一种用于飞机结冰的海绵冰模型及应用

基于两相流理论,采用欧拉法对飞机结冰进行数值模拟,在空气流场速度分布的基础上,求解水滴流场,得到水滴收集率和撞击极限.结果表明:欧拉法比拉格朗日法在计算水滴收集效率和撞击极限方面有优势,尤其是在较大的水滴平均等效直径情况下.对翼型的冰形和圆柱表面的温度预测数据和实验数据进行对比,圆柱冰形厚度误差在15.0%之内,计算结果与实验结果吻合较好,同时表明结冰模型是有效可行的.      

模拟飞机迎风面三维积冰的数学模型

针对飞机迎风面的积冰建立了三维积冰模型,给出了模型的求解方法和求解步骤.该模型不但可以模拟明冰积冰、霜冰积冰和不结冰三种情况下的冰层生长,还可以模拟未凝结水膜在冰层表面的流动,而且在求解过程中可以自动判断过冷水滴撞击到迎风面以后的积冰形态.利用该模型数值模拟了翼型与平板相正交而形成的简单三维结构上的积冰过程,并将所得结果中翼型上三维冰形的二维截面与美国航空航天局(NASA)的冰形进行了对比,获得了较好的一致性,证实了所建立的积冰模型是合理的.      

结冰条件下的飞机飞行动力学仿真

基于飞机结冰参量模型对飞机在结冰条件下的飞行动力学特性进行了仿真研究.提出一种飞机结冰参量模型的参数计算方法,并针对一定结冰气象条件下的不同结冰时间对飞机的结冰严重程度进行了评估,基于小扰动理论对飞机结冰前和不同结冰严重程度下的纵向、横侧动稳定性以及操纵响应进行了仿真计算,根据仿真计算结果分析了不同结冰严重程度对飞机造...     

构建航空发动机滑油系统稳态模型

研究模拟不同飞行条件下滑油系统稳态工作对滑油系统的设计和故障诊断具有重要的参考价值。基于部附件特性，提出了依据8个航空发动机性能参数，用向量计算和插值算法取代迭代算法来构建滑油系统稳态模型的方法，并对发动机在海平面、最大工作状态条件下的滑油系统性能参数进行了验证计算。计算结果与设计数据吻合较好，误差在5％以内，表明所建立的稳态模型是有效的。滑油在各轴承腔和齿轮箱中的流量分配随空气压力变化，计算误差主要来自轴承腔和齿轮箱压力分布假设，为进一步提高计算精度，必须建立航空发动机内部空气系统模型。     

离心力对于旋转叶片表面积冰影响的数值模拟研究

为了加深对旋转叶片表面积冰现象的认识,发展了一种适用于旋转表面积冰预测的数学模型,并采用该模型研究了离心力对于旋转叶片表面积冰的影响。通过对积冰控制体内的由于撞击水滴形成的薄水膜流动的质量、动量和能量守恒进行分析,发展了旋转贴体非正交曲线坐标系下的积冰模型并给出了相应的计算方法。所发展模型的动量方程中考虑了离心力对水膜流动的影响,并且在能量方程中考虑了净流出水带走的能量。采用文献中旋翼表面的积冰试验结果对所发展的模型和计算方法进行了验证,所计算得到的冰厚与试验结果吻合较好,计算得到的冰厚精度相比于LWICE软件有所提高。计算结果还表明,离心力增大会导致水膜速度在叶片展向上的分量变大,致使流出控制体的水质量增加,最终导致冰厚在驻点附近略微变小。     

