Numerical Study of Aerodynamics and Flow Physics of the 30P30N Three-Element Airfoil in Dynamic Ground Effect

Abstract

The ground effect aerodynamics of high lift devices is very important for the safe take-off and landing of large aircrafts. The flow fields around the 30P30N three-element airfoil in static ground effect (SGE) and dynamic ground effect (DGE) are simulated by solving the Reynolds Averaged Navier-Stokes equations and the Spalart-Allmaras turbulence model. The relative motion between the airfoil and the ground in DGE is dealt with by the dynamic laying mesh technology. The lift in SGE and DGE decreases with the reduction in ride height.For large ride heights, the lift in DGE is the same as the value in the SGE with the same angle of attack (AOA). For small ride heights, the lift in DGE is larger than that in the SGE with the same AOA, which is due to additional pressure increment on the lower surface resulting from the compression work. The flow velocity in the gaps of 30P30N in DGE is bigger than that in SGE with the same AOA, which is due to the larger pressure difference between the lower and supper surfaces as a result of the compression work. Nomenclature c = chord length of the clean airfoil C p = pressure coefficient C L = lift coefficient h = ride height, i.e. the distance from the trailing edge of the airfoil to the ground l = local coordinate in the gap Ma = Mach number Re = Reynolds number based on the clean airfoil chord U = local velocity U ∞ = free stream velocity U v = airfoil sinking velocity α = angle of attack (AOA) γ = flight path angle θ = pitch angle ΔC L = the increment of lift coefficient

Experimental investigation of the ground effect on a wing without/with trailing edge flap

“…Except for take-off and landing, aircraft can have some missions require operating close to the ground such as sailplanes. Some of the deepest investigations of the impact of ground effect on the aerodynamic characteristics of wings were realized by Qu et al (2014Qu et al ( , 2015aQu et al ( , 2015bQu et al ( , 2015cQu et al ( , 2016aQu et al ( , 2016b they focused on both dynamic/static ground effect to simulate numerically the landing operation of a NACA 4412 and 30P30N three-element airfoils and found that at the same angle of attack, simulation case with the dynamic ground where compression work effect is higher, gave the best results. Jung et al (2012b) studied numerically with a moving-ground boundary condition several aerodynamic characteristics to specify the best airfoil performance, clearance, angle of attack and the range of Re number, it has been conclusively demonstrated that NACA4406 with its small thickness produced higher lift coefficient and its performance is better at small angles of attack and minimal clearance.…”