Investigation of impinging single and twin circular synthetic jets flow field
| Autor: | Gennaro Cardone, Tommaso Astarita, Cuono Massimo Crispo, Carlo Salvatore Greco, Giusy Castrillo |
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| Přispěvatelé: | Greco, CARLO SALVATORE, Castrillo, Giusy, Crispo, Cuono Massimo, Astarita, Tommaso, Cardone, Gennaro |
| Rok vydání: | 2016 |
| Předmět: |
General Chemical Engineering
Aerospace Engineering 02 engineering and technology 01 natural sciences 010305 fluids & plasmas Physics::Fluid Dynamics symbols.namesake Optics Saddle point 0103 physical sciences Fluid Flow and Transfer Processes Physics Turbulence business.industry Mechanical Engineering Mechanics 021001 nanoscience & nanotechnology Stagnation point Vortex ring Adverse pressure gradient Nuclear Energy and Engineering Particle image velocimetry Synthetic jet symbols Strouhal number Flow field Impinging jets Particle image velocimetry Synthetic jets Turbulence Vortex ring 0210 nano-technology business |
| Zdroj: | Experimental Thermal and Fluid Science. 74:354-367 |
| ISSN: | 0894-1777 |
| DOI: | 10.1016/j.expthermflusci.2015.12.019 |
| Popis: | Synthetic jets are largely used in the electronic cooling field; indeed their heat transfer performances have been widely investigated. The heat transfer performances have been enhanced through the design of innovative synthetic jet devices, as the twin synthetic jets device. Obviously the heat transfer performances of the classic and innovative synthetic jet devices are strictly related to their impinging flow field. Therefore the behavior of impinging single and twin circular synthetic jets in phase opposition is experimentally investigated by using Particle Image Velocimetry (PIV) at Reynolds and Strouhal numbers equal to 5100 and 0.024, respectively. Several nozzle-to-plate distances (H), ranging between 2 and 10 nozzle diameters (D), have been investigated. The time-averaged behavior of the velocity components has been reported and discussed. Their distributions, near the impinging plate, have been described. For the single jet, at short nozzle-to-plate distances (H/D6), the axial velocity profile is bell-shaped. This is ascribed to the adverse pressure gradient strength and the potential core-like region extension. External oscillations are observed in all the flow field quantities near the impinging plate at 2 diameters from the stagnation point due to a secondary counter rotating vortex ring generation. The presence of such a counter rotating vortex ring decreases as the nozzle-to-plate distance increases. Comparing the two synthetic jet configurations, higher axial velocity and turbulence level but lower axial phase-correlated organized contribution to velocity have been found for the twin case because of the jets interaction. The evolution of the flow field for both configurations has been explained through phase-averaged measurements. High turbulence is observed along the shear layer emanated by the nozzle edge and in the vortex ring core. During the suction phase the saddle point shows a different behavior in the two configurations. In the single case, the saddle point reaches the impinging plate causing injection of air from the plate into the device. Differently the twin configuration generates two saddle points which do not reach the impinging plate because of the presence of the other impinging synthetic jet. |
| Databáze: | OpenAIRE |
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