RT Journal Article
T1 Heat transfer enhancement in turbulent boundary layers with a pulsed slot jet in crossflow
A1 Castellanos García de Blas, Rodrigo
A1 Salih, Gianfranco
A1 Raiola, Marco
A1 Ianiro, Andrea
A1 Discetti, Stefano
AB The convective heat transfer enhancement in a turbulent boundary layer (TBL) employing a pulsed, slot jet in crossflow is investigated experimentally. A parametric study on actuation frequencies and duty cycles is performed. The actuator is a flush-mounted slot jet that injects fluid into a well-behaved zero-pressure-gradient TBL over a flat plate. A heated-thin-foil sensor measures the time-averaged convective heat transfer coefficient downstream of the actuator location and the flow field is characterised by means of Particle Image Velocimetry. The results show that both the jet penetration in the streamwise direction and the overall Nusselt number increase with increasing duty cycle. The frequency at which the Nusselt number is maximised is independent of the duty cycle. The flow topology is considerably altered by the jet pulsation. A wall-attached jet rises from the slot accompanied by a pair of counter-rotating vortices that promote flow entrainment and mixing. Eventually, a simplified model is proposed which decouples the effect of pulsation frequency and duty cycle in the overall heat transfer enhancement, with a good agreement with experimental data. The cost of actuation is also quantified in terms of the amount of injected fluid during the actuation, leading to conclude that the lowest duty cycle is the most efficient for heat transfer enhancement.
PB Elsevier
SN 1359-4311
YR 2023
FD 2023-01-25
LK https://hdl.handle.net/10016/37711
UL https://hdl.handle.net/10016/37711
LA eng
NO The work has been supported by the project ARTURO, ref. PID2019-109717RB-I00/AEI/10.13039/501100011033, funded by the Spanish State Research Agency. Funding for APC: Universidad Carlos III de Madrid (Read & Publish Agreement CRUE-CSIC 2022). Paul Murphy is kindly acknowledged for his support during the experimental campaign.
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RD 18 jul. 2024