Effect of Optimized Roughness Distribution Elements on the Behavior of Phase portrait Circuits in Critical Reynolds

Optimization of the height and length distribution of roughness elements as an effective passive flow control tool was investigated in the current study. The purpose of this paper was to investigate the roughness element's effect and its location on upstream of the laminar separation bubble from phase portrait point of view. Consequently, the effect of the roughness element features on the bubble's behavior is considered on the vortices behind the NASA-LS0417 cross-section at the pre-stall angles. The consequences express that the distribution of roughness in the appropriate dimensions and location could contribute to increasing the performance of the aerofoil and the interaction of vortices produced by roughness elements with shear layers on the suction side. It is worth noting that due to the small size and low velocity of the flight of MAVs, the formation of the well-known phenomenon of laminar separation bubble is almost imminent. Since this phenomenon greatly affects the aerodynamic performance and patterns of the Phase portrait circuit, its recognition, investigation and control can be a key parameter. In the meantime, the results show the emergence of nested loops from the Phase portrait circuit due to flow arrangement changes. Also, the distribution of roughness in the appropriate dimensions and location can be recognized as a factor that helps to increase the performance of the aerofoil, and can be the basis of the work of MAV designers.