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为实现固体微推力器工作过程的一体化模拟,基于Fluent计算软件的二次开发功能(UDF)和简化化学动力学模型,实现了固体推进剂的二维气-凝相绝热微尺度燃烧模型的建立,该模型针对固体微推力器所用双基推进剂,包含两步凝相反应和五步气相反应,燃速、推进剂表面温度和组分质量分数基于燃面物理特性计算得到,并考虑了粘性作用对气相和凝相反应的影响。针对0.5MPa,1.0MPa,2.0MPa和5.1MPa四种工况进行了计算,结果表明,高压工作环境下出现发光火焰区,且随表面压力增大而逐渐靠近壁面,凝相反应区厚度和嘶嘶区、暗区主要反应物在燃面的质量分数随推进剂表面压力增大而减小。对称面处推进剂燃速,推进剂表面温度和气相火焰结构与实验结果基本一致。由于壁面附近较高的粘性作用,气相火焰在壁面位置更加靠近推进剂燃面,并导致壁面位置推进剂燃速高于对称面位置。该模型实现了二维环境下考虑分步凝相反应的推进剂绝热燃烧模型的一体化计算,较好地拓展了原模型的应用范围。
In order to realize the integrated simulation of working process of solid micro thrusters, based on the secondary development function (UDF) of Fluent calculation software and simplified chemical kinetic model, the two-dimensional gas-condensed phase adiabatic microscale combustion model of solid propellant The model is based on the double-base propellant used in solid micro thrusters, including two-step condensation reaction and five-step gas phase reaction. The combustion rate, propellant surface temperature and mass fraction are calculated based on the physical characteristics of the combustion surface. Effect of Viscosity on Gas Phase and Condensation Reaction. According to the calculation of 0.5MPa, 1.0MPa, 2.0MPa and 5.1MPa, the results show that the luminous flame zone appears under the high pressure working environment, and as the surface pressure increases, it gradually approaches the wall. The thickness and coking In the hysterics and dark areas, the mass fraction of the main reactants on the burning surface decreases with the increase of the surface pressure of the propellant. Burning rate of propellant at the symmetry plane, propellant surface temperature and gas-phase flame structure are in good agreement with experimental results. Due to the higher viscous effect near the wall, the gas-phase flame is closer to the combustion surface of the propellant at the wall and results in a higher burning rate of the propellant on the wall than on the plane of symmetry. The model realizes the integrated calculation of the adiabatic combustion model of propellants considering the step-by-step condensation reaction in two-dimensional environment, which expands the application range of the original model well.