Prediction of electrical characteristics of a non-transferred arc-plasma torch using principles of dynamic similarity

The theory of dynamic similarity has been used to construct a generalized current-voltage characteristic (CVC) of a non-transferred, straight polarity, solid electrode arc-plasma torch. The enthalpy number obtained from the energy equation has been found to significantly influence the characteristics of the electric arc. The generalized CVC developed has been found to match with experimental parameters of other torches having the same basic principle of design and used elsewhere. The electrothermal efficiency of the plasma torch has been determined and put in the form of a generalized correlation using dimensionless numbers. The use of the theory of dynamic similarity to obtain a generalized correlation has been therefore found to be more appropriate.