机械控制式CFM56发动机VBV系统建模

可调放气活门属于航空发动机系统中的压气机气流控制系统,其主要作用是调节流经低压压气机和高压压气机的气流,防止压气机失速、喘振,对发动机安全、稳定运行极其重要,而在发动机控制系统中,可调放气活门属于执行机构。通过对液压机械式控制的CFM56发动机可调放气活门的结构以及运动规律的研究,根据液压传动机构中阀控液压马达的基本原理建立燃油齿轮马达流量-压力模型,得到燃油齿轮马达在给定参数下转速、角度和转矩的变化规律;通过对放气活门机构进行动力学分析,根据第二类拉格朗日动力学方程建立放气活门机构拉格朗日动力学模型,在对模型进行线性化处理后通过计算得到放气活门机构的角度变化曲线。     

某活门最小流量摆动故障分析

某型燃油计量装置调试过程中出现最小流量波动问题,故障定位在关断活门上,为了从活门结构及装配上分析故障原因,建立以燃油流量为输出、高压油压力为输入的活门传递函数。通过分析可得,阻尼比过小将导致最小流量波动,增加遮盖量后进行试验,验证了该措施能够有效解决最小流量波动问题。     

斯特林发动机高压燃烧系统油氧伺服控制系统设计

对某型船用斯特林发动机采用"柴油+氧气"的高压燃烧系统燃料伺服控制技术进行了研究,在已有燃油执行机构和氧气执行机构及控制策略的基础上,研制了一款小型的专用油氧流量伺服控制器,实现了对燃油执行机构和氧气执行机构的同时控制,简化了控制系统,提高了油氧流量的控制精度和调节的协调性,改善了氧燃比,取得了良好的效果。     

某型直升机发动机滑油温度进黄区的故障分析与改进验证

通过研究某型直升机发动机滑油系统原理,分析了发动机滑油的冷却原理,阐述了发动机滑油温度与恒温活门工作状态之间的关系。通过分析,找出了发动机滑油温度进黄区的故障原因,并给出了解决方案及验证结果。     

点火燃油流量对发动机加力接通结果的影响

作为加力接通控制逻辑中较为重要的影响因素,加力点火燃油流量直接决定了发动机接通加力的可靠性。特别是在高空小表速区域,进气流量较小,为了得到合适的油气比,需要对加力点火燃油流量进行精确调节。某型涡扇发动机利用燃油流量特性线控制加力点火燃油流量,并利用飞行试验在高空小表速区域针对多种试验方案进行了对比验证试飞。试验结果表明:流量特性线可以在高空小表速区域精确调节发动机加力点火燃油流量;较小的加力点火燃油流量可以提高加力接通可靠性,但会影响小加力状态的工作稳定性。     

基于AMESim的涡桨发动机燃油计量装置仿真

对某型涡桨发动机燃油计量装置的原理进行分析,在AMESim下建立相应的计量装置仿真模型。借助AMESim的二次开发平台AMESet构建专用的模块,为某型涡桨发动机燃油调节器的计量活门开发了新元件,解决了AMESim液压库中只有一维变量控制阀门开度无法满足实际系统中双输入量同时控制供油量的问题。仿真结果与实验数据一致,从而证明了建模的合理性,为新型燃油调节系统的开发设计提供了理论支持。     

某燃油泵安全活门启闭特性研究

对某燃油泵安全活门启闭特性进行研究。由于某型燃油泵安全活门开启压力与安全活门达到公称流量时的调定压力之间的差值偏大，导致安全活门启闭特性不好。为解决上述问题，对该安全活门的结构、功能和工作原理进行分析。通过对其启闭特性进行计算和仿真分析，发现主阀直径、主阀阻尼孔直径、主阀弹簧刚度、先导阀阻尼孔直径以及回油管路直径等参数对其启闭特性有一定的影响。最后根据机理分析结果来优化安全活门的主要结构参数，达到改善安全活门启闭特性的目的。     

飞机燃油系统活门关闭特性分析和试验研究

随着飞机燃油系统的广泛应用,由于压力和流量的增大,燃油系统活门在关闭过程中容易出现结构变形,导致活门出现卡死和无法完全关闭的现象。通过建立球形燃油活门的三维流固耦合动力学模型,基于Workbench平台,对活门关闭过程瞬态特性进行仿真分析。结果表明:流道中活门关闭旋钮为易变形结构,在流体压力作用下变形量较小;变形量随开度呈非线性正相关变化,在进口压力逐渐增大时,压力差随之变大,此时活门无法正常关闭;对同类活门做对比分析试验,发现仿真和试验结果基本吻合,提出适当降低流量和压力是延长活门寿命的重要方法。     

U-3-15(L)型飞机调速器回桨活门维修技术探析与总结

调速器是保证飞机螺旋桨正常工作的核心部件,其中调速器的回桨活门组件通过对油路的控制来实现螺旋桨的桨叶角变化,即变大距、变小距、顺桨和回桨,进而达到保持或改变发动机转速的目的。主要阐述了U-3-15(L)型调速器回桨活门的基本工作原理,总结了活门销的研磨的经验以及具体分析了回桨活门故障实例现象、起因、排除过程,有助于维修人员加深理论认识,提高工作效率。     

