Influence of transitional and turbulent flow on electrical, optical, morphological and chemical characteristics of a nitrogen rotating gliding arc

Ananthanarasimhan, J. and Rao, L. (2022) Influence of transitional and turbulent flow on electrical, optical, morphological and chemical characteristics of a nitrogen rotating gliding arc. In: Journal of Physics D: Applied Physics, 55 (24).

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Abstract

The work reports the effect of flow regime on plasma characteristics of an atmospheric N2 rotating gliding arc (RGA). When changed from transitional (5 SLPM) to turbulent (50 SLPM) flow, operation mode transitioned from glow to spark discharge due to frequent reignition events; the average reduced electric field (EN) and electron temperature raised (38 → 92 Td, 0.84 → 2.2 eV); and gas temperature (T g ) slightly cooled (2973 → 2807 K). Molecules generated for 100 eV of energy input (G-factor) increased by a factor of 20 and 65, for the chemically active singlet and triplet metastable states of N2, respectively - a promising feature for chemical applications. A sudden three fold increase in the energy efficiency, achieving a destruction of 3.0±0.2 g·kWh-1 of dilute toluene ( 112±10 ppmV) at highly turbulent flow corroborated the enhancement of the G-factor, EN and T g ; and indicated the sensitivity of plasma properties to the flow regime. Interestingly, for flows having Reynolds number ≥ 3×104, the bandhead of N2+ shifted from 0-0 at 391.4 nm to 3-3 at 383.3 nm attributed to higher-level perturbations, showing again the sensitivity. The smallest eddies (η≈6 μ m) is less than the discharge diameter (dd≈ 220±90 μm), and thermal/mass Péclet number > 1. The eddies of size ≤dd advected the plasma species, wrinkled/distorted the discharge, and increased the reignition events, eventually affected the plasma properties including the chemical performance (energy efficiency), which is observed in this work. © 2022 IOP Publishing Ltd.

Item Type:	Journal Article
Publication:	Journal of Physics D: Applied Physics
Publisher:	IOP Publishing LtdIOP Publishing Ltd
Additional Information:	The copyright of this document belongs to IOP Publishing Ltd
Keywords:	Energy efficiency; Nitrogen; Nitrogen plasma; Plasma diagnostics; Reynolds number; Toluene; Turbulent flow, Electrical characteristic; Flow regimes; G factors; Gliding arc; Optical characteristics; Plasma properties; Plasma's diagnostics; Re-ignition; Rotating gliding arc; Toluene conversion, Electric arcs
Department/Centre:	Division of Mechanical Sciences > Centre for Sustainable Technologies (formerly ASTRA)
Date Deposited:	19 May 2022 08:53
Last Modified:	19 May 2023 10:07
URI:	https://eprints.iisc.ac.in/id/eprint/71927

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