Deflagration-to-detonation Transition in Stratified Oxygen – Liquid Fuel Film Systems

ABSTRACT

Deflagration-to-detonation transition (DDT) in gas (oxygen)–liquid n-heptane film and gas (oxygen)–liquid n-decane film systems is registered experimentally using a fused or exploding wire as a weak ignition source that generates a primary shock wave with a Mach number ranging from 1.02 to 1.6. In a straight smooth-walled channel of rectangular cross section 54 × 24 mm, 3 and 6 m long with one open end, the DDT is obtained at distances 900 to 4000 mm from the ignition source 3 to 1700 ms after ignition. The DDT is obtained for n-heptane and n-decane films 0.2 to 0.7 mm thick, which corresponds to the overall fuel-to-oxygen equivalence ratios of 15 to 40. The registered detonation velocities range from 1400 to 2000 m/s. In several experiments, a high-velocity quasi-stationary deflagration front propagating at an average velocity of 700–1100 m/s is recorded. The structure of this front includes the leading shock wave followed by the reaction zone separated from each other by a time delay of 90 to 190 μs. The results obtained are important for explosion safety and for better understanding of the operation process in the continuous-detonation and pulse-detonation combustors of advanced rocket and air-breathing engines with the supply of liquid fuel in the form of a wall film.

KEYWORDS:

• Deflagration-to-detonation transition
• stratified gas–film system
• weak ignition
• liquid hydrocarbon fuel
• oxygen

Acknowledgments

This work was financially supported by the Ministry of Education and Science of Russia under state contract No. 13.1902.21.0014 (agreement No. 075-15-2020-806) within the framework of the Federal Target Program “Research and Development in Priority Areas of Development of the Scientific and Technological Complex of Russia for 2014–2020.”

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Notes

¹ an open-source suite of tools for problems involving chemical kinetics, thermodynamics, and transport processes; www.cantera.org; retrieved 13 Nov. 2020.)

Additional information

Funding

This work was supported by the Ministry of Education and Science of Russian Federation [State contract No. 13.1902.21.0014 (agreement No.075-15-2020-806)].