Abstract
Behavior of an inward flow between two parallel disks was experimentally investigated. The inward flow is applied to a nozzle head of a laser micro jet machining for stable and high-velocity jet generation. The laser beam extends working region by total internal reflection in the water jet. It is, therefore, important that the water jet keeps laminar condition. This research is the first step to obtain criteria of a laser micro jet nozzle, and the flow mode in an enlarged model was investigated by flow visualization using dye injection and tracer particles. As a consequence, turbulent motion was captured in accelerated inward flow in the radial slit when flow rate was increased. An acceleration parameter, KV, was adapted to the experimental condition in this paper, and was used as the limiting value until the dye starts to spread. As a result, it is investigated that the spread of the injected dye had occurred when KV ‹ 1.9 × 10-5. When KV › 3.0 × 10-5, the transition to turbulence had not occurred and the spread of the injected dye had avoided.
