Assessment of thermal-hydraulic performance in synthetic-jet-actuated ribbed channels

This study proposes a thermal management strategy that integrates a zero-net-mass-flux synthetic jet (SJ) into a ribbed channel to intensify heat transfer in confined spaces. A validated finite-volume method is employed to assess the SJ-induced phase-dependent modulation of the thermo-hydraulic performance at an SJ Reynolds number of 377.5. Quantitative analysis indicates that the combined effects of the SJ and rib turbulators promote flow disturbances, yielding a maximum local velocity increase of 33.3%. During the ejection phase, the inherently unsteady SJ reduces the instantaneous hydraulic loss by approximately 26.5% through momentum injection at a constant channel mass flow rate, whereas the suction phase produces a comparable increase in flow resistance. The instantaneous comprehensive performance coefficient (CPC) ranges from 0.937 to 1.071, corresponding to a maximum deterioration of 6.3% during suction and a maximum enhancement of 7.1% during ejection relative to the inactive-SJ baseline. However, the time-averaged CPC over five consecutive statistically periodic cycles is 0.996, indicating that the opposing effects of the ejection and suction phases largely compensate over complete actuation cycles. When turbulence-induced transport is incorporated into the entropy-generation analysis, thermal and viscous irreversibility become comparable in magnitude, while the cycle-averaged total entropy generation changes by only approximately 0.17% relative to the inactive-SJ case. Overall, under the investigated operating condition, SJ actuation produces pronounced phase-dependent modulation of the flow, thermo-hydraulic performance, and irreversibility, while its influence on the cycle-averaged performance remains marginal.