Experimental study of confined turbulent rectangular jets

Laser-Doppler velocimetry and pressure measurements are presented of mean and turbulent velocity components, Reynolds shear stresses, and wall static pressure distributions for a rectangular air jet confined in a rectangular mixing duct of aspect ratio 4. The jet-exit cross-sectional aspect ratio and the mixing duct to jet-exit height ratio are 40 and 10, respectively. The Reynolds number, based on the mixing duct hydraulic diameter and bulk mean velocity, and bulk mean velocity ratio of primary to secondary flows are 2.8 x 10(4) and 9, respectively. It is found that the measured centerline mean velocity decay parallels that reported from confined circular jet study. The streamwise turbulence intensity and Reynolds shear stress levels augment largely in the regions of flow separation. Moreover, the pumping effect is characterized by a wall static pressure coefficient rise up to a value as high as 5 over the entrance value.