Unsteady analysis of jet impingement under vibration conditions

Abstract

The vibration of thermodynamic machinery will affect its cooling system. In this research, a high-resolution simulation of jet impingement was performed to quantify the unsteady turbulent convection under vibration conditions. A newly developed Self-Adaptive Turbulence Eddy Simulation (SATES) method was used. The Reynolds number was Re = 23000, the jet-to-wall distance was fixed at H/D = 2, and the vibrating frequency of the impinging wall f varied from 0 to 200 Hz. Compared with the static wall case, the maximum enhancement of the stagnation point and area averaged Nusselt number within r/D = 1 could reach up to 5% due to the larger primary vortices, whereas it could reduce the heat transfer by 10% beyond r/D = 3 due to the suppression of the wall vortices development. Based on the unsteady analysis and Proper Orthogonal Decomposition (POD) pattern, the modes controlled by vibration were recognized and their contributions to the heat transfer performance were also evaluated. The introduction of the vibration promoted the development of the primary vortices and changed the radial alternating motion to a vertical alternating motion at the wall jet region. The former was beneficial for the heat transfer, while the latter was unfavorable.