基于振动信号的柴油发动机转速测量EI北大核心CSCD

利用振动信号测量发动机转速是一种不解体检测的重要方法,但其对发动机振动频率要求较高,因此转速急剧变化时,对测量精度影响较大。提出了基于希尔波特包络和自相关的新方法;利用小波变换消除基线漂移,再通过短时时间窗进行类稳态分析,并采用希尔伯特包络和三次自相关对信号进行时域分析,计算短时窗内的发动机转速,通过移窗法得到连续的发动机转速。通过在发动机台上进行变工况试验,同步采集振动信号和转速传感器信号进行对比分析,在急加速条件下转速测量最大误差小于1.4%,能够有效的满足柴油发动机转速的实时性和精确性要求,在车辆不解体检测和无负荷测功方面有很大应用前景。     

基于振动信号的柴油发动机转速测量

利用振动信号测量发动机转速是一种不解体检测的重要方法,但其对发动机振动频率要求较高,因此转速急剧变化时,对测量精度影响较大。提出了基于希尔波特包络和自相关的新方法;利用小波变换消除基线漂移,再通过短时时间窗进行类稳态分析,并采用希尔伯特包络和三次自相关对信号进行时域分析,计算短时窗内的发动机转速,通过移窗法得到连续的发动机转速。通过在发动机台上进行变工况试验,同步采集振动信号和转速传感器信号进行对比分析,在急加速条件下转速测量最大误差小于1.4%,能够有效的满足柴油发动机转速的实时性和精确性要求,在车辆不解体检测和无负荷测功方面有很大应用前景。     

一种新型汽车柴油发动机转速测量仪校准装置的设计

<正>汽车柴油发动机转速测量仪(以下简称"转速测量仪")是用于检测柴油发动机转速测量必备的计量仪器,为保证其转速检测结果的准确、可靠,转速测量仪必须用准确度更高一级的计量标准仪器——汽车柴油发动机转速测量仪校准装置(以下简称"校准装置")对其进行校准。一、问题来源转速测量仪实际上是一种利用振动原理对发动机转速进行测量的计量仪器。当校准装置配置的专用发动机每次喷油时,对应的发动机高压油管便会因其     

某型发动机涡轮盘整体振动模态的有限元分析

对某型航空发动机的第一级高压涡轮盘和叶片进行了振动模态有限元分析.分别对完全自由和在螺栓安装孔处进行全约束后两种状态进行振动模态计算,并且对计算结果和振型进行了分析,同时参照发动机的工作转速进行判断分析,得出结论在发动机的工作转速内,该级涡轮盘具有足够的振动频率安全裕度,不会出现共振现象.     

浅谈电喷发动机怠速不稳的原因分析与排除

汽车发动机的怠速是一种工作状况。指的是在发动机空载运转时，发动机就处于怠速状态。发动机怠速时的转速被称为怠速转速。怠速转速可以通过调整风门大小等来调整其高低。一般来讲，怠速转速以发动机不抖动时的最低转速为最佳。不同型号的汽车发动机，其怠速额定值均有不同的范围，如果发动机怠速值低于或超过规定的范围，就会出现阶段熄火、转速不稳等现象。出现这些现象时，应及时判断、检查和排除故障。     

涡轴发动机起动信号的奇异值分解研究

针对涡轴发动机动力涡轮转子起动过程中的振动信号,采用奇异值分解方法实现非平稳振动信号的去噪和奇异值重构,从中提取起动信号的振动特性。发现某涡轴发动机凸台1和凸台2的振动主频为154 Hz,为涡轴发动机2阶临界转速的2/3倍频,凸台3的振动主频为160 Hz。这些振动特征可为发动机振动排故和动平衡提供参考信息。     

直升机传动系统扭转振动的分析

为了获得直升机传动系统扭转振动的特性,对直升机传动系统的扭转振动进行了计算和分析.在简化传动系统结构的基础上,将直升机传动系统划分为若干个轴段和圆盘的子系统,根据振型叠加原理,得到了直升机传动系统扭转振动的解,分析了传动系统的扭转频响函数.结果表明:传动系统扭转频响函数幅值的峰值出现在低阶固有频率附近;不同频率激振源的部件引起传动系统同阶扭转共振时,发动机的转速不等,发动机到激振源部件的传动比大,发动机的转速高;在同阶扭转共振中,桨叶引起传动系统扭转共振时,发动机的转速最高.     

