PLASMA GENERATOR CHARACTERISTICS AND RELATED HEAT TRANSFER STUDIES

Abstract

The report describes an experimental study of the performance characteristics of the plasma generator and the bulk heat transfer measurements from a high temperature gas after leaving the plasma arc. Preliminary tests on the original plasma generator as designed by D. Male, Mechanical Engineering class of 1961-62, indicated arc instability at high gas flow rates and a high erosion rate of the cathode. By reversing the polarity and introducing a water-cooled copper anode combined with a transpiration-cooled porous cathode, the arc stability was improved and the erosion rate of the cathode reduced. The performance characteristics of the new design were studied, with the plasma generator operating under an electric field potential of 18 - 25 volts, field current 70 - 100 amperes and a transpiration fluid flow of 80 - 200 gm./min. The heat transfer phenomenon from the high temperature gas was studied using a parallel-cocurrent—flow, tube-and-shell heat (ii) exchanger. The heat exchanger was instrumented to permit measurement of the longitudinal temperature variations of the cooling water, the tube wall and the hot gas stream. A heat transfer analysis was then carried out with the necessary corrections applied to account for the temperature measurement techniques and the variations in physical properties of the hot gas