Pressure drop measurements and flow visualization surrounding roughness elements

Abstract

The objective of the investigation was to characterize the flow properties surrounding discrete heat-transfer augmentation roughness elements. Tests were performed in a recirculating wind tunnel arrangement with a test section Reynolds number on the order of 10. Several roughness shapes were examined, including a rectangular rib, a trapezoidal rib, and a trapezoidal rib with rounded corners at the base and at the top of the roughness elements. A flow visualization technique employing small tracers allowed both flow direction and flow velocity to be obtained. Pressure drop measurements were taken and the results compared with values obtained under related conditions at Eidgenossisches Institut fur Reaktorforschung (EIR) and transformed using the Warburton-Pirie and the Dalle Donne method. The flow visualization and pressure drop measurements revealed several important factors which resulted in a recommended change in the present shape of the gas-cooled fast breeder fuel rod roughness elements.