Modern manufacturing industry demands low cost and high efficient welding processes to remain competitiveness in the time of globalization. In this study, conventional gas metal arc welding （GMAW） was modified, a do...Modern manufacturing industry demands low cost and high efficient welding processes to remain competitiveness in the time of globalization. In this study, conventional gas metal arc welding （GMAW） was modified, a double-electrode GMAW （DE-GMAW） system is developed and DE-GMAW process is implemented through optimization of the design and process parameters and suitable selection of igniting sequence of double arcs. High speed welding tests were carried out to examine the effects of different factors on occurrence of weld formation defects. Through observing the weld bead appearance in DE-GMA W, the values of critical welding speed were determined under different levels of welding current and welding speed.展开更多
In order to obtain the impact frequency of resonant coal breaking by self-excited oscillation pulsed supercritical carbon dioxide(SC-CO_(2))jet,large eddy simulation was used to analyze the formation and development p...In order to obtain the impact frequency of resonant coal breaking by self-excited oscillation pulsed supercritical carbon dioxide(SC-CO_(2))jet,large eddy simulation was used to analyze the formation and development process of self-excited oscillation pulsed SC-CO_(2)jet,the variation of jet impact frequency in the nozzle and the free flow field,and the variation of jet impact frequency at different positions in the jet axis and under different cavity lengths.The test device of jet impact frequency was developed,and experiments were performed to verify the conclusions of the numerical simulations.The results show that the frequency of the self-excited oscillation pulsed SC-CO_(2)jet is different in the nozzle and the free flow field.In the nozzle,the frequency generated by the fluid disturbance is the same,and the jet frequency at the exit of the nozzle is consistent with that inside the nozzle.In the free flow field,due to the compressibility of CO_(2),the pressure,velocity and other parameters of SC-CO_(2)jets have obvious fluctuation patterns.This feature causes the impact frequency of the self-excited oscillation pulsed SC-CO_(2)jet to decrease gradually in the axis.Changing the cavity length allows the adjustment of the jet impact frequency in the free flow field by affecting the disturbance frequency of the self-excited oscillation pulsed SC-CO_(2)jet inside the nozzle.展开更多
基金The authors wish to thank the financial support for this research from the National Natural Science Foundation of China （Grant No. 50675119）.
文摘Modern manufacturing industry demands low cost and high efficient welding processes to remain competitiveness in the time of globalization. In this study, conventional gas metal arc welding （GMAW） was modified, a double-electrode GMAW （DE-GMAW） system is developed and DE-GMAW process is implemented through optimization of the design and process parameters and suitable selection of igniting sequence of double arcs. High speed welding tests were carried out to examine the effects of different factors on occurrence of weld formation defects. Through observing the weld bead appearance in DE-GMA W, the values of critical welding speed were determined under different levels of welding current and welding speed.
基金Supported by National Natural Science Foundation of China(52174170,51974109)Basic Research Funds of Henan Polytechnic University(NSFRF220205)Strategic Consulting Research Project of Henan Research Institute of China Engineering Science and Technology Development Strategy(2022HENZDB03)。
文摘In order to obtain the impact frequency of resonant coal breaking by self-excited oscillation pulsed supercritical carbon dioxide(SC-CO_(2))jet,large eddy simulation was used to analyze the formation and development process of self-excited oscillation pulsed SC-CO_(2)jet,the variation of jet impact frequency in the nozzle and the free flow field,and the variation of jet impact frequency at different positions in the jet axis and under different cavity lengths.The test device of jet impact frequency was developed,and experiments were performed to verify the conclusions of the numerical simulations.The results show that the frequency of the self-excited oscillation pulsed SC-CO_(2)jet is different in the nozzle and the free flow field.In the nozzle,the frequency generated by the fluid disturbance is the same,and the jet frequency at the exit of the nozzle is consistent with that inside the nozzle.In the free flow field,due to the compressibility of CO_(2),the pressure,velocity and other parameters of SC-CO_(2)jets have obvious fluctuation patterns.This feature causes the impact frequency of the self-excited oscillation pulsed SC-CO_(2)jet to decrease gradually in the axis.Changing the cavity length allows the adjustment of the jet impact frequency in the free flow field by affecting the disturbance frequency of the self-excited oscillation pulsed SC-CO_(2)jet inside the nozzle.
