Effects of nozzle-inlet chamfering on pressure drop and heat transfer in confined air jet impingement

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.