Three-dimensional Flow Visualization and Piv Measurement in near Field of Strongly Buoyant Jet
نویسندگان
چکیده
The near-field structure of strongly buoyant jet issuing from a square nozzle at low Froude and Reynolds numbers is studied by using three-dimensional LIF flow visualization and scanning PIV. These experimental techniques allow the visualization of unsteady three-dimensional flow phenomenon occurring in the near-field of strongly buoyant jet. It is found that the buoyant jet is unstable to the positive buoyancy forces, which promote the inflow motion near the nozzle exit. The surrounding low temperature fluid moves into the nozzle along the nozzle corner and mixes with the high temperature fluid deep into the nozzle. Then, the flow pattern inside the nozzle becomes highly complex to promote the laminar to turbulent transition of the vertical buoyant jet. The statistical flow characteristics of the strongly buoyant jet are evaluated from the three-dimensional scanning PIV measurement, and the result indicates the presence of axisymmetric mean-flow and velocity fluctuations along the interface between the main flow and the inflow in the nozzle.
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