Aero-Structural Design Optimization of Adaptive Shock Control Bumps

Abstract

Shock control bumps (SCB) are a transonic flow control device that aim to reduce the overall drag due to a normal shock on a typical passenger jet at cruise. The concept of adaptive SCB which can be deployed for best use are investigated through an aero-structural design tool that produces optimal geometries. The optimizer uses a surface based performance metric to highlight the importance of the flow quality around the SCB as well as including a structural element that is required to provide the necessary flexibility to deform. The performance metric produces the target pressure distribution and successfully smears the shock. It is found that the structural constraint does not inhibit bump height and global airfoil performance is not significantly a↵ected, L/D varies < 0.6%. The aerodynamic pressure loading can be utilised to produce a new family of SCB geometries that are unachievable with mechanical actuation alone. The study shows that adaptive SCB that exploit the naturally occurring pressure field around an airfoil in a passive way are a feasible technology to mitigate the poor o↵-design performance of static SCB.

Review of Adaptive Shock Control Systems

“…As mentioned before, Jinks et al [81,86] could keep the maximum von Mieses stresses below the limit of 90% yield stress. This is also true for the two-actuator solution in both actuation points [87].…”

“…While in [81] (2015) the maximum stress in the single actuation point is approximately 69% of the yield stress, Jinks et al [86] (2016) could reduce this value to a reported 58% yield stress. Hence, in both approaches the stresses are far below 90% yield stress (safety factor: 10%) which the authors chose as limit.…”

“…Although for this concept the thin flexible plate is not explicitly described as a 0.4 mm thin plate, it is to be assumed that a similar plate as in [81,86] (Sections 2.3.1 and 2.3.2) is used in [87], since the authors mention that the aerodynamic pressure also plays an important role by forming the SCB shape. However, the authors do not describe the importance of the cavity pressure for this concept, which could mean that it is comparably independent of this variable.…”

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

“…Recently, studies by Rhodes and Santer [25,26] showed numerically that morphing SCBs, which can be deployed through the actuation of a flexible membrane, are possible where designs have been generated that offer an optimum trade-off between structural, material, and aerodynamic constraints. Further, research from Jinks et al [27][28][29][30] demonstrated the efficacy of the morphing SCB experimentally and numerically in pre-buffet flows. A limitation of this technique is that under current materials technologies, the sharp geometries required for wedge-bumps (especially in 3D) are not feasible due to sharp corners, requiring large variations in Gaussian curvature over short distances, as well as the additional actuation required.…”

Optimal aero-structural design of an adaptive surface for boundary layer motivation using an auxetic lattice skin

“…These methods can be broadly split into two groups: those which apply load directly to the aerofoil skin, and those which use topologically designed wing ribs to distribute an actuation load to the variable region. Applications where the actuation is applied directly to the skin include transonic shock control bumps (Jinks et al 2016) and stall prevention through an oscillating suction surface (Jones et al 2015). In these examples the variation in geometry is localised to the upper surface of the aerofoil, an area of low curvature, and the overall variation in geometry is small.…”