DOI: 10.1615/THMT-18
ISBN Print: 978-1-56700-468-7
ISBN Online: 978-1-56700-467-0
ISSN Print: 2377-2816
Effects of droplet size on the ignition of conventional and alternative jet fuels in turbulent air
摘要
Ignition and flame propagation in turbulent flows are detrimentally affected by fuel droplets. However, recent work has shown that small droplets can enhance flame speeds. In this work, spherically expanding flames following a laser spark were visualised in uniform dispersions of Jet A and ATJ-8 droplets in turbulent air by schlieren and OH*-chemiluminescence. This allowed for measurements of ignition probability and flame speed in well-characterised polydisperse sprays. Increasing droplet size and polydispersity of the spray resulted in lower ignition probabilities and flame speeds. Nevertheless, an enhancement of flame speed was noticed for fuel-lean conditions, being attributed to preferential propagation around droplets. Hence, successful ignition events were mostly observed when large burning droplets were found in the kernel. In comparison to Jet A, ATJ-8 presented a higher ignitability in stoichiometric and fuel-rich conditions, but required more energy to ignite in lean conditions.