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High-speed tomographic imaging of hostile engineering processes using absorptionbased measurements presents a number of difficulties. In some cases, these challenges include severe limitations on the number of available measurement paths through the subject, and the process of designing the geometrical arrangement of those paths for best imaging performance. This paper considers the case of a chemical species tomography system based on near-IR spectroscopic absorption measurements, intended for application to one cylinder of a multicylinder production engine. Some of the results, however, are applicable also to other hardfield tomographic modalities in applications where similar constraints may be encountered. A hitherto unreported design criterion is presented for optimal beam geometry for imaging performance, resulting in an irregular array with only 27 measurement paths through the subject for the engine application. Image reconstruction for this severely limited geometry is considered at length, using both simulated and experimental phantom data. Novel methods are presented for the practical generation of gaseous phantoms for calibration and testing of the system. The propane absorption coefficient at 1700nm is measured. Quantitative imaging of propane plumes in air is demonstrated, showing good localisation of circular plumes with diameter as small as 1/5 of the subject diameter and excellent imaging of multiple plumes.

This article describes experiments on the combined determination of the distribution of liquid metal and argon in the submerged entry nozzle (SEN) and of the flow in the mold of a small-scale physical model of a continuous slab caster. For visualizing the metal distribution in the SEN, mutual inductance tomography (MIT) is applied, while the flow in the mold is determined by contactless inductive flow tomography (CIFT). The results of the latter are validated in part by ultrasonic Doppler velocimetry (UDV). Accompanying measurements provide information about the levels in the tundish and in the mold, as well as on the pressure in the SEN. Depending on the gas flow rate, various flow regimes are identified, among them pressure and mold level oscillations, transitions between double and single vortex flows, and transient single port ejections.

This paper reports the application of optical tomography and Chemical Species Tomography (CST) to the characterisation of the in-cylinder

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