Fundamental Study of CH4-Air Combustion Under an Axisymmetric Small-scale Rectangular Combustor Using Computational Modeling

Abstract

The optimization of the design and operating conditions of industrial combustors depends on the fundamental study of combustion dynamics and flow behaviors. Complete combustion increases the thermal efficiency as well as reduces the emission significantly. A study of this kind also allows exploring alternative fuels that would increase the combustion efficiency thus the life cycle of the systems. To develop a highly-performed combustion system for rocket engines or power plants, fundamental research under an axisymmetric small-scale combustor is considered in this study. The k-Ɛ (2 Eqn.) and species transport model (STM) are used to study the flow turbulence and combustion behavior, respectively. A Parallel flow injection configuration of fuel and air is considered. In this study, combustion behavior is investigated at a wide range of fuel and air flowrate conditions while keeping the air slot dimension (240 mm) and fuel injection slot diameter (10 mm) constant. The fuel velocity (FV) and air velocity (AV) are changed from 2 m/s to 30 m/s so that a better test matrix could be proposed. At each run, turbulence, the flame temperature, reaction heat release rate, mass fraction of CO2, etc are studied. It is seen that the combustion temperature increases with the increase in fuel injection velocity. The static flame temperature reaches its maximum (2177 K-2287 K) and falls within the standard limits of CH4-Air combustion. The mass fraction of CO2 is found to be within the acceptable limit (0.121-0.153). The heat of the reaction is found to be high at variable Reair and ReCH4 conditions. It is observed that the computational models used in this study are capable of predicting the flow and combustion behaviors accurately.