Direct Numerical Simulation of Spray Flame-Wall Interaction under Compression-Ignition Engine Relevant Conditions*

Development of compression-ignition (CI) engines with higher thermal efficiencies and reduced CO₂ emissions warrants the accurate prediction of wall heat loss. In this work, Direct Numerical Simulation (DNS) is used to predict heat flux through chamber-wall during spray flame-wall interaction process, inside a constant volume chamber under CI engine relevant conditions. The simulations employ an Eulerian-Lagrangian framework. The fuel droplets are assumed to be single-component n-decane, whose combustion is modeled using a 2-step chemical scheme designed to predict ignition delay time and burnt gas temperature, for a wide range of equivalence ratio and fresh gas temperature. DNSs are performed for varying fuel injection pressure yielding varying fuel injection velocity. The spray combustion fields are used to analyze the relationship between Nusselt and Reynolds numbers corresponding to wall heat transfer, along with the dependence of representative velocity on heat transfer coefficient.