Fuel and Combustion

Fuel and Combustion

Influence of Thermal Radiation Models on Prediction of Reactive Swirling Methane/Air Flame in a Model Gas Turbine Combustor

Authors
Farzad Bazdidi Tehrani 1
Hamed Zeinivand 2
1 School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran
2 Aerospace Organization, Tehran, Iran
Abstract
A numerical simulation of reactive swirling methane/air non-premixed flame in a new three-dimensional model combustion chamber is carried out to assess the performance of two thermal radiation models, namely, the Discrete Transfer Radiation Model and the P-1 Model. A Finite Volume staggered grid approach is employed to solve the governing equations. The second-order upwind scheme is applied for the space derivatives of the advection terms in all transport equations. The SIMPLEC algorithm is used to handle the velocity and pressure coupling. The eddy dissipation model is employed to predict the heat release and the Reynolds stress turbulence model is applied to simulate the flow behavior. A weighted-sum-of-gray-gases model is used for the gas radiative properties. Computational results with and without the radiation effects are compared with the available experimental data and the two radiation models are evaluated in terms of computational efficiency and prediction accuracy. Comparison of present numerical results with experimental data reveals that the thermal radiation mode is important especially for heat flux on the walls. Both the Discrete Transfer Radiation and P-1 radiation models predict temperature distribution reasonably well, although the latter involves a relatively high computational cost. The P-1 model overestimates heat flux on the walls.

Highlights

The main purpose of the present work is to numerically investigate the influence of two different thermal radiation models on the modeling of turbulent swirling non-premixed methane/air flame in a model gas turbine combustion chamber. Two models, namely, the DTRM and P-1 model are employed to predict the radiation heat transfer. The main conclusions are drawn as follows:

(1) The Reynolds stress turbulence model well predicts the combustor flow with a swirl number of 0.55. Two recirculation zones (central toroidal recirculation and corner recirculation zones) with two shear layers appear in the combustion chamber. The central toroidal recirculation zone attached to a reversed flow plays the main role in flame stability. Also, the corner recirculation zone increases the heat transfer to the walls.

(2) With the consideration of thermal radiation using both the present models, the predicted flame temperatures along the axial distance of the chamber are noticeably closer to the experimental data. Also, both radiation models predict temperature distribution across the chamber width reasonably well, displaying similar trends. Nevertheless, the use of DTRM involves a relatively high computational cost.

(3) The P-1 radiation model remarkably over-predicts the total heat flux on the walls. This is due to the presence of a local heat source in the combustion chamber.

 

Keywords
: Reactive swirling flow
Eddy dissipation model
Reynolds stress model
Radiation model
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