Cold Flow Investigation of Primary Zone Characteristics in Combustor Utilizing Axial Air Swirler

This paper presents a cold flow simulation study of a small gas turbine combustor performed using laboratory scale test rig. The main objective of this investigation is to obtain physical insight of the main vortex, responsible for the efficient mixing of fuel and air. Such models are necessary for predictions and optimization of real gas turbine combustors. Air swirler can control the combustor performance by assisting in the fuel-air mixing process and by producing recirculation region which can act as flame holders and influences residence time. Thus, proper selection of a swirler is needed to enhance combustor performance and to reduce NOx emissions. Three different axial air swirlers were used based on their vane angles i.e., 30°, 45°, and 60°. Three-dimensional, viscous, turbulent, isothermal flow characteristics of the combustor model operating at room temperature were simulated via Reynolds- Averaged Navier-Stokes (RANS) code. The model geometry has been created using solid model, and the meshing has been done using GAMBIT preprocessing package. Finally, the solution and analysis were carried out in a FLUENT solver. This serves to demonstrate the capability of the code for design and analysis of real combustor. The effects of swirlers and mass flow rate were examined. Details of the complex flow structure such as vortices and recirculation zones were obtained by the simulation model. The computational model predicts a major recirculation zone in the central region immediately downstream of the fuel nozzle and a second recirculation zone in the upstream corner of the combustion chamber. It is also shown that swirler angles changes have significant effects on the combustor flowfield as well as pressure losses.

• Yehia A. Eldrainy
• Mohammad Nazri Mohd. Jaafar
• Tholudin Mat Lazim

• cold flow
• numerical simulation
• combustor;turbulence
• axial swirler.

[1] Lefebvre A. H. (1983), "Gas turbine combustion" McGraw-Hill series
[2] Correa, S.M., "A Review of NOX Formation under Gas-Turbine
Combustion Conditions" Combustion Science and Technology, vol. 87,
pp.329-362, 1993
[3] M. Mellor, "Design of Modern gas Turbine Combustors", Academic
Press, 1990.
[4] Philip P. Walsh and Paul Fletcher (2005), "Gas turbine Performance"
Blackwell Science
[5] Y. Wang, V. Yang, and R.A. Yetter "Numerical Study on Swirling Flow
in an Cylindrical Chamber" 42nd AIAA Aerospace Sciences Meeting,
2004, Reno, Nevada
[6] Karvinen and H. Ahlstedt "Comparison of Turbulence Models in Case
of Jet in Cross Flow Using Commercial CFD Code" Engineering
Turbulence Modeling and Experiments 6, 2005, Elsevier Ltd.
[7] Launder, B.N. and Spalding, D. B. Lectures in Mathematical Models of
Turbulence. Academic Press, London, England, 1972
[8] Lin, S. and Griffiths, A. J. "CFD simulation of cooling air flows within
shrouded finned heater/cooler systems used on barrel extruders"
Proceedings of the Joint ASME/JSME Fluid Engineering Annual
Conference, USA, 1995.
[9] FLUENT 6.2 User's Guide, Fluent Inc. 2005
[10] Versteeg, H.K. and Malalasekera, W., "An Introduction to
Computational Fluid Dynamics, the Finite Volume Method", Longman
Group Ltd., 1995.
[11] Eldrainy YA, Aly HS, Saqr KM, Mohd Jaafar M.N. Augmentation of
Turbulence and Mixing in Gas Turbine Combustors by Introducing
Unsteady Effects. International Conference on Mechanical, Industrial,
and Manufacturing Technologies (MIMT 2010) 2010.
[12] Yehia A. Eldrainy, Hossam S. Aly, Khalid M. Saqr, and Mohammad
Nazri Mohd Jaafar, "A Multiple Inlet Swirler for Gas Turbine
Combustors", International Journal of Mechanical Systems Science and
Engineering 2:2 2010.