基于压力信号的船用柴油机共轨系统高压油泵典型故障诊断研究

基于AMESim液力仿真平台搭建高压油泵仿真模型,对2种高压油泵典型故障进行仿真分析。采用小波变换方法将压力信号分解为低频波动信号和高频脉动信号,提取高频脉动信号无量纲参数波形因子为故障特征,建立高压油泵故障诊断模型。结合仿真和柴油机台架试验的高压油泵故障数据,验证了该诊断方法的有效性。     

风力发电机组叶片故障诊断

风机叶片的裂纹和断裂是导致风机机组事故的重要因素之一,尽早诊断出风机叶片的故障部位与故障程度,对安全生产具有意义重大.本文将叶片振动信号作为研究对象,利用小波分解方法对其进行信号分解,并与时域和频域方法处理结果进行对比分析,得出诊断结论.仿真结果表明：小波分解方法可以更有效的获取故障特征信号,具有较高的故障诊断率.     

汽轮机动静碰磨振动信号去噪方法分析研究

为确保汽轮机组故障诊断特征提取的准确性,由于现场实际振动信号掺有大量不确定噪声信号,针对现场采集的实际振动信号,进行分析去噪研究.采用小波分析、经验模态分解等方法进行分解去噪,并进行去噪对比.最后分析结果显示,基于集合经验模态分解(EEMD)的去噪方法,在对有突变故障的诊断信号自适应分解去噪弥补了经验模态分解和小波分解的缺陷,有较好的效果.     

基于Lab VIEW的小波理论在风力机齿轮箱故障诊断中的应用

给出一种基于Lab VIEW实现信号的小波包络分析的方法。在Lab VIEW的高级信号处理工具箱中包含了小波包信号分解和重构的模块,利用这些模块快速实现了小波包分解,然后对风电机组齿轮箱采集振动数据进行包络分析,得到了直观的包络谱线,进而得到准确判断风力发电机组的实际工作状态。另外采用小波分解对齿轮箱故障振动信号进行消噪滤波,通过小波包分解系数求取频带能量,根据各个频带能量的变化提取故障特征,为实现智能诊断提供故障特征值。     

基于小波分析与气缸压力的气门故障诊断

将小波分析引入气缸压力的分析与研究，对其进行二进小波分解，计算分解后尺度1上信号各频带的能量百分比，从中获得诊断特征量，从而对气门间隙进行故障诊断。结果表明用小波分析处理气缸压力信号较FFT更有效，作者采用的诊断方法与特征量是有效和可行的。     

基于小波能量熵和粗糙集的振动故障诊断研究

通过对不同振动故障信号进行小波包分解,得到若干个小波分解系数,进而从中获得各小波系数能量,并以此为特征进行基于粗糙集理论的特征约简分析,根据约简后生成的诊断规则对故障样本进行诊断,在确定故障的基础上,通过小波能量谱熵来衡量故障严重程度.实验结果显示通过基于粗糙集理论的RSES软件实现故障诊断准确率较高,同时能量谱熵参数可以在一定程度上衡量故障程度.     

基于小波包特征向量弹性BP算法的故障诊断

为精确诊断转子故障,采用了基于小波包能量特征向量的弹性BP神经网络和最速下降BP算法神经网络的故障诊断方法,对采集到的信号进行3层小波包分解,构造小波包特征向量,对样本进行3层BP网络训练,实现智能化故障诊断。结果表明采用改进的BP算法优于最速下降BP算法,训练的网络可以很好地诊断转子故障。     

小波变换在数字滤波中的实现

叙述了小波、小波包的理论,采用Mallet的小波分解和重构的算法,通过把具体的信号分解到不同的频率段上,然后对信号重构,借助这种方法达到对信号进行数字滤波的目的,着重阐述了小波滤波原理和小波数字滤波分解和重构的算法。     

基于小波包的泵站机组振动信号特征分析

提出了一种应用小波包分析对泵站机组振动信号进行特征分析的方法。与小波分析相比,小波包分析能对信号的高频频带进一步分解,提高了频率分辨率。利用小波包对泵站机组振动信号进行了信号压缩与消噪以及奇异性分析,为诊断机组振动故障提供了决策依据。对泵站机组主轴摆度和轴承振动实测信号进行了分析,结果表明小波包分析可有效提取原始信号的特征。     

发电机组转子机械故障诊断的DWPT方法

研究了小波理论及小波包(DWPT)分解技术在发电机组故障特征提取和诊断中的应用。针对发电机组的常见故障及其表现特征，结合对某故障发电机组的实际测试，利用小波包分解技术对该发电机组的振动信号进行了分析诊断，得到了与实际情况完全相同的结果。研究结果表明：利用小波消噪方法和小波包分解技术在时城内能更准确地判断发电机组的工作状态，该方法也为其它复杂机械的故障诊断提供了新路径。     

Relationship between pressure drop and cell resistance as a diagnostic tool for PEM fuel cells

An increase in pressure drop, particularly on the cathode side of PEM fuel cell, is a reliable indicator of PEM fuel cell flooding, while an increase in cell resistance is a reliable indicator of fuel cell drying. By monitoring both pressure drop and cell resistance in an operational fuel cell stack it was possible to diagnose either flooding or drying conditions inside the stack. These parameters may be used for making decisions on corrective actions.     