具有温控回油功能的模块化国III燃油精滤器

由于现在国III发动机的燃油喷射压力高,需要在滤清器内设置一个温控回油装置,当回油温度高于设定的温度时,燃油回油箱,当回油温度低于设定的温度时,燃油进入滤清器,经过滤后重新进入燃油高压油路系统。     

Efficiency measurement and uncertainty discussion of an electric engine powered by a "self-breathing" and "self-humidified" proton exchange membrane fuel cell

The efficiency of an automotive engine based on a "self-breathing" and "self-humidified" proton exchange membrane fuel cell stack (PEM FC) connected to a dc brushless electrical motor was measured under variable power load conditions. Experiments have been carried out on a small scale 150 W engine model. After determining the fuel cell static polarization curve and the time response to power steps, the system was driven to copy on the test bench a "standard urban load cycle" and its instantaneous efficiencies were measured at an acquisition rate of 5 Hz. The integral system efficiency over the entire urban load cycle, comprising the losses of the unavoidable auxiliary components of the engine, was then calculated. The fuel cell stack was operated mainly in "partial" dead-end mode, with a periodic anode flow channel purging, and one test was carried out in "pure" dead-end mode, with no anode channel purging. An uncertainty analysis of the efficiencies was carried out, taking into account either type A and type B evaluation methods, strengthening the discussion about the outcomes obtained for a system based on this novel simplified FC type. For our small scale engine we measured over the standard urban cycle, on the basis of the H(2) high heating value (HHV), a tank-to-wheel integral efficiency of (18.2+/-0.8)%, when the fuel cell was operated with periodic flow channel purging, and of (21.5+/-1.3)% in complete dead-end operation mode.     

轴承冲洗机设计

为满足轴承冲洗机油液的清洁度要求,全新设计制造一种轴承冲洗机.轴承冲洗机采用供油箱和回油箱的双油箱结构,供、回油箱分别连接供油泵和回油泵,供油管路和回油管路上设置油滤,供油泵打出的油液经过油滤进入轴承,油液从轴承油孔喷出后流回油箱,回油箱中的油液过滤干净后,提供给供油箱,通过这种双过滤循环系统可保证冲洗油液的清洁度要求.供、回油箱隔板上部位置开有连通孔,使两油箱液面动态平衡,消除供、回油流量的不匹配.轴承冲洗机能够达到油液的清洁度要求,使冲洗完的航空发动机轴承内无杂质,保证轴承的使用性能和寿命.     

Development of a novel rotary flow control valve with an electronic actuator and a pressure compensator valve for a gas turbine engine fuel control system

This paper presents a new rotary proportional flow control valve with Cam-Nozzle configuration. The rotating cam against the fixed nozzle changes the flow area and then can meter the fuel flow. This valve equipped with a pressure compensator plunger type valve to retaining constant pressure difference across the flow control or metering valve. The cam shaft directly coupled to an electronic servomotor type rotary actuator and then it is possible to apply digital control techniques such as pulse width modulation (PWM) in this control system. This new valve configuration is developed for an electro hydro mechanical fuel control system in a gas turbine engine. In addition to aero engine application, this type of flow metering valve can widely be used in industrial hydraulic systems. In this unit, the output flow is proportional to the cam's angular position (or throttle command) and it is not sensitive to pressure fluctuations at nozzle inlet and outlet. The aim of this new design is to modify a manual single adjusted hydro-pneumatic fuel control unit to obtain a new electro-hydraulic fuel control system for a gas turbine engine. The main innovations in the presented fuel metering unit include new design of the rotary valve opening shape (Cam-Nozzle) without metal to metal contact, use of a rotary electronic actuating mechanism and also direct coupling between the actuator and the rotating cam. The increased fuel metering precision in the new flow control valve has improved the ultimate control accuracy of system. A computer simulation software based on the proposed model, is performed to predict the steady state and transient performance and to analyze effect of important design parameters on valve outlet fuel flow and obtain the final design parameters. The validity of the proposed valve configuration is assessed experimentally in the steady state and transient modes of operation. The results show good agreement between simulation and experimental in both modes (max. 4% deviation).     

