Towards Designing with 3-D Bumps for Wing Drag Reduction

Eastwood, Jeremy P.; Jarrett, Jerome P.

doi:10.2514/6.2011-1168

Cited by 3 publications

(1 citation statement)

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“…13 Further understanding of how this vorticity is produced is therefore desirable, to allow an improved design of bump geometry suited to this purpose. It has already been suggested that the vortical nature of the wake is controlled by the tail geometry [9][10][11]19 although the mechanisms which generate the vorticity is still largely not understood.…”

Section: Introductionmentioning

confidence: 99%

Vortical structures on three-dimensional shock control bumps

Colliss

Babinsky

Nübler³

et al. 2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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The vortical wake structure produced by a three-dimensional shock control bump (SCB) is thought to be useful for controlling transonic buffet on airfoils. However, at present the vorticity produced is relatively weak and the production mechanism is not well understood. Using a combined experimental and computational approach, a preliminary investigation on the wake vorticity for different bump geometries has been carried out. The structure of the wake for on-and off-design conditions are considered, and the effects on the downstream boundary layer demonstrated. Three main vortical structures are observed: a primary vortex pair, weak inter-bump vortices and shear flow in the lambda-shock region. The effect of pressure gradients on vortex strength is examined and it is found that spanwise pressure gradients on the front section of the bump are the most significant parameter influencing vortex strength. Nomenclaturec = Airfoil chord length H ≡ δ * θ = Incompressible boundary layer shape factor M ∞ = Freestream Mach number Re χ ≡ ρU∞χ µ = Reynolds number based on length scale χ u ≡ (u, v, w) = Stream-wise, tunnel floor-normal velocity components [m/s] u ∞ = Free-stream velocity x, y, z = Stream-wise, tunnel floor-normal, tunnel span-wise coordinates [mm] x s = Streamwise shock position relative to bump tip [mm] α = Angle of attack [ • ] δ = Boundary layer thickness (measured to 99% freestream velocity) [mm] δ * = Incompressible boundary layer displacement thickness [mm] θ = Incompressible boundary layer momentum thickness [mm] λ c = Complex eigenvalue of velocity gradient tensor ∇u µ = Dynamic viscosity [kg/(ms)] ρ = Density [kg/m 3 ] ψ ≡ tan −1 v u = Vertical flow angle [ • ] ω x = Streamwise component of vorticity [s −1 ] * PhD student, AIAA student member.

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Section: Introductionmentioning

confidence: 99%