Heat transfer mechanism and influence factors in supercritical CO2 jet impingement cooling under unconventional physical property changes

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(2)

Published: Feb. 1, 2025

The unconventional physical property variations of supercritical carbon dioxide (S-CO2) near the pseudocritical point present challenges in understanding heat transfer mechanisms and influencing factors when applying S-CO2 to jet impingement cooling. Therefore, a numerical model CO2 cooling different phase states is established, considering non-equilibrium change actual thermophysical properties while accounting for fluid-solid coupling transfer. This study examines influence high flux various inlet conditions on performance jets. In addition, effectiveness sub-critical compared with that impingement. found exhibits significantly superior CO2, an increase average coefficient approximately 45%–50%. When temperature below pseudo-critical temperature, 15%–20% higher than it exceeds temperature. enhancement attributed increased capacity due large specific layer at chip surface. Furthermore, does not experience critical (CHF) phenomenon, providing advantage density surfaces. once pressure increases levels, effect further becomes minimal. results can provide references design systems high-power electronic devices using S-CO2.

Language: Английский

Suppression of flow separation in a scramjet inlet using Görtler vortices

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(4)

Published: April 1, 2025

This study addresses the issue of boundary layer separation in inlet a scramjet engine by employing strategy centered on Görtler vortices. Numerical simulations are conducted to explore suppression through use these vortices at Mach 8. The inlets comprise two-stage compression ramps and cowl. turning angle between two is closely related occurrence set 10° 15°, with variations cowl position. Our findings indicate that follows natural transition, their intensity influenced position number, which characterizes instability, determined evaluating curvature momentum thickness, both tied an unsteady bubble. intensified downstream A comparison results two-dimensional cases without reveals near throat entrance effectively suppressed owing transport Consequently, mass flow rate ratio duct inflow increases significantly, exceeding 0.9. Therefore, proves be valuable method for suppressing critical ensuring duct.

Language: Английский