Experimental investigation of expansion effect on shock wave boundary layer interaction near a compression ramp

Relaminarization effects in hypersonic flow on a three-dimensional expansion–compression geometry

“…The expanded boundary layer has a near-wall velocity deficit that results in enhanced susceptibility to separation and, consequently, a larger mean separation length. This explains the experimental findings of Zheltovodov et al (1993) and Huo et al (2022) on tandem expansion-compression geometries where larger separation regions were observed with stronger upstream expansions (larger K). As Re increases, the recovery (or the re-transition process) of the expanded boundary layer is expedited (Goldfeld & Lisenkov 1991), and the separation length decreases (Zheltovodov et al 1993;Xie et al 2022).…”

“…(1993) and Huo et al. (2022) on tandem expansion–compression geometries where larger separation regions were observed with stronger upstream expansions (larger ). As Re increases, the recovery (or the re-transition process) of the expanded boundary layer is expedited (Goldfeld & Lisenkov 1991), and the separation length decreases (Zheltovodov et al.…”

“…One of these cases, at Mach 2.9 with a 25 • ramp, was computationally simulated by Fang et al (2015), who showed that while the outer part of the expanded boundary layer is accelerated, as was suggested by Chew (1979) and Zheltovodov et al (1993), the inner layer is in fact retarded after the expansion corner. Recently, Huo et al (2022) (Mach 3.4) varied the length of the expansion region as well as the expansion and compression angles, and showed that the separation region in front of a compression ramp is larger when an upstream expansion is introduced.…”

“…Recently, Huo et al. (2022) (Mach 3.4) varied the length of the expansion region as well as the expansion and compression angles, and showed that the separation region in front of a compression ramp is larger when an upstream expansion is introduced.…”