气相沉积法反应器内碳纳米管纤维运动模拟

Motion simulation of carbon nanotube fibers in a vapor deposition reactor

为了研究碳纳米管纤维在气相沉积法反应器内的运动形态,并分析纤维运动形态对生成碳纳米管纤维的影响,首先采用数值模拟的方法对气相沉积法反应器内的气体流场进行数值求解,得到反应器内的气体流场的速度;然后在此气体流场中建立碳纳米管纤维模型并对其进行受力分析,得到纤维动力学方程,与气体流场控制方程组联立得纤维/气体两相流动模型;最后利用求解得到反应器内的气体速度,再对纤维动力学方程进行数值求解,从而得到碳纳米管纤维在反应器内的运动形态。模拟结果表明:气相沉积法反应器内的气体流场呈层流状态;由于气体从中心流入,纤维反应器中心轴线附近有较大波动,中心轴线附近气体流动区域逐渐扩大,加速度方向也产生改变,使得气体速度方向、大小均发生改变,纤维通过波动纠缠可以增加纤维束中纤维的连接,使之不易分散开来;而靠近壁面的气体流动逐渐稳定,导致靠近壁面的纤维运动形态逐渐平缓。通过模拟得到的纤维运动形态对形成碳纳米管纤维束有良好的促进作用。

In order to study the motion morphology of carbon nanotube fibers in a vapor deposition reactor and the impact of motion morphology on the formation of carbon nanotube fibers,this paper first employs the method of numerical simulation to solve the gas flow field in the vapor deposition reactor numerically and then figures out the velocity of gas flow field in the reactor.After that,a carbon nanotube fiber model is built in this gas flow field and a force analysis is conducted to obtain a fiber dynamics equation.Combined with the gas flow field control equation set,we can get a fiber/gas two-phase flow model.Finally,the fiber dynamics equation is solved numerically,with the gas velocity in the reactor obtained through calculation,so as to get the motion morphology of carbon nanotube fibers in the reactor.The simulation results indicate that the gas flow field in the vapor deposition reactor presents a laminar flow state.Since the gas flows in from the center,there is a great fluctuation near the central axis of the fiber reactor.The gas flow area near the central axis gradually expands,and the direction of acceleration changes,making the direction and magnitude of gas velocity change accordingly.The undulating entanglement of fibers can increase the bond of fibers in the fiber bundle,making it difficult to spread out.The gas flow near the wall gradually becomes stable,making the fiber motion near the wall gradually flatten out.The motion morphology of fibers obtained through simulation has a good promoting effect on the formation of carbon nanotube fiber bundles.