A comparative study of scale-adaptive and large-eddy simulations of highly swirling turbulent flow through an abrupt expansion
Paper in proceeding, 2014

The strongly swirling turbulent flow through an abrupt expansion is investigated using highly resolved LES and SAS, to shed more light on the stagnation region and the helical vortex breakdown. The vortex breakdown in an abrupt expansion resembles the so-called vortex rope occurring in hydro power draft tubes. It is known that the large-scale helical vortex structures can be captured by regular RANS turbulence models. However, the spurious suppression of the small-scale structures should be avoided using less diffusive methods. The present work compares LES and SAS results with the experimental measurement of Dellenback et al. (1988). The computations are conducted using a general non-orthogonal finite-volume method with a fully collocated storage available in the OpenFOAM-2.1.x CFD code. The dynamics of the flow is studied at two Reynolds numbers, Re=6.0×104 and Re=105 , at the almost constant high swirl numbers of Sr=1.16 and Sr=1.23, respectively. The time-averaged velocity and pressure fields and the root mean square of the velocity fluctuations, are captured and investigated qualitatively. The flow with the lower Reynolds number gives a much weaker outburst although the frequency of the structures seems to be constant for the plateau swirl number.

Author

Ardalan Javadi

Chalmers, Applied Mechanics, Fluid Dynamics

Håkan Nilsson

Chalmers, Applied Mechanics, Fluid Dynamics

IOP Conference Series: Earth and Environmental Science

17551307 (ISSN) 17551315 (eISSN)

Vol. 22 022017

27th IAHR Symposium on Hydraulic Machinery and Systems, IAHR 2014
Montreal, Canada,

Subject Categories

Energy Engineering

Fluid Mechanics and Acoustics

Areas of Advance

Energy

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

DOI

10.1088/1755-1315/22/2/022017

More information

Latest update

3/10/2022