LPP with swirling flow
Under lean operating conditions there are self-sustained flame instabilities limiting the range of operations. They are induced either by the weakness of the lean flame stabilization process, or by a pressure modulated incoming flow that may induce a periodic variation in the equivalence ratio, or shear layer instabilities through vortex shedding phenomena, enhanced by the high sensitivity of the reactant reaction rate to variations in temperature and mixture composition. Under these conditions an additional flow pulsation arises due to the presence of a precessing vortex core (PVC), which is not fully discussed in the literature in the context of LPP technology, and may also modulate periodicity in heat release leading to flame instabilities. Their impact on overall combustion performance is dependent on several factors, such as the fuel supply and mixture ratio and may help to reduce NOx emissions and fuel consumption through enhanced large-scale turbulence, as discussed and shown for the precessing jet burners. The PVC structure was addressed in the work taken here.
Recent publications include:
- Shtork S. I., Cala C. E., Fernandes E. C., and Heitor M. V., Coherent Helical Structures in Swirl Flows. Technical Physics Letters, 2005, Vol. 31, Issue 8, pp. 660-662. (http://scitation.aip.org/tpl/)
- Shtork S.I., Comas O., Fernandes E.C., and Heitor M.V., Aerodynamic structure of unsteady swirling flow downstream of a sudden expansion. Thermophysics and Aeromechanics, 2005, Vol. 12, No. 2, pp. 217-228. (http://www.maik.rssi.ru/contents/thphaero/thphaero2_5v12cont.htm)
- Fernandes E.C., Heitor M.V., Shtork S.I. An analysis of unsteady highly turbulent swirling flow in a model vortex combustor. Experiments in Fluids, 2005; http://dx.doi.org/10.1007/s00348-005-0034-4.
- Cala C.E., Fernandes E.C., Heitor M.V., Shtork S.I. Coherent structures in unsteady swirling jet flow. Experiments in Fluids, 2005; http://dx.doi.org/10.1007/s00348-005-0066-9.
- Shtork S.I., Cala C.E., Fernandes E.C., Heitor M.V. Study of unsteady swirling flow in a model vortex burner. Proc. 8th International Conference on Optical Methods of Flow Investigation, 28th June - 1th July 2005, Moscow, Russia.
- Fernandes E.C., Shtork S.I., Vieira N.F. Acoustic diagnostics of unsteady reacting flow in a swirl stabilized lean-premixed combustor. Proc. 12th International Congress on Sound and Vibration. 11-14 July, 2005, Lisbon, Portugal.
- Fernandes E.C., Heitor M.V., Shtork S.I., Vieira N.F. Helical structures identification in a swirl-stabilized lean-premixed combustor. Proc. 5th International Seminar on Flame Structure, 11-14 July, 2005, Novosibirsk, Russia.
- Cala C.E., Fernandes E.C., Heitor M.V., Shtork S.I., Vieira N. F. PVC Dynamics in a model lean-premixed combustor. Abs. Lean Combustion Technology II: Promise and Practice. Engineering Conferences International, April 25—29, 2004, Tomar, Portugal (http://www.engconfintl.org/4al.html).