The effect of multi-plate array spacing on grid-generated turbulence

This study compares measurements of the streamwise integral length scale, the root mean square (r.m.s.) of the streamwise component of velocity, and the r.m.s. of the normal component of velocity obtained at the exit of a plate array with measurements obtained at the same position for the “open pipe case”. The “open pipe case” is defined as the empty tube, without the plates in place, i.e., the apparatus becomes grid flow entering an unobstructed pipe. In general, this study finds that the length scale in the streamwise direction decreases with increasing plate spacing while the r.m.s. velocity in the streamwise direction increases as the plate spacing increases for fixed values of x/M (i.e., the streamwise direction to mesh-spacing ratio). These measured trends are consistent with a simple model based on vortex elements and conservation of angular momentum.