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Show Further improvements should be the result of combustion model developments, assessing non-equilibrium effects and especially leading to an improved description of fluctuations in the flame, mainly of temperature fluctuations for high temperature processes. INTRODUCTION Environmental concerns impose strict limits on NOx (NO+NO2) emissions from industrial applications. These limitations make necessary that the manufacturers of combustion systems redesign existing burners, in' order to comply with present and future emission regulations. Oxygen-fuel combustion is one of the preferred technical solutions to NOx reduction in a rapidly increasing number of industrial applications. The oxy-fuel burner has to be carefully designed in order to avoid high flame temperature or high oxygen concentration effects, thus efficiently reducing NOx production. Numerical simulations have become a powerful tool in the design of combustion systems, given their rapidly increasing accuracy, as well as the availability of sophisticated software equipping high capacity-high speed computers. A significant effort from numerous researchers has been placed in the investigation of NOx formation in combustion applications, generally for single free jet hydrocarbon- or hydrogen-air flames. The primary aim of these studies has been to develop models to properly scale N O x emissions with primary variables such as fuel composition, initial jet velocity, jet exit diameter, etc. One goal of the models is to extend the understanding of these turbulent free jet flames to more complex, practical combustion systems such as industrial furnaces (recirculating flows), equipped with a large variety of industrial burners. While the numerical simulation of combustion systems has improved constantly in 2 |