Abstract
Clean combustion technologies and efficient energy harvesting methods are the focal points of current combustion research. The swirling flows are employed to achieve a well-mixed, homogenous fuel-air mixture for an efficient combustion in a gas turbine engine. The current study simulates an air-diluted methanol spray in a swirling hot co-flow. Atomization, the phase change of liquid fuel, and the mixing of the gaseous fuel with the oxidizer are essential physical processes that must be modeled to simulate liquid fuel combustion. The study involves using an Eulerian-Lagrangian method, a common technique in multiphase simulations, wherein it resolves the continuous gas phase using the Eulerian approach. In contrast, the dispersed liquid phase is handled using the Lagrangian approach. The Flamelet Generated Manifold (FGM), a computationally efficient yet accurate combustion model, simulates the gas-phase reactions within the multiphase simulations. An increase in swirl provides better fuel-oxidizer mixing and higher turbulence to the flow. The former is desirable for efficient combustion; the increase in the latter may tend to cause local flame extinction or delayed auto-ignition. Analysis of swirl numbers between 0.2 and 0.6 is carried out to analyze its effect on the auto-ignition and flame stability. It is noted that the lift-off height increases as the swirl number increases due to a delayed ignition. Further, Proper Orthogonal Decomposition (POD) is used to analyze the ignition kernel and flame propagation around different vortical structures contributing to the evolution of the swirl-dominated flow field.
