Effects of Nanosecond Repetitively Pulsed Plasma Discharges on a Propagating Hydrogen--Air Flame

Abstract

Pressure-gain combustion cycles have been a topic of intense scientific research in recent years. Pulse detonation combustors are one promising technology for successfully implementing these pressure-gain cycles. These combustors frequently rely on obstacles for accelerating a propagating flame and inducing the deflagration-to-detonation transition. The use of obstacles, however, has several disadvantages. Replacing such obstacles with nanosecond repetitively pulsed plasma discharges may be advantageous to developing this technology further. Proof of concept has been achieved demonstrating the effectiveness of this strategy at enhancing the transition to detonation. This work is a closer investigation into the effect of these plasma discharges on flames with varying turbulence intensities and propagation velocities. For velocities below 200 m/s, the effect is minimal and transition to detonation does not occur. The effect of plasma discharges on flame acceleration also begins to diminish for the current configuration and pulse repetition frequency at speeds above 400 m/s. This give a range where nanosecond repetitively pulsed plasma discharges may be used effectively for efficient flame acceleration and transition to detonation.

Effect of the plasma location on the deflagration-to-detonation transition of a hydrogen–air flame enhanced by nanosecond repetitively pulsed discharges

“…A single orifice plate with a blockage ratio of 0.43 is installed at a distance of 540 mm from the headwall. This orifice plate is meant to accelerate the flame to speeds at which plasma actuation located at about 1000 mm from the headwall can efficiently accelerate the flame further, as experimentally determined by the authors in [16]. At a distance of 1080 mm from the headwall, a UVtransparent acrylic glass tube is installed to allow for visual observation of the flame and plasma discharges.…”