Counterflow spray combustion modeling

Regimes of Spray Vaporization and Combustion in Counterflow Configurations

“…Numerical analyses were developed in parallel efforts. Continillo and Sirignano (1990) provided for the first time a two-continua formulation for spray flames in counterflow mixing layers and the conditions needed for the solution to remain self-similar in the vicinity of the stagnation point, where fluid properties are functions of the distance to the stagnation plane. The two-continua description applies to the dilute spray conditions typically found in the main vaporization and combustion region of practical liquid-fueled combustion devices (Sirignano, 2010), when the interdroplet distances are significantly larger than the droplet diameter and, for the counterflow configuration, smaller than the mixing-layer thickness.…”

Stabilization and Blowout of Gaseous- and Spray-Jet Flames

“…In their model, a stream containing a quasimonodisperse fuel spray, fuel vapor, oxidizer, and inert gas impinges on an air jet. The presence of the fuel vapor in one stream allows partial premixing to occur such that, in an initially slightly oxidizer rich mixture, a premixed flame may develop in addition to the dual diffusion flames observed in previous studies [19,20,22].…”

“…Extinction and re-ignition processes allow adequate time for local partial premixing to occur. The level of induced strain (at the inner zone interface) prevents the existence of segregated diffusion and premixed components of the partially premixed structure, thus a single merged reacting layer exists [27,22]. Finally, in Fig.…”

“…The shear layer provides a region of enhanced mixing and aids in theentrainment of air due to large-scale vortices [33]. It is important to note that, when a fully developed inner zone exists, the hot region between the two reaction zones, laden with droplets, is primarily responsible for diffusion of fuel vapor to feed both flame structures [22]. The oxidizer for the inner zone diffuses into the flame from the spray side of the flame front.…”

Experimental and Numerical Study on Combustion Mechanism of Liquid Fuel Spray Entering Gaseous Flame Front

“…In order to observe the spray flame structures in detail, an appropriate flowfield where advanced optical techniques can be used should be chosen to extract the basic characteristics of spray flames. The spray flames stabilized in a counterflow have been accepted as a useful tool for the investigation of their structures (6) - (13) , because the similarity solution (7) on the centerline defines the entire flowfield if a monodisperse smallsized spray of highly volatile liquid fuel is used and almost all droplets prevaporize before entering the reaction zone. However, the numerical simulation with the similarity solution becomes inaccurate if we deal with actual polydisperse spray flames in which the combustion reaction zone interacts intensively with the unburned spray.…”