Three-dimensional jet issuing from the cruciform nozzle. I - Mean flow properties

The mean flow properties of a three-dimensional jet issuing from a cruciform nozzle with a sufficiently large value of the aspect ratio were measured. The mean velocity profile shows the existence of a saddle-back shaped velocity defect region on the y = 0 and z = 0 slices of the upstream region. It is confirmed that the entire mean velocity profile maintains a criss-cross shape up to the downstream cross section of x/d = 150, where d is the jet nozzle width. The velocity scale decays as (x/d) to the -0.46 in the region beyond x/d = 75. The rate of the decay is smaller than those of the two-dimensional and the axisymmetric jets. The similarity of mean velocity profile on the representative slices is valid on the y = z slice in the region beyond x/d = 50, and on the z = 0 slice in the region beyond x/d = 75.