Turbulent flow field structure of initially asymmetric jets

The near field structure of round turbulent jets with initially asymmetric velocity distributions is investigated experimentally. Experiments are carr ied out using a constant temperature hot -wire anemometry system to measure streamwise velocity in the jets. The measurements are undertaken across th e jet at various streamwise stations in a range starting from the jet exit plane and up to a downstream location of twelve diameters. The experimental results include the distributions of mean and instantaneous velocities, vo rticity field, turbulence intensity, and the Reynolds shear stresses. The a symmetry of the jet exit plane was obtained by using circular cross -sectio n pipes with a bend upstream of the exit. Three pipes used hers include a s traight pipe, and 90 and 160 degree-bend pipes. Therefore, at the upstream of the pipe exit, secondary flow through the bend and mean streamwise veloc ity distribution could be controlled by changing the curvature of pipes. Th e jets into the atmosphere have two levels of initial velocity skewness in addition to an axisymmetric jet from a straight pipe. In case of the curved pipe, a six diameter-long straight pipe section follows the bend upstream of the exit. The Reynolds number based on the exit bulk velocity is 13,400. The results indicate that the near field structure is considerably modifie d by the skewness of an initial mean velocity distribution. As the skewness increases, the decay rate of mean velocity at the centerline also increase s.