分子热力学理论模型──氩模型与液体粘度的理论计算

应用张克武气体氩模型理论微分方程，导出液体粘度理论方程和“正烷烃沸点下的粘度值相同”的定理。本法以４０种不同构型２５８种无机、有机、强缔合性的醇、酸、二醇及非极性纯质１５２８个实验数据检验，平均误差１．８５％。其精度比著名的Ｖａｎ Ｖｅｌｘｅｎ ｅｔ ａｌ．法高９倍以上达到实验允许误差范围内。解决了近百年来无法精确计算的液体粘度这个技术科学上的关键难题。有重大理论意义和重要应用价值。

液体输运现象新理论Ⅰ液体粘度理论方程和2个定理

将张克武气体氩模型理论微分方程加以发展,推广应用到凝聚态物理学前沿基础研究中,导出液体粘度理论方程,并据理论分析引出两个定理。以42类328种无机、有机、极性与非极性纯质1928个实验数据检验,平均误差1.64％,达到实验容许误差范围内。其精度比美国(科学院、工程院)两院著名院士Prausnitz[2001]推荐的最优公式高8倍。在一些情况下,仅需给出熔点和沸点就可准确地从理论上计算出粘度值。解决了过去百年来国际分子物理学中无可靠方法计算液体粘度的科学难题,是百年来工程科技基础理论研究领域中的一个重大突破。

Effect of Helium-Argon Mixtures on the Heat Transfer and Fluid Flow in Gas Tungsten Arc Welding

A transient finite element model has been developed to study the heat transfer and fluid flow during spot Gas Tungsten Arc Welding （GTAW） on stainless steel. Temperature field, fluid velocity and electromagnetic fields are computed inside the cathode, arc-plasma and anode using a unified MHD formulation. The developed model is then used to study the influence of different helium-argon gas mixtures on both the energy transferred to the workpiece and the time evolution of the weld pool dimensions. It is found that the addition of helium to argon increases the heat flux density on the weld axis by a factor that can reach 6.5. This induces an increase in the weld pool depth by a factor of 3. It is also found that the addition of only 10% of argon to helium decreases considerably the weld pool depth, which is due to the electrical conductivity of the mixture that increases significantly when argon is added to helium.