Ice accretion and release in fuel systems
Ice accretion and release in fuel systems
复制标题
燃料系统中的冰积聚和释放
作者：
J. Lam;R. Woods
2008年B777在希思罗机场发生事故后，认证机构要求波音、空客和劳斯莱斯对其劳斯莱斯Trent发动机飞机燃料系统进行结冰分析和测试。从这些活动中获得的经验和测试数据由空客提炼并发布给EASA ICAR项目进行研究和分析。本文概述了空中客车的增冰和释放试验。简要介绍了测试平台、测试程序和方法，并介绍了冰释放调查的主要发现。增冰厚度不均匀；但是，通常在c. $ mathm {2；mathrm {m} mathrm {m}} $厚。从钻机测试中收集的冰的分析表明，冰是非常多孔的。孔隙度在很大程度上取决于水是如何被引入和混合在结冰测试平台上的。与注入法相比，标准的空中客车方法产生的增冰孔隙率更高。从空中客车结冰调查中发现，增加冰的孔隙率为0.90。渗透率与孔隙度的关系是根据已发表的大气中新降雪的数据和模型推断出来的。导出渗透率$ mathm {7.0 * 10^{-9}；将mathrm{mathrm{m}}^{mathrm{2}}}}$应用于含多孔壁衬的管道流动CFD分析，确定加冰的剪应力。结果表明：25%、50%和75%的堆积冰的界面抗剪强度小于$ mathm {15.3；mathrm {Pa}} $, $ mathrm {20.7;mathm {Pa}}$和$ mathm {26.1；分别mathrm {Pa}} $。
ABSTRACT Following the B777 accident at Heathrow in 2008, the certification authorities required Boeing, Airbus, and Rolls-Royce to conduct icing analysis and tests of their Rolls-Royce Trent engined aircraft fuel systems. The experience and the test data gained from these activities were distilled and released by Airbus to the EASA ICAR project for research and analysis. This paper provided an overview of the Airbus ice accretion and release tests. Brief narratives on the test rigs, the test procedure and methodology were given and key findings from the ice release investigations were presented. The accreted ice thickness was non-uniform; however, it is found typically c. $mathrm{2;mathrm{m}mathrm{m}}$ thick. Analysis of the accreted ice collected from the rig tests showed the ice was very porous. The porosity is very much dependant on how the water was introduced and mixed in the icing test rigs. The standard Airbus method produced accreted ice of higher porosity compared to that produced by the injection method. The porosity of the accreted ice from Airbus icing investigations was found to be c. 0.90. The relationship of permeability with porosity was inferred from published data and models for freshly fallen snow in the atmosphere. Derived permeability $mathrm{7.0 imes 10^{-9};mathrm{mathrm{mathrm{m}}^{mathrm{2}}}}$ was then applied in the CFD analysis of pipe flow with a porous wall lining to determine the shear stress on the accreted ice. It showed that 25%, 50% and 75% of the accreted ice has interface shear strength of less than $mathrm{15.3;mathrm{Pa}}$, $mathrm{20.7;mathrm{Pa}}$ and $mathrm{26.1;mathrm{Pa}}$, respectively.