Assessment of Unsteady RANS in Predicting Swirl Flow Instability Based on LES and Experiments

Abstract Swirl flows play an important role in many engineering applications such as modern gas turbines, aero propulsion systems etc. While the enhanced mixing and stabilisation of the flame caused by the swirl are desirable features, such flows often exhibit hydrodynamic instabilities called precessing vortex core. For design purposes it is very important to predict such instabilities. Computational fluid dynamics (CFD) using Reynolds-averaged Navier–Stokes (RANS) type turbulence models are state of the art for the prediction of flow properties in engineering practice. The objective of this paper is therefore to evaluate the performance of the unsteady RANS (U-RANS) method in predicting the precessing vortex core phenomenon. To this end, an unconfined swirling flow with precessing vortex core at swirl number 0.75 and Reynolds number ranging from 10 000 to 42 000, investigated by means of both experiments and large eddy simulation, is utilised. The results show that U-RANS is able to capture the precessing vortex core both qualitatively and in parts quantitatively.

[1]  James J. McGuirk,et al.  Large Eddy Simulation of Isothermal Confined Swirling Flow with Recirculation , 2002 .

[2]  Franz Durst,et al.  a Parallel Block-Structured Multigrid Method for the Prediction of Incompressible Flows , 1996 .

[3]  Amsini Sadiki,et al.  Large eddy simulation of combustion processes under gas turbine conditions , 2004 .

[4]  F. Williams,et al.  Turbulent Reacting Flows , 1981 .

[5]  Scot L. Haire,et al.  STRUCTURE-BASED TURBULENCE MODELING FOR WALL-BOUNDED FLOWS , 2000, Proceeding of First Symposium on Turbulence and Shear Flow Phenomena.

[6]  D. B. Spalding,et al.  Turbulent shear flows , 1980 .

[7]  Brian Launder,et al.  Multiple-Time-Scale Concepts in Turbulent Transport Modeling , 1980 .

[8]  S. Leibovich.  THE STRUCTURE OF VORTEX BREAKDOWN , 1978 .

[9]  T. B. Gatski,et al.  General explicit algebraic stress relations and best approximation for three-dimensional flows , 1998 .

[10]  Rhj Sellin,et al.  Engineering Turbulence - Modelling and experiments 3 , 1996 .

[11]  R. Chanaud.  Observations of oscillatory motion in certain swirling flows , 1965, Journal of Fluid Mechanics.

[12]  T. Gatski,et al.  On explicit algebraic stress models for complex turbulent flows , 1992, Journal of Fluid Mechanics.

[13]  János M. Beér,et al.  Combustion in swirling flows: A review , 1974 .

[14]  A. Hauser,et al.  LES OF CONFINED METHANE–AIR DIFFUSION FLAMES USING OSCILLATING INFLOW CONDITIONS , 2002 .

[15]  Philip J. Smith,et al.  Modeling of swirl in turbulent flow systems , 1986 .

[16]  T. O’Doherty,et al.  Vortex breakdown: a review , 2001 .

[17]  T. Shih,et al.  Constitutive Relations and Realizability of Single-Point Turbulence Closures , 1996 .

[18]  D. Lilly,et al.  A proposed modification of the Germano subgrid‐scale closure method , 1992 .

[19]  Jos Derksen,et al.  Simulation of vortex core precession in a reverse‐flow cyclone , 2000 .

[20]  Elias Balaras,et al.  INTERACTION OF THE INNER AND OUTER LAYERS IN LARGE-EDDY SIMULATIONS WITH WALL-LAYER MODELS , 2002 .

[21]  P. Durbin.  A PERSPECTIVE ON RECENT DEVELOPMENTS IN RANS MODELING , 2002 .

[22]  Dan S. Henningson,et al.  Turbulence and Transition Modelling , 1996 .

[23]  P. Moin,et al.  A dynamic model for subgrid-scale variance and dissipation rate of a conserved scalar , 1998 .

[24]  David F. Fletcher,et al.  CFD simulation of precession in sudden pipe expansion flows with low inlet swirl , 2002 .

[25]  M. Lesieur,et al.  New Trends in Large-Eddy Simulations of Turbulence , 1996 .

[26]  B. Launder,et al.  Development and application of a cubic eddy-viscosity model of turbulence , 1996 .

[27]  Masud Behnia,et al.  Reynolds averaged simulation of unsteady separated flow , 2003 .

[28]  A. Maltsev,et al.  Towards the Development and Assessment of Complete CFD Models for the Simulation of Stationary Gas Turbine Combustion Processes , 2003 .

[29]  P. Spalart.  Strategies for turbulence modelling and simulations , 2000 .