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WARSAW UNIVERSITY OF TECHNOLOGY INSTITUTE OF HEAT ENGINEERING DIVISION OF AEROENGINES

WARSAW UNIVERSITY OF TECHNOLOGY INSTITUTE OF HEAT ENGINEERING DIVISION OF AEROENGINES. 3-D ELECTRICAL CAPACITANCE TOMOGRAPHY FOR FLAME VISUALIZATION. Piotr Wolanski @ Zbigniew Gut. University of Michigan, Aerospace Engineering, 6 - May - 2009. Introduction. ELECTRICAL CAPACITANCE

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WARSAW UNIVERSITY OF TECHNOLOGY INSTITUTE OF HEAT ENGINEERING DIVISION OF AEROENGINES

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  1. WARSAW UNIVERSITY OF TECHNOLOGY INSTITUTE OF HEAT ENGINEERING DIVISION OF AEROENGINES 3-D ELECTRICAL CAPACITANCE TOMOGRAPHY FOR FLAME VISUALIZATION Piotr Wolanski @ Zbigniew Gut University of Michigan, Aerospace Engineering, 6 - May - 2009

  2. Introduction ELECTRICAL CAPACITANCE TOMOGRAPHY 2D

  3. Measurement system – principle of operation The basic idea of ECT is to measure the changes in the electrical capacitances between all possible combinations of electrodes that occur when a dielectric material is introduced into the measurement space. These inter-electrode capacitance changes are caused by variations in the permittivity of the material inside the vessel: • - permittivity A – area of electrode d – distance between electrodes

  4. Measurement system – 2D

  5. Układ pomiarowy 7 8 6 9 5 4 10 3 11 2 12 1 Analog-Digital Converter Control & reconstruction Sensor

  6. Algorith of reconstruction The complete set of relationships for all electrode pairs can be written in matrix form as follows: forward problem inverse problem The method which we shall use is called: Linear Back Projection (LBP) C – matrix containing the normalized electrode-pair capacitances;K – matrix containing the normalized pixel permittivity;S – matrix containing the set of sensitivity matrices for each electrode-pair.

  7. Reconstruction – iterative algorithm model ILBP LBP set of normalized electrode-pair capacitances C1 no end of iteration yes

  8. Reconstruction – combustion process When fuel is burning, a large number of charged particles are generated. These will modify both the permittivity and conductivity of the reaction zone. So, signal level depends on the concentrations of the various kinds of charged particles present during combustions. Charges generated during combustion: • electrons • positive ions • negative ions CHEMI-IONIZATION THERMAL IONIZATION

  9. Research – different burners configuration

  10. Reconstruction

  11. Reconstruction – simple LBP and with iterations LBP LBP LBP 50 iterations 50 iterations 50 iterations

  12. Reconstruction of gaseous flame Reconstructed images of single flame inside the model cylinder can

  13. Reconstruction of gaseous flame Flame front Combustion products and air Flame front Combustion mixture Combustion mixture Combustion products and air Gas Gas supply

  14. Reconstruction of gaseous flame ignition Decreasing gas flow Constant gas flow Flame extinguish Reconstruction of flame and the variations of normalized flame capacitance for different flame intensity.

  15. Reconstruction of gaseous flame temperature profile (full scale) normalized pixel permittivity profile

  16. Reconstruction of gaseous flame temperature profile (range 500oC - 1200oC) normalized pixel permittivity profile

  17. Reconstruction of gaseous flame incombustionchamber GTD-350 turboshaft engine

  18. Reconstruction of gaseous flame incombustionchamber Picture of the combustion chamber GTD-350 with ECT visualization of flame.

  19. Reconstruction of gaseous flame incombustionchamber Reconstruction of flame in the combustion chamber GTD-350 and variations of normalized capacitance charge for different flame intensity.

  20. Reconstruction of gaseous flame incombustionchamber Reconstruction of flame in the combustion chamber GTD-350 and variations of normalized capacitance charge for different flame intensity.

  21. Reconstruction of gaseous flame incombustionchamber Reconstruction of flame in the combustion chamber GTD-350 and variations of normalized capacitance charge for defective combustion process.

  22. 3-D ECT Development of techniques to get an image of a 3D object in an cylindrical combustion chamber.

  23. Reconstruction – 2.5D

  24. Reconstruction – 2.5D + 2.5D reconstruction of beam model using 2D chamber.

  25. Reconstruction – 2.5D 2.5D reconstruction of beam model using 2D chamber.

  26. Measurement system – 3D 1 row 2 row 3 row 4 row View of capacitance tomography electronic unit (six cards).

  27. Mesh Nodes=855 Elements=1612 Nodes=7680 Elements=13338

  28. Sensitivity map 1 7 11 3D sensitivity map between 1-11 and 1-7 electrodes 2D sensitivity map between 1-5 electrodes

  29. Software • The ECT-3D program allows: • control system; • data acquisition with on-line image monitoring; • image visualization in a very wide range of formats and views; • data storage in different formats; • and more .....

  30. Reconstruction 3D objects

  31. Reconstruction 3D objects

  32. Reconstruction 3D of gaseous flame

  33. Reconstruction 3D of gaseous flame

  34. Reconstruction 3D of gaseous flame gas + water + NaCl gas

  35. Development of techniques to get an image of a 3D object in an annular combustion chamber.

  36. Images reconstruction in an annular chamber View of a model annular chamber.

  37. Images reconstruction in an annular chamber 2D images reconstruction in an annular chamber using measurement data from8 electrodes sensor.

  38. Images reconstruction in an annular chamber 3D images reconstruction in an annular chamber using spherical object from 24 electrodes sensor (8x3).

  39. Summary – 3D • 3-D ECT system was designed and build at the Warsaw University of Technology • special algorithm for image reconstruction was prepared and tested • reconstruction of the 3-D images of dynamic flames were tested • obtained data are very promising • addition of NaCl significantly increase signal from flame • it is still necessary to overcome some problems of signal processing and reconstruction of images to get better time and spatial resolution

  40. Thank you for your attention!

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