【作者】 施红；

【导师】 蒋彦龙；

【作者基本信息】 南京航空航天大学 ， 人机与环境工程， 2013， 博士

【摘要】 飞机空气导管系统主要负责从发动机、APU和地面气源引出高温压力气体输送到防冰系统、环控系统、液压系统等子系统。管系穿越机翼、发动机吊挂、机身等多个区域，管路故障不仅影响整个空气管理系统功能的实现，也会给周围其他系统带来安全隐患，故此空气导管的安全性和可靠性成为飞机安全设计的重要内容。本文主要从理论推导、数值仿真、实验模拟等方面对飞机空气导管管路系统设计所涉及的关键技术如传热流动特性、应力安全设计和评估方法及泄漏探测技术开展研究。具体工作内容如下：（1）空气导管管路工作机制与设计参数的选择给出了ARJ21-700的空气导管管路系统布置图，根据管路系统关断阀位置及管内气流属性，将管路系统分为引气系统、防冰系统、配平系统、空调管路系统和笛形管系统，详细介绍了各个子系统管路及其附件的工作机制。其次，给出了飞机空气导管管路的属性参数，提出了飞机空气导管采用空气层绝热和固体材料绝热的多层绝热设计思路，并推导了飞机空气导管多层绝热设计的计算方法。最后，结合空气导管的不同引气方式、飞行加速度、导管的校核标准以及外界环境温度确定了空气导管的计算工况，为空气导管的设计提供边界条件。（2）空气导管管内外传热流动特性研究基于流体网络算法和有限体积法开展对空气导管管内外传热流动特性的分析工作，获得了管系在不同边界条件下的温度、压力和流量等参数特性以及空气导管管外的温度场分布。研究结果表明：尽管小流量的管路破坏对管系本身的输送特性影响较小，但对周围环境温度的影响需要引起重视。此外，较好的PID控制逻辑和阀门的开关特性能改善管路的压力脉动。最后，从导管的空间布置来说，导管向下布置以及导管管径的增加均会加强导管与舱内空气的换热。管道的布置主要考虑其对座舱热载荷以及自身热损失的影响，对于给定管径的管道系统，可构建关于货舱三角区传递给座舱热负荷以及管道自身热损失的优化函数，给出最优的管道布置位置。（3）基于有限元的管系应力和位移安全设计方法在分析飞机飞行工况和应力安全评定准则的基础上，提出了基于空间梁单元、壳单元、实体单元的空气导管应力分析、补偿与校核的设计方案。分析了含有直管、弯管、阀门、球形接头、滑动接头、法兰、管路组件的空气导管管系梁单元模型、壳单元模型，同时给出了空气导管相关关键部位实体模型的建模方法。最后，考察了应力校核标准、飞行加速度、管内气体压力、温度及管道附件布置位置对管道应力补偿的影响。（4）引气系统的应力和位移安全设计采用提出的管系安全设计方法对ARJ21-700飞机空气导管的引气系统进行管系应力安全计算、补偿、校核与优化设计。在补偿过程中，提出了承重设计优先、位移约束及应力释放交替补偿、采用管系结构划分进行应力补偿、滑动接头对称布置等设计思路。同时，基于球形接头偏转角度的大小进行管系优化设计。最后，提出了基于Miner理论和雨流计数法分析管系的疲劳寿命的方法。（5）高温压力管道的泄漏探测技术研究在研究现有国外飞机空气导管泄漏探测系统工作原理的基础上，指出了现有探测系统的不足，基于热敏材料和组合电路提出了三种结构简单、具有定位泄漏部位能力的飞机高温压力导管泄漏探测系统及方法。其次，搭建了管道泄漏探测试验台，研究了加热段长度、管道气体温度对探测响应时间的影响。同时，结合FLUENT的三维泄漏流场的计算，分析了不同压力、温度、绝热层厚度、导流孔大小及泄漏位置对探测性能的影响。最后，推导了小孔泄漏流量的计算方法，并基于上述研究结果提出了探测系统优化布置的方案。更多还原

