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Show the temperature distribution in a radiant tube. It is easily seen that there is a marked difference between the instantaneous and average fuel distributions in the radiant tube. It is obvious that actual performance of the flame is closely related to the instantaneous fuel distribution which depends on the turbulence existing in the flow field. Possibility of Future Visualization Visualization techniques are means to visualize phenomena. Each visualization technique is based on knowledge on the processes to directly record the signals intrinsically emitted from an object in a form of an image or to record the signals generated by converting the signals deri va ble from an object into those recordable in an image. The visualization techniques classified in direct photography are of the former type, and most of the other ones are of the latter type. In a visualization technique of the latter type, the signals derivable from an object should be converted into sensible signals. This process is the same as those for general measurements. This fact implies that any of the processes for measurements can be a basic part of a visualization technique. To visualize phenomena needed is a system composed of some of various substances and equipments, such as a film, a magnetic tape, sensors, photomultipliers, an image intensifier, mirrors, lens, a prism, a diffraction grating, filters, a light source, a video recorder, a television, and a camera. Obviously, the quality of an image depends on the quality of the system. The quality of the system can be kept high only when each of substances and equipments composing it is carefully selected and at the same time their setting is properly made. The basic feature of visualization is to record a certain property which is spatially distributed. Thus, the selection of the substances and equipments of which the system is composed and their setting should be made to increase spatial resolution. In certain cases, instantaneous images with sufficient time resolution are required. To satisfy such a requirement, also a careful selection of the substances and equipments should be made. Recently invented visualization techniques are mostly supported by processing systems. Two maj or functions of the processing systems are recording faint signals and selecting necessary signals. An appropriate processing system can convert faint signals into those of intensity sufficient to record using a usual recording system. It should be noted that in the process the signal/noise ratio should be increased, and that if the signal/noise ratio is inherently low, the signals could not be improved. Using a processing system for selecting necessary signals, an image recorded on a film or magnetic tape can be analyzed and displayed in a form of a comprehensible image. Figures 16-18 are good examples of such images. It seems that visualization of flames and combustion phenomena in furnaces is needed to satisfy the requirements in energy utilization and environment research. The improvement of visualization techniques should contribute to 15 |
