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-   -   3D Ejector Thrust Calculation (http://www.cfd-online.com/Forums/fluent/44375-3d-ejector-thrust-calculation.html)

Emmanuel April 6, 2007 13:59

3D Ejector Thrust Calculation
 
In the 3D model of an axisymmetric nozzle and ejector combination I computed before, I modeled just one quarter (taking advantage of the symmetry) of the whole model. Using surface integral I obtained the expected velocity at the ejector outlet, the area of this surface is one quarter the actual area as expected.

My problem is the thrust of the ejector. The axisymmetric model gave me a value about 4N using Report-->Forces option, this was close to my expected result. For the 3D model I was expecting about 1N (which is a quarter because of the area is a quarter) for the thrust, but the obtained about 0.08N which is much smaller.

I have checked my units and scale and do not know what could be wrong.

The thrust on any wall surface can be simply calculated from the total force acting on the wall boundary (ejector wall) through Report-->Forces option. In the Force report panel, you can specify the Force vectors and select the ejector wall under Wall Zones option. When you click on the Print option, the total force acting on the desired wall surface will be printed on the FLUENT console window.


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