13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Project supported by MinKnock Project n ENK6-CT Ildio S. Guerreiro Edgar C. Fernandes Laboratory of Thermofluids, Combustion and Environmental Systems Instituto Superior Tcnico -Technical University of Lisbon, PortugalTime-resolved description of a flame front propagation toward an inclined wall - The effect of local stretch on flame speed 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Background overview Objectives Experimental Setup Global setup Laser and camera characteristics Combustion chamber condition Intermediary results Data treatment Sample visualizations Final results Flame speed/stretch correlations Relevant effects of stretch on flame speed Effect of flame/wall interaction Conclusions Presentation Outline 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Recent works Foucher, et al., 2002 Wall Methane 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Recent works wall flame U wall Non-Wrinkled Symmetric flame Wrinkled Symmetric flame Wrinkled Non-Symmetric flame Rolo, N., 2005 Propane 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Flame/wall interaction wall n U W SuSu burned unburned Flame Front Objectives: - Obtain stretch/flame speed (S u ) sorrelations -Flow effect on flame/wall interaction Markstein Length 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Experimental Setup 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Technical characteristics Spectra Physics Ar-Ion Laser-5W Seeding: DANTEC Safex Inside Nebelfluid Kodak CCD High speed camera - 240x256 Typical data: 1000fps ; 1/1000s Spatial resolution for flame front displacement: 0.5mm Spatial resolution for velocity vectors: 29vectors/20mm 1.5vector/mm Propane/air mixtures: Eq. Ratios 0.86 and 1.52 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Data processing 1 m/s Flow PIV Processing Flame front detection - Thresh detection; - Noise reduction Original image (PIV) W 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Data processing k c (curvature) Flame Front r k s (flow) Flame Front U Total stretch 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Inclined-wall / Non-Symmetric Flame k and S u along a flame front 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Plane-wall / Flame n U W SuSu Lean ( =0.86 ) L exp( 0.86 ) = mm L theo( 0.7 ) = mm Rich ( =1.52 ) L exp( 1.52) = mm L theo( 1.7 ) = mm k=[-3000, 0] k=[-100, 0] Present results Law & Sung, 2000 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Flow variations in wall interaction 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Relevance of flow stretch Lean ( =0.86 ) Rich ( =1.52 ) Total stretch 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Flow stretch distributions Lean ( =0.86 ) Rich ( =1.52 ) PDF 13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, June, 2006 Conclusions Time-resolved PIV was used to characterize flame-wall interaction The flow between flame and wall is not stagnant, and induces aerodynamic effects Linearity between S u and k for very high stretch values k c >>>>k s k s increases when flame is close to the wall