Numerical simulation of local wall heating and cooling effect on the stability of a hypersonic boundary layer

Impedance-Near-Zero Acoustic Metasurface for Hypersonic Boundary-Layer Flow Stabilization

“…This is not in line with our conventional physics understanding of hypersonic boundary-layer stabilization. Actually, our findings can be evidently explained by examining the pressure distributions of the Mack second mode using a high-order accurate direct numerical simulation (DNS) [8,12]. As shown in the upper subplot of Fig.…”

“…2(a), a slot of periodic suction blowing at a fixed frequency of f = 138.74 kHz is introduced at the beginning of the surface. At this frequency, the typical Mack second mode will be excited along the second half of the surface [8]. The surface is 0.2m long with an isothermal wall temperature of T w = 293 K. Its first half is rigid, and an impedance boundary condition is implemented along the second half [highlighted area in Fig.…”

“…Each time an acoustic wave is reflected at the sonic line, it changes from a compression wave to an expansion wave and vice versa. The longitudinal wavelength of the Mack second mode is about twice the boundary-layer thickness, and its frequency reaches hundreds of kHz corresponding to the ultrasonic band [8].…”

Theoretical Modeling and Optimization of Porous Coating for Hypersonic Laminar Flow Control

“…According to Ref. [22], the Mack second mode dominates along the second half of the plate. Taking the baseline case as an example (Fig.…”

“…The freestream flow conditions are the same as in the experiment of Bountin et al [21]: Mach number Ma ∞ 6.0, unit Reynolds number Re ∞ 10.5 × 10 6 m −1 , and temperature T ∞ 43.18 K. The wall is isothermal with a temperature of T w 293 K. The numerical method and code validation are available in Ref. [22]. An unsteady disturbance is introduced at the beginning of the plate by a slot of periodic suction-blowing at the fixed frequency of 138.74 kHz.…”