Flameless Oxidation (FLOX) is high temperature air and low amount oxygen combustion. This type of combustion was initially titled as large excess enthalpy combustion; today it is known as Flameless Oxidation, High temperature air oxidation, Low NOx injection, and Colorless combustion. In this process the space which is designed to be used for the oxidation of fuel, is more occupied by inert gases than by oxygen, and the oxygen content in this space is too low. In this article, the nonpremixed FLOX of air and biogas (60% CH4, 40%CO2) has been studied using computational fluid dynamics, and the results have been compared to Colorado\\\\\\\'s experiments. The governing equations of flow are mass conservation equation, momentum equation, turbulence equation, and species and energy transfer, while all of them are in cylindrical coordinate. K-ɛ renormalized group (RNG-K-ɛ) equations were used to calculate the expressions of turbulence model. Eddy dissipation concept (EDC) model was used to simulate the combustion flow, and calculation of species transfer, and discrete ordinates (DO) model was applied to correlate the radiant energy. Control volume method was used to solve the governing equations and SIMPLE algorithm was used for the coupling of velocity and pressure field, then the impact of H2 addition on combustion chamber temperature, temperature gradient, heat stress, and pollutants were surveyed. The excellent accordance between numerical and experimental results validates the current numerical method and approves its ability for the purpose of modeling of similar situations.

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