Drag and heat transfer on surfaces with small longitudinal fins

An investigation is conducted regarding the drag characteristics of longitudinally ribbed surfaces using various configurations which attempt to confine the turbulent wall bursts to regions of small transverse extent in the initial birth region. The ratio of heat transfer increase to drag increase for the high area ratio rib configurations is determined and the heat transfer efficiency of the present surfaces is compared with data found in the literature. The drag data obtained indicate local 'wetted area skin friction' reductions but due to the increased surface area the planform drag is increased in most instances. There is no indication of drag reduction with the rectangular ribbed models that had sharp leading and fin tip edges. Heat transfer data indicate that several of the triangular grooved models have efficiencies approximately 10 percent higher than that of a smooth flat plate.