A Large Eddy Simulation Study of the Flame Structures of Piloted Turbulent Dimethyl Ether Flames

Abstract

Dimethyl ether (DME) is an intriguing biofuel of the formula CH3OCH3 that has the potential to replace traditional fossil fuels. However, combustion of this biofuel is potentially different from conventional fuels. Current models exist for simulating the combustion of turbulent, piloted, partially-premixed methane-based flames. This project inquires into whether these models will adequately predict the turbulent flame structure of the DME-based flames by comparing a simulated turbulent, piloted, partially-premixed DME-based flame to established experimental results of an identical flame. During the project, several iterations of the turbulent DME-based flame are simulated. It becomes evident that future iterations of the same flame will not lead to alignment with prior experimental flames. The thesis concludes with a sensitivity analysis, testing the variance of the flame structure at different pilot and co-flowing velocities. While the sensitivity test did not yield a flame with a significantly similar flame structure to experimental flames, it did reveal that a higher pilot velocity is more aligned to our desired flame structure than lesser pilot velocities. Examination of the visualization of the flame structure reveals that radial mixing with the oxidizer may have occurred too rapidly for the pilot flame to stabilize the bulk fuel flow. An analysis of the same flame over a finer mesh grid is left for future study.