%0 Journal Article
%T Stability and Blowout Behavior of Jet Flames in Oblique Air Flows
%A Jonathan N. Gomes
%A James D. Kribs
%A Kevin M. Lyons
%J Journal of Combustion
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/218916
%X The stability limits of a jet flame can play an important role in the design of burners and combustors. This study details an experiment conducted to determine the liftoff and blowout velocities of oblique-angle methane jet flames under various air coflow velocities. A nozzle was mounted on a telescoping boom to allow for an adjustable burner angle relative to a vertical coflow. Twenty-four flow configurations were established using six burner nozzle angles and four coflow velocities. Measurements of the fuel supply velocity during liftoff and blowout were compared against two parameters: nozzle angle and coflow velocity. The resulting correlations indicated that flames at more oblique angles have a greater upper stability limit and were more resistant to changes in coflow velocity. This behavior occurs due to a lower effective coflow velocity at angles more oblique to the coflow direction. Additionally, stability limits were determined for flames in crossflow and mild counterflow configurations, and a relationship between the liftoff and blowout velocities was observed. For flames in crossflow and counterflow, the stability limits are higher. Further studies may include more angle and coflow combinations, as well as the effect of diluents or different fuel types. 1. Introduction A multitude of studies have been performed on lifted jet flames and their behavior in various air flow configurations. In such partially premixed flames, the characteristics of the surrounding air flow (velocity, temperature) can strongly impact the overall combustion process and the stability parameters. As fuel flows from a nozzle and mixes with the air, the fuel and oxidizer concentrations vary throughout space and time. The extent of mixing due to turbulence also changes depending on the surrounding flow. The perpetually varying concentrations help to determine the overall behavior of a flame: its shape, velocity, size, color, temperature, and composition. In parallel, the heat release serves to laminarize regions and serves to limit reducing mixing. In particular, two important behavioral parameters are liftoff and blowout velocity. Initially, a jet flame will remain attached to the nozzle at low fuel velocities. However, at a critical jet velocity, the flame will lift off from the nozzle and stabilize at a position downstream due to the inability of the flame to remain anchored on the burner [1]. While there is, in general, a regime where the flame can stabilize, increasing the jet velocity will ultimately lead to blowout, in which the flame is extinguished. This behavior
%U http://www.hindawi.com/journals/jc/2012/218916/