表面结构对纳米级气膜稀薄流域分布的影响

摘要

磁头与磁盘的特征高度目前已经下降到纳米量级，在此微小间隙下，气体表现出明显的稀薄效应特征。建立适用于纳米间隙下的控制方程，并根据方程特点采用特殊处理方法成功对控制方程进行数值求解，采用数值分析和实验方法分析表面结构变化对稀薄流域和磁头飞行姿态的影响。研究结果表明：在纳米级气膜润滑间隙下，采用逆 Knud-sen 数来划分稀薄流域比仅从特征膜厚高度方面考虑更合理；负压型磁头的主要工作区间在滑流区和过渡区，且过渡流域所占比例要明显高于滑流区域。稀薄效应最大的区域不是在气膜厚度最薄的磁头尾部，而是在压力突然下降且气膜较薄的阶梯过渡区域；磁头 U 型气垫、尾端两侧浅台阶和中间台阶结构变化会影响气流流向，从而影响压力分布，使得稀薄流域也跟随发生变化。%The characteristic height of the magnetic head has down to the nanoscale,and the gas shows obviously rare-fied effect characteristics at this micro gaps.The control equation introducing the rarefied effect was established and solved successfully using numerical method based on special treatment scheme.The effect of the surface structure on the gas film rarefied region and flying attitude was analyzed by numerical analysis and experimental tests.The results show that:the gas flow regime divided depending on the inverse Knudsen number is more reasonable than that only from the view of film thickness;negative slider mainly works in the slip-flow and transition regions and the area proportion of transition regions is significantly higher than that of the slip regions;the maximum rarefied effect occurs at the side edges where the flying height is thinner and the pressure is lower but not in the minimum flying height on the rear;the variations of the U-shaped slider,both trailing sides slider and the trailing intermediate slider of the magnetic head makes the air flow changes,which directly affects the pressure distribution and rarefied regions of the gas film.