Thermal Science 2016 Volume 20, Issue 2, Pages: 473-482
https://doi.org/10.2298/TSCI130514149V
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Experimental study of a water-mist jet issuing normal to a heated flat plate
Vouros Andreas (Laboratory of Applied Thermodynamics, Mechanical Engineering and Aeronautics Department, University of Patras, Greece)
Vouros Alexandros (Laboratory of Applied Thermodynamics, Mechanical Engineering and Aeronautics Department, University of Patras, Greece)
Panidis Thrassos (Laboratory of Applied Thermodynamics, Mechanical Engineering and Aeronautics Department, University of Patras, Greece)
A parametric experimental study on the development of a round jet spray
impacting a smooth, heated, flat plate has been accomplished. The main
objective of this effort was to provide information characterizing the flow
structure of a developing mist jet, issuing vertically towards an upward
facing, horizontal heated plate, by means of simultaneous droplet size and
velocity measurements. Phase Doppler Anemometry was used, providing also
information on liquid volume flux. The fine spray of small atomized droplets
(0.5-5.0 μm), was generated using a medical nebulizer. Two low Reynolds
number jets (Re=2952, 3773) issuing from a cylindrical pipe have been tested.
The distance between the jets’ exit and the plate was 50 cm. A stainless
steel non-magnetic flat plate of dimensions 1000x500x12mm3 was used as target
wall. Constant heat flux boundary conditions were established during
measurements. Results indicate that the heat flux from the plate is
influencing the evolution of the spray jet, diminishing its velocity and
turbulence. Average droplet sizes are affected little by the heat flux,
although for the non-heated sprays, droplet sizes increase at locations very
close to the plate. A significant effect on droplet volume flow rate is also
reported.
Keywords: Droplet evaporation, mist jet, Phase Doppler Anemometry, spray cooling