In this paper we describe an experimental study of the shielding gas flow state in a still atmosphere and windy conditions by visualization of the flow and analyzing the gas concentration around the nozzle. Then a simple method to obtain the suitable gas flow rate of CO
2 arc welding in windy condition can be suggested.
Results of the experiments are summarized as follows.
1) CO
2 gas concentration in the wall jet in a still atmosphere is maximum on the plate surface. It decreases lineally parting from the plate surface and decreases exponentially by increasing of X/d.
2) CO
2 gas concentration of the shielding gas jet in windy conditions is decided by Us, uj, H and d. Each curve showing the relation between qCO
2/qCO
2+AIR and U0/uj has the similarity throughout the experiment.
3) The suitable gas flow rate of the CO
2 arc welding in windy conditions can be estimated by the qCO
2/qCO
2+AIR-U0/uj curve with some H/d used in welding.
4) Application of this oil smoke method to visualization of the shielding gas flow is usefull over the wide range of Reynolds number. And this method will be avialble to investigate the shielding gas effect of the narrow-gap welding.
View full abstract