飞机异常结冰的过冷凝固机理及理论研究
发布时间：2019-06-01 16:59
【摘要】：在航空活动广泛普及的今天,飞机结冰仍然是飞行安全的重大威胁,近二十年来造成了多起灾难性事故。自1994年以来,人们在一系列严重结冰事故发现了危险的异常结冰现象:防冰系统后产生了冰脊以致无法正常除冰,以及超出当时结冰适航条例范围(FAR 25.1419和附录C)的过冷大粒径水滴(SLD)环境。说明原有的飞机防除冰手段难以保证结冰飞行安全。经过二十年的研究,美国联邦航空局(FAA)推出了最新的结冰适航条款(FAR 25.1420和附录O),初步提出了SLD环境中的结冰适航要求。但现在仍然缺乏可靠的结冰预测和防护手段,这是由于产生异常结冰的机理还未得到很好的解释。研究现状表明,现有的飞机SLD结冰研究聚焦在于水滴动力学方面,未深入研究冰生长的机理。而对过冷水性质的研究进展则揭示了传统飞机结冰理论的不足。这要求更深入的研究过冷水结冰机理,建立可解释异常结冰的飞机结冰理论,支持结冰预测、防护及适航性验证等方面的研究。这项研究将对我国民机结冰适航有直接的支持,并且对过冷水物理、传热、凝固相关交叉学科研究有推动作用。本文围绕解释飞机异常结冰的目标,以过冷水结冰物理特性为切入点,开展结冰机理,飞机结冰理论和结冰预测应用三部分研究:1、研究大粒径过冷水滴的破碎形式产生条件和碰撞结冰的过程,得到水滴的多因素破碎机理和碰撞非定常传热机理认识;研究飞机表面过冷水生长的基本物理过程,得到过冷水层中结冰速率和形态演化的机理认识。2、研究飞机表面过冷水层结冰的演化理论和过冷水滴碰撞耦合结冰演化理论,提出反映过冷水结冰物理特性和水滴粒径效应的耦合结冰演化理论,3、研究飞机异常结冰数值预测算法,提出了水滴多因素破碎模型,过冷水滴碰撞模型和多阶段过冷结冰模型。对异常结冰特征的产生过程和条件进行了研究,为飞机结冰预测、防除冰设计和适航验证做准备。本文具体研究过程为:1、通过理论分析和两相流数值模拟研究了不同水滴破碎形式发生的条件、破碎的子液滴粒径和破碎发生的位置,掌握水滴不同破碎形式的发生机理,得到水滴的两类破碎形式发生的判据;通过风洞实验研究了过冷水滴碰撞结冰的过程,通过对水滴碰撞结冰过程和冰形状特征的分析,得到了过冷水滴碰撞产生的流动、张力影响和传热的耦合关系,对过冷水滴碰撞壁面结冰的运动和非定常传热过程进行了理论分析,得到两者耦合机理的认识。2、通过机理实验研究了壁面上过冷水结冰过程,发现三阶段的冰生长现象,研究了其中冰生长速率和形态变化的规律,并研究了材料性质对冰生长的影响。通过理论分析得到了结冰演化过程的机理解释,以及非定常状态下凝固界面的稳定性判据。通过Lattice Boltzmann-相场方法对流动环境中冰枝的生长过程进行了研究,得到冰枝在流动环境中的生长规律,补充实验和理论的不足。3、通过理论分析研究了过冷水层中多阶段结冰演化过程,包括冰在水层连续和间断时的生长阶段演化理论;研究了大过冷水滴破碎和碰撞结冰过程,包括水滴破碎过程影响水滴粒径分布和碰撞位置的理论,水滴的碰撞运动、非定常传热与影响冰表面稳定性的理论。得到了飞机上过冷水的耦合结冰演化理论。4、通过飞机的二维结冰数值方法,研究并校验了水滴多因素破碎模型、水滴碰撞非定常传热模型、多阶段过冷结冰模型,并且同经典Messinger结冰模型进行结冰对比研究,得到异常结冰的特征认识:在稳态结冰时,过冷水中冰枝的生长速度和温度的关系为幂函数,能产生比经典Messinger结冰模型预测更快的结冰速率和更强的溢流冰;在非定常结冰时,模型中结冰形态的转换会带来结冰速率的突变;大粒径水滴的碰撞会影响结冰形态,也会导致异常的结冰速率产生。这些效应在冰型上体现为明显的溢流台阶冰,是异常结冰的主要特征之一。本文的创新点为:在理论上,发现了过冷水壁面结冰的演化机理并提出飞机结冰的基础理论,给出了非定常结冰时的冰界面稳定性判据;在实验方法上,通过严格控制过冷水/水滴的条件得到了可靠的过冷水结冰机理认识;在应用上,建立了能有效模拟SLD结冰特征的飞机结冰数值模型和算法。
[Abstract]:Aircraft icing is still a major threat to flight safety today, which has caused many catastrophic accidents in the past two decades. Since 1994, there has been a risk of abnormal ice-freezing in a series of serious ice-icing incidents: the ice-prevention system has developed an ice ridge so that it is unable to de-ice, and the subcooled large-diameter water drop (SLD) environment beyond that of the ice-worthiness regulations at that time (FAR 25.1419 and Appendix C). It is difficult to ensure the safety of icing flight by the conventional method for preventing and controlling the ice. After two decades of research, the FAA has introduced the latest icing and airworthiness provisions (FAR 25.1420 and Appendix O), which initially proposed the icing requirements in the SLD environment. However, there is still a lack of reliable forecasting and protection means, which is not well explained due to the mechanism of abnormal icing. The research status shows that the research focus on the existing aircraft SLD ice is the water drop dynamics, and the mechanism of ice growth is not in-depth study. The research progress on the cold water property reveals the deficiency of the traditional aircraft icing theory. This requires a more in-depth study of the mechanism of cold water icing, to establish an aircraft icing theory that can explain the abnormal icing, to support research on the aspects of icing prediction, protection and airworthiness verification. This study will provide a direct support for the ice-worthiness of the civil aircraft in our country, and it has an impelling effect on the cross-disciplinary research related to the physical, heat transfer and solidification of cold water. In this paper, a three-part study of the freezing mechanism, the icing theory of the aircraft and the application of the icing prediction is carried out on the basis of the objective of explaining the abnormal icing of the aircraft, the freezing mechanism, the icing theory of the aircraft and the application of the icing prediction are studied in three parts:1. The conditions of the crushing of the supercooled water droplets with large particle size and the process of collision and freezing are studied. The mechanism of multi-factor crushing and the mechanism of the unsteady heat transfer of the water drop are recognized; the basic physical process of the overcold water growth on the surface of the aircraft is studied, and the mechanism of the freezing rate and the form evolution in the cold water layer is obtained. In this paper, the evolution theory of the surface overcold