Numerical simulation of methane-hydrogen-air premixed combustion in turbulence

Abstract

3D modeling is based on an experimental platform named turbulence constant volume combustion chamber (CVCC). The turbulence model applies the realizable k-ε model. The combustion model applies the premixed combustion model. Simulation of methane-hydrogen-air turbulent premixed combustion is realized using the model. The initial condition is T0 °C = 298 K, P0 = 1 bar and the gas equivalence ratio is φ = 1. The characteristics of flame are analyzed by modifying the turbulence intensity (uRMS = 0 m/s, 0.7 m/s, 1.3 m/s, 2.0 m/s)and hydrogen fraction (R (H2) = 0%, 10%, 30%, 50%). It is calculated that in the process of spherical flame combustion and propagation, the pressure increase rate increases first and then decreases. Turbulence intensity and hydrogen fraction have similar effect on the flame propagation process. If the turbulence intensity is used as an independent variable, the flame propagation rate increases with its increase. When the flame radius is 30 mm, the flame propagation velocity of 2.0 m/s turbulence intensity is about 2.7 times that of laminar flow. Due to which both the maximum combustion pressure and the maximum pressure rise rate are monotonically increasing. As it increases, the combustion pressure rises and falls the fastest. As the R (H2) increases, the flame propagation rate can significantly increase. When R (H2) is 50%, the maximum velocity is 4.82 m/s, which is about 1.5 times that of the maximum of pure methane. When R (H2) is high, the greater the maximum pressure is, the shorter the time for the maximum pressure to occur will be. When R (H2) is 50%, the maximum pressure is about 9 bar, which is 2.25 times of the force of pure methane combustion.