动力对全机水滴收集率的影响计算

针对飞机在飞行中遭遇过冷水滴撞击并结冰现象,建立了适合于发动机带动力情况下结冰过程水滴收集率计算的三维数值方法和计算程序.其基本思路为:采用多块技术与SIMPLE方法计算空气流场,以流场分布的计算结果为基础,求解水滴相的控制方程,进而获得物体表面的水滴收集率.空气相控制方程和水滴相控制方程均写成典型输运方程的形式,采用一致的有限体积法离散求解,方便了计算程序的编制.对某型运输机巡航构型有/无动力条件的水滴收集率进行了比较计算,获得了不同直径水滴在飞机表面的撞击特征以及水滴收集率在飞机机翼、平尾、垂尾和发动机进气道唇口上的分布规律.研究表明:(1)发动机是否带动力对机翼、平尾、垂尾的水滴收集率基本无影响;(2)飞机带动力主要影响发动机进气道唇口处的水滴收集率,带动力后唇口的收集率比无动力情况高,水滴撞击范围增大,在进行防除冰研究和设计时需引起重视.     

A new vortex sheet model for simulating aircraft wake vortex evolution

A new vortex sheet model was proposed for simulating aircraft wake vortex evolution.Rather than beginning with a pair of counter-rotating cylindrical vortices as in the traditional models,a lift-drag method is used to initialize a vortex sheet so that the roll-up phase is taken into account.The results of this model report a better approximation to a real situation when compared to the measurement data.The roll-up induced structures are proved to influence the far-field decay.On one hand,they lead to an early decay in the diffusion phase.On the other hand,the growth of linear instability such as elliptical instability is suppressed,resulting in a slower decay in the rapid decay phase.This work provides a simple and practicable model for simulating wake vortex evolu tion,which combines the roll-up process and the far-field phase in simulation.It is also proved that the roll-up phase should not be ignored when simulating the far-field evolution of an aircraft wake vortex pair,which indicates the necessity of this new model.     

涡扇发动机短舱结冰试验相似方法

通过分析短舱表面结冰缩比试验相似要求,在保证绕流流场、水滴撞击特性和结冰冰型相似的基础上,分别采用基于气流雷诺数,气流韦伯数和水滴韦伯数3种速度选取方法建立了试验相似准则。利用该准则获得了明冰和霜冰条件下涡扇发动机短舱1/2缩比模型的结冰试验参数,开展了短舱进气道表面结冰冰型预测,对参考模型和缩比模型表面过冷水滴撞击特性、结冰特性、溢流水分布特性进行了分析。结果表明:采用基于气流韦伯数和水滴韦伯数速度选取方法的相似准则,在明冰和霜冰条件下均能保证缩比模型与参考模型表面水滴撞击特性相似,且相似性不受结冰温度影响;溢流水变化趋势与参考模型相似,流动极限相近;缩比模型表面冰型均与参考模型相似,该方法能够为短舱结冰试验参数选取提供依据。      

飞机结冰冰形测量方法研究进展

不同气象环境下飞机部件的结冰外形是飞机结冰研究不可缺少的内容,它对开展结冰气动分析、结冰防护设计、结冰飞行操作和结冰适航取证等研究具有重要意义。结合国内外冰形测量技术发展现状,从接触测量方法和非接触测量方法两个方面分别介绍了现有冰形测量技术的操作流程及测量原理,系统分析总结了各自存在的优缺点。在此基础上,结合飞机结冰和结冰风洞试验的特点,归纳了冰形测量技术下一步发展面临的挑战,包括全类型结冰的精确测量、结冰全貌三维测量和结冰生长过程实时测量等,同时,从基础测量手段与数值计算融合发展的角度,展望了冰形测量方法未来的发展趋势。     

A new online modelling method for aircraft engine state space model

To overcome the drawbacks of current modelling method for aircraft engine state space model, a new method is introduced. The form of state space model is derived by using Talyor series to expand the nonlinear model that is implicit equations and involves many iterations. A partial derivative calculation method for iterations is developed to handle the influence of iterations on parameters. The derivative calculation and the aerothermodynamics calculations are combined in the component level mode...     