大型工业炉多燃烧器燃油供应系统节能技术

对在大型工业炉多燃烧器情况下燃油供应系统存在的能源浪费问题进行了分析与研究，提出在回油调节的基础上采用在供油泵出口设定压力对回油背压进行控制、在燃烧器前设置减压阀以及变量供油等节能工艺技术。这些措施的采用不仅降低了能耗，而且有助于系统供油稳定。     

Oil Degradation in a Diesel Engine with Dual-Loop Lubricating System

A common lubricating oil sump is used in most modern internal combustion engines for cooling, wear protection, and friction reduction. This requires compromises during base oil and additive selection as a result of differing needs for lubricant performance in engine subsystems. The use of a dual lubricating loop, providing separate oil sumps for the power cylinder and valve train subsystems, was investigated experimentally to determine the effect of system segregation on oil degradation. A small diesel engine was modified, installed in a commercial generator unit, and operated for one oil drain cycle. Oil sampling was tailored to assess base and acid numbers, oxidation, soot concentration, water content, and viscosity changes. The experiment complemented an earlier study that investigated the fuel economy benefits of such a lubricating configuration. These include longer drain intervals for the cylinder head and power cylinder subsystems, improved wear performance for the valve train, and opportunities for alternative material selection during engine design. The experiment demonstrated protection of the valve train subsystem from soot contaminants in the power cylinder. Lower total acid number and oxidation tendency was also observed in the valve train.     

拉瓦尔式燃料流量调节阀流量特性分析

燃料供给的实时、精确调节是冲压发动机技术研究的重点,对提高发动机的效率、改善发动机的工作性能具有重要的意义。为实现冲压发动机气态燃料在高温下流量的精确调节,提出了一种新型的拉瓦尔式燃料流量调节阀,以对流入发动机燃烧室的高温气态燃料进行流量调节。首先,开发了一种用于燃料供应的高温流量调节阀,然后通过采用有限元分析方法,分析了流经主阀阀口的气态燃料速度及压力的分布,从而找出了流量变化规律。研究结果表明,采用拉瓦尔管状阀口的流量调节阀,在不改变阀芯位移量以及一定入口压力条件下,流经阀口的燃料流量保持不变,且与出口压力无关。     

Visualization of liquid fuel behavior in a spark ignition engine during starting and warm-up

The liquid fuel behavior in the intake port and the cylinder during starting and warm-up was visualized through visualization windows using a high speed CCD camera. The videos were taken with the engine firing under cold conditions in the simulated start up process, at 1.000 and 1.200 RPM and intake manifold pressure of 0.5 bar. The variables examined were the injector geometry and injector type (normal and air-assisted). The visualization results show several features of the liquid fuel behavior: 1) backward strip-atomization of the fuel film along the periphery of the intake valves by the valve overlap backflow: 2) forward strip-atomization of the fuel film on the surfaces of the intake system into droplet streams by the intake air flow: 3) film flow which forms significant liquid puddles at the valve surface and at the vicinity of the intake value: and 4) squeezing of the liquid film at the valve lip and seat into large droplets in the valve closing process. Some of the liquid fuel survives combustion into the next cycle. The time evolution of the in-cylinder liquid film is influenced by the injection geometry and port surface temperature. Photographs showing the liquid fuel features and an explanation of the observed phenomena are given in the paper.     

Influence of the flow area around the ball valve on the flow characteristics of the injector control valve

The increase in common rail pressure can lead to increased cavitation inside the injector, resulting in degradation of injector performance and reduced life. The paper investigates the effect of the pressure block structure parameters (initial flow area around the ball valve) on the velocity field, pressure field, fuel gas phase volume fraction and drain rate of the control valve. The relationship between the initial flow area around the ball valve on the cavitation strength and unloading rate inside the valve was revealed. The results show that both the reduction of the flow area around the ball valve and the increase of the cavitation intensity inhibit the rate of oil discharge from the control valve. The reduction of the fuel flow area inhibits the expansion of the low-pressure region (0–1 MPa) within the flow layer, thus limiting the development of cavitation. The reduction of the cavitation area increases the fuel flow rate, however, the increase in flow rate increases the cavitation phenomenon, and these changes form a cycle (Reviewer 5. comment 2). The increase in cavitation inhibits the control valve pressure relief rate more significantly than the decrease in the initial flow area around the ball valve. Based on this, a stepped-pressure block model is proposed. The stepped pressure block model can effectively reduce the cavitation strength near the seal and enhance the oil discharge rate of the control valve. The study can provide a reference for the engineering optimization design of high-pressure common rail injector control valves.     

冷却油路型射流管式伺服阀的热力学研究

 射流管式电液伺服阀因抗污染能力强、灵敏度高、失效对中等特点,被广泛应用于航天、航空、船舶等领域。介绍了冷却油路型射流管式电液伺服阀的结构原理,建立了稳态传热过程的热流量方程。利用有限元软件ANSYS 对冷却油路型射流管式电液伺服阀进行了热力学分析,并分析了力矩马达内部温度分布以及热梯度等物理量。试验验证了冷却油路型射流管式电液伺服阀的冷却效果,为冷却油路型射流管式伺服阀的结构设计、热力学研究提供了理论依据。     

一种简单的负流量控制方法

工程机械中负流量控制节能方法已经得到成功的应用,但其进口主控制换向阀订货周期长,价格高,所以提出了一种以泵一液控换向阀压力开关先导阀梭阀～国产多路换向阀为系统环节来实现负流量控制的简单方法,既可降低成本,缩短制造周期,又基本达到了节能控制的功能。简单负流量控制方法在整机无动作时,能让主泵排量减到最小,从而配合发动机怠速模式,起到降低油耗的作用。