Fluid–structure–thermal interaction of a self-fluttering membrane in turbulent channel flow

Abstract

This study investigated the fluid–structure–thermal interaction of a fluttering membrane in turbulent channel flow at three different modes (straight mode, unsaturated flutter mode, and saturated flutter mode) and increasing Reynolds number. Using a high-speed camera at 2 kHz and a data-acquisition system at 51.2 kHz, the deformation shapes of a piezoelectric membrane and the temporal voltage variations were simultaneously recorded. Unlike the fluttering membrane in a parallel, unconfined flow, the flutter amplitude of the membrane in the channel exhibited an asymptotic behavior with the Reynolds number and eventually reached a saturated state. Different from the membrane characteristics at the unsaturated flutter mode, the membrane at the saturated flutter mode exhibited a dramatic fluttering behavior, with large flutter amplitude and front stationary points. Furthermore, the statistical flow quantities and the heat transfer performance were examined. The variations in the streamwise and vertical velocity components were closely related to the pressure loss and the heat transfer enhancement, respectively. In addition, the thermal enhancement factor was largest at the unsaturated flutter mode because of the high friction factor. Finally, through membrane shape identification, the spatiotemporal evolutions of flow–structure dynamics were captured. The relationships between the streamwise velocity and the pressure loss and between the vertical velocity and the heat transfer enhancement were further investigated phase by phase. According to the vorticity distributions, two small vortices occurred at the saturated flutter mode, which enhanced the heat transfer performance.