Time resolved 3D measurements of turbulent flames are required to further understanding
of combustion and support advanced simulation techniques (LES). Computed Tomography
of Chemiluminescence (CTC) allows a flame’s 3D chemiluminescence profile to be
obtained by inverting a series of integral measurements. CTC provides the instantaneous
3D flame structure, and can also measure: excited species concentrations, equivalence
ratio, heat release rate, and possibly strain rate. High resolutions require simultaneous
measurements from many view points, and the cost of multiple sensors has traditionally
limited spatial resolutions. However, recent improvements in commodity cameras makes
a high resolution CTC sensor possible and is investigated in this work.
Using realistic LES Phantoms (known fields), the CT algorithm (ART) is shown to
produce low error reconstructions even from limited noisy datasets. Error from selfabsorption
is also tested using LES Phantoms and a modification to ART that successfully
corrects this error is presented. A proof-of-concept experiment using 48 non-simultaneous
views is performed and successfully resolves a Matrix Burner flame to 0.01% of the domain
width (D). ART is also extended to 3D (without stacking) to allow 3D camera
locations and optical effects to be considered. An optical integral geometry (weighted
double-cone) is presented that corrects for limited depth-of-field, and (even with poorly
estimated camera parameters) reconstructs the Matrix Burner as well as the standard geometry.
CTC is implemented using five PicSight P32M cameras and mirrors to provide 10
simultaneous views. Measurements of the Matrix Burner and a Turbulent Opposed Jet
achieve exposure times as low as 62 μs, with even shorter exposures possible. With only
10 views the spatial resolution of the reconstructions is low. However, a cosine Phantom
study shows that 20–40 viewing angles are necessary to achieve high resolutions (0.01–
0.04D). With 40 P32M cameras costing £40000, future CTC implementations can achieve
high spatial and temporal resolutions.