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 $2.1\times {10}^6\le Re\le 2.7\times {10}^6$ 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.

Flow control can significantly improve the aerodynamic performances of delta wings. Yet, despite numerous studies of vortex control by leading-edge blowing still little research is focused on the post-stall regime and further consideration of the shear-layer reattachment through flow control is needed. This paper reports on the effects of unsteady jets on the global flow field at a very high angle of attack, α = 45^◦. For this, Detached-Eddy Simulations are conducted and validated with wind tunnel test results. The vortex shedding of the unperturbed delta-wing flow is investigated and compared to the perturbed case. It concludes that unsteady blowing energizes the shear layer and reorders at the same time the shedding mechanism eventually forming a big burst vortex structure that increases the lift significantly.

Manipulation of vortex instabilities for aerodynamic performance increase is of great interest in numerous aeronautical applications. With increasing angle of attack, the leading-edge vortex of a semi-slender delta wing becomes unsteady and eventually collapses, endangering the flight stability. Hence, active flow control by pulsed blowing stabilizes the vortex system, enlarging the flight envelope for such wing configurations. The most beneficial outcome is the reattachment of the separated shear layer during post-stall, contributing to a lift increase of more than 50%. In contrast to high power consuming brute-force actuation, manipulating the flow instabilities offers a more efficient alternative for mean flow field control, which has direct repercussions on the aerodynamic characteristics. However, the flow mechanisms involving jet–vortex and vortex–vortex interactions and the disturbance convection through the flow field are little understood. This paper reports on the unsteady flow field above a generic half delta wing model with a $65°$ sweep angle and its response to periodic blowing. Numerical and experimental results are presented and discussed in a synergistic manner.