Control of Transonic Buffet by Shock Control Bumps on Wing-Body Configuration

Mayer, R.; Lutz, Thorsten; Krämer, Ewald; Dandois, Julien

doi:10.2514/1.c034969

Cited by 26 publications

(23 citation statements)

References 32 publications

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“…More recent studies consider SCBs applied to shock buffet control 16,17 . Two dimensional SCBs can delay transonic buffet onset by introducing a region of attached flow between the shock wave and the trailing edge of a supercritical wing, postponing complete flow breakdown 18 .…”

Section: Introductionmentioning

confidence: 99%

“…Three dimensional bumps applied to shock oscillation control have a different working principle because they generate two streamwise vortices adjacent to the bump which energise the boundary layer. They operate as 'smart' vortex generators 17 . For this reason, their design position is more upstream than the two dimensional ones.…”

Section: Introductionmentioning

confidence: 99%

“…The main issue is that the optimal position for wave drag reduction is always different from the one for shock buffet suppression. A trade-off is needed to improve the overall mean and unsteady characteristics of an aerofoil 17 .…”

Section: Introductionmentioning

confidence: 99%

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An investigation on a supercritical aerofoil with a wavy leading edge in a transonic flow

Degregori

Kim

2020

Physics of Fluids

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A compressible large-eddy simulation is performed to study the effects of a wavy leading edge (WLE) applied on a supercritical aerofoil in a transonic flow at Re∞ = 5.0 × 105 and M∞ = 0.7. The wavelength and peak-to-trough amplitude of the WLE used in this study are 5% and 2.5%, respectively, of the mean aerofoil chord. The primary aim of this study is to understand the aerodynamic characteristics of the modified aerofoil over a range of incidence angles. For this reason, a slow heaving motion is imposed where the geometric angle of attack is gradually increased from αg = 2° to 7° without a significant dynamic (added mass) effect, i.e., a quasi-linear range. The new transonic flow study shows significantly different findings (with some similar features) to the previous low-speed flow studies. It is observed in the quasi-linear range that the modified aerofoil achieves a performance improvement at low and moderate angles because of a drag reduction in the leading edge region and downstream of the laminar–turbulent (L–T) transition point. The leading edge (LE) analysis shows that the maximum pressure coefficient remains equal to that of the baseline case only at the trough and peak sections. The relative decrease in pressure at the LE results in the drag reduction. The transonic flow at the LE is analyzed in further detail to show a reversed flow region at the trough and its influence on the boundary layer development over the aerofoil. In addition, the spanwise variation of the boundary layer characteristics over the modified aerofoil is evaluated and analyzed. One of the most notable findings in this paper is that the flow at the trough becomes supersonic even at low angles of attack, and this results in an enhanced LE flow acceleration spread across the span, which seems facilitated by using a short WLE wavelength. This flow behavior is qualitatively explained by using an analogy between a channeling effect and a convergent–divergent nozzle in a transonic flow. Another notable observation is that there is an upstream movement of the laminar–turbulent transition point seemingly related to the flow distortion around the WLE. Interestingly, the flow distortion introduces a three dimensionality into the laminar boundary layer, but it keeps the flow laminar, so the benefits of the laminar supercritical aerofoil are not lost. These LE phenomena have a major impact on the shock structure at high incidence angles where the more energetic laminar boundary layer changes the shock structure over the modified aerofoil. This can be crucial to control the shock buffet phenomenon.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An investigation on a supercritical aerofoil with a wavy leading edge in a transonic flow

Degregori

Kim

2020

Physics of Fluids

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“…Since transport aircraft usually travel at transonic speeds, wave drag generated by transonic shocks on the wing surfaces also provides a significant contribution to overall aircraft drag. Furthermore, the phenomenon of buffet can occur which can lead to structural vibrations and thus limit the flight envelop [6][7][8]. For a review of transonic shock buffet the reader is referred to Giannelis et al [9].…”

Section: Introductionmentioning

confidence: 99%

Review of Adaptive Shock Control Systems

et al. 2021

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Drag reduction plays a major role in future aircraft design in order to lower emissions in aviation. In transonic flight, the transonic shock induces wave drag and thus increases the overall aircraft drag and hence emissions. In the past decades, shock control has been investigated intensively from an aerodynamic point of view and has proven its efficacy in terms of reducing wave drag. Furthermore, a number of concepts for shock control bumps (SCBs) that can adapt their position and height have been introduced. The implementation of adaptive SCBs requires a trade-off between aerodynamic benefits, system complexity and overall robustness. The challenge is to find a system with low complexity which still generates sufficient aerodynamic improvement to attain an overall system benefit. The objectives of this paper are to summarize adaptive concepts for shock control, and to evaluate and compare them in terms of their advantages and challenges of their system integrity so as to offer a basis for robust comparisons. The investigated concepts include different actuation systems as conventional spoiler actuators, shape memory alloys (SMAs) or pressurized elements. Near-term applications are seen for spoiler actuator concepts while highest controllability is identified for concepts several with smaller actuators such as SMAs.

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“…Contour-bumps, alternatively, are usually described by a smooth, continuous surface deformation (relative to wedge-bumps). The efficacy of these geometries is still contested in terms of their performance in drag reduction in pre-buffet conditions; however, both approaches seem to offer either alleviation in 2D/3D [22,23] or complete suppression in 2D [24] in on-design conditions. Given that these devices inherently must be designed for a particular flight condition for optimal performance, the impact of a fixed SCB on a wing can often lead to diminished off-design performance relative to the clean wing configuration.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Investigation of the Geometric Parametrisation of Shock Control Bumps for Transonic Shock Oscillation Control

Geoghegan

Giannelis

Vio

2020

Fluids

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At transonic flight conditions, shock oscillations on wing surfaces are known to occur and result in degraded aerodynamic performance and handling qualities. This is a purely flow-driven phenomenon, known as transonic buffet, that causes limit cycle oscillations and may present itself within the operational flight envelope. Hence, there is significant research interest in the development of shock control techniques to either stabilise the unsteady flow or raise the boundary onset. This paper explores the efficacy of dynamically activated contour-based shock control bumps within the buffet envelope of the OAT15A aerofoil on transonic flow control numerically through unsteady Reynolds-averaged Navier–Stokes modelling. A parametric evaluation of the geometric variables that define the Hicks–Henne-derived shock control bump will show that bumps of this type lead to a large design space of applicable shapes for buffet suppression. Assessment of the flow field, local to the deployed shock control bump geometries, reveals that control is achieved through a weakening of the rear shock leg, combined with the formation of dual re-circulatory cells within the separated shear-layer. Within this design space, favourable aerodynamic performance can also be achieved. The off-design performance of two optimal shock control bump configurations is explored over the buffet region for M = 0.73, where the designs demonstrate the ability to suppress shock oscillations deep into the buffet envelope.

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Control of Transonic Buffet by Shock Control Bumps on Wing-Body Configuration

Cited by 26 publications

References 32 publications

An investigation on a supercritical aerofoil with a wavy leading edge in a transonic flow

An investigation on a supercritical aerofoil with a wavy leading edge in a transonic flow

Review of Adaptive Shock Control Systems

A Numerical Investigation of the Geometric Parametrisation of Shock Control Bumps for Transonic Shock Oscillation Control

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