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Rheological behavior of alcohol-resistant foam concentrates and its impact on pipe flows
Fire Safety Journal ( IF 3.4 ) Pub Date : 2021-01-24 , DOI: 10.1016/j.firesaf.2021.103289
Youquan Bao , Huiqiang Zhi , Lu Wang

The rheological behavior of alcohol-resistant foam concentrates and its impact on pipe flows play critical roles in the scientific design of foam fire-extinguishing systems. In the present work, the equilibrium flow curve, yield stress and thixotropy of alcohol-resistant foam concentrates are experimentally studied, and the effects of the yield stress and thixotropy on pipe flows are theoretically analyzed. The results show that the equilibrium flow curves of alcohol-resistant foam concentrates conform to the Herschel-Bulkley model, and the thixotropic behavior can be well represented by a structural kinetics model that we have established. Ignoring the yield stress or thixotropy of alcohol-resistant foam concentrates will result in an overoptimistic calculated pressure loss in pipe flows. When the thixotropy of alcohol-resistant foam concentrates is incorporated in pipe flow modeling, the nominal shear rate at the pipe wall is no longer a fixed value but gradually increases with time until it reaches a steady-state value. The steady-state value depends on the equilibrium flow curve of the alcohol-resistant foam concentrate and the shear stress at the pipe wall. Based on the initial structural strength and equilibrium flow curve of alcohol-resistant foam concentrates, a method for estimating the design pressure loss in pipe flows is proposed.



中文翻译:

耐酒精泡沫浓缩物的流变行为及其对管道流动的影响

耐醇泡沫浓缩物的流变行为及其对管道流动的影响在泡沫灭火系统的科学设计中起着至关重要的作用。在本工作中,通过实验研究了耐醇泡沫浓缩液的平衡流曲线,屈服应力和触变性,并从理论上分析了屈服应力和触变性对管道流动的影响。结果表明,耐醇泡沫浓缩液的平衡流动曲线符合Herschel-Bulkley模型,并且触变行为可以通过我们建立的结构动力学模型很好地表示。忽略耐醇泡沫浓缩液的屈服应力或触变性将导致计算出的管道流量压力损失过分乐观。当将抗酒精泡沫浓缩物的触变性纳入管道流动模型时,管壁的名义剪切速率不再是固定值,而是随着时间逐渐增加,直到达到稳态值。稳态值取决于耐醇泡沫浓缩物的平衡流量曲线和管壁处的剪切应力。基于耐醇泡沫浓缩液的初始结构强度和平衡流量曲线,提出了一种估算管道流量设计压力损失的方法。稳态值取决于耐醇泡沫浓缩液的平衡流量曲线和管壁处的剪切应力。基于耐醇泡沫浓缩液的初始结构强度和平衡流量曲线,提出了一种估算管道流量设计压力损失的方法。稳态值取决于耐醇泡沫浓缩物的平衡流量曲线和管壁处的剪切应力。基于耐醇泡沫浓缩液的初始结构强度和平衡流量曲线,提出了一种估算管道流量设计压力损失的方法。

更新日期:2021-02-01
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