【Abstract】 High temperature pneumatic duct system of the aircraft is bled from the engines, APU andground responsible for the anti-icing system,environment control system,hydraulic system and so on.The duct system is routed throughout the airframe, wings and engine pylon, the accidental rupture cannot only make pressure drop dramatically in the ducts, but also lead to the malfunction of thecorresponding system and the equipments around it. So the reliability and durability of the ducts arevery important for flight safety. The performances of the heat transfer and fluid flow, thermal stresscompensation methods and overheat detection technology are conducted in this paper via theoreticalderivation, numerical and experimental simulation. The thesis has the following major contents:(1) mechanism of the duct system and selection of the design parameters.The space layout of the pneumatic duct system of ARJ21-700is presented. According to theposition of the shut-off valve in the duct system, the pneumatic duct system is divided into fivesubsystems: bleed system, anti-ice system, trim system, pack discharge system and piccolo system.The mechanism of various subsystems and their accessories are introduced. And then, the attributeparameters of the duct system are given. The multilayer insulations design is adopted in this paper andits computing method is derived. Finally, the calculation conditions are determined by the air bleedway, flight acceleration, design criterion and environment temperature, which provide the boundaryconditions for the further calculation.(2)Study on the heat transfer and fluid flow characteristics of the internal and externalducts.The fluid network theory and the finite volume method are adopted to analysis the internal andexternal heat transfer and flow characteristics of the duct system. The temperature, pressure and flowrate of each node in the pipeline as well as the external temperature field of the duct system areobtained. The research results show that the rupture with small flow rate has less effect on thetransport characteristics, but its influence on the neighboring environment temperature requiresattention. A better PID control logic and switching characteristics of the valve can improve thepressure pulsation of the duct system. Furthermore, the total heat transfer of the cabin air increaseswith the duct in down location and diameter.The space layout of the duct system needs to consider itsheat loss and the heat load transferring to the cabin. For a given duct system, optimized layout of the duct can be achieved by establing the proper optimal object functions with heat loss of the duct andthe thermal load transferring to the cabin.(3)Stress and displacement safety design of the duct system with finite element method.By analyzing the flight state and safe assessment methods, the stress analysis, compensation andoptimization method of the aircraft duct system is developed by combination with beam element, shellelement and solid element model. Meanwhile, the beam element model and shell element model ofthe duct system with straight pipe bend, flange, ball joint, sliding seal and rod is derived and therelevant key part is modeled by solid element model. Finally, the influencing factors such as safetydesign criterion, the flight acceleration, temperature, pressure of the air and the layout of theaccessories on the stress distribution of the duct system are investigated.(4) Stress and displacement safety design of the bleed system and its influence factorsTaken bleed system of ARJ21-700as an example, the stress analysis, compensation, checkingand optimization work are conducted by the method mentioned above. In the process of compensation,some design ideas such as load-bearing design firstly, displacement constraints and stress releasewith alternate compensation rule, stress compensation by duct unit dividing method, symmetricalarrangement of the slide joint are pointed out. Meanwhile,the layout of the duct system is optimizedbased on the angle of deflection of the ball joint.Finally, fatigue properties of the duct system arestudied by Miner fatigue damage theory and rain-flow counting method.(5)Leakage detection technology of the high temperature pneumatic duct system.Based on the study of the duct overheat detector of commercial aircraft in existence, threemodified overheat detection systems based on heat-sensitive property material and combinationalcircuits with simple structure, high reliability and global positioning capabilities are designed, whichfill a strategic gap in duct overheat detection region. Also, the overheat detection experiment platformis built. The influences of the overheat length and internal air temperature on the system response timeare conducted. Meanwhile,based on the three-dimension flow field simulation of the leakage byFLUENT, the influences of pressure,temperature,thickness of the insulation,the deflector size andthe leakage position on the detection system are investigated. Finally, the computing method of flowrate of eyelet leak is derived and the detection layout is optimized according to the present results.更多还原