Combined heat and power system based on a proton conducting SOFC and a supercritical CO2 Brayton cycle triggered by biomass gasification

An integrated combined heat and power system was developed by combination of a proton conducting solid oxide fuel cell and a supercritical carbon dioxide Brayton cycle triggered by air-gasification of peach stone. Equivalence ratio, fuel cell temperature, fuel utilization factor and pressure ratio were considered as parameters with respect to power and heat productions as response variables. Analysis of variance showed that fuel utilization factor and fuel cell temperature with shares of 76.6% and 11.5% contribute the most on the power production while the most important factors on heat production are fuel utilization factor and equivalence ratio with shares of 54.1% and 44.8%, respectively. Power production is improved by increasing fuel cell temperature, decreasing equivalence ratio and decreasing fuel utilization factor. Regression models for predicting power (with R² of 98.47%) and heat (with R² of 91.77%) were proffered using analysis of variance with errors smaller than 1%. Multi-objective optimization results revealed that equivalence ratio of 4, fuel cell temperature of 680 °C, fuel utilization factor of 0.82 and pressure ratio of 5.11 were optimum conditions to achieve the maximum power (138 kW) and heat (195 kW).     

基于排气噪声的柴油机各缸工作不均匀故障诊断

对计算机和声传感器采集排气噪声,研究了9种工况下柴油机排气噪声在时域的周期性规律,对柴油机排气噪声信号进行了自相关分析,提取参数来表征排气噪声的周期性规律.对这个参数在3种转速下的值进行了详细分析,发现此参数在各转速下均能判断出失火及喷油器压力过小故障,在高转速下判别气门类故障也很有效.通过编写相应的故障诊断程序,输入排气噪声样本和对应的转速后即可判断出故障,该方法具有非接触、操作简单、成本低的特点.     

柴油机电控燃油喷射系统喷油特性的方差分析

共轨压力和喷油脉宽是高压共轨柴油机燃油喷射系统两个最重要的参数,也是电控柴油机运行性能的两个决定性因素。在自行研制的高压共轨喷油系统上进行了喷油特性试验,并利用双因素方差分析法对不同共轨压力和喷油脉宽下的喷油特性样本值进行了显著性检验。分别检验了共轨压力和喷油脉宽对喷油量以及喷油一致性的影响程度,提出了基于F值的共轨系统工作分析。检验结果表明：喷油量对喷油脉宽的敏感性比共轨压力强,共轨压力和喷油脉宽及其交互效应对喷油一致性没有显著影响。     

柴油机电控燃油喷射系统喷油特性韵方差分析

共轨压力和喷油脉宽是高压共轨柴油机燃油喷射系统两个最重要的参数，也是电控柴油机运行性能的两个决定性因素。在自行研制的高压共轨喷油系统上进行了喷油特性试验，并利用双因素方差分析法对不同共轨压力和喷油脉宽下的喷油特性样本值进行了显著性捡验。分别捡验了共轨压力和喷油脉宽对喷油量以及喷油一致性的影响程度，提出了基于F值的共轨系统工作分析。检验结果表明：喷油量对喷油脉宽的敏感性比共轨压力强，共轨压力和喷油脉宽及其交互效应对喷油一致性没有显著影响。     

柴油机燃油系统故障诊断的研究

介绍了采用一种不解体柴油机燃油系统故障诊断的新方法，通过检测高压油管的弹性变形量，提取了反映燃油系统故障状态的特征向量，并利用模糊模式识别技术成功地诊断了燃油系统的各种典型故障。     

Numerical investigation on the water saturation of proton exchange membrane fuel cells with channel geometry variation

Many factors, such as mole fractions of oxygen and hydrogen, help improve the performance of proton exchange membrane fuel cells. The variation of mole fractions can be achieved by changing the operating pressure and relative humidity of the fuel cells. The changes in operating conditions are directly related to the electrochemical reaction and water generation of the fuel cells. The geometrical shape of the fuel cells also should be considered a factor in predicting performance because this affects the species' reaction speed and distribution. The current study considers four geometrical cell shapes with varied lengths and electrode and gas channel numbers. The variation in inlet pressