Hayato Mori

Dynamics of the Streamwise Vortices in an Axisymmetric Mixing Layer

The interaction of axisymmetric and streamwise vortices in the axisymmetric mixing layer developing along the jet boundary was investigated by a flow visualization technique. The jet was excited by axial and azimuthal perturbations to stabilize and enhance axisymmetric and streamwise vortices. A laser fluorescent dye and a laser light sheet were used to visualize the mixing layer. The three-dimensional views of the boundary surface of mixing layer were constructed by applying the Taylor hypothesis to the cross-sectional images. By the three-dimensional views, the interaction of axisymmetric and streamwise vortices was revealed, and the entrainment rate of the jet was also discussed in relation to the vortical structure.Copyright

Simultaneous Measurements of Velocity and Fluctuating Static-Pressure in a Circular Jet

Velocity and fluctuating static-pressure were measured simultaneously in a circular jet in order to discuss the pressure transport of turbulent energy and the generation mechanism of aerodynamic sound in relation to vortical structure. A combined sensor, which consists of X-type hot-wire and pressure probe, was used for the simultaneous measurements. The air jet was issued from a sharp-edged circular orifice under the excitation at the interaction mode so that velocity and fluctuating static-pressure can be determined in space and time domains by using phase-average technique. The results suggest that the simultaneous measurements with the phase-average technique give us useful information to reveal the turbulent shear flow phenomena. In particular, the pressure transport is closely related to vortical structure, and intense sound sources are caused by the vortex merging and by the acceleration of vortices during vortex pairing.Copyright

Relation of the Vortical Structure and the Entrainment in the Initial Region of a Plane Jet

The relation of the vortical structure and the entrainment in the initial region of a plane jet was investigated under the four conditions of vortex generators by vorticity measurements. The vortices were enhanced and stabilized by streamwise and spanwise disturbances. The three-dimensional views of the vortices were constructed by applying the Taylor hypothesis to the phase-average vorticities, and the entrainment was discussed in relation to the vortical structures. The result reveals the enhancement of entrainment by the interaction of spanwise and streamwise vortices