water layer on the surface of the aircraft and the theory of supercooled water drop collision coupled ice evolution are studied, and the coupled icing evolution theory, which reflects the physical characteristics of the cold water and the particle size effect of the water droplets, is put forward, and the numerical prediction algorithm for the abnormal icing of the aircraft is studied. A water-drop multi-factor crushing model, a supercooled water drop collision model and a multi-stage supercooled ice model are proposed. The production process and conditions of the abnormal icing characteristics are studied, and the preparation of the aircraft icing prediction, the control of the ice design and the airworthiness verification is carried out. The specific research process of this paper is as follows:1. The conditions, the size of the broken sub-droplets and the location of the break-up are studied by the theoretical analysis and the numerical simulation of two-phase flow, and the occurrence mechanism of the different breaking forms of the water droplets is mastered. The criterion of the two types of crushing forms of the water drops is obtained, the process of the super-cooled water drop collision and freezing is studied through the wind tunnel experiment, the flow, the tension effect and the coupling relation of the heat transfer are obtained through the analysis of the water drop collision freezing process and the ice shape characteristic, In this paper, a theoretical analysis of the motion and the unsteady heat transfer process of the supercooled water drop collision wall surface is carried out, and the coupling mechanism of the two is obtained.2. The ice formation process of the cold water on the wall surface is studied by the mechanism experiment, and the ice growth phenomenon of the three stages is found. The law of the rate of ice growth and the change of morphology was studied, and the effect of the properties of the material on the growth of ice was studied. The mechanism of the freezing evolution process and the stability criterion of the solidification interface under the unsteady state are obtained through the theoretical analysis. In this paper, the growth process of ice branches in the flowing environment was studied by the Lattice Boltzmann-phase field method, and the growth rule of the ice branches in the flowing environment was obtained. comprises the theory of the evolution of the growth phase of the ice in the continuous and intermittent water layer, The theory of unsteady heat transfer and the stability of ice surface. Based on the two-dimensional icing numerical method of the aircraft, a multi-factor crushing model, a water drop collision unsteady heat transfer model and a multi-stage supercooled ice model were studied and verified by the two-dimensional icing numerical method of the aircraft. and compared with the classical Messinger icing model, the characteristics of the abnormal ice formation are obtained: when the steady-state ice is frozen, the relationship between the growth speed and the temperature of the ice branches in the over-water is a power function, and the icing rate and the stronger overflow ice can be predicted more quickly than the classical Messinger icing model; In the case of unsteady ice formation, the transformation of the ice form in the model results in a sudden change in the freezing rate; the impact of the large-particle-size water droplets will affect the formation of the ice, which can also lead to an abnormal rate of ice formation. The effect of these effects on the ice form is the obvious overflow step ice, which is one of the main characteristics of the abnormal ice formation. The innovation point of this paper is that, in theory, the evolution mechanism of the freezing of the cold water wall is found and the basic theory of the icing of the aircraft is put forward, and the stability criterion of the ice interface during the unsteady ice formation is given; and in the experimental method, By strictly controlling the condition of the over-water/ water drop, it is recognized that the freezing mechanism of the cold water is reliable. In the application, the numerical model and the algorithm of the icing of the aircraft with the characteristics of the SLD icing can be effectively simulated.
