The Affect of Wake Flow Instability on Flow Past an Offset-fin Array

Flow characteristics in an offset-fin array was studied by means of flow visualization. When the Reynolds number based on fin thickness t exceeds a critical value, the wake of a fin becomes unsteady, exhibiting wavy or vortical motion. When instability occures in the wake of a fin, the boundary layer and flow characteristics around the downstream fins are affected. It is found that the wake flow instability is strongly dependent on the Reynolds number based on fin thickness as well as on the fin pitch 2S. It is also found that the frequency of discrete vortices varies with a change in Reynolds number, but, more noticeably, varies with a change in the parameter t/2S.