【作者】 蒋峻峰；

【导师】 洪若瑜；

【作者基本信息】 苏州大学 ， 应用化学， 2010， 硕士

【摘要】 本文系统地研究了磁性流体动量和热量传递过程。用FVM(finite volume method)、FEM(finite element method)方法离散微分方程,通过实验与模拟结合的方法,达到宏观动力学、传热模拟。(1)考察了单突扩管下突扩管比例对流场的影响,研究了随着雷诺数变化突扩管内流场从稳态对称型到稳态非对称型的转变。通过外加磁场的耦合作用,研究磁场的“消涡”作用。(2)基于单突扩模型,研究了突扩-突缩管中流体流动。结果表明,在低雷诺数下管内流动呈稳态对称型。随着雷诺数增大,管内会出现涡阶分离。根据(1)的经验,在管中央外加电磁场实现“消涡”。(3)考察了突扩管内含圆柱空洞的管内流体流动。根据卡门涡街原理,对突扩管涡流、圆柱绕流进行分析。通过引入电磁场,使用N-S方程/电磁场方程耦合求解,达到高雷诺数下的流动稳定。(4)以硝酸锶、氯化铁、氢氧化钠以及多种表面活性剂为原料,使用共沉淀法合成纳米锶铁氧体。通过TEM、XRD、VSM等方法表征锶铁氧体性能,获得最佳制备条件。(5)将制备好的锶铁氧体纳米颗粒溶于水相中置于热疗仪器的螺旋管中。通过改变表观电流实现对磁性流体的升温效应研究。结果显示低固含量锶铁氧体的升温效果明显。(6)使用数学模拟的方法研究了磁性流体的热疗温度分布。建立合理的二维模型,使用生物传热方程进行计算。研究了不同磁场强度,不同交变频率,不同颗粒粒径,不同磁性流体固含量对升温效果的影响。更多还原

【Abstract】 The momentum and heat transfer of magnetic fluid were studied. FVM (finite volume method) and FEM (finite element method) were used to discrete partial differential equation. With the combination of experimental method and numerical simulation, macrodynamics and heat transfer were investigated.(1) The expansion ratio was investigated in this part. The streamline pattern changed from symmetric to asymmetric as Raynolds number increased. The "elimination of vortexes" was also studied under the application of external magnetic field.(2) The expansion-contraction model was simulated later based on expansion model in (1), results of which showed that the flow pattern remained symmetrical under low Raynolds number. As Raynolds number increased, the asymmetric phenomenon and bifurcation appeared successively. The external magnetic field was also applied to make the vortexes disappeared.(3) The model of an expansion with a cylinder was investigated. The fluid flowing across the sudden expansion and around cylinder was comprehensively considered. Results showed that the flow pattern was stable under high Raynolds number with the introduction of magnetic field.(4) Nano-strontium hexaferrite (SrFe12O19) particles were prepared by co-precipitation method, using strontium nitrate (Sr(NO3)2), ferric chloride (FeCl3·6H2O), sodium hydroxide and several surfactants as starting materials. The optimum preparation conditions were obtained by TEM, XRD and VSM analysis.(5) The prepared strontium hexaferrite nano-particles were dispersed in water and then placed in hyperthermia apparatus. The temperature rise effect was investigated by changing the apparent current. Results showed that aqueous with low solid content had remarkable heating effect. (6) Numerical method was applied to investigate the temperature distribution of hyperthermia. 2 dimensional (2-D) model was established and the bioheat transfer equation was used for calculation. Different conditions such as magnetic field strength, AC frequency, particle size and solid content were considered.更多还原