发动机主动间隙控制系统的应用及发展趋势

为了尽可能减少燃油消耗,并进一步降低使用成本和环境影响,航空发动机需要保持较高的整机效率。由于涡轮间隙严重影响涡轮效率,为消除其不利影响,分析了叶尖间隙形成和变化的机理及主要影响因素,重点综述了3种不同的主动间隙控制系统的控制方法及其技术特点,总结了主动间隙控制在提高整机效率、降低燃油消耗、减少排放、降低维护费用等方面的巨大收益,并对主动间隙控制技术的关键技术和未来发展方向进行了讨论。认为国内需要认识到主动间隙控制技术的重要性并大力开展其关键技术研究。     

EEFAE - efficient and environmentally friendly aero engine - technology platform

Future aero engines will need to be more reliable, have lower operating costs and have significantly lower environmental impact than those currently in-service. The EEFAE technology platform will test advanced technologies capable of providing significant improvement in future generations of aero engines     

Three-dimensional tracking using on-board measurements

The development of a three-dimensional tracker using onboard measurements is described. A system model based on aircraft dynamics is derived. A full 3-D tracking system that can be split, with a part operating onboard and a part operating on the ground, is developed. Attitude angle and aircraft airspeed measurements are processed to estimate the components of the aircraft velocity with respect to the surrounding air. These are then used to obtain estimates of the aircraft position and ground speed. The tracker is designed so that the number of quantities transmitted to the ground station is kept to a minimum. The tracker was evaluated with real data and was found to perform well, resulting in a considerable improvement over the conventional first-order Kalman filter     

跨声串列转子及前后排叶片匹配特性分析

在叶尖折合切线速度为381 m/s的条件下,利用跨声串列转子技术实现了总压比为2.25、负荷系数高达0.55的风扇转子设计.基于数值模拟结果,分析了串列转子前后排叶片独特的匹配特性,及其与常规压气机匹配特性不同的原因;并进一步推导验证了前后排叶片气动参数之间的解析关系,为利用常规压气机设计体系进行跨声串列转子设计提供数...     

基于浴盆曲线故障率函数的FFOP预计方法

与传统可靠性指标中假设产品的随机失效不可避免不同,无故障工作期(FFOP)内产品不会发生任何故障(即零故障)。首先阐述了FFOP的概念内涵、与平均故障间隔时间(MTBF)的区别和联系,提出了一种FFOP的预计方法。该方法假设产品的故障率函数具有浴盆曲线特征、故障发生过程为泊松过程、产品具有固定的免维修工作期。然后以一种改进的Weibull分布函数描述具有浴盆曲线函数特征产品的故障率。基于泊松过程理论,给出了FFOP的预计算法、流程和仿真验证手段。最后以某型无人机舵机为案例对研究方法的可用性进行了验证。结果表明:FFOP与免维修工作期(MFOP)、置信度水平密切相关,及时维修的产品能够保证较长的FFOP。在工程应用时,FFOP的确定应综合考虑运行维护费用进行权衡。     

Avionics cost of ownership

The cost of ownership of avionics includes not only the development and acquisition cost, but also the yearly operating and support (O and S) (maintenance) cost of hardware, software, and support equipment. This paper presents an avionics cost of ownership methodology developed for USAF, its data sources, and business metrics computed for USAF decision makers as we move toward operating avionics as a business. The business model is used to determine which existing avionics are candidates for replacement with new technology and to prioritize the replacements. These avionics are often used on multiple aircraft types which necessitates analysis of the causes of the high cost of ownership on each type. Databases are used to document the processing functions, data flow, and constraints of the item being analyzed. These constraints include physical, environmental, electrical, and data interfaces. Databases containing alternatives are evaluated against standard mission scenarios for aircraft utilizing these high cost avionics to determine their impact on performance, O and S costs, and mission effectiveness. The results of the foregoing analyses steps are then used in life cycle cost analyses which consider different retrofit scenarios for each alternative for each aircraft type against the avionics being analyzed for replacement. The alternatives are prioritized and a risk analysis performed considering technical, schedule, and cost growth risks. The avionics cost of ownership methodology described in this paper processes data from USAF maintenance organizations. This has revealed the very large expenditures being made to support highly unreliable avionics. These methods can be applied to all military and commercial aircraft systems to determine not only the cost of ownership of existing systems, but also the cost of ownership of new systems when they are retrofit     

