推广使用REM37BY电嘴

在我院使用的活塞发动机飞机中,点火系统故障率居高不下,其中又以电嘴积铅带来的发动机抖动故障居多。本文通过对比分析,以及实际监控使用的具体情况,证明了REM37BY电嘴能使这一故障大大减少,并且能节约成本,缩短工时,具有较大的推广价值。     

CAN总线在电液伺服阀性能测试系统中的应用

伺服阀性能测试系统中，测控电路和计算机间的模拟信号传输易受外界干扰，而把信号以数码形式通过CAN总线传输的方法，可以彻底消除外界干扰问题，还能提高系统的性能和可靠性。介绍了CAN总线硬件电路、程序设计及CANopen通讯协议的实现，讨论了CAN总线在测试系统上的实际应用。     

变循环发动机双外涵匹配研究

针对带核心机驱动风扇的双外涵变循环发动机,提出了1种用于双外涵匹配分析的数值模拟方法。利用计算流体力学Fluent软件对其初步流路进行了研究及优化,在此基础上对双外涵模式流场、不同前涵道引射器状态下的单外涵模式流场进行分析。结果表明:第1外涵道的角度和流通面积对总压恢复系数的影响较大;在由双外涵模式转换到单外涵模式过程中,应将前可变面积涵道引射器开到最大以减小总压损失。该方法能够有效地应用于双外涵变循环发动机流路优化及双外涵匹配分析,为变循环技术的深入研究提供参考。     

某型压差活门的动态特性分析

压差活门是航空发动机数控系统燃油计量装置中重要的液压部件,其稳定性和动态性能直接影响控制系统的整体性能。根据压差活门非线性微分方程,采用小偏差线性化方法,推导出了压差活门的动态数学模型,得到了压差活门的方框图以及传递函数。选取某压差活门参数建立了Simulink仿真模型,分别在频域和时域分析了其动态性能。结果表明:在频域上,比较了有无节流器时的回路增益函数伯德图,认为敏感油路上的节流器可以改善稳定性且提高控制精度,通过设计节流器的尺寸可以调节穿越频域,从而改善系统的动态性能;在时域上,分析了不同节流器尺寸下阶跃响应的动态性能,其试验结果与实际工程经验一致。     

变结构控制在基于脉冲比例阀的燃油调节系统中的应用

针对航空发动机燃油控制系统中二阶非定常执行机构通常出现设计困难的问题,介绍一种变结构控制方法,将二阶非定常执行机构变成确定的一阶惯性环节,该方法既充分利用其优点"不变性"又可以规避其突出缺点"抖振",特别适用于驱动脉冲比例调节阀;同时提出脉冲比例阀的变结构调节中遇到的实际问题(例如微分的精度问题)的解决办法,以及影响该方法可行性的若干必要条件。结果表明:符合条件时变结构控制在基于脉冲比例阀的燃油调节系统中是可行的。     

基于互锁双指令控制的电磁阀驱动电路设计

为满足体积及重量强约束条件下的动力系统电磁阀控制需求，提出了一种基于互锁双指令控制的电磁阀驱动电路设计方案。采用逻辑相反的互锁指令与串并联设计的阀门驱动电路结构形式，设计了基于McBSP内总线交互的电磁阀控制流程，建立了150N电磁阀驱动电路仿真模型及阀门电流测试平台。仿真及测试结果表明，该驱动电路能够有效实现二度故障下的电磁阀开启与关闭。     

A novel architecture of electro-hydrostatic actuator with digital distribution

To address the flow imbalance rapidly of the asymmetric Electro-Hydrostatic Actuator (EHA), this paper presents a novel architecture of asymmetric EHA with the Digital Distribution (EHA-DD). It also improves the flow nonlinearity and control accuracy of the pump, especially in the low-speed condition. The digital distribution with two High-Speed on–off Valves (HSVs) not only balances flow instead of the check valves, but also replaces the pump at the low-speed to control output flow by adjusting the PWM signal. The pump and HSVs are the crucial components to control flow output. Firstly, the flow calculation models of the pump and the duty ratio inversed model of the HSV are obtained through experimental tests and the identification method. To get the control input signal for the required flow, the pump speed and PWM duty ratio for the HSVs are inversed to compensate for flow output. Further, a multimode digital flow distribution control method based on pump speed, mainly including the pump-controlled mode for large flow demand and valve-controlled mode for little flow demand, is proposed to control the accurate flow output actively. The step extension experiments based on the flow calculation models are conducted on the EHA-DD prototype under elastic, opposite varying load. The results demonstrate that the EHA-DD realizes little position error by accurate flow control, and it is also beneficial to improve the service life of the pump.     

A novel framework for liquid propellant engine’s cooling system design by sensitivity analysis based on RSM and multi-objective optimization using PSO

One of the challenges of combustion chamber and nozzle design in a Liquid Propellant Engine (LPE) is to predict the behavior and performance of the cooling system. Therefore, while designing, the optimization of the cooling system is always of great importance. This paper presents the multi-objective optimization of the LPE’s cooling system. To this end, a novel framework has been developed, resulting from the application of the Response Surface Method (RSM) and the correlation coefficients matrix, sensitivity analysis and the The Particle Swarm Optimization (PSO). based on this method, the input variables, constraints, objective functions, and their surfaces were identified. In terms of multi-optimization algorithms, RSM and PSO are utilized to get global optimum. In conclusion, the methodology capability is to optimize the LPE’s cooling system, 6 percentage increase in total heat transfer and 7 bar decrease cooling system pressure loss, which resulted in a 1.2-seconds increase in the specific impulse of the engine.     

西安某粘接材料厂室内供暖、热水系统的设计

基于厂方对供热系统的要求,根据供热建筑物、机房和可利用设施的实际情况,采用一台换热器,通过阀门的切换,实现了供暖和供热水的分段运行。将蒸汽发生器的进水与系统补水有机地整合为一个系统,有效地解决了机房面积过小的实际困难。利用自来水的压力和热水箱与浴室的高差解决了热水供应的实际问题。     

SAR performance-based fault diagnosis for electro-hydraulic control system: A novel FDI framework for closed-loop system

Model-based fault diagnosis serves as an efficient and powerful technique in addressing fault detection and isolation (FDI) issues for control systems. However, the standard methods and their modifications still encounter some difficulties in algorithm design and application for complex higher-order systems. To avoid these difficulties, a novel fault diagnosis framework based on multiple performance indicators of closed-loop control system is proposed. Under this framework, a so-called performance residual vector is constructed to measure the differences between the real system and the nominal model in terms of system stability, accuracy, and rapidity (SAR) respectively. The criteria for quantification, normalization of the SAR residuals and the explicit mappings between the thresholds and the required performance are given. FDI can be easily achieved simultaneously by monitoring the normalized residual vector length and direction in the SAR performance residual space. A case study on electro-hydraulic servo control system of turbofan engine is adopted to demonstrate the effectiveness of the proposed method.