Geometry Measurements of Turbulent Dimethyl Ether/Air Flames with Novel Levels of Preheat Temperature and Dilution

Abstract A new turbulent flame burner, called the Vitiator-Assisted Preheat Oxygen Reducing (VAPOR) burner was designed to provide higher levels of reactant preheat temperature (TR, up to 1100K), Reynolds number (Re), and dilution with inert gases than in previous studies. The burner was demon- strated to provide stable dimethyl ether (DME)/air flames for both premixed and diffusion flame cases. An advantage of the design is that it avoids the need for a surrounding pilot flame, which was required in some previous studies. A pilot flame complicates any attempts to model the experiment. DME was selected because it is a low-carbon fuel that can be produced from bio-fuels and natural gas. The need for a new burner arises from the lack of flame measurements at high levels of TR, Re and inert dilution. Additionally, experimental measurements of DME/air combustion is an area of opportunity in alternative fuels research. In realistic engines, combustion often occurs when reactants are preheated, diluted with inerts (sometimes due to gas recirculation), and when Reynolds numbers are large. However, for the vast majority of previous turbulent flame studies, the reactant tempera- ture was limited to room temperature. To demonstrate the usefulness of the VAPOR burner, some measurements are reported and compared to previous studies and theoretical models. The normalized flame height for premixed flames was measured to decrease by 19% as the preheat temperature was increased from 600K− 1000K, and increase by 14% as the oxygen concentration was reduced from 21% − 15% for a preheat temperature of 600K. The normalized flame height for diffusion flames was measured to decrease by 7% as the preheat temperature was increased from 600K− 1100K. This work demonstrated the VAPOR burner’s potential for the study of premixed and diffusion jet flames subjected to novel levels of preheat at controllable levels of dilution.