Chiu C.-PLu YSheng Y.-TYeh S.-IYang J.-T.JING-TANG YANG2022-03-222022-03-22202107351933https://www.scopus.com/inward/record.uri?eid=2-s2.0-85111050293&doi=10.1016%2fj.icheatmasstransfer.2021.105467&partnerID=40&md5=ad8caaaf857c8dc09eb96cb3380a3a26https://scholars.lib.ntu.edu.tw/handle/123456789/598056To promote the efficiency of non-premixed combustion, we designed slot structures with a simple geometry on the side of a conical burner named a shuttlecock-like conical burner. The slot structure which can introduce the air co-flow naturally into the cone instead of using other and complicated geometry is inspired from the particular shape of a shuttlecock serving as a missile in badminton sport. Therefore, the air co-flow not only produces a recirculation zone on the edge of the burner but also moves directly into the burner. The combustion condition transforms from non-premixed to partially premixed combustion; the mixing and reaction of fuel and oxidant are hence greatly enhanced. We observed the structures of the flame and the flow of a shuttlecock-like conical burner, and examined its reaction characteristics with measurements of the chemiluminescence of OH* and the flame temperature. The observation of an isothermal flow field demonstrates that the air co-flow moves directly into the burner via the slots. Double pairs of vortex structures are observed above the exit of the burner because the introduced air co-flow decreases the strength of the outer vortex, allowing the central jet to form an inner vortex. The reaction zone of a shuttlecock-like conical burner hence approaches not only the central region of the flame but also the burner exit. The reaction intensity of the fuel of a shuttlecock-like conical burner is also stronger than that of an ordinary conical burner (without the slots). The designed shuttlecock-like conical burner is significantly useful to serve as a reference to improve the combustion efficiency of non-premixed combustion. ? 2021 Elsevier LtdFlame temperatureOH* chemiluminescenceReaction intensityReaction zoneShuttlecock-likeSlot structureCombustionEfficiencyFlame researchFuelsVortex flowCo-flowFlame structureFlame temperaturesNon-premixedNonpremixed combustionOH chemiluminescenceReaction zonesSlot structuresChemiluminescencejournal article10.1016/j.icheatmasstransfer.2021.1054672-s2.0-85111050293