基于振动的发动机转速高精度动态测量新方法

提出一种无需编码盘和鉴相装置的往复发动机瞬态转速测量新方法.该方法是基于发动机振动信号最低谐次频率获得发动机的估计转速,在发动机转速平稳或波动不大情况下采用离散频谱校正技术对估计转速进行校正以提高测量精度;在发动机处于升速或降速等非平稳状态时则利用获得的估计转速对发动机进行阶次跟踪,利用阶次谱获得估计转速校正参数,从而实现对发动机瞬态转速的动态测量.台架实验和不同缸数的实车测试都验证了该算法在发动机转速提取上具有很高的精度.较之在文献中常见的基于编码器的转速测量方法,这种方法硬件简单,特别适用于在用车日常维护和检测中使用.     

缸内直喷增压三缸机整车集成中的振动噪声问题研究

以搭载缸内直喷增压三缸发动机为对象,研究其在整车集成中的振动噪声问题。三缸机主要激励力不同于传统的四缸发动机,对动力总成悬置系统匹配和发动机平衡策略提出的要求也不同。三缸机的主要激励力为1.5阶,导致部件共振转速提高,车身的振动噪声性能也必须进行与之相适应的优化。增压器和高压供油系统的噪声也影响车内声品质,需要得到关注并对其进行优化。     

缸内直喷增压三缸机整车集成中的振动噪声问题研究

以搭载缸内直喷增压直喷三缸发动机为对象,研究了其在整车集成中的振动噪声问题。三缸机主要激励力区别于传统的四缸发动机,对动力总成悬置系统匹配和发动机平衡策略提出了不同的要求。三缸机的主要激励力为1.5阶使部件共振转速提高,车身的振动噪声性能也必须做出相适应的优化。增压器和高压供油系统的噪声也影响到车内声品质,需要进行关注和优化。     

Hydrophilicity of soot particles formed in the combustion chamber of a jet engine

The particles of soot, formed in the combustion chamber of a jet engine under conditions typical of a cruising power mode, are capable of adsorbing a considerable amount of water vapor owing to their microcrystalline structure, microporosity, and chemically heterogeneous surface.     

Static and dynamic novelty detection methods for jet engine health monitoring

Novelty detection requires models of normality to be learnt from training data known to be normal. The first model considered in this paper is a static model trained to detect novel events associated with changes in the vibration spectra recorded from a jet engine. We describe how the distribution of energy across the harmonics of a rotating shaft can be learnt by a support vector machine model of normality. The second model is a dynamic model partially learnt from data using an expectation-maximization-based method. This model uses a Kalman filter to fuse performance data in order to characterize normal engine behaviour. Deviations from normal operation are detected using the normalized innovations squared from the Kalman filter.     

Rotational torsion fatigue failure of an engine driven fuel pump coupling

Between 2005 and 2007 serious flight safety concerns arose when a small fleet of single engine basic trainer aircraft experienced five critical failures of engine driven fuel pump (EDFP) couplings, and a further instance of a cracked coupling. Consequent investigations showed that the coupling fractures were likely to have been caused by a combination of reverse torsional loading and bending. Engine ground runs were then carried out to evaluate linear and torsional engine vibration levels in the drive train affecting the fuel pumps. Analysis of the vibration data indicated that engines, which had caused pump‐coupling failures exhibited high‐amplitude torsional vibration at certain power settings. The excessive vibration level was eventually attributed to detuning of the crankshaft counterweight dampers. This investigation resulted in a change to the maintenance practises on the aircraft in question and no fuel pump failures have occurred since December 2008.     

