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

Institute of Heat Engineering – Warsaw University of Technology Introduction 2D ELECTRICAL CAPACITANCE TOMOGRAPHY

Institute of Heat Engineering – Warsaw University of Technology 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

Institute of Heat Engineering – Warsaw University of Technology Measurement system – 2D

Instytut Techniki Cieplnej – Politechnika Warszawska Układ pomiarowy Sensor Analog-Digital Converter Control & reconstruction

Institute of Heat Engineering – Warsaw University of Technology Algorith of reconstruction The complete set of relationships for all electrode pairs can be written in matrix form as follows: 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. inverse problem forward problem The method which we shall use is called: Linear Back Projection (LBP)

Institute of Heat Engineering – Warsaw University of Technology Reconstruction – iterative algorithm model LBP ILBP yes no set of normalized electrode-pair capacitances C 1 end of iteration

Institute of Heat Engineering – Warsaw University of Technology 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

Instytut Techniki Cieplnej – Politechnika Warszawska Research – different burners configuration

Instytut Techniki Cieplnej – Politechnika Warszawska Reconstruction

Instytut Techniki Cieplnej – Politechnika Warszawska Reconstruction – simple LBP and with iterations 50 iterations LBP 50 iterations

Institute of Heat Engineering – Warsaw University of Technology Reconstruction of gaseous flame Reconstructed images of single flame inside the model cylinder can

Institute of Heat Engineering – Warsaw University of Technology Gas supply Flame front Combustion mixture Gas Flame front Combustion mixture Combustion products and air Reconstruction of gaseous flame

Institute of Heat Engineering – Warsaw University of Technology Reconstruction of gaseous flame Reconstruction of flame and the variations of normalized flame capacitance for different flame intensity. ignition Constant gas flow Decreasing gas flow Flame extinguish

Institute of Heat Engineering – Warsaw University of Technology Reconstruction of gaseous flame temperature profile (full scale) normalized pixel permittivity profile

Institute of Heat Engineering – Warsaw University of Technology Reconstruction of gaseous flame normalized pixel permittivity profile temperature profile (range 500 o C o C)

Institute of Heat Engineering – Warsaw University of Technology Reconstruction of gaseous flame in combustion chamber GTD-350 turboshaft engine

Institute of Heat Engineering – Warsaw University of Technology Picture of the combustion chamber GTD-350 with ECT visualization of flame. Reconstruction of gaseous flame in combustion chamber

Institute of Heat Engineering – Warsaw University of Technology Reconstruction of flame in the combustion chamber GTD-350 and variations of normalized capacitance charge for different flame intensity. Reconstruction of gaseous flame in combustion chamber

Institute of Heat Engineering – Warsaw University of Technology Reconstruction of flame in the combustion chamber GTD-350 and variations of normalized capacitance charge for different flame intensity. Reconstruction of gaseous flame in combustion chamber

Institute of Heat Engineering – Warsaw University of Technology Reconstruction of flame in the combustion chamber GTD-350 and variations of normalized capacitance charge for defective combustion process. Reconstruction of gaseous flame in combustion chamber

Institute of Heat Engineering – Warsaw University of Technology 3-D ECT Development of techniques to get an image of a 3D object in an cylindrical combustion chamber.

Institute of Heat Engineering – Warsaw University of Technology Reconstruction – 2.5D Simulation of the 36-electrode 3D ECT sensor. 3D measurement and image reconstruction in contrast to the 2.5D interpolation

Institute of Heat Engineering – Warsaw University of Technology Reconstruction – 2.5D 2.5D reconstruction of beam model using 2D chamber. +

Institute of Heat Engineering – Warsaw University of Technology Reconstruction – 2.5D 2.5D reconstruction of beam model using 2D chamber.

Institute of Heat Engineering – Warsaw University of Technology Measurement system – 3D 1 row 2 row 3 row 4 row View of capacitance tomography electronic unit (six cards).

Institute of Heat Engineering – Warsaw University of Technology Mesh 2D3D Nodes=855 Elements=1612 Nodes=7680 Elements=13338

Institute of Heat Engineering – Warsaw University of Technology Sensitivity map 3D sensitivity map between 1-11 and 1-7 electrodes D sensitivity map between 1-5 electrodes

Institute of Heat Engineering – Warsaw University of Technology 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.....

Institute of Heat Engineering – Warsaw University of Technology Reconstruction 3D objects

Institute of Heat Engineering – Warsaw University of Technology Reconstruction 3D objects

Institute of Heat Engineering – Warsaw University of Technology Reconstruction 3D of gaseous flame

Institute of Heat Engineering – Warsaw University of Technology Reconstruction 3D of gaseous flame

Institute of Heat Engineering – Warsaw University of Technology gas gas + water + NaCl Reconstruction 3D of gaseous flame

Institute of Heat Engineering – Warsaw University of Technology Development of techniques to get an image of a 3D object in an annular combustion chamber.

Institute of Heat Engineering – Warsaw University of Technology View of a model annular chamber. Images reconstruction in an annular chamber

Institute of Heat Engineering – Warsaw University of Technology 2D images reconstruction in an annular chamber using measurement data from 8 electrodes sensor. Images reconstruction in an annular chamber

Institute of Heat Engineering – Warsaw University of Technology Images reconstruction in an annular chamber 3D images reconstruction in an annular chamber using spherical object from 24 electrodes sensor (8x3).

Institute of Heat Engineering – Warsaw University of Technology 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 Summary – 3D

Institute of Heat Engineering – Warsaw University of Technology Thank you for your attention!