Temperature distribution in an impinging gas jet from inter-ferometric measurements.

A hot gas jet was produced by an Argon plasma torch and was played on a water cooled rotating cylinder mounted 30 mm above the nozzle of the torch. The power and gas flow rate to the torch were varied. A Mach-Zehnder interferometer was used to form the interference fringe shift patterns. A version of the Abel Transformation was used to derive radial temperature distribution results from collimated measurements of fringe shift along parallel chords at points long the axis of the jet. The axial temperatures of the jet were found to be between 800 K and-8000-K. No results were possible in the area of the jet close to the cool surface due to turbulence in the fringe pattern. Relationships between input conditions to the torch and the temperatures in the jet were sought but no conclusions could be drawn due-to the severe limitations found in the analysis. In the range of power, 1.3 to 3 kW, and flow rate, 1.4 to 4.3 1/min, supplied to the torch, the number of fringe shifts observed in the interferograms was small, usually less than 2.5, making the fitting of fringe shift curves to the experimental data points uncertain. Tests undertaken fitting different shaped curves to a sample set of data caused 50-100% variations in the resulting radial temperature distribution. Slight variations in the radius of the jet measured from the interferograms caused large changes in on-axis temperature, though the distribution-towards the outer edge of the jet was unaffected. A similar-phenomenon was observed by changing the number of iteration points used in the numerical analysis. Areas for further work are identified and discussed, in the thesis.