An experimental investigation of the effect of the distance between the fuel and air nozzles on NOx emission at different temperatures and oxygen concentrations of the oxidizer in high air temperature combustion cylindrical furnace was conducted. Highly preheated oxidizer (air and nitrogen) was injected in the furnace through an oxidizer nozzle positioned at the center of the base of the cylindrical furnace. Propane was injected through three different sets of fuel nozzles, one set working at a time. As a result, the emission of NOx decreased as the distance between the fuel nozzles and the oxidizer nozzle increased. Also, at lower preheating temperatures and lower O_2 concentrations of the oxidizer, the emission of NOx tends to become uniform.

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A double column with the dissimilar material of different stiffness ratio is used in various fields. When the boundary of this double column is dynamically seen, a discontinuous joint field side is a singularity point with a very big stress. The crack occurs easily in phase boundary of the different kind material for that reason. The stress analysis of vicinity at the edge of the crack to which destruction is expected to evaluate this in strength is necessary. The stress intensity factor is effective to clarify the behavior of the states when the crack of a double column exists in the phase boundary at the vicinity of the crack. This research is a photoelasticity method and due to the coustics method carrying out the experiment analysis because of the stress intensity factor.

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