Experimental investigation of coaxial impinging air jets

Highlights: • Coaxial confined impinging turbulent air jets are investigated experimentally. • Hydrodynamical and thermal characteristics are examined. • Effect of the flowrate ratio on the uniformity and intensity of heat transfer is determined. This study experimentally investigates hydrodynamical and thermal characteristics of coaxial confined impinging turbulent air jets. Various values of the dimensionless nozzle-to-plate distances and dimensionless flowrate ratio are tested for a constant total flowrate. It is shown that flowrate ratio enhances significantly the uniformity of the heat transfer and increases the average Nusselt number while increasing nozzle-to-plate distance decreases the intensity of convective heat transfer over the impingement plate. For pressure distribution on the impingement plate, subatmospheric regions are observed. The results obtained for coaxial case are also compared with those for the single circular impingement jet.