Hostname: page-component-848d4c4894-nr4z6 Total loading time: 0 Render date: 2024-05-21T00:34:30.785Z Has data issue: false hasContentIssue false

Linear and Non-Linear Turbulence Model Predictions of Vortical Flows in Lobed Mixers

Published online by Cambridge University Press:  03 February 2016

H. Salman
Affiliation:
Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough, Leicestershire. LE11 3TU. UK. email: G.J.Page@lboro.ac.uk tel: +44 (0) 1509 227205, fax: +44 (0) 1509 227275
D. Jiang
Affiliation:
Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough, Leicestershire. LE11 3TU. UK. email: G.J.Page@lboro.ac.uk tel: +44 (0) 1509 227205, fax: +44 (0) 1509 227275
G.J. Page
Affiliation:
Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough, Leicestershire. LE11 3TU. UK. email: G.J.Page@lboro.ac.uk tel: +44 (0) 1509 227205, fax: +44 (0) 1509 227275
J.J. McGuirk
Affiliation:
Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough, Leicestershire. LE11 3TU. UK. email: G.J.Page@lboro.ac.uk tel: +44 (0) 1509 227205, fax: +44 (0) 1509 227275

Abstract

Lobed mixers are widely used in gas turbine engines to increase mixing between hot and cold streams and consequently reduce jet noise. CFD predictions are presented for a simplified experimental configuration of a planar, three lobe geometry. Results are shown for a standard linear k–ε turbulence model, the same model with a time scale limitation invoked and a non-linear quadratic model also employing a time scale limitation. Comparisons are presented between the three models for axial velocity, velocity vectors, shear stress and turbulence kinetic energy at a selected plane in the mixing region. The non-linear model was found to have little influence on the mean flow but some effect on the turbulence structure was observed. Comparison with measurements showed that all major features were reproduced but detail differences were evident. The use of a time scale limit reduced peak values of predicted turbulence quantities by 20-30%. As compared to the standard linear model, the time scale limited non-linear model moved the position of the zero streamwise circulation location by about one lobe wavelength upstream so giving better agreement with experiment.

Type
Research Article
Copyright
Copyright © Royal Aeronautical Society 2004 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Paterson, R.W.Turbofan forced mixer nozzle flow field - a benchmark experimental study”, ASME Jnl. of Eng. for Gas Turbines and Power, 106, pp. 692698, (1984).Google Scholar
2. Koutmos, P., McGuirk, J.J.Isothermal velocity and turbulence measurements downstream of a model multilobed turbofan mixer”, Experiments in Fluids, 8, pp. 183191, (1989).Google Scholar
3. McCormick, D.C., Bennett, J.C. Jr.Vortical and turbulent structure of a lobed mixer free shear layer”, AIAA Journal., 32, pp. 18521859, (1994).Google Scholar
4. Yu, S.C.M., Yip, T.H.Measurements of velocities in the near field of a lobed forced mixer trailing edge”, The Aeronautical Journal, 101, pp. 121129, (1997).Google Scholar
5. Frost, T.H.Practical by-pass mixing systems for fan jet aero engines”, Aeronautical Quarterly, 141, (1966).Google Scholar
6. Kozlowski, H., Kraft, G.Experimental evaluation of exhaust mixers for an energy efficient engine”, AIAA Paper 801088, (1980).Google Scholar
7. Koutmos, P. McGuirk, J.J.Turbofan forced mixer/nozzle temperature and flow field modelling”, Int. Jnl. of Heat and Mass Transfer, 32, pp. 11411153, (1989).Google Scholar
8. Tsui, Y-Y, Wu, P-W.Investigation of the mixing flow structure in multilobe mixers”, AIAA Journal, 34, pp. 13861391, (1996).Google Scholar
9. O’Sullivan, M.N., Krasnodebski, J.K., Waitz, I.E., Greitzer, E.M., Tan, C.W., Dawes, W.N.Computational study of viscous effects on lobed mixer flow features and performance”, AIAA Journal of Propulsion and Power, 12, pp. 449456, (1996).Google Scholar
10. Salman, H., McGuirk, J.J. and Page, G.J.A numerical study of vortex interactions in lobed mixer flow fields”, AIAA Paper 993409, 30th AIAA Fluid Dynamics Conf., Norfolk, Virginia, U.S.A., (1999).Google Scholar
11. Anderson, W.K., Thomas, J.L. and Van Leer, B., ‘Comparison of Finite Volume Flux Vector Splittings for the Euler Equations,’ AIAA Journal, 24, no. 9, pp 1453–60. (1986)Google Scholar
12. Page, G.J., Zhao, H., McGuirk, J.J., “A parallel multi-block Reynolds-averaged-Navier-Stokes method for propulsion installation applications”, 12th Int. Symp. on Air Breathing Engines, Melbourne, Australia, Vol.1, pp. 864876, (1991).Google Scholar
13. Launder, B.E. and Spalding, D.B.The numerical computation of turbulent flows”, Comp.Methods in Applied Mech. and Eng., 3, pp. 269289, (1974).Google Scholar
14. Durbin, P.A.On the k–ε stagnation point anomaly,” Int. Jnl. of Heat and Fluid Flow, 17, pp 8990, (1996).Google Scholar
15. Moore, J.G. and Moore, J.Realizability in two-equation turbulence models,” AIAA Paper 993779, 30th AIAA Fluid Dynamics Conference, Norfolk, Virginia, USA. (1999)Google Scholar
16. Speziale, C.G.On non-linear k-l and k-ε models of turbulence”, Jnl. Fluid Mech., 178, pp. 459475, (1987).Google Scholar
17. Suga, K.Development and application of a non-linear eddy viscosity model sensitised to stress and strain invariants”, Ph.D. Thesis, UMIST (1995).Google Scholar
18. Apsley, D.D and Leschziner, M.A.A new low-Reynolds number non-linear two-equation turbulence model for complex flows”, Int. Jnl. of Heat and Fluid Flow, 19, pp 2-9-222, (1998).Google Scholar
19. Gessner, F.B. and Emery, A.F.The numerical prediction of developing turbulent flow in rectangular ducts”, ASME Jnl. of Fluids Eng., 103, pp445453, (1981).Google Scholar
20. Myong, H.K. and Kobayashi, T.Prediction of three-dimensional developing turbulent flow in a square duct with an anisotropic low-Reynolds-number k-ε model”, ASME Jnl. of Fluids Eng., 113, pp 608615, (1991).Google Scholar