CHALMERS HEATED CONTRACTION FLOW

1
CHALMERSHEATED CONTRACTION FLOW

• Overview
• Turbulence generally enhances scalar transport
  such as heat and mass
• transfer. This means that the effective
  diffusivity of scalar is augmented by
• turbulence. A cross correlation between velocity
  and scalar fluctuation is a
• physical quantity that represents the
  contribution of our turbulence to effective
• diffusivity. This quantity is called a turbulent
  scalar flux. Among various
• transport processes of turbulent heat transport
  is our central concern,
• because of its importance in engineering and
  industrial process relevant to
• heat transfer and combustion.
• The transport equation of a passive scalar, e.g.,
  temperature, in turbulent
• flows, applying the Reynolds decomposition, is
  given by
• Where D is thermal diffusivity.
• Under strong turbulent condition, the thermal
  diffusivity term can be neglected
• when compared to the diffusion by turbulent
  motion. However the cross
• correlation between the temperature and velocity
  is unknown and a closure is
• necessary. Generally this closure consists of
  defining a turbulent diffusivity.

• Concluding Remarks
• References
• 1.F. Lemoine, Y. Antoine, M. Wolff, M. Lebouche
  Simultaneous
• Temperature and 2D velocity measurements in a
  turbulent Heated jet
• using combined laser-induced fluorescence and
  LDA Experiments in

• Experimental setup consists of several instrument
  installation and
• calibration which includes installation of grid
  in the wind tunnel,
• set up of Prandtl tube and thermocouple for some
  primary
• measurement of velocity and temperature inside
  the tunnel and
• setup of a proper heating devise which was the
  most challenging
• part. Calibration consisted of calibration of
  Hot-wire in two
• temperature and interpolation of the curves
  between the other
• temperatures.
• The Hot-wire is most preferable technique for
  resolving the small
• fluctuation of the flow in comparison to the
  other optic methods
• like LDA or PIV. Cold-wire is used to measure the
  fluctuation of

• Experimental Fluid mechanics Project
• Turbulence Research Laboratory
• December 2006 ,Chalmers University of Technology