In comparison to the case with no ground effect, the airfoil situated close to the ground enhanced power extraction efficiency. The findings indicated that the ground influenced both force behavior and power extraction performance. The IB-LBM was used to perform numerical simulations. The simulation was performed at a Re of 1100, with a two-dimensional laminar flow system and a harmonic plunge and pitch rotating motion imposed. 23, 24 numerically simulated the power extraction mode of the NACA0015 airfoil close to the ground. Accordingly, the vortices might be compressed to oblate shape and propagate obliquely in the wake. As the frequency of oscillation rose, the vortex interaction became increasingly more.
Furthermore, the vortex formed by the foil interacted with that caused by the ground. Whenever the foil was put near the ground, there was a significant decrease in drag and an increase in lift compared with the scenario with no ground. According to the findings, the ground influenced both force behaviors and flow patterns. The IB-LBM was employed for numerical simulation at Re =150. In order to simulate the motion of the insect wing cross-section, a standard NACA0012 airfoil with harmonic plunge and pitch rotation was used. 22 evaluated the contribution of the ground effect on the flapping insect wing in forward flight. They determined that flapping close to the ground increases lift force by 47% while decreasing drag force by 20%. 21 studied the flapping-flying model relying on the actual behaviors of the birds under the ground effect. This study offered physical insight into an understanding of aerodynamics and flow structures for insect typical hovering flight with a ground effect, as well as flying mechanics related to insect perching on the body. The ground effect was found to alter thrust under three regimes: force increase, decrease, and recovery. Using an Immersed Boundary-Lattice Boltzmann Method (IB-LBM), Gao and Lu 20 explored the ground effect during the regular hovering flight of elliptic foil. They revealed that the lift in dynamic ground effect (DGE) was greater than static ground effect (SGE) they also explained the phenomenon of lift amplification in DGE. The \(C_l\)/ \(C_d\) increases by reducing the airfoil and ground distance, especially at \(h_\) utilizing a finite volume technique. The results indicate a direct relationship between the airfoil’s aerodynamic performance ( \(C_l\)/ \(C_d\)) and the ground effect. Moreover, the impacts of Reynolds number ( Re), Strouhal number ( St), and average ground clearance of the flapping airfoil are investigated. Dragonfly-inspired and NACA4412 airfoils are selected in this research to assess the geometry effect on aerodynamic efficiency. The analysis is carried out on the basis of an unsteady Reynolds-averaged Navier-stokes (URANS) simulation, whereby the Transition SST turbulence model simulates the flow characteristics.
Thus far, the aerodynamic efficiency of the dragonfly-inspired flapping airfoil has not been challenged by an asymmetric cambered airfoil considering the ground effect phenomenon, especially in the MAV flight range.
This research numerically investigates the flapping motion effect on the flow around two subsonic airfoils near a ground wall.
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