5 m/s injection velocity

The first study concern a "low" fuel injection velocity. We have solved the problem until a time of 35 ms. On the following  picture, we can see result on fuel mass fraction inside the injector.
The first phenomenon that we note concern the symmetry of the flow. It's confirmed by the two cross sections of fuel mass fraction.
Moreover, we note a fall in fuel mass fraction near the wall for a cross section x= 0.1. This phenomenon can due to a recirculation area behind fuel jets. In order to see these recirculation areas, we have ploted the shaded contour of U velocity : indeed, U velocity is negative near the wall behind fuel jets, which could be explained by recirculation areas.
The mean fuel mass fraction have been ploted after the last solution (at 22 ms i.e. 50000 iterations) during 30000 iterations. We can conclude the same remarks than the instantaneous fuel mass fraction contours : the flow is almost symmetrical, the outlet flow is not mixed.

Finally, this injection velocity is too low because air and fuel are not mixed in the outlet of the injector. Actually, fuel flow rate is not enough important compared to the air flow rate. A solution is to increase fuel velocity.
 
 


Shaded contours of fuel mass fraction at t=35 ms
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Sections of fuel mass fraction in x=0.1 (middle of the injector) and x=0.21 (outlet of the injector)
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Shaded contours of U velocity (in x direction) at t=35 ms.
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Mean shaded contours  of fuel mass fraction


 Mean outlet cross section of fuel mass fraction

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