Abstract
Diamond wing configurations for low signature vehicles have been studied in recent years. Yet, despite numerous research on highly swept, sharp edged wings, little research on aerodynamics of semi-slender wings with blunt leading-edges exists. This paper reports on the stall characteristics of the AVT-183 diamond wing configuration with variation of leading-edge roughness size and Reynolds number. Wind tunnel testing applying force and surface pressure measurements are conducted and the results presented and analysed. For the investigated Reynolds number range of 2.1 × 10 6 ≤ R e ≤ 2.7 × 10 6 there is no significant influence on the aerodynamic coefficients. However, leading-edge roughness height influences the vortex separation location. Trip dots produced the most downstream located vortex separation onset. Increasing the roughness size shifts the separation onset upstream. Prior to stall, global aerodynamic coefficients are little influenced by leading-edge roughness. In contrast, maximum lift and maximum angle of attack is reduced with increasing disturbance height. Surface pressure fluctuations show dominant broadband frequency peaks, distinctive for moderate sweep vortex breakdown. The experimental work presented here provides insights into the aerodynamic characteristics of diamond wings in a wide parameter space including a relevant angle of attack range up to post-stall.
Highlights
IntroductionThe understanding of the complex flow field for low/moderately swept wings (leading-edge sweep angles in the range of φ = 45◦ –55◦ ) is essential for designing modern low-radar signature uninhabited aerial vehicles (UAV) [1]
The understanding of the complex flow field for low/moderately swept wings is essential for designing modern low-radar signature uninhabited aerial vehicles (UAV) [1]
The experimental results are presented in form of crossflow vorticity distribution, global and local aerodynamic coefficients
Summary
The understanding of the complex flow field for low/moderately swept wings (leading-edge sweep angles in the range of φ = 45◦ –55◦ ) is essential for designing modern low-radar signature uninhabited aerial vehicles (UAV) [1]. The flow field around this wing constitutes a vortex system that differs to some extent from “classical” leading-edge vortex separation from a sharp edge of a slender swept wing (sweep angle φ > 60◦ ), for which extensive investigations have been conducted [3]. Concerning vortex breakdown, early investigations [4,5] demonstrated a strong dependence on the leading-edge sweep angle φ, and small effect of the trailing edge sweep angle. Vortex breakdown is shifted downstream with increasing leading-edge sweep, this leads to an increase in maximum lift coefficient and corresponding angle of attack.
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