EXPERIMENTAL AND NUMERICAL INVESTIGATION OF SELF-SUSTAINED OSCILLATIONS IN CHANNELS WITH PERIODIC STRUCTURES

An experimental and numerical investigation was conducted into channel flows with transverse vortex generators, periodically attached to one channel wall. The oscillatory behavior of the flow is studied. Data f or heat transfer and flow losses of the oscillating flow are presented for Re = 350 and various rib heights. The unsteady u and v components of the velocity vector were recorded via a two-component hot-wire ane mometer. The results are directly compared with numerical solutions of the full Navier-Stokes equations. Self-sustained flow oscillations ar e found both experimentally and numerically for Re greater than or equ al to 350. Alternate and dynamic shedding of large vortex structures f rom the ribs is observed by smoke-wire flow visualization as well as v isualization of the numerically determined how field. The appearance o f lower harmonics is observed when mio shed vortices grow together. Th e numerically calculated flow field is verified experimentally. The en ergy equation is then solved, and heat transfer characteristics are st udied numerically. A heat transfer enhancement up to a factor of 1.826 compared to plane channel flow is observed.