An optimization model of parameter matching for aircraft catapult launch

To efficiently and fully utilize aircraft carrier resources, an optimization model is presented to deal with parameter matching between aircraft and carrier in the process of aircraft catapult launch. Based on carrier aircraft longitudinal dynamic equations and theorem of kinetic energy in catapult launch course, the work characteristics of different forces are learned and a theory model of parameter matching is deduced. In view of the uncertainty of the model parameters of the theory model and the low matching accuracy of the approximate model, an optimization model of parameter matching is introduced in line with the structure of theory model and the approximate model and is generated by the proposed immune genetic algorithm. Compared with the original genetic algorithm and immune algorithm, the proposed algorithm has better calculation accuracy and convergence. The calculation results show that the optimization model occupies certain application value of engineering estimation from the comparison with the relevant literature data and has higher precision than the approximate models. The validity of the proposed approach is verified with numerical case study on a carrier based aircraft.     

基于Myers模型的三维结冰数值仿真

三维结冰表面上的水膜流动和结冰增长是结冰计算模型应考虑的核心内容,其中广泛应用的是Myers模型。Myers模型考虑了空气剪切力和空气压力对结冰表面水膜流动的影响,以及冰层、水膜和空气之间的导热与对流传热对结冰速率的影响。本文在使用Myers模型进行结冰预测时,发现Myers模型对霜冰转化为明冰的判断标准存在缺陷,会在结冰极限处产生不合理的冰角。因此对Myers模型的结冰类型判断标准进行了修改,对机翼表面的结冰过程进行了更加准确的模拟,并应用了有效的离散算法计算水膜流动和结冰增长过程。对比了二维NACA0012翼型的单步法、多步法计算结果和实验结果。明冰结冰温度较低时,本文计算结果与实验结果吻合很好,明冰结冰温度较高时,本文对上冰角的计算与实验结果有一定差距。本文提供了三维GLC-305后掠翼的结冰计算结果和实验结果的对比,冰角厚度的计算结果略小于实验结果,但整体趋势一致。     

锥角对旋转整流罩积冰影响的模拟实验

采用缩比模型对4种不同锥角的旋转整流罩进行了冰风洞积冰模拟实验.推导出旋转表面积冰相似参数,并根据重要参数的匹配确定缩比整流罩模型的积冰实验参数.在实验中采用高速摄像系统记录冰生长过程及最终冰形.结果表明:4种锥角的整流罩表面积冰均由初期生成、分布连续的明冰和后期增长迅速的白色霜冰构成;锥角小于等于74°的整流罩表面霜冰为针状或粒状,积冰厚度较小;锥角大于80°的整流罩表面霜冰为羽毛状,积冰厚度较大,并伴随冰脱落现象,锥角较大的整流罩冰脱落位置向下游移动.      

Modelling and analysis of initial icing roughness with fixed-grid enthalpy method based on DPM-VOF algorithm

Ice particles could form under the continuous impingement of incoming supercooled droplets in icing conditions, which will change the surface roughness to enhance the further heat and mass transfer during icing process. A fixed-grid porous enthalpy method based on the improved Discrete Phase Model(DPM) and Volume of Fluid(VOF) integrated algorithm is developed to solve the multiphase heat transfer problem to give more detailed demonstration of the formation of initial ice roughness. The algorith...     

基于Kriging模型的冰风洞试验冰形参数化方法

为增强冰形使用的可靠性,基于Kriging模型,提出了冰形曲线参数化的方法.以多组冰风洞试验冰形为对象,分析了方法的可操作性及其关键参数对结果的影响规律.同时,结合等效砂粒高度的概念,阐述了参数化冰形实际应用中的有效建议.研究表明:方法是可行的,它在保证了原冰形几何特征的基础上,有效光滑了小尺度的尖角和凹陷,优化了原冰...     

