ポリエチレンチューブ内溶発アークのコア領域およびシース領域のガス流速の算定

抄録

An arc burning through a polyethylene tube (PE arc) involves an axial gas flow due to ablation of the tube wall. This paper provides estimation of the mean gas flow velocities of core and sheath regions, ν_c and ν_s, in the PE arc, The "two-zone model" and some assumptions accompanied with the PE arc are applied to equilibrium equations of energy, momentum and mass. The ν_c and ν_s are derived as functions of electrical input energy, enthalpies and mass densities of core and sheath regions, ablation mass, and cross-sections of core region and tube. These variables are able to be obtained from experimental values on electrical field strength, radial temperature distribution and mass decrease of PE tube, and theoretical values on thermodynamic properties of PE vapor.
The values of ν_c and ν_s of the arc burning through a 10 mm-length PE tube are estimated for various currents (5, 10, 15 A) and tube inner diameters (2, 4mmφ). The result shows that ν_s agrees with the experimental one and ν_c is three to four times as high as ν_s.