Simulation of Partially Premixed Flames Burning a Variety of Fuels

Partially premixed flames are hybrid flames containing multiple reaction zones that are synergistically coupled through chemistry, heat release, and transport. Such flames occur in many applications including Bunsen burners, industrial furnaces, gas-fired domestic burners, diesel engines, and gas turbine combustors. Partially premixing also occurs in spray combustion systems, lifted flames, and turbulent combustion. Consequently, a detailed understanding of the steady and transient structure of partially premixed flames is important from both practical and scientific considerations.

We are simulating these flames using time-accurate, higher order numerical methods with detailed transport and chemistry models. Simulations are validated through detailed comparison with non-intrusive measurements from a parallel experimental effort under the direction of Professor Ishwar K. Puri. Measurements include particle image velocity (PIV), laser Doppler velocimetry (LDV), Digital Holography Interferometry (HI), and chemiluminescence from flames. In addition, advanced numerical diagnostic and flow visualization tools are used to characterize the detailed flame structure and other fundamental properties including flame stretch, propagation speed, flame stabilization, liftoff and blowout behavior. The transient flame characteristics are also investigated in order to examine the processes of flame-vortex interactions and the flame response to external perturbations. Both burner-stabilized and lifted partially premixed flames burning a variety of fuels (i.e., hydrogen, methane, propane, and n-heptane) in slot burner and axisymmetric configurations are computed.