Difference between revisions of "Sig Turbulence / Dellenback Abrupt Expansion"

Revision as of 08:54, 25 May 2009

1 Testcase description and experimental results

Håkan Nilsson, Chalmers University of Technology, Gothenburg, Sweden

The turbulent swirling flow in an abrupt expansion was experimentally investigated by Dellenback, Metzger, and Neitzel [1]. The geometry is illustrated in Figure 1. The inlet is located at the smaller diameter, where either a pure axial, or swirling flow at different swirl and Reynolds numbers is imposed.

Figure 1: Dellenback Abrupt Expansion geometry

The measurements were taken at the cross-sections shown in figure 2.

Figure 2: Measurement cross-sections

Dellenback presented 9 cases: 3 with purely axial flow, and 6 with swirl:

$Re = \frac{U_{b,in}D_{in}}{\nu}$	$S = \left. \frac{\int_0^{R_{in}}V_\theta V_zr^2dr}{R_{in}\int_0^{R_{in}}V_z^2rdr}\right\|_{z/D_{in}=-2.00}$
30,000	0.00, 0.60, 0.98
60,000	0.00, 1.16
100,000	0.00, 0.17, 0.74, 1.23

At each cross-section the following data is available:

Axial mean velocity profiles.
Tangential mean velocity profiles.
Axial RMS velocity profiles.
Tangential RMS velocity profiles.
Most data sets show measurements on both sides of the centerline as a check for symmetry.

The geometric data used in this case-study are the following:

Inlet diameter	$D_{in} = 50.78 mm$
Outlet diameter	$D_{out} = 98.5 mm$
Expansion ratio	$D_{out}/D_{in} = 1.94$
Inlet length	$2*D_{in}$
Outlet length	$10*D_{in}$

Future work using this case-study should refer to Gyllenram and Nilsson [4], and Nilsson and Gyllenram [5].

2 Published computational results

Computations have been performed by Schluter et al. [2], Gyllenram, Nilsson and Davidson [3], Gyllenram and Nilsson [4,5], and Gyllenram [6]. Gyllenram and Nilsson [4] validates a filtered k-omega SST model using this test case. Nilsson and Gyllenram [5] implemented the kOmegaSSTF model in OpenFOAM, and validated it using this test case. The case-study was first presented by Nilsson [7], at the 4th OpenFOAM Workshop in Montreal.

3 References

[1] Dellenback, P.A., Metzger, D.E., and Neitzel, G.P., "Measurements in Turbulent Swirling Flow Through an Abrupt Expansion", AIAA Journal, 26(6), pp.669-681 , 1987.

[2] Schluter, J.U., Pitsch, H., and Moin, P., "Large Eddy Simulation Inflow Conditions for Coupling With Reynolds-Averaged Flow Solvers", AIAA Journal, 42(3), pp. 478-484, 2004.

[3] Gyllenram, W., Nilsson, H., and Davidson, L., "Large Eddy Simulation of Turbulent Swirling Flow Through a Sudden Expansion", IAHR 2006, Yokohama, 2006, Paper, Slides

[4] Gyllenram, W., and Nilsson, H., "Design and Validation of a Scale-Adaptive Filtering Technique for LRN Turbulence Modeling of Unsteady Flow", Journal of Fluids Engineering, May 2008, Vol 130.

[5] Nilsson, H., and Gyllenram, W., "Experiences with OpenFOAM for water turbine applications", 1st OpenFOAM Conference, Old Windsor, London, 2007. Paper, Slides

[6] Gyllenram, W., "Analytical and Numerical Studies of Internal Swirling Flows", PhD Thesis, Chalmers University of Technology, Gothenburg, Sweden, 2008, ISBN 978-91-7385-104-6, CPL, Thesis, Errata, Slides

[7] Nilsson, H., "The Dellenback Abrupt Expansion OpenFOAM Case-Study", 4th OpenFOAM Workshop, Montreal, June 1-4, 2009. Slides will be made available after the workshop.

4 How to get the files

The OpenFOAM Dellenback Abrupt Expansion cases described in the following sections were developed as a case-study for the Fourth OpenFOAM Workshop, Montréal, 2009, and can be found at the OpenFOAM-extend SourceForge project. It includes complete OpenFOAM cases and automatic post-processing of the results. The block-structured hexahedral meshes are parameterized and generated with m4 and blockMesh. Instructions on how to run the cases follow below.

Get all the current case files by doing:

 
 cd $FOAM_RUN
 svn checkout http://openfoam-extend.svn.sourceforge.net/svnroot/openfoam-extend/trunk/Breeder_1.5/OSIG/Turbulence/dellenbackAbruptExpansion

In the descriptions below, we thus assume that the dellenbackAbruptExpansion directory is located in the $FOAM_RUN directory

Update your files every now and then by doing:

 
 cd $FOAM_RUN/dellenbackAbruptExpansion
 svn update

See further info at OpenFOAM-extend webpage

Required libraries:

profile1DfixedValue in libOpenFoamTurbo.so
Added turbulence models TODO

5 Test cases

Here you can find generic test cases that can be modified for your purposes. The test cases include parameterized mesh generation with several meshes, complete case set-up, and automatic post-processing using sample, foamLog and gnuplot.

You can contribute cases if you come up with more ideas. In that case, please try to follow the same directory structure and name conventions. Add instructions on the new cases in this Wiki.

5.1 dellenbackAbruptExpansion

This case is set up for simpleFoam and kEpsilon, but can be used to run any other steady RAS simulation, by editing constant/RASProperties, and choosing the most appropriate m4 script for mesh generation (wall-functions or low-Re).

5.2 transientDellenbackAbruptExpansion

This case is set up for transientSimpleFoam and kOmegaSSTF, but can be used to run any other transient RAS simulation, by editing constant/RASProperties, and choosing the most appropriate m4 script for mesh generation (wall-functions or low-Re).

6 Others

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@@ Line 115: / Line 115: @@
 You can contribute cases if you come up with more ideas. In that case, please try to follow the same directory structure and name conventions. Add instructions on the new cases in this Wiki.
-=== DAEkEpsilon ===
+=== dellenbackAbruptExpansion ===
-This case can be used to run any other steady RAS simulation, by editing constant/RASProperties, and choosing the most appropriate m4 script for mesh generation (wall-functions or low-Re).
+This case is set up for simpleFoam and kEpsilon, but can be used to run any other steady RAS simulation, by editing constant/RASProperties, and choosing the most appropriate m4 script for mesh generation (wall-functions or low-Re).
-=== DAEtransientkOmegaSSTF ===
+=== transientDellenbackAbruptExpansion ===
-This case can be used to run any other transient RAS simulation, by editing constant/RASProperties, and choosing the most appropriate m4 script for mesh generation (wall-functions or low-Re).
+This case is set up for transientSimpleFoam and kOmegaSSTF, but can be used to run any other transient RAS simulation, by editing constant/RASProperties, and choosing the most appropriate m4 script for mesh generation (wall-functions or low-Re).
 == Others ==