An experimental investigation of the effects of nozzle ellipticity on the flow structure of co-flow jet diffusion flames



Título del documento: An experimental investigation of the effects of nozzle ellipticity on the flow structure of co-flow jet diffusion flames
Revista: Journal of the Brazilian Society of Mechanical Sciences
Base de datos: PERIÓDICA
Número de sistema: 000312066
ISSN: 0100-7386
Autores: 1
Instituciones: 1University of Calgary, Department of Mechanical and Manufacturing Engineering, Calgary, Alberta. Canadá
Año:
Volumen: 23
Número: 1
Paginación: 105-114
País: Brasil
Idioma: Inglés
Tipo de documento: Artículo
Enfoque: Experimental
Resumen en inglés The flow structure of cold and ignited jets issuing into a co-flowing air stream was experimentally studied using a laser Doppler velocimeter. Methane was employed as the jet fluid discharging from circular and elliptic nozzles with aspect ratios varying from 1.29 to 1.60. The diameter of the circular nozzle was 4.6 mm and the elliptic nozzles had approximately the same exit area as that of the circular nozzle. These non-circular nozzles were employed in order to increase the stability of attached jet diffusion flames. The time-averaged velocity and r.m.s. value of the velocity fluctuation in the streamwise and transverse directions were measured over the range of co-flowing stream velocities corresponding to different modes of flame blowout that are identified as either lifted or attached flames. On the basis of these measurements, attempts were made to explain the existence of an apparent optimum aspect ratio for the blowout of attached flames observed at higher values of co-flowing stream velocities. The insensitivity of the blowout limits of lifted flames to nozzle geometry observed in our previous work at low co-flowing stream velocities was also explained. Measurements of the fuel concentration at the jet centerline indicated that the mixing process was enhanced with the 1.38 aspect ratio jet compared with the 1.60 aspect ratio jet. On the basis of the obtained experimental data, it was suggested that the higher blowout limits of attached flames for an elliptic jet of 1.38 aspect ratio was due to higher entrainment rates
Disciplinas: Ingeniería
Palabras clave: Equipo y maquinaria,
Ingeniería de transportes,
Jets,
Flamas de difusión,
Toberas,
Elipticidad
Keyword: Engineering,
Equipment and machinery,
Transportation engineering,
Jets,
Diffusion flames,
Nozzles,
Ellipticity
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