Laminar burning velocities of 2-methyltetrahydrofuran at elevated pressures

The laminar burning velocities (LBVs) and cellular instability of 2-methyltetrahydrofuran (2-MTHF) were investigated at the unburned temperature of 423 K and pressures from 1 to 10 atm in a cylindrical constant-volume vessel. The LBVs of 2-MTHF/air flame exhibit a notably dropping with increasing pressure. The cellular instability analysis indicates that the critical flame radius of 2-MTHF/air mixture monotonically increases with increasing pressure and the flame surface suffers more badly cellularity under higher pressures. The critical flame radius exhibits non-monotonic variation versus phi and the most unstable flames appear at phi approximate to 1.3. It is observed that the measured Markstein length of 2-MTHF/air mixture decreases with increasing phi and P-u, leading to an earlier formation of wrinkling and cracks with respect to preferential-diffusional instability. Further investigation found that by using a mixture of 14.2% oxygen with 85.8% helium in place of air as bath gas at 10 atm can effectively suppress the cellular instability. Two recently developed models were used to simulate the experimental results and explore the chemical kinetic effects on LBV. Reaction path analysis reveals that the most consumption of 2-MTHF/air at stoichiometric conditions is through the abstraction of H-atom to form radical C5H9O-5. While the competitiveness of decomposition by C-C scission yielding CH3 and tetrahydrofuran radical is relatively weak. Sensitivity analysis illustrates that smallspecies reactions show a controlling effect on LBV. The increasing pressure leads to an evident increase in the sensitivity coefficient of the recombination reaction H+O-2 (+M) = HO2 (+M). The reduction of H atom concentration will cause competition to the initiation reaction H + O-2 = O + OH. This could lower the overall oxidation rate and reduce the burning velocity. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

The study investigated the laminar burning velocities and cellular instability of 2-methyltetrahydrofuran at different pressures, revealing significant changes in flame behavior with increasing pressure. The use of a specific oxygen and helium mixture was found to effectively suppress cellular instability. Additionally, chemical kinetic effects on burning velocity were explored, highlighting the importance of small species reactions and sensitivity to pressure changes.