Informatics Publishing Limited

Akram Zeid ¹, Ahmed Farag ²

Affiliations
1 Marine Eng. Technology Dept., College of MT.
2 T, AASTMT, Alexandria, EG

Abstract

This paper presented a study of the natural gas combustion in a swirl gas turbine combustor. The effect of the primary air swirl number, primary air/fuel mass ratio and the secondary/primary air mass ratios on the flow field and combustion characteristics of natural gas in air is investigated. For this purpose, a test rig was constructed including a vertical test combustor provided with an air swirler mounted at its upstream. Primary air, secondary air, and fuel lines are also included. Four different air swirlers having the same blockage ratio of 0.72 are used for the present investigation. The swirlers have the same hub (inner) diameter of 72 mm and the same outer diameter of 100 mm. The swirlers have different vane angles of 15^o, 30^o, 45^o, and 60^o to generate swirl numbers of different strengths of about 0.23, 0.5, 0.85 and 1.5, respectively. A three dimensional model was used to simulate the non reacting and reacting flows by using the computational fluid dynamics package Fluent 6.3. Comparing the measured test data with the numerical computations, a reasonable agreement is found. The results show that, increasing the primary air/fuel ratio and the secondary/primary air mass ratio leads to decreasing the average flame temperature and consequently the flame size. Increasing the secondary/primary air mass ratio leads to a decrease in the axial CO and CO₂ concentrations and an increase in O₂ concentration at the combustor exit.

Keywords

Gas Turbine Combustor, Swirl Number, Secondary Air, Natural Gas Combustion Characteristics

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