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纳米流体作为一种较高的导热介质,广泛应用于各个传热领域.鉴于纳米颗粒导热系数和成本之间的矛盾,本文提出了一种混合纳米流体.为了研究混合纳米流体颗粒间相互作用机理和自然对流换热特性,在考虑颗粒间相互作用力的基础上,利用多尺度技术推导了纳米流体流场和温度场的格子Boltzmann方程,通过耦合流动和温度场的演化方程,建立了Cu/Al2O3水混合纳米流体的格子Boltzmann模型,研究了混合纳米流体颗粒间的相互作用机理和纳米颗粒在腔体内的分布.发现在颗粒间相互作用力中,布朗力远远大于其他作用力,温差驱动力和布朗力对纳米颗粒的分布影响最大.分析了纳米颗粒组分、瑞利数对自然对流换热的影响,对比了混合纳米流体(Cu/Al2O3-水)与单一金属颗粒纳米流体(Al2O3-水)的自然对流换热特性,发现混合纳米流体具有更强的换热特性.
Nanofluids, as a kind of high thermal conductivity medium, are widely used in all heat transfer fields.In view of the contradiction between the thermal conductivity and the cost of nanoparticles, a hybrid nanofluid is proposed in this paper.In order to study the mechanism of interfacial interaction between nanofluids Based on the interaction between particles, the Lattice Boltzmann equation of flow field and temperature field of nanofluids was deduced by using multi-scale technique. The evolution equation of the flow field and temperature field of the nanofluids was established. The Cu / Lattice Boltzmann model of nanofluids mixed with water was investigated to study the interaction mechanism of nanofluids and the distribution of nanoparticles in the cavity. It was found that the Brownian force is far greater than the other forces in the interparticle interaction. The influence of force and Brownian force on the distribution of nanoparticles is the greatest.The effect of nanoparticle composition and Rayleigh number on natural convection heat transfer is analyzed and the effects of mixing nanofluid (Cu / Al2O3-water) and single-metal particle nanofluid (Al2O3 - water) convective heat transfer characteristics and found that the hybrid nanofluid has a stronger heat transfer characteristics.