沥青发泡过程和发泡条件参数的仿真研究

发布时间：2018-03-28 09:23

  本文选题：泡沫沥青　切入点：发泡过程　出处：《长安大学》2014年硕士论文

【摘要】：我国是公路里程的大国，每年产生的沥青路面废旧材料就高达上亿吨，而对废旧材料的利用率却非常低。近几年来，国内开始引进泡沫沥青冷再生设备来改善这种情况。泡沫沥青技术中发泡装置是至关重要的部分，揭示沥青发泡过程，确定发泡装置的结构及工艺参数，设计有效、合理的发泡装置对泡沫沥青技术的研究具有重要的意义。沥青发泡过程的研究，对改善发泡效果和泡沫沥青的实际应用具有重要的理论和工程意义。 根据沥青的实际发泡过程，建立了沥青发泡膨胀过程仿真模型，利用先进计算流体力学软件Fluent,首次对沥青喷出发泡腔外的实际发泡膨胀过程进行模拟研究，建立了模拟结果与实验数据之间的直接关联关系。通过仿真数据与实验数据的对比分析，验证了建立的沥青发泡过程的仿真模型基本符合实际沥青发泡过程。 利用建立的仿真模型，研究了发泡条件参数对发泡膨胀率的影响，分析得出发泡用水量和发泡过程中的空气压力对发泡膨胀率的影响并不显著，而发泡用沥青的温度和沥青的流量对发泡膨胀率的影响比较显著。发泡用水量在1.5%到2.5%范围变化和发泡过程中的空气压力在0.3MPa到0.6MPa范围变化时对发泡膨胀率的影响不明显，当沥青入口流量从100g/s到180g/s变化时和沥青温度从150℃到170℃变化时，，膨胀率是一个稳定增长的过程。 建立了发泡腔内仿真模型，利用Fluent软件对发泡腔内部的多相耦合场进行了分析。在发泡过程中，空气的吹入可以促进水汽与沥青的碰撞、附着，增加水汽被沥青包裹的机会。空气不参与相变和沥青的发泡过程，但可以改善发泡效果，同时，减少了沥青与发泡腔的粘附，并起到清洁发泡腔的作用。沥青和水的入口角度、速度直接影响沥青和水汽的混合效果，导致沥青的发泡效果不同。发泡过程的水用于产生水蒸气，并为沥青泡沫膨胀提供动力。发泡中的高温沥青一方面为水的蒸发提供热量；另一方面，包裹水汽泡，形成沥青泡沫。 利用有限元数值模拟方法，通过对发泡腔内、外沥青发泡过程的数值模拟，可以有效地对所设计的发泡腔结构、发泡效果及其影响因素进行一定的预先评价，对实际发泡设备的生产及应用具有一定的指导意义。
[Abstract]:China is a large country of highway mileage, producing hundreds of millions of tons of used asphalt pavement materials every year, but the utilization ratio of waste materials is very low. In recent years, In order to improve the situation, the foaming device is the most important part in the foamed asphalt technology, which reveals the foaming process of asphalt, determines the structure and technological parameters of the foaming device, and is effective in design. The reasonable foaming device is of great significance to the study of foamed asphalt technology, and the study of the foaming process of asphalt has important theoretical and engineering significance for improving the foaming effect and the practical application of foamed asphalt. According to the actual foaming process of asphalt, the simulation model of asphalt foaming and expanding process is established. The actual foaming and expanding process of asphalt ejecting foaming cavity is studied for the first time by using advanced computational fluid dynamics software Fluent. The direct correlation between the simulation results and the experimental data is established, and the simulation model of the asphalt foaming process is verified by comparing the simulation data with the experimental data, which basically accords with the actual asphalt foaming process. By using the simulation model, the influence of the foaming condition parameters on the foaming expansion rate is studied. The results show that the influence of water consumption and air pressure during foaming process on the foaming expansion rate is not significant. However, the influence of temperature and flow rate of foamed asphalt on the foaming expansion ratio is obvious. The influence of air pressure in the process of foaming is not obvious when the range of water consumption is 1.5% to 2.5% and the air pressure in the process of foaming varies from 0.3MPa to 0.6MPa. When the inlet flow rate of asphalt varies from 100g/s to 180g/s and the temperature of asphalt varies from 150 鈩

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