Sidewall effects in laminar ramp induced shockwave boundary layer interactions

Shock-wave boundary layer interactions (SWBLI) play a significant role in control surfaces and engine inlets. However, most simulations commonly assume span-periodic or 2D. Recent research conducted by Lusher and Sandham (2020) investigated the effects of sidewalls in impinging-type SWBLI (ISWBLI). This study’s focus is to numerically explore the influence of sidewalls in a three-dimensional context for ramp-induced SWBLI (RSWBLI). First a 2D ramp-induced separated boundary layer interaction with a ramp angle of $6.8°$ was identified. This configuration produced the same pressure rise and separation characteristics as those reported by Katzer (1989) at a Mach number of 2 and an impinging Reynolds number of $3\times 10^5$. Subsequently, the sidewall was introduced for Aspect Ratio 1 and the results were analysed. From the analysis it was found out that the separation length for the 3D case is 14% greater than that observed in the 2D simulation. Upon comparison with the ISWBLI study of Lusher and Sandham (2020), it was found that (a) the sidewall and central separation are connected in RSWBLI, contrasting with ISWBLI, (b) the extent of sidewall separation in RSWBLI is very limited compared to the impingement interaction, and (c) RSWBLI displays characteristics closer to an owl-like separation of second kind, whereas in ISWBLI exhibits characteristics of the first kind of separation. Even though having identical shock-strength and separation length for both R & I SWBLI in 2D configuration, the introduction of sidewall resulted in a distinct topology and dynamics of interaction .