Publications

Numerical and experimental investigation of turbulent DME jet flames

Bhagatwala, Ankit; Luo, Zhaoyu; Shen, Han; Sutton, Jeffrey A.; Lu, Tianfeng; Chen, Jacqueline H.

Results are presented here from a three-dimensional direct numerical simulation of a temporally-evolving planar slot jet flame and experimental measurements within a spatially-evolving axisymmetric jet flame operating with DME (dimethyl ether, CH3OCH3) as the fuel. Both simulation and experiment are conducted at a Reynolds number of 13050. The Damköhler number, stoichiometric mixture fraction and fuel and oxidizer compositions also are matched between simulation and experiment. Simultaneous OH/CH2O PLIF imaging is performed experimentally to characterize the spatial structure of the turbulent DME flames. The simulation shows a fully burning flame initially, which undergoes partial extinction and subsequently, reignition. The scalar dissipation rate (χ) increases to a value much greater than that calculated from near-extinction strained laminar flames, leading to the observed local extinction. As the turbulence decays, the local values of χ decrease and the flame reignites. The reignition process appears to be strongly dependent on the local χ value, which is consistent with previous results for simpler fuels. Statistics of OH and CH2O are compared between simulation and experiment and found to agree. The applicability of OH/CH2O (formaldehyde) product imaging as a surrogate for peak heat release rate is investigated. The concentration product is found to predict peak heat release rate extremely well in the simulation data. When this product imaging is applied to the experimental data, a similar extinction/reignition pattern also is observed in the experiments as a function of axial position. A new 30-species reduced chemical mechanism for DME was also developed as part of this work.