【作者】 梁鹏；

【导师】 杨立新；

【作者基本信息】 北京交通大学 ， 热能工程， 2017， 硕士

【摘要】 飞机在积冰条件下飞行,空气中的过冷水滴撞击到飞机部件如机翼、发动机整流罩表面会发生结冰,结冰会影响飞机的气动特性,因此,为了防止旋转整流罩表面积冰,需开展旋转整流罩积冰模拟实验研究,掌握积冰规律。本文搭建小型冰风洞,将旋转整流罩简化为旋转锥体并通过可视化方法得到了不同结冰工况下的积冰形貌,通过图像分析得到不同种类积冰的生长特性规律;建立简化理论模型,分析水滴在旋转锥体表面的运动及凝固;最后利用两流体模型结合壁面撞击模型进行数值研究。通过实验和数值两种研究方法,对旋转锥体表面结冰机理进行了深入分析,为全面、清楚地描述该现象的规律积累经验,奠定了一定的研究基础。通过可视化实验研究得到了不同锥体转速、来流温度、液态水含量下旋转锥体表面积冰形貌,积冰形貌主要分为霜冰、瘤状冰和刺状冰,并通过图像分析得到了不同工况下霜冰、瘤状冰的积冰生长特性,结果表明:霜冰、瘤状冰在旋转锥体表面的总积冰生长速率随温度的降低、液态水含量的升高以及转速的降低而增大。在锥尖位置轴向积冰生长速率要远大于径向值。刺状积冰特性不同于霜冰和瘤状冰,本文主要分析了其存在区域和冰刺长度的变化规律,结果表明:刺状冰通常首先在靠近锥体底部的位置形成,并逐渐向锥尖位置扩展。刺状冰积冰区域和冰刺生长速率随液态水含量增大和转速提高而增加,且液态水含量的影响作用更显著。根据图像分析建立了实际结冰表面,利用两相流模型结合壁面撞击模型对过冷水滴的运动轨迹进行了计算,得到了局部水收集系数,并与实验结果进行对比验证,吻合性较好,并分析了锥体转速、来流速度、水滴直径对光滑表面和实际表面上局部水收集系数的影响,结果表明:锥体表面局部水收集系数随着转速的增大而减小;随着水滴直径的增大而增大;随着来流速度的增大而增大,实际表面和光滑表面存在差异。更多还原

【Abstract】 Ice accretions may occur when the subcooled water droplets impact on the airplane surfaces such as wing and spinner and so on when the airplane flies under icing conditions.Ice accretions may affect the aerodynamic characteristics of the flight.In order to prevent icing on spinner,we need to do some experiments on icing of spinner and study the mechanism of icing on spinner.A small ice wind tunnel was built,and the ice accretion tests on sub-scale rotating spinner model were conducted in detail with visualization experiments in icing wind tunnel and the ice shapes were got under different conditions.The law of icing shapes were obtained by image analysis method.A simplified model was built to analyze the movement and heat transfer of water droplets.The two-phases model combined with the wall impacting model were used to simulate.The mechanism of water droplets freezing was gained by experiment and simulation study,and some experiences were got on the icing.The ice shapes in different temperatures,liquid water contents and rotating speeds were revealed by visualization experiments.There were three ice shapes,they were rime ice,glaze ice and spiny ice.The influence of conditions on the processes of rime ice and glaze ice were knew by using image analysis method.The results showed that ice grow rate was increased with the decrease of temperature and rotating speed and the increase of liquid water content.The axial growth rate was much larger than the radial.Spiny ice was different from the rime ice,the area and length of spiny ice were analyzed,the results showed that the spiny ice was appeared near the bottom first,and then to the cone tip.The area and length were increased with the increase of liquid water content and rotating speed,and the liquid water content effect was obvious.A simplified model was built to explain the icing on spinner.The ice surfaces were built by using image analysis method,and then simulate the phenomenon of water droplets movement by using two-phases model combined with wall impacting model.The local water collect coefficient were obtained and compared with experimental results,and matched very well,then the influences of rotating speed,median volume diameter,rotating speed and two types of surfaces on local water collect coefficient were analyzed.The results showed that the local water collect coefficients were increase with the decrease of rotating speed and the increase of median volume diameter and rotating speed.The local water collect coefficient between the smooth surfaces and ice surfaces was different.更多还原