STEP: a tool for estimating avionics life cycle costs

An overview is presented of how the US Air Force has had significant success in the estimation of life cycle costs (LCC) for avionics hardware and software using the Standardization Evaluation Program (STEP) model for estimating operating and support (O&S) costs. The capabilities of the existing STEP model as well as ongoing enhancements to provide a total LCC estimating methodology are described. In addition to the standard cost reports, STEP has the capability to assess the impact of reliability on life cycle cost. Another unique feature of the STEP model is the capability to assess the impact of retest OK (RTOK) on life cycle costs. The acquisition enhancement is being accomplished in three parts each of which will produce a distinct, usable product. The three products are an automated database, an analogy estimating capability, and a parametric estimating technique. Each is briefly discussed     

机载电子产品可靠性定量加速增长试验技术

传统的可靠性试验在环境与时间上存在不足,已很难满足现代飞机可靠性试验工作的要求.基于故障物理学,通过研究航空电子类机载设备在综合环境应力条件下的故障原因及其分布规律,结合传统可靠性加速试验和增长试验的特点,提出一种可靠性试验的新方法,详细介绍具体的试验方法、试验流程、试验应力、故障处理要求和评估方法等关键技术,并将其应用在受试产品的典型案例中.结果表明:当产品试验时间达到952.4 h时,故障数为0,可以认为该产品以70％的置信度确定产品的平均故障间隔时间已达到25 000 h;本文提出的可靠性试验方法能够有效解决基于环境模拟的传统可靠性试验方法和评估技术不能在短的研制周期内评估高可靠性指标要求的机载设备的工程难题,可以实现加速因子的多样、可控,有效地缩短试验时间,节约试验经费.     

多级压气机中可控扩散叶型研究的进展与展望 第二部分 可控扩散叶型的实验与数值模拟

目前 ,大量的可控扩散叶型 (CDA)已设计应用于多级轴流压气机中。通过亚音、跨音叶栅实验 ,证明了在可比的气动设计条件下 ,CDA叶栅可以达到更高的临界马赫数、更大的冲角范围和更高的负荷。通过单级或多级测试 ,CDA提供了更高的效率、更高的负荷、且易于进行级间匹配 ,并最终减少研发费用 ,提高喘振裕度 ;由于 CDA叶型具有增厚的前缘和尾缘 ,这为压气机寿命的提高提供了保证     

刷式密封摩擦生热温度场数值计算及试验

在摩擦热热源条件下建立了CFD多孔介质数值计算模型,对某型航空发动机刷式密封摩擦生热温度场进行计算分析,开展了刷式密封装置全工况条件下摩擦生热试验研究,采用红外成像技术实现了刷式密封动态温度场实时监测。根据试验结果对摩擦生热温度场计算方法进行了修正,引入了刚度修正系数,并对刚度修正系数进行了确定及验证。总结出经过试验验证的航空发动机刷式密封摩擦生热温度场计算分析及试验方法,结果表明:与全工况试验结果相比,计算误差值从48.15%减少到10.67%。      

基于时间推进的涡扇发动机整机通流数值模拟

为实现航空发动机整机流场与性能快速分析,基于准三维控制方程模型,开发了整机通流数值模拟程序。程序基于计算流体力学理论,并考虑了引气、冷却和喷油等发动机中的物理现象。为模拟叶片对气流偏转作用,推导了一种鲁棒的无粘叶片力模型,同时采用粘性力模型模拟粘性损失效应。采用该程序对某型双轴分排涡扇发动机一个地面试车工况点进行了整机数值仿真,并与实验数据进行了对比验证。结果表明,所发展程序求解稳定,能够自动捕捉激波,并且可以快速获得完全收敛的航空发动机整机准三维流场,单工况点计算时长不大于30min。其中计算截面平均参数与实验测量偏差不大于8%,符合工程应用精度需求。     

考虑排放影响的飞机多学科优化设计

随着民用航空运输业的发展,飞机对气候环境的影响越来越受到重视。为了满足未来飞机设计中经济性和环保性等指标,有必要在飞机概念设计阶段综合考虑成本和排放的影响。本文使用全球平均温度变化作为衡量飞机排放对气候影响的标准,分析了飞机巡航高度和速度对于排放物的影响。进一步,通过整合气动、重量、成本和排放等学科模型,建立了飞机概念设计阶段的多学科优化框架。基于该优化框架,以机翼平面形状、飞行速度和高度等参数为优化变量,分别以排放最小和成本最低为目标,进行了单目标和多目标优化设计研究。Pareto最优前沿的优化结果显示,单位排放成本的高低会影响成本相对于排放性能的变化趋势。     

