The aerodynamic aspects of indirect thrust measurement by the impulse method have been studied both experimentally and numerically. The underlying basic aerodynamic principle is outlined, the phenomena in subsonic, supersonic and arc-heated jets are explored, and factors affecting the accuracy of the method are studied and discussed. Results show that the impulse method is reliable for indirect thrust measurement if certain basic requirements are met, and a simple guideline for its proper application is given.
Cheng-Kang WuHai-Xing WangXian MengXi ChenWen-Xia Pan
A modelling study is performed to investigate the characteristics of both plasma flowand heat transfer of a laminar non-transferred arc argon plasma torch operated at atmosphericand reduced pressure.It is found that the calculated flow fields and temperature distributions arequite similar for both cases at a chamber pressure of 1.0 atm and 0.1 atm.A fully developed flowregime could be achieved in the arc constrictor-tube between the cathode and the anode of theplasma torch at 1.0 atm for all the flow rates covered in this study.However the flow field couldnot reach the fully developed regime at 0.1 atm with a higher flow rate.The arc-root is alwaysattached to the torch anode surface near the upstream end of the anode,i.e.the abruptly expandedpart of the torch channel,which is in consistence with experimental observation.The surroundinggas would be entrained from the torch exit into the torch interior due to a comparatively largeinner diameter of the anode channel compared to that of the arc constrictor-tube.
