Mass/heat transfer in a ribbed passage with cylindrical vortex generators:The effect of generator-rib spacing

The effect of vortex generators on the heat transfer from internally ribbed passages is studied experimentally using a mass transfer technique. Cylind rical vortex generators placed directly above the ribs have been used in th is study. Results are reported on the effect of the spacing between the vor tex generator and the ribs. Detailed distributions of the Sherwood number c ontours and the centerline Sherwood number distributions are presented. Rey nolds number values of 5000, 10,000, and 30,000 are studied and three gener ator-rib-spacing/rib-height (s/e) values of 0.55, 1, and 1.5 are considered . It is shown that at small generator-rib spacings (s/e=0.55), the two act as a single element, and lead to a retardation of the shear layer developme nt past the reattachment point. This is generally associated with lower hea t transfer. At a larger generator-rib spacing (s/e =1.5), the generator wak e and the rib shear layer interact with each other to promote mixing and he at transfer.