基于BOM的航空企业元器件采购技术实现

为了降低航空企业经营成本,按照产品的实际生产需求进行采购,利用信息化技术实现了一种基于BOM的航空企业元器件采购技术,描述了航空企业当前元器件采购的现状及存在的问题,分析了在产品数据管理系统中按照BOM生成元器件物资申购单面临的挑战,并针对挑战提出了解决方法。最终将元器件申购信息传递到物资采购系统,达到了对元器件精细化采购的目的。     

Electrochemical machining of burn-resistant Ti40 alloy

This study investigates the feasibility of using electrochemical machining(ECM) to produce critical aeroengine components from a new burn-resistant titanium alloy(Ti40), thereby reducing costs and improving efficiency relative to conventional mechanical machining.Through this, it is found that an aqueous mix of sodium chloride and potassium bromide provides the optimal electrolyte and that the surface quality of the Ti40 workpiece is improved by using a pulsed current of1 k Hz rather than a direct current.Furthermore, the quality of cavities produced by ECM and the overall material removal rate are determined to be dependent on a combination of operating voltage, electrolyte inlet pressure, cathode feeding rate and electrolyte concentration.By optimizing these parameters, a surface roughness of 0.371 lm has been achieved in conjunction with a specific removal rate of more than 3.1 mm3/A?min.     

脉冲爆震燃烧效率的探索性试验研究

为了对脉冲爆震燃烧过程的燃烧效率有一个初步了解,在分析脉冲爆震发动机工作原理的基础上,设计了一套带有压力可调单向阀结构的取样系统,并进行了试验验证.试验针对爆震频率为5Hz、当量比为1的汽油和空气混气,测试了爆震波充分发展前后不同位置处爆震燃烧过程的燃烧效率,结果表明可以利用设计的取样系统进行脉冲爆震发动机燃烧效率的测量,试验还发现在脉冲爆震室后爆震发展比较充分的位置,测取的燃烧效率比较高,最高可达99.6%.     

虚拟仪器技术在航空发动机智能检测中的应用

利用NI公司的LabW indows/CVI虚拟仪器作为开发平台,设计了一套适用于某型航空发动机地面试车的智能检测系统。实际检测结果表明:该系统较真实地反映了被测航空发动机的试车参数、工作状态及试车曲线。与传统的检测方法相比,既节省了成本,又提高了检测效率。     

民用飞机健康管理技术研究

随着民用飞机的系统集成度和复杂性大大提高,为降低民用飞机的运营成本、提高安全性和可靠性,民用飞机健康管理系统成为航空制造行业的发展趋势。本文简要介绍了民用飞机健康管理技术在国内外的发展现状,现阶段技术条件下所面临的问题以及所涉及的关键技术。着重介绍了民用飞机健康管理技术研究的方法和研究的内容,并对民用飞机健康管理技术未来的发展趋势进行了展望。     

双储液器环路热管稳态运行特性的实验研究

 双储液器环路热管的独特设计可以解决常规单储液器环路热管地面重力场中运行姿态受限的问题,拓展常规环路热管的应用领域。对双储液器环路热管在3种特定姿态下的稳态运行特性进行了实验研究,验证了双储液器环路热管即使在最为苛刻的姿态下仍可正常运行的能力。通过对实验结果的分析可得：双储液器环路热管在重力辅助姿态下的工作温度偏低是由系统外回路压降变化引起的;可变热导区内工作温度随热载荷的变化是由控温储液器的能量平衡所决定。此外,实验发现双储液器环路热管在热载荷递增和递减过程会出现温度迟滞现象。     

驾驶员模糊控制模型与仿真分析

根据飞机驾驶员的控制行为，建立了驾驶员的基本模糊控制模型，然后利用李雅普洛夫综合法设计了两种自适应算法，来调整基本模糊控制模型的某些参数，建立了两类自适应模糊控制模型。对风切变大气环境下飞机进场下滑过程进行了仿真计算，结果表明，所建立的模型是合理的，能在一定程度上反映驾驶员的操纵情况。     

悬臂式挠性薄片气体动压径向轴承试验研究

悬臂式挠性薄片气体动压径向轴承的静态加载和运行试验结果分析表明:悬臂式挠性薄片气体动压径向轴承有较好的弹性;径向轴承能在较宽的转速范围内稳定运行在,具有较好的高转速性能,对工作环境条件不敏感,并具有良好的动特性。研制的悬臂式气体动压径向轴承满足涡轮冷却器的要求。