Zbigniew Gut

Flame Imaging Using 3D Electrical Capacitance Tomography

Electrical Capacitance Tomography for visualization of combustion process is based on measurement of variation of electrical properties of flame, such as electrical permittivity and conductivity of the reaction the zone. The signal level depends on the concentration of various charged particles in the combustion zone. Possible carriers are electrons and positive and negative ions. These charged particles may be formed as a result of chemical reactions, which are called chemi-ionization and thermal ionization. These properties in a combustion chamber are measured with specially designed electrodes. Distribution of charged particles in the combustion zone is reconstructed from measurements of electrical signal from the electrodes using linear back projection or iterative linear back projection algorithm.

Flame visualizations using electrical capacitance tomography (ECT)

Stray-immune circuits are available that will measure very small floating capacitances at high speed These circuits have facilitated the development of Electrical Capacitance Tomography (ECT), which uses fixed, robust metal plates as sensors, arranged non-intrusively around the periphery of the volume of interest. The phenomenon of flame ionization is well understood, with general agreement that the concentration of all the major ions maximize at the flame front. There is also strong experimental evidence to suggest that the presence of carbon particles (and their precursors) results in a large increase in the charge carrying capacity of the flame. This paper reports some initial results from using ECT to visualize the position, size, composition and movement in flames in open and closed combustion chambers.