DNS of flow and heat transfer characteristics of multiple impinging jets

Abstract

Multiple impinging jet (MIJ) is widely used for cooling of industrial applications such as electric device, blades of gas turbine, hot steel and so on, since it possesses high performance of heat transfer rate and is easier to implement into various systems. Thus, in order to improve the heat transfer performance, it is indispensable to elucidate the detail of flow phenomenon. In the present study, in order to analyze the flow and heat transfer characteristics formed by the interaction of MIJ, we conduct the DNS (direct numerical simulation) of 13 and 19 round impinging jets and investigate the influence of interference between jets. From the instantaneous velocity distribution, it is observed that each jet impinges the impingement wall and diffuses in the radial direction in both multiple jets. From the time-averaged velocity and Nusselt number distribution, it is confirmed that flow phenomena such as up-wash flow due to the interaction between jets are generated and that the Nusselt number shows a high value at the impinging points and decreases toward the outside of the calculation region. In addition the heat transfer performance decreases in the interaction region between the jets.

Numerical Investigation of Heat Transfer and Pressure Force from Multiple Jets Impinging on a Moving Flat Surface

“…no turbulence modeling, are still limited to single jets or small Reynolds numbers, i.e. Re=1500 [20]. In order to better understand the complex flow, some LES simulations of jet arrays were performed, although these simulations are computationally extremely expensive [21].…”