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The aim of the present work is to investigate theoretically the secondary air ports arrangement on the NG flamecombustion characteristics. The normal secondary air was introduced into the combustion chamber through its first halflength. Nine different port arrangements are discussed. There are three levels (vertical heights) groups. They are four, eigh tand sixteen levels so that first level of each group starts at 100 mm that equals 10% of the combustor len gth. Each grouplevel has four, eight and sixteen ports. Therefore the number of total ports per level is varied from 16 (four levels with fo urports) to 256 (16 levels with sixteen ports) ports. A theoretical model was used to study the different arrangements. Themodel consists of a vertical combustor with an air swirler, primary air line, and secondary air and fuel lines. The air swirlernumber and the primary air to fuel rat io are kept constant for all running conditions and they are 0.87 and 50, respec tively.A three dimensional model was used to simulate the turbulent reacting flow using computational fluid dynamics package(Fluent 6.3). For validation, the comparison between the measured and calculated axial temperature distribution was madeand shows a good agreement. A remarkable effect of using the secondary air on temperature maps was found. For any valueof SPAR > 0.0, the flame became wider in diameter and longer in length. The flame length increased by about 58, 100 and125 % when the SPAR increased from 0 to 90% for the ports arrangement of 4x4, 8x8 and 16x16 level groups, respectively