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Journal of applied research and technology
versão On-line ISSN 2448-6736versão impressa ISSN 1665-6423
J. appl. res. technol vol.10 no.5 Ciudad de México Out. 2012
Studies of the Precessing Vortex Core in Swirling Flows
M.O. Vigueras-Zuñiga1, A. Valera-Medina*2, N. Syred3
1 Facultad de Ingeniería, Universidad Veracruzana, Veracruz, Veracruz, México.
2 Centro de Tecnología Avanzada, CIATEQ A.C. Queretaro, Qro, México *agustin.valera@ciateq.mx.
3 School of Engineering, Gas Turbine Research Centre, Cardiff University, Wales, United Kingdom.
Abstract
Large scale coherent structures play an important role in the behavior of the combustion regime inside any type of combustor stabilized by swirl, with special impact on factors such as flame stability, blow off, emissions and the occurrence of thermo-acoustic oscillations. Lean premixed combustion is widely used and is known to impact many of these factors, causing complex interrelationships with any coherent structure formed. Despite the extensive experimentation in this matter, the above phenomena are poorly understood. Numerical simulations have been used to try to explain the development of different regimes, but their extremely complex nature and lack of time dependent validation show varied and debatable results. The precessing vortex core (PVC) is a well-known coherent structure whose development, intensity and occurrence has not been well documented. This paper thus adopts an experimental approach to characterize the PVC in a simple swirl burner under combustion conditions so as to reveal the effects of swirl and other variables on the latter. Aided by a high speed photography (HSP) system, the recognition and extent of several different types of PVCs were observed and discussed.
Keywords: swirling flows, PVC, high speed photography.
Resumen
Las estructuras coherentes de larga escala juegan un importante papel en el comportamiento de la combustión dentro de cualquier quemador estabilizado por arremolinamiento, impactando especialmente en factores como la estabilidad y extinción de la flama, emisiones y la aparición de oscilaciones termo-acústicas. La combustión en estado pobre es ampliamente utilizada y es sabido que impacta también en estos factores, causando una compleja interrelación con las estructuras que se forman. A pesar del extensivo trabajo experimental en el campo, el fenómeno antes mencionado no es completamente entendido. Se han utilizado simulaciones numéricas para explicar el desarrollo de diferentes regímenes, pero su extremamente compleja naturaleza y la falta de validación temporal han llevado a grandes debates en el campo. El centro de vórtice precesor (CVP) es una estructura coherente bien conocida cuyo desarrollo, intensidad y ocurrencia no se han documentado completamente. Por ello, este artículo adopta una aproximación experimental para caracterizar al CVP en un quemador sencillo bajo condiciones de combustión que revelen el efecto de arremolinamiento así como otras variables. Se llevó a cabo el reconocimiento de muchos diferentes tipos de CVP con la ayuda de un sistema de fotografía de alta velocidad.
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