An experimental study of multiple jet mixing

Results of hot-wire measurements in an incompressible jet issuing from an array of rectangular lobes, equally spaced with their small dimensions in a line, both as a free jet, and as a confined jet, are presented. The quantities measured include mean velocity and the Reynolds stress in the two central planes of the jet at various stations downstream of the nozzle exit. In the case of a single rectangular free jet, the flow field of the jet is found to be characterized by the presence of three distinct regions in the axial mean velocity decay. In the case of a multiple free jet, the flow field for downstream distance X greater than 60D (D = width of a lobe) resembles that of a jet exiting from a two dimensional nozzle with its short dimension being the long dimension of the lobe. In case of a confined multiple jet the flow field is observed to be nearly homogeneous and isotropic for X greater than 60D.