Numerical and Experimental Validation of Three-Dimensional Shock Control Bumps

König, Benedikt; Pätzold, Martin; Lutz, Thorsten; Krämer, Ewald; Rosemann, Henning; Richter, Kai; Uhlemann, Heiko

doi:10.2514/6.2008-4001

Cited by 8 publications

(6 citation statements)

References 7 publications

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“…A two-step pressure rise is obtained, and improved pressure recovery is achieved, with the effect of reducing wave drag [1]. The streamwise location of the oblique shock is fixed by the surface curvature at the front of the bump, and this has been reported to have the additional beneficial effect of stabilising the shock [2].…”

Section: Introductionmentioning

confidence: 99%

Off-design performance of 2D adaptive shock control bumps

Gramola

Bruce

Santer

2020

Journal of Fluids and Structures

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Adaptive shock control bumps can exploit the on-design drag-reducing potential of 2D bumps, while mitigating their off-design performance deterioration through geometric modifications. In this study, experiments and simulations have been employed to investigate the wave-drag reducing potential of (actuated and unconstrained) 2D adaptive shock control bumps over a wide range of shock positions. Experiments were carried out in the Imperial College supersonic wind tunnel, modelling the adaptive bump as a flexible surface placed beneath a Mach 1.4 shock wave. 2D RANS CFD simulations of the flow in a parallel channel with a solid bump complement experiments. Wave drag was demonstrated to be proportional to the ratio of inlet to exit stagnation pressure in a blow-down wind tunnel for a given shock position. The shock exhibits a hysteretic behaviour when travelling in the wind tunnel working section, governed by the wave drag reducing potential of the bump. The actuated adaptive bump tested reduces wave drag over a wider operational envelope than solid bumps as experiments revealed the presence of three preferred structural configurations, which lead to a significantly enlarged hysteresis region. Finally, tests on unconstrained bumps were shown to increase wave drag, both on-and off-design, due to the unfavourable bump shapes that result from (only) passive actuation, suggesting that some constraints are required to achieve desirable surface deformations.

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Section: Introductionmentioning

confidence: 99%

Off-design performance of 2D adaptive shock control bumps

Gramola

Bruce

Santer

2020

Journal of Fluids and Structures

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“…Bruce and Colliss 21 argued that the reason is that an array of spanwise spaced discrete 3D bumps can produce a quasi-2D shock structure due to the overlap of flow structures of adjacent 3D bumps. However, in the numerical simulations by Qin et al 11 and Ko¨nig et al, 22 it is obvious that the flow fields exhibit strong 3D structures in terms of surface pressure distributions, although the spanwise wave patterns do exhibit some similarity.…”

Section: Introductionmentioning

confidence: 97%

“…However, in the numerical simulations by Qin et al. 11 and König et al., 22 it is obvious that the flow fields exhibit strong 3D structures in terms of surface pressure distributions, although the spanwise wave patterns do exhibit some similarity. After reviewing numerous research works focusing on the comparison of 2D and 3D bumps, Bruce and Colliss 21 pointed out that the relation between 2D and 3D bumps was still unclear.…”

Section: Introductionmentioning

confidence: 97%

Quantitative comparison of 2D and 3D shock control bumps for drag reduction on transonic wings

Deng

Qin

2018

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…However, the drag reduction is slightly lower over a swept wing because of the lower contribution of wave drag to the total drag. Three-dimensional SCBs have the same working principle as the twodimensional counterpart for wave drag reduction 14 . A good performance is observed over unswept wings, while the efficiency is decreased over swept wings 15 .…”

Section: Introductionmentioning

confidence: 99%

Mitigation of transonic shock buffet on a supercritical airfoil through wavy leading edges

Degregori

Kim

2021

Physics of Fluids

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Mitigation of shock buffet phenomenon over a supercritical aerofoil by means of wavy leading edges (WLEs) is analysed with implicit large eddy simulations (ILES). A Dassault Aviation's V2C aerofoil is simulated in a transonic flow with Re ∞ = 5.0 × 10 5 and M ∞ = 0.7 at α = 7.0 o . This aerofoil profile is designed for transonic flows, delaying the onset of wave drag and decreasing the skin friction drag. The results of this upstream flow condition on a straight aerofoil is a large oscillation of lift and drag coefficients. In the first part, timeaveraged aerodynamic characteristics over a straight leading edge (SLE) aerofoil and three modified aerofoils with different wavy amplitudes are compared. The results show that overall WLE aerofoils are more efficient than SLE ones and the aerofoil with the lowest amplitude (h = 0.0075) is the most efficient, increasing lift coefficient and decreasing drag coefficient. The flow unsteadiness has a key role for aerofoils in transonic flows at moderate and high angles of attack. Hence, the second part of the paper is a detailed unsteady analysis of flow phenomena. The starting point is an investigation of unsteady aerodynamic performance. It is observed that WLE aerofoils are capable of significantly decreasing low-frequency oscillations' amplitude, identified with shock buffet. The best performance is obtained with h = 0.0125 where a high-frequency oscillation becomes the dominant unsteady phenomenon. High-frequency oscillations are identified through the application of a frequency filtering method to the flow field. It is proved that the oscillation on the SLE aerofoil is related to vortex shedding, while the one on WLE aerofoils is related to laminar separation bubble (LSB) breathing. Overall, the unsteady analysis shows a connection between shock buffet and LSB breathing phenomena on wavy aerofoils and identifies the WLE amplitude as a key parameter to control this relation and mitigate the shock buffet.

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Numerical and Experimental Validation of Three-Dimensional Shock Control Bumps

Cited by 8 publications

References 7 publications

Off-design performance of 2D adaptive shock control bumps

Off-design performance of 2D adaptive shock control bumps

Quantitative comparison of 2D and 3D shock control bumps for drag reduction on transonic wings

Mitigation of transonic shock buffet on a supercritical airfoil through wavy leading edges

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