基于动力学边界的结冰飞机安全预警方法

结冰严重破坏飞机的动力学特性,使飞机的非线性和动力学耦合特性表现明显,导致传统的安全预警方法无法准确有效地评估飞行存在的潜在风险,易引发飞行事故。为解决此问题,提出了一种基于动力学边界的新型安全预警方法,该方法可综合考虑飞机的动力学耦合特性,可为结冰飞机的实时安全预警系统的构建提供有力的理论支撑。首先,基于微分流形理论确定结冰飞机精确的动力学边界,并详细分析了飞机结冰对动力学边界的影响;其次,利用动力学边界相对距离对飞行风险进行量化,结合动力学边界的特性确定了安全预警的方法;最后,搭建了飞行仿真训练系统,并以着陆为训练科目,通过与传统迎角安全预警方法对比,得到基于动力学边界安全预警方法的优越性。研究结果表明,相比于传统迎角限制方法,动力学边界安全预警方法可提前发现飞行中存在的潜在风险,且基于此方法的飞行训练系统可对驾驶员进行结冰安全操纵训练可提高结冰飞机的飞行安全。     

A methodology for constructing the aircraft design schema

Aircraft collaboration design is based on a unified set of schemas containing data and model representations and interfaces across disciplines. The aircraft design schema is a central data model that specifies the paradigm for the representation of a full lifecycle model of aircraft design. The construction of the schema currently lacks theoretical guidance. This paper designs a novel methodology to construct the aircraft design schema, a fully functional, logical, and self-consistent methodology. The methodology defines a schema matrix that includes implementation strategies, principles, processes, meta-object facility, views, scenarios, and products. The aircraft conceptual design schema is constructed according to the methodology, which is a hands-on approach to help understand the concept and implementation. The features of the methodology are analyzed, and the methodology and the aircraft conceptual design schema are presented to address the pain points of multiple solution trade-offs, multiple iterations, and multidisciplinary coupling in aircraft conceptual collaboration design.     

A practical filter error method for aerodynamic parameter estimation of aircraft in turbulence

It is common for aircraft to encounter atmospheric turbulence in flight tests. Turbulence is usually modeled as stochastic process noise in the flight dynamics equations. In this paper, parameter estimation of nonlinear dynamic system with both process and measurement noise was studied, and a practical filter error method was proposed. The linearized Kalman filter of first-order approximation was used for state estimation, in which the filter gain, along with the system parameters and the initial states, constituted the parameter vector to be estimated. The unknown parameters and measurement noise covariance were estimated alternately by a relaxation iteration method, and the sensitivities of observations to unknown parameters were calculated by finite difference approximation. Some practical aspects of the method application were discussed. The proposed filter error method was validated by the flight simulation data of a research aircraft. Then, the method was applied to the flight tests of a subscale aircraft, and the aerodynamic stability and control derivatives were estimated. All the estimation results were compared with the results of the output error method to demonstrate the effectiveness of the approach. It is shown that the filter error method is superior to the output error method for flight tests in atmospheric turbulence.     

机翼积冰数值模拟

采用计算流体力学（CFD）方法对三段翼和MS-317后掠翼进行了积冰数值模拟研究,基于欧拉两相流理论,应用分区算法,对空气流场和水滴流场进行了数值求解,得到水滴收集率.求解3-D积冰模型得到积冰量.将MS-317的冰形计算结果与实验数据以及软件LEWICE3D的计算结果进行了对比.结果显示:三维积冰模型具有较好的精度,虽然预测的冰形与实验数据有一些差异,最大厚度方面,误差在13.1%以内,但是积冰的类型与体积和实验数据基本一致.      

进气道蒙皮拉形数值模拟的探讨

蒙皮拉形是航空航天制造领域的一种重要的加工方法，其先进程度是衡量一个国家飞机制造能力和水平的重要标志之一，因此发展蒙皮拉形技术对于我国航空制造业具有十分重要的意义。本文旨在应用有限元软件Mare／Mentat对现阶段进气道蒙皮拉形生产过程中存在的问题，采用数值模拟结合生产性试验验证的方法进行分析研究，提出解决方案，以确定该零件生产的工艺方案和工艺参数。