Experimental ablation processes study on an electrothermal launcher
An experimental parametric study has been performed to analyse the influence of time on the ablation processes in the capillary of an electrothermal launcher. A 600 kJ, 16 cells pulse forming network (PFN) was used. The time discharge was varied from 350 /spl mu/s to 100 /spl mu/s by changing the cell number (from 16 to 4) and then the capacitance (from 1760 /spl mu/F to 440 /spl mu/F). The parametric study has been performed at a constant voltage level (13 kV). The ablated masses have been measured for different time discharge and the results have been compared with a 0-D code.
A global theoretical approach for the electrothermal gun: scaling laws and a 0-D time-dependent model
In this paper, a theoretical analysis of the physical processes taking place in the electrothermal gun is presented. In a first step, using the basic conservation equations (energy, mass, charge) integrated over the whole time of the discharge, scaling laws are derived. These laws provide the temperature, the mass, the resistance of the plasma and the current going through it, as functions of the stored electrical energy. In a second step, a 0D time-dependent model is presented. This model takes into account the evolution of the complete system consisting of the electrical source, the plasma burner and the motion of the projectile. Special attention is given to the ablation phenomena and a microscopic description which differs from prior publications is derived. Finally, comparisons with experiments are given and good agreements are obtained. >
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.