Calculation of post-arc current in a Laval nozzle

The post-arc current and the critical RRRV were determined by the computer simulations for a Laval nozzle (or Frind &Rich nozzle). In order to investigate the thermal recovery characteristics after current zero, the simulation of steady-state arc of 1000(A) current, the simulation of transient arc generated by the current which decreases with the rate of i/d=27.0(A//spl mu/d) before current zero, and the simulation of hot- gas flow were carried out in the upstream pressure range of 0.6- 7.0(MPa) respectively. A commercial computational fluid dynamics (CFD) program "PHOENICS" was used for the simulations. The semi-experimental arc radiation model was adapted to consider the radiation energy transport and Prandtl's mixing length model was employed as the turbulence model. The electric field and the magnetic field were calculated with the same grid structure used for the simulation of the flow field. The results obtained by implementing a two-dimensional differential arc model into PHOENICS have been verified by comparison with the test results presented by the research group of GE Co. (General Electric Company).