-facing surfaces of airfoils produced by PolyJet. On both surfaces, surface roughness measurements were performed on two crossing directions. The results showed that horizontal build direction where surfaces of airfoils were parallel to the build platform experienced lower surface roughness than the vertical build direction. Vertically oriented specimens showed a considerable degree of distortions especially in trailing edges along with very high surface irregularities on side walls. In general, glossy or matte finish settings resulted in similar surface roughness values and specimens located along X direction showed better surface quality than specimens located along Y direction with an inconsiderable difference. Besides this, CFD analysis revealed that surface roughness caused by printing strategies directly influences the aerodynamic performance of the fixed-wing UAVs (Unmanned Aerial Vehicles) to considerable degrees. The increase in the drag force coefficient, due to surface roughness, reached almost 7.5% for high cruise velocity at 0° angle of attack and 13% at 10° angle of attack in which stall commences.
Highlights
Unmanned aerial vehicles (UAV) are flying robots that fly remotely or autonomously without carrying a human operator [1]
For vertically oriented samples, when measurements were performed along the Z axis, parallel to the build direction, a higher amount of surface roughness values were observed than values taken along the X or Y axes
The experimental part of study focused on the effect of tray location, build direction and surface finish options on surface roughness values of airfoil geometries printed in PolyJet
Summary
Unmanned aerial vehicles (UAV) are flying robots that fly remotely or autonomously without carrying a human operator [1]. Among different UAVs, especially small or mini UAVs, they find their usage in different industries and applications (search and rescue operations, security and surveillance purposes, air pollution detection, road traffic monitoring, delivery of goods, agriculture, photogrammetry and remote sensing purposes, etc.) due to their low cost and simplicity of operation [2,3,4]. P.S. and Jeyan reviewed the classifications of small UAVs in terms of operating altitude, endurance, operating range, maximum take of weight and payload. Their review revealed that an average operating range of 30–40 km, an average operating altitude of 3500 m, an average endurance of 3–4 h and an average maximum takeoff weight of 30 kg can be used as working parameters in UAV applications based on the literature [5]
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