Etude de la combustion de gaz de synthèse issus d'un processus de ...

Chapter 3
3.2.5.2 Analysis of the flow at the chamber core
The whole movement has been analyzed, and an initial assessment of turbulent
fluctuations was provided from the whole filed measurements. Specific field
measurements are now exposed to evaluate the properties of turbulence in detail. The
turbulent characteristics are evaluated thanks to PIV measurements with time
resolution of 5 kHz along one field of 13x13 mm and image resolution of 512x512
pixels. The investigated zone is close to the center of the chamber (1.5 mm to the left),
where the mean and fluctuating velocities remain relatively elevated along a 10 ms
period after TDC. Figure 3.15 shows the fluctuation velocity components in this zone.
tel-00623090, version 1 - 13 Sep 2011
Figure 3.15 – Time evolution of the space speed fluctuations variation (reprinted from Strozzi,
2008). The zone 1 corresponds to the bottom left corner of PIV field, and the zone 4
corresponds to the entire field.
It is observed that both velocity components fluctuations decrease after TDC with
similar amplitude. The kinetic energy is evaluated only from two velocity components
as follows:
' 2 ' 2
= + (3.10)
k u v
It is therefore, slightly underestimated (~20%) due to the lack of the third component.
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