Numerical analysis of dominant parameters in synthetic impinging jet heat transfer process

How forcing frequency of synthetic jet would affect heat transfer attracts wide attention, however, studies conducted by different authors or the same study but with slightly distinct conditions often led to disparate results. In regard to the forcing frequency-induced intricate phenomena in heat transfer process of synthetic jet, a mechanism analysis focusing on the effect of St is proposed in this work. In the present study, the emphases are to explore the effects of frequency (f = 10-75 Hz) and dimensionless parameters, i.e. Reynolds number (Re = 10,000 20,000) as well as Strouhal number (St = 0.1285-0.4498), on these physical processes of synthetic jet. The results demonstrate that there is an interval of St from 0.24 to 0.48 that corresponds to the highest range of time-area averaged Nusselt number under each Re. Moreover, Re or frequency would largely influence amplitude and variation trend of area averaged Nusselt number with normalized time respectively. However, interestingly, the variation trend of area averaged Nusselt number with respect to normalized time exhibits high similarity under the conditions of the same St even with different Re and frequency. Furthermore, the evolutions of flow field with normalized time are also analogous at the same St, which can lead to the similarity in the variation of heat transfer rate. (C) 2019 Elsevier Ltd. All rights reserved.