含铝凝胶燃料的流变特性研究

在庚烷/硝酸异丙酯混合体系中加入不同粒径的无机纳米凝胶剂,实现燃料凝胶化;并在部分样品中添加纳米铝粉,制得一系列凝胶燃料;以此来研究凝胶剂粒径和铝粉含量对凝胶燃料流变性能的影响规律。采用激光共聚焦显微镜、比重杯和氧弹量热仪测试凝胶燃料的微观形貌、密度与燃烧热；利用流变仪测试凝胶燃料的剪切变稀性、蠕变性以及非线性黏弹性等流变性能。结果表明:凝胶化的燃料具有更高的密度和体积燃烧热；大粒径凝胶剂体系的假塑性更明显，网络强度更大，但内部结构易碎；铝粉的加入破坏了絮凝体网络的连续性，增强了凝胶燃料的塑性，降低了蠕变恢复能力，但会提升凝胶燃料的整体强度。添加质量分数20%的铝粉后，凝胶燃料的零切黏度η₀提高了6倍，储能模量G′₀ 提高了3倍，蠕变恢复能力r_c 下降了33%。

Rheological Properties of Aluminium-Containing Gel Fuel

In the mixed system of heptane/isopropyl nitrate, different sizes of inorganic nano gel were added to fuel gelation, and a series of gel fuels were prepared by adding nano aluminum powder in some samples. Effects of gel size and aluminum content on rheological properties of gel fuel were investigated. A confocal microscope, a specific gravity cup and an oxygen bomb calorimeter were used to test the micro morphology, density and combustion heat of fuel. Rheological properties of fuel, such as shear thinning, creep and nonlinear viscoelasticity, were measured by a rheometer. Results show that the gelation fuel has higher density and volumetric combustion heat. Pseudoplasticity of the large-size gel system is more obvious, the network strength is bigger, but the internal structure is fragile. The addition of aluminum powder destroys the continuity of the agglomerate network, enhances the plasticity of the gel fuel, reduces the creep recovery ability, but enhances the overall strength of the gel fuel. After adding 20% (mass fraction) aluminum powder, η₀?of gel fuel increases by six times, G′₀increases by three times, and r_c decreases by 33%.