Sig Turbulence / Dellenback Abrupt Expansion

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 swirls and Reynolds numbers is imposed.

Figure 1: Dellenback Abrupt Expansion geometry

2 Published computational results

Computations have been performed by Schluter et al. [2], and Gyllenram and Nilsson [3,4].

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

4 Geometric data of the ERCOFTAC centrifugal pump [2][3][4]

The case is set up according to the instructions in the ERCOFTAC database. The different parameters used in this case are showed below:

Impeller
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	$mm$

5 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 that solve the flow in the domain (2D) 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

You will also need the profile1DfixedValue boundary condition. To install and use it, see Sig Turbomachinery Library OpenFoamTurbo

6 Directory structure

The structure of the dellenbackAbruptExpansion directory is as follows:

Coming soon: print-out from 'tree' command.

The "cases" directory contains the different test cases.
The "measurements" directory contains all the data measured by Dellenback et al. [1]. The data is re-arranged to facilitate the automatic post-processing.

Here is what you can find in the "cases" directory:

Coming soon: print-out from 'tree' command.

All cases have the same sub-directory structure. Here is an example based on the ??? case:

Coming soon: print-out from 'tree' command.

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.