Separation and flow unsteadiness control in a compression corner induced interaction using mechanical vortex generators: Effects of vane size and inter-device spacing

An experimental investigation was conducted to control separation characteristics of a 24 degrees compression corner induced interaction in a Mach 2.0 flow using an array of mechanical vortex generators (VGs) with rectangular vanes (RRV) placed 6.8d upstream of the interaction. The objective was to study the effect of (i) inter-VG spacing (s/h = 12, 9.5, 8.0, 6.1, 5.7, 5.5, 4.9, and 4.7), (ii) vane chord length (c/h = 7.2, 4.2, and 3.0), and (iii) vane angle (alpha = 24 degrees, 20 degrees, 18 degrees, and 16 degrees) in controlling the interaction and on the surface flow topology. These modifications reduce the projected area of VGs in the array from the conventional VG design of RRV2 (c/h = 7.2 and s/h = 9.5) to RRV8 (c/h = 3.0 and s/h = 4.7) by 41%. Reducing s/h also reduces the inter-VG region of the separation significantly that helps to achieve maximum reduction in the streamwise extent of separation up to 83% and in the peak rms value up to 80%. The former improves the overall pressure recovery from 3.0 to 3.4, thereby moving closer toward the inviscid value of 3.8. Surface flow topology shows that the VG array splits a single large spanwise separation bubble for no control into multiple smaller scale individual separation cells placed side-by-side all along the span of the interaction. This helps to reduce the magnitude of mass exchange imbalance across each individual separation cell and, hence, stabilizes the overall interaction relative to no control. The best VG configuration of RRV8 shifts the dominant frequency of fluctuations to approximately 2kHz or St = 0.19, which is nearly an order of magnitude higher than that for no control. Published under an exclusive license by AIP Publishing.

Automated summary

An experimental investigation was conducted to study the control of separation characteristics induced by a 24 degrees compression corner in Mach 2.0 flow. The study focused on the effect of different parameters, such as inter-VG spacing, vane chord length, and vane angle, on the interaction and surface flow topology. The results showed that reducing inter-VG spacing and modifying the VG configuration can significantly reduce separation and improve pressure recovery. The use of mechanical vortex generators helped stabilize the interaction by splitting a large separation bubble into smaller individual separation cells.