Rotational effects in density—Stratified reacting gases

✍ Scribed by Felix Weinberg

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 357 KB
• Volume: 78
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(89)90011-4

✦ Synopsis

Attention is drawn to the effects of centrifugal fields on thermally stratified gases in vortices. These effects were first observed in plasma jets, where they appear to prolong the life of free radicals within hot pockets, but they are likely to affect a variety of other combustion phenomena. The main mechanism in turbulent systems involves the coalescence of hot pockets of gas in the cores of vortices and the consequent delay in theft intermixing with the cold surrounding medium. An approximate theory that compares coalescence times with mixing times, along with a rough experimental simulation, establishes the conditions under which the effect is important and shows that relatively modest rotation rates give rise to appreciable centrifugal effects that delay the mixing of fluids of different densities. Experimental verification is provided by laser-induced fluorescence records of OH distributions. The results imply that the general neglect of such effects in combustion systems, in which regions of cold reactants and hot products interact with vortices, may not be justified.