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

Abstract

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.

Experimental Characterization of Upper Trailing Edge Flaps for Transonic Buffet Control

“…Colliss et al (2016); Ogawa et al (2008) have confirmed that an array of 3D SCBs is more efficient than a 2D bump configuration (which spans along the full span of the model as described in detail by Zhang et al (2021)) in view of the streamwise vortices developing from the tail of the bumps. Applications of the use of SCBs for controlling buffet are discussed in the numerical studies of Mayer et al (2018) and Geoghegan et al (2020), which confirmed the dependence of the performance of a SCB on its size, shape and position relative to the shock. Similarly D' Aguanno et al (2021b) experimentally showed the dependence of the control efficacy on the spanwise spacing of the SCBs.…”

Numerical analysis of shock characteristics control based on bump

“…The shape of shock control bump can be defined by Hicks-Henne function (Geoghegan et al 2020). The function is able to characterize the height, skewness and local coordinate position of the smooth bump shape.…”

“…In recent years, with the development of smart materials, researchers attempt to embed a smart actuator into the wing to construct an active bump. The bump control can change the local shape of wing at shack wave position, compress air flow, weaken strength of the shock wave, and reduce the drag of the shock wave (Mayer et al 2018, Geoghegan et al 2020. Zhang et al (2022) applied the unsteady Reynolds-averaged Navier-Stokes (URANS) method to numerical simulation and explored the control effect of the two-dimensional (2D) shack wave bump on the supercritical airfoil at transonic buffet condition.…”

Review of Adaptive Shock Control Systems

“…The goals of shock control are to implement a device which reduces the shock strength and consequently wave drag and/or to delay the buffet onset and thus to reduce emissions, extend the flight envelop and/or reduce flow induced vibrations. While the drag reduction potential of SCBs has been investigated over almost the past three decades [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25], buffet control by SCBs has been investigated less extensively [6][7][8][9][26][27][28][29]. For detailed research on buffet control via SCBs the reader is referred to Mayer [6] and Mayer et al [7].…”