MUSCLES. Presented by: Frank Wetzel University of Karlsruhe (TH) - EBI / VBT month review, 3 December 2003, IST, Lisbon

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1 MUSCLES Modelling of UnSteady Combustion in Low Emission Systems G4RD-CT R&T project within the 5 th Framework program of the European Union: 1

2 Numerical computations of isothermal flow and mixing field for the future Lean Blow Out test case 2

3 EBI contributions to MUSCLES Goals: Investigations on the influence of turbulent mixing and reaction on lean blow-out characteristics Structure of work: Month 0 6: Extension of 2-domain-1step kinetic model for the combustion of highly diluted hydrocarbon/air mixtures Validation by means of laminar premixed flame calculations and comparison with detailed mechanisms Month 6 12: Implementation in existing JPDF model and testing of enhanced kinetic sub-module Month 12 18: Isothermal test case and calculations of isothermal flow fields Validation of isothermal PDF calculations on basis of existing e xperimental results Implementation of necessary modifications to the JPDF module Month 18 36: Comparison of calculated PDF with experimental data for reacting case Improvement of JPDF model in order to calculate lean extinction phenomena with the desired accuracy Calculation of lean blowout limits for different operating conditions 3

4 Motivation for the selected test case Airblast atomizer application - used in modern combustion systems - stable combustion process with high thermal throughput and low noxious emissions Experimental data for validation of numerical computations - should be available from VATELEC cancelled - we provide: - in-house measured data of flow and time-averaged mixing fields under isothermal and reacting conditions partly performed within LOPOCOTEP selection of test case 4

5 System under investigation combustion chamber 100 mm 100 mm 100 mm 220 mm 5

6 System under investigation simplified contour 100 mm 100 mm 100 mm 220 mm 6

7 System under investigation clipping region of geometry 7

8 System under investigation clipping of computational grid 8

9 System under investigation airblast atomizer nozzle secondary swirler atomizer lip primary swirler 9

10 Boundary conditions numerical setup Z X Y

11 Flow field radial profiles of velocity components 11

12 Flow field axial velocity CFD Exp. 12

13 ~ Mean of Mixture-Fraction f - comparison with experimental data CFD-computation (JPDF module) experimental data 13

14 ~ Mean of Mixture-Fraction f - comparison with MCF-computation JPDF module MCF-computation 14

15 ~ Variance of the Mixture Fraction f 15

16 ~ Variance of the Mixture Fraction f 16

17 Variance of the Mixture Fraction f ~ 1 f 1 17

18 Variance of the Mixture Fraction f ~ f f 1 f f 18

19 Conclusion Test case - airblast atomizer application - detailed experimental data available Computational grid and numerical setup Comparison of CFD-calculations with experimental data - measured flow and mixing field can be reproduced by CFD-calculation - in near nozzle part: differences detected probably due to small deviations in swirl number - idea: include channels of swirl-generating device into computational grid Distribution of calculated mixture fraction variance and probability density distributions 19

20 EBI further contributions to MUSCLES Goals: Investigations on the influence of turbulent mixing and reaction on lean blow-out characteristics Structure of work: Month 0 6: Extension of 2-domain-1step kinetic model for the combustion of highly diluted hydrocarbon/air mixtures Validation by means of laminar premixed flame calculations and comparison with detailed mechanisms Month 6 12: Implementation in existing JPDF model and testing of enhanced kinetic sub-module Month 12 18: Isothermal test case and calculations of isothermal flow fields Validation of isothermal PDF calculations on basis of existing e xperimental results Implementation of necessary modifications to the JPDF module Month 18 36: Comparison of calculated PDF with experimental data for reacting case Improvement of JPDF model in order to calculate lean extinction phenomena with the desired accuracy Calculation of lean blowout limits for different operating conditions 20