Effects of transverse vibration on heat transfer and turbulent flow of supercritical carbon dioxide in distinct flow regimes

In advanced aerospace thermal management systems, the interaction between vibrational force fields and supercritical carbon dioxide (SCO2) turbulent flow remains poorly understood, particularly regarding the anisotropic turbulence modulation across distinct flow regimes. This study addresses this gap by employing large eddy simulation to systematically investigate the effects of transverse vibration (50 Hz frequency and 5 g acceleration) on SCO2 heat transfer and turbulence in narrow pipes (1 and 2 mm diameters). By modulating the Grashof number (Gr*) through pipe diameter variation, two representative flow regimes, that is heat transfer deterioration (HTD) and recovery (HTR), were characterized. Results reveal that transverse vibration induces significant anisotropic turbulence, enhancing turbulent statistics in the vibration direction (x-axis) with heat transfer coefficients (HTC) improved by 32% (1 mm) and 48% (2 mm). However, vibration-induced shear suppresses the M-shaped velocity profiles critical to HTR in the orthogonal direction (y-axis), reducing turbulent kinetic energy by 6.2% in the mainstream region (y+ > 30). Notably, HTD regions exhibit 1.3-fold greater vibration-driven HTC enhancement compared to HTR regions, attributed to weakened buoyancy effects under vibration. These findings provide actionable insight for optimizing SCO2-based thermal systems under vibrational environments.