Vortical Structures on Three-Dimensional Shock Control Bumps

Abstract

Three-dimensional shock control bumps have long been investigated for their promising wave drag reduction capability. However, a recently emerging application has been their deployment as 'smart' vortex generators, which o↵set the parasitic drag of their vortices against their wave drag reduction. It is known that 3D SCBs produce streamwise vortices under most operating conditions; however, there have been very few investigations which have aimed to specifically examine the relevant flow structures. In particular, the strength of the vortices produced as well as the factors influencing their production are not well known. This paper uses a joint experimental and computational approach to test three di↵erent SCB shapes, categorising their flow structures. Four common key vortical structures are observed, predominantly shear flows, although all bumps also produce a streamwise vortex pair. Both cases with and without flow separation on the bump tails are scrutinised. Finally, correlations between the strength of the main wake vortices and pressure gradients at various locations on the bumps are assessed to investigate which parts of the flow control the vortex formation. Spanwise flows on the bump ramp are seen to be the most influential factor in vortex strength.

Boundary-Layer Development Downstream of Normal Shock in Transonic Intakes at Incidence

“…The ellipsoidal working volume measures 130µm in diameter. Paraffin particles, with a diameter of approximately 0.5µm [9], are used to seed the flow. The laser emitting head and receiving optics are mounted on a three-axis traverse.…”

Using Shock Control Bumps to Improve Transonic Fan/Compressor Blade Performance

“…They concluded that the bump height, width and position of the bump peak are the key parameters. Collins et al [9] tested shock control bumps in a wind tunnel, and analysed the performance of shock control bumps at off-design conditions.…”

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

“…It is obvious that 3D bumps can be more easily integrated into the structure of the wing and more easily deformed actively due to their geometrical compactness, considering the potential development of adaptive bumps. Furthermore, 3D bumps also provide the possibility to generate streamwise vortices [15][16][17], which are beneficial for improving the off-design performances, such as buffet alleviation, investigated by Eastwood and Jarrett [18]. Recently, Jones et al [19] investigated the effects of swept flows for 3D bumps, and a new geometric parameter, termed bump orientation, was found to be crucial to the performance under swept flows.…”