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Drag reduction and vortex evolution mechanisms of single-hole micro-blowing in a supersonic turbulent boundary layer

Year: 2025
Type: article
Abstract: Micro-blowing techniques have shown significant potential for friction drag reduction in supersonic turbulent boundary layers, yet the pore-scale interaction mechanisms remain poorly understood. This study employs Direct Numerical Simulation (DNS) to investigate the fundamental physics of single-hole micro-blowing in a supersonic turbulent boundary layer. The results reveal a dual-regime drag reduction mechanism for the single-hole micro-blowing system: upstream reduction driven by adverse pressure gradients and downstream reduction dominated by mean convection effects. Micro-blowing establishes a three-layer shear interaction system (“wall-air film-mainstream”) downstream through the formation of a low-speed air film, which effectively reduces near-wall skin friction and turbulent fluctuation intensity. The study identifies two key vortex-mediated mechanisms: the generation of a counter-rotating streamwise vortex pair that forms vorticity sheets in the near-wall region, and their sign-dependent interactions with turbulent induced vorticity sheets (intensification for same-sign interactions and weakening for opposite-sign cases). The micro-blowing induced vorticity sheet serves as a near-wall barrier, reducing both the frequency and intensity of “turbulent vortex-wall” interactions. Additionally, the low-speed sweep flow induced by micro-blowing streamwise vortices contributes to skin friction reduction. A key finding is the remarkable stability of drag reduction under turbulent vortex interference─the micro-blowing system maintains its baseline performance when interacting with turbulent streamwise vortices, demonstrating robustness for practical applications.
DOI: 10.1016/j.cja.2025.103830
Language: English
Open Access status: hybrid
Estimated APC paid: $2,000
OpenAlex ID: W4414770560
FWCI: 2.228
Cites: 44
Cited by: 5
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