Flame Stability in Inverse Coaxial Injector Using Repetitive Nanosecond Pulsed Plasma

Abstract

Recently, methane has been investigated as a feasible fuel for propulsion systems. The higher boiling point and higher density of methane, compared with hydrogen, makes its storage tank lighter, cheaper, and smaller to launch. Methane is abundant in the outer solar system and can be harvested on Mars, Titan, Jupiter, and many other planets and therefore, it can be used in reusable rocket engines. However, there are still some technological challenges in the methane engines development path. For example, ignition reliability and flame stability are of great importance. These challenges can be addressed by integrating low-temperature plasma (LTP) through repetitive nanosecond pulsed (RNP) discharge to the injector design. This research focuses on air/CH4 jet flames in a single-element coaxial shear injector coupled with RNP plasma discharge to study the influence of LTP on ignition characteristics and flame stability using advanced diagnostic techniques. The experiments have been performed for different fuel composition, jet velocities, discharge voltages, and frequencies at atmospheric conditions. The transient flame behavior including flame oscillation is studied using direct photography by CMOS high-speed camera. The effect of plasma discharge location on flame stability is also investigated. To demonstrate the effectiveness of RNP discharge on liftoff and blowout/blowoff velocities, the jet velocity at the critical conditions is measured and the enhancements of flame stability are then evaluated. The collected experimental data have shown that the RNP discharge can significantly extend the stability by reducing the liftoff height and increasing the velocity of blowout/blowoff phenomena.

On the ignition kernel formation and propagation: an experimental and modeling approach

“…In this context, we review two types of plasma (i.e. thermal and nonthermal) and a few common sources of ignition such as laser, spark discharge [14,15], nanosecond discharge [16,17], and dielectric barrier discharge (DBD).…”

Role of Experimental, Modeling, and Simulation Studies of Plasma in Sustainable Green Energy

“…Plasma, an intriguing state of matter, offers tremendous potential for converting renewable energy sources into usable forms. One such application is the stabilization of ignition and extending the flammability limits [29,30], owing to both radicals as well as the thermal effect [31,32]. The non-thermal plasma can stabilize the combustion and even maintain the flame for an equivalence ratio of 0.95 [33].…”