Two-dimensional direct numerical simulation of spray flames - Part 1: Effects of equivalence ratio, fuel droplet size and radiation, and validity of flamelet model

The effects of equivalence ratio, fuel droplet size, and radiation on jet spray flame are investigated by means of two-dimensional direct numerical simulation (DNS). In addition, the validity of an extended flamelet/progress- variable approach (EFPV), in which heat transfer between droplets and ambient fluid including radiation is exactly taken into account, is examined. n-decane (C₁₀H₂₂) is used as liquid spray fuel, and the evaporating droplets' motions are tracked by the Lagrangian method. The radiative heat transfer is calculated using the discrete ordinate method with S₈ quadrature approximation. The results show that the behavior of jet spray flame is strongly affected by equivalence ratio and fuel droplet size. The general behavior of the jet spray flames including the heat transfer between droplets and ambient fluid with radiation effect can be captured by EFPV.