【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：V244.15
本文编号：2490435
[Abstract]:Aircraft icing is still a major threat to flight safety today, which has caused many catastrophic accidents in the past two decades. Since 1994, there has been a risk of abnormal ice-freezing in a series of serious ice-icing incidents: the ice-prevention system has developed an ice ridge so that it is unable to de-ice, and the subcooled large-diameter water drop (SLD) environment beyond that of the ice-worthiness regulations at that time (FAR 25.1419 and Appendix C). It is difficult to ensure the safety of icing flight by the conventional method for preventing and controlling the ice. After two decades of research, the FAA has introduced the latest icing and airworthiness provisions (FAR 25.1420 and Appendix O), which initially proposed the icing requirements in the SLD environment. However, there is still a lack of reliable forecasting and protection means, which is not well explained due to the mechanism of abnormal icing. The research status shows that the research focus on the existing aircraft SLD ice is the water drop dynamics, and the mechanism of ice growth is not in-depth study. The research progress on the cold water property reveals the deficiency of the traditional aircraft icing theory. This requires a more in-depth study of the mechanism of cold water icing, to establish an aircraft icing theory that can explain the abnormal icing, to support research on the aspects of icing prediction, protection and airworthiness verification. This study will provide a direct support for the ice-worthiness of the civil aircraft in our country, and it has an impelling effect on the cross-disciplinary research related to the physical, heat transfer and solidification of cold water. In this paper, a three-part study of the freezing mechanism, the icing theory of the aircraft and the application of the icing prediction is carried out on the basis of the objective of explaining the abnormal icing of the aircraft, the freezing mechanism, the icing theory of the aircraft and the application of the icing prediction are studied in three parts:1. The conditions of the crushing of the supercooled water droplets with large particle size and the process of collision and freezing are studied. The mechanism of multi-factor crushing and the mechanism of the unsteady heat transfer of the water drop are recognized; the basic physical process of the overcold water growth on the surface of the aircraft is studied, and the mechanism of the freezing rate and the form evolution in the cold water layer is obtained. In this paper, the evolution theory of the surface overcold water layer on the surface of the aircraft and the theory of supercooled water drop collision coupled ice evolution are studied, and the coupled icing evolution theory, which reflects the physical characteristics of the cold water and the particle size effect of the water droplets, is put forward, and the numerical prediction algorithm for the abnormal icing of the aircraft is studied. A water-drop multi-factor crushing model, a supercooled water drop collision model and a multi-stage supercooled ice model are proposed. The production process and conditions of the abnormal icing characteristics are studied, and the preparation of the aircraft icing prediction, the control of the ice design and the airworthiness verification is carried out. The specific research process of this paper is as follows:1. The conditions, the size of the broken sub-droplets and the location of the break-up are studied by the theoretical analysis and the numerical simulation of two-phase flow, and the occurrence mechanism of the different breaking forms of the water droplets is mastered. The criterion of the two types of crushing forms of the water drops is obtained, the process of the super-cooled water drop collision and freezing is studied through the wind tunnel experiment, the flow, the tension effect and the coupling relation of the heat transfer are obtained through the analysis of the water drop collision freezing process and the ice shape characteristic, In this paper, a theoretical analysis of the motion and the unsteady heat transfer process of the supercooled water drop collision wall surface is carried out, and the coupling mechanism of the two is obtained.2. The ice formation process of the cold water on the wall surface is studied by the mechanism experiment, and the ice growth phenomenon of the three stages is found. The law of the rate of ice growth and the change of morphology was studied, and the effect of the properties of the material on the growth of ice was studied. The mechanism of the freezing evolution process and the stability criterion of the solidification interface under the unsteady state are obtained through the theoretical analysis. In this paper, the growth process of ice branches in the flowing environment was studied by the Lattice Boltzmann-phase field method, and the growth rule of the ice branches in the flowing environment was obtained. comprises the theory of the evolution of the growth phase of the ice in the continuous and intermittent water layer, The theory of unsteady heat transfer and the stability of ice surface. Based on the two-dimensional icing numerical method of the aircraft, a multi-factor crushing model, a water drop collision unsteady heat transfer model and a multi-stage supercooled ice model were studied and verified by the two-dimensional icing numerical method of the aircraft. and compared with the classical Messinger icing model, the characteristics of the abnormal ice formation are obtained: when the steady-state ice is frozen, the relationship between the growth speed and the temperature of the ice branches in the over-water is a power function, and the icing rate and the stronger overflow ice can be predicted more quickly than the classical Messinger icing model; In the case of unsteady ice formation, the transformation of the ice form in the model results in a sudden change in the freezing rate; the impact of the large-particle-size water droplets will affect the formation of the ice, which can also lead to an abnormal rate of ice formation. The effect of these effects on the ice form is the obvious overflow step ice, which is one of the main characteristics of the abnormal ice formation. The innovation point of this paper is that, in theory, the evolution mechanism of the freezing of the cold water wall is found and the basic theory of the icing of the aircraft is put forward, and the stability criterion of the ice interface during the unsteady ice formation is given; and in the experimental method, By strictly controlling the condition of the over-water/ water drop, it is recognized that the freezing mechanism of the cold water is reliable. In the application, the numerical model and the algorithm of the icing of the aircraft with the characteristics of the SLD icing can be effectively simulated.
【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：V244.15
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