某导弹弹体对主发动机转子振动的响应

根据主发动机在转子最大不平衡量作用下产生的激振力，应用动态分析有限元法计算了导弹飞行过程中弹体在发动机额定转速和巡航转速下的稳态响应，为进一步分析弹上仪器的响应及其可靠性提供理论依据。     

Analysis of in‐flight vibration of a twin‐engine turbo propeller aircraft

A data recorder was utilized to record in‐flight vibration of a twin engine turbo propeller (feeder) aircraft. The data recorded produced power spectral density (PSD) profiles which are currently used in laboratory settings to drive vibration tables in order to simulate a particular vehicle type. Overall Grms values were averaged and compared to previous research studies. The data collected from this research study could be utilized for packaging research when developing products and packages that will pass through a distribution cycle which includes transportation via a feeder aircraft. One example of this type of distribution cycle is the small parcel shipping environment. The PSD profiles which were analyzed from this research could simulate in‐flight aircraft vibration of the aircraft chassis in a laboratory environment. This will enable further research in the air transport environment. Copyright © 2009 John Wiley & Sons, Ltd.     

船舶主机气囊隔振系统动态特性分析

提出了将气囊隔振器应用于船舶主机隔振，介绍了该隔振装置的特性，并进行了动力学分析。分析表明，气囊隔振系统能够大幅度减小主机激振力向船体基座的传递。在其他条件不变时，系统具有定常频率特性，各气囊压力的分布对系统固有频率、力传递特性没有影响，而对主机输出端的位移有一定影响，应该通过优化设计使联轴节的振动最小。     

Investigation of a Bird Strike Incident of a Military Gas Turbine Engine

This paper investigates a bird strike incident of a military gas turbine engine. The jet pipe temperature of the engine shoot up and rotor speed reduced suddenly during takeoff roll. Long flame was noticed from the engine and aircraft crashed at runway end. Forensic analysis of remnants collected from flow passages confirmed the bird ingestion. Blockage of flow passages due to the presence of bird has led to engine surge and high gas temperature resulting in extensive damage of low pressure turbine module. The paper also proposes remedial measures to avoid such bird strikes during flight.     

热环境下某飞行器振动特性分析与模型修正

基于结构热振动理论,针对某型复合材料结构飞行器建立其热环境下结构动力学计算的有限元模型。对该结构进行结构动态特性分析,并结合地面常温的模态实验数据对该有限元模型进行优化。得到该结构常温下的振动特性及其受给定温度场影响的变化情况。针对该类复合材料结构建模及模型修正的方法,给出较为合理的优化方法及优化结果,对工程实际有一定的指导意义。     

Application of Dempster-Shafer Theory in Aircraft Maintenance Time Assessment: A Case Study

Abstract:

The goal of this case study is to demonstrate the use of the Dempster-Shafer Theory of Evidence as a decision aid to predict aircraft maintenance times during Turkish Air Force wartime tactical operations. A questionnaire was administered to aircraft maintenance experts to investigate maintenance times of major aircraft failure modes (ignition, fuel, and electrical). An example examining jet engine aircraft failure is presented to demonstrate use of the developed approach. The results of this methodology provide a useful and specific application area for the Dempster-Shafer Theory to aid a decision maker in making wartime tactical decisions.     

汽车液阻悬置动特性和隔振性能分析

为分析某一型号轿车发动机液阻悬置在低频的动态特性,建立该悬置集总参数模型,应用MATLAB软件仿真的动特性曲线与试验曲线基本吻合,表明所建立的液阻悬置模型能较精确分析该悬置的动特性;并应用ADAMS/CAR软件建立整车模型,通过整车仿真来比较液阻悬置和橡胶悬置的隔振性能,结果表明前者具有更好的隔振性能。