Experimental study of the mean structure and quasi-conical scaling of a swept-compression-ramp interaction at Mach 2

Abstract

This study investigates the mean flow structure of two shock-wave boundary-layer interactions generated by moderately swept compression ramps in a Mach 2 flow. The ramps have a compression angle of either $19^{\circ }$ or $22.5^{\circ }$ and a sweep angle of $30^{\circ }$. The primary diagnostic methods used for this study are surface-streakline flow visualization and particle image velocimetry. The shock-wave boundary-layer interactions are shown to be quasi-conical, with the intermittent region, separation line and reattachment line all scaling in a self-similar manner outside of the inception region. This is one of the first studies to investigate the flow field of a swept ramp using particle image velocimetry, allowing more sensitive measurements of the velocity flow field than previously possible. It is observed that the streamwise velocity component outside of the separated flow reaches the quasi-conical state at the same time as the bulk surface flow features. However, the streamwise and cross-stream components within the separated flow take longer to recover to the quasi-conical state, which indicates that the inception region for these low-magnitude velocity components is actually larger than was previously assumed. Specific scaling laws reported previously in the literature are also investigated and the results of this study are shown to scale similarly to these related interactions. Certain limiting cases of the scaling laws are explored that have potential implications for the interpretation of cylindrical and quasi-conical scaling.

Dynamics of strong swept-shock/turbulent-boundary-layer interactions

“…have been validated in conjunction with experiments for both the SCR (Vanstone et al 2016(Vanstone et al , 2018 and SF (Baldwin et al 2016;Arora et al 2018) configurations. These include comparisons of surface flow visualization, surface pressure and all three velocity components in both Cartesian and spherical coordinates, which are discussed by Adler & Gaitonde (2017, 2018b, 2019a.…”

“…shock-induced flow separation for delta-wing configurations (Miller & Wood 1984;Donohoe & Bannink 1997)). As such, recent efforts have refocused examination from 2-D configurations toward these swept STBLIs (Adler & Gaitonde 2018b;Mears, Arora & Alvi 2018;Vanstone et al 2018). However, there are significant structural differences between 2-D and 3-D interactions which suggest that the flow structure and underlying mechanisms (including those associated with unsteadiness) in 2-D interactions cannot be directly extended to three dimensions.…”

“…These thrusts have been prompted by several recent advances in massively parallel simulations (Poggie, Bisek & Gosse 2015) as well as time-resolved unsteady measurements of high-speed flows (Beresh et al 2015) and other novel measurement techniques (Fahringer & Thurow 2018). The effort combines experimental measurements of the SCR (Vanstone et al 2016(Vanstone et al , 2018 and SF (Baldwin et al 2016;Jones et al 2017;Arora et al 2018) interactions, along with high-fidelity large-eddy simulations (Adler & Gaitonde 2017, 2018b, 2019a of both configurations. The swept-impinging-shock (SIS) interaction is also of great interest, and is the subject of parallel experimental (Doehrmann et al 2018) and computational (Gross, Little & Fasel 2018) efforts, but is not considered here.…”

Flow Similarity in Strong Swept-Shock/Turbulent-Boundary-Layer Interactions

“…Several interesting trends with interaction strength are then assimilated in terms of dependence on the inceptive-origin/ virtual-conical-origin relationship. Validation results with the experiments of Vanstone et al [39,40] as well as Arora et al [37] and Baldwin et al [38] are purposefully deferred to Sec. III.E, to allow for discussion of the observations in the context of results elaborated in earlier sections.…”

“…Aspects of unsteadiness that relate to the mean flow are also discussed, though for brevity, detailed discussions of spectra are deferred to a forthcoming paper. The simulations are grounded in parallel experimental campaigns for both the SF [37,38] and SCR [39,40] interactions. However, the present LES are not inhibited by the limitations of near-wall measurement resolution or fidelity, as are current experimental or RANS-based techniques, respectively.…”