The effect of changing the nozzle geometry on the pressure drop and local heat transfer distribution in confined air jet impingement on a small heat source was experimentally investigated. Heat transfer and pressure drop measurements obtained with chamfered nozzles were compared to those obtained with a square-edged (non-chamfered) nozzle of the same diameter for different turbulent Reynolds numbers in the range of 5000-20,000, nozzle-to-target spacings, chamfer angles and chamfer lengths. The ratio of average heat transfer coefficient to pressure drop was enhanced by as much as 30.8% as a result of chamfering the nozzle, with narrow chamfering providing the better performance. (C) 2000 Elsevier Science Ltd. All rights reserved.