Numerical Investigations of Vortical Flow on Swept Wings with Round Leading Edges

Abstract

The present work is investigating the vortex-dominated flow physics as well as the aerodynamic behavior of swept wing configurations with round leading edges. The research is based on numerical simulations using the computational fluid dynamics method DLR TAU. The target configurations are swept wings of constant aspect ratio, variable leading-edge contours, and leading-edge sweep angles. The work deals with the onset of the vortical flow at the leading edge for constant and variable leading-edge nose radii, the influence of the angle of attack, the leading-edge sweep, and the onflow Mach number. Furthermore, the aerodynamic behavior is analyzed and assessed, as well as the specific flow physics in the vicinity of the vortical flow separation at round leading edges. The objective of the present work is to provide a contribution for the design and assessment of the physical characteristics of swept wing configurations. Furthermore, sensitivities will be given for the design process. In addition, the current investigation provides a deeper understanding of the separation onset process and the flow physics of swept wing configurations with round leading edges. Nomenclaturewing reference length, depth of the wing, m M ∞ = onflow Mach number, equal to a∕U ∞ p = pressure, N∕m 2 q ∞ = onflow dynamic pressure, N∕m 2 Re ∞ = Reynolds number, equal to U ∞ · c ref ∕ν r = radius at nose of the profile, m r N = nondimensional leading-edge contour radius, equal to r∕c ref s = wing semispan, m T = temperature, K t = time, s U ∞ = onflow velocity, m∕s u = local velocity within the flowfield, m∕s x, y, z = Cartesian coordinates, m y W = initial wall distance, distance of first grid point from wing surface, m y = nondimensional value to assess resolution of boundary-layer wall unit, equal to τ W ∕ρ p · y W ∕ν α = angle of attack, deg β = angle of sideslip, deg γ = circulation Δt = discrete time step, s Δx = discrete step in space, m μ = dynamic viscosity, Ns∕m 2 ν = kinematic viscosity, m 2 ∕s ρ = density, kg∕m 3 τ W = wall friction, N∕m 2 φ = wing sweep, deg k∂ρ∕∂tk = density residual, kg∕m 3 s Subscripts le = leading edge r = root ref = reference parameter ∞ = onflow condition

Experimental investigation of the flow structures over a 40° swept wing

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Design and sizing of an aeroelastic composite model for a flying wing configuration with maneuver, gust, and landing loads

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Leading-Edge Roughness Affecting Diamond-Wing Aerodynamic Characteristics

“…This results in higher lift and lower drag coefficients. Schütte conducted an extensive numerical investigation of the flow field sensitivity to the change in leading-edge sweep ϕ, angle of attack α, Mach number Ma and leading-edge radius r le [13]. He demonstrated that the separation onset moves upstream with decreasing r le and ϕ, on one hand, and with increasing α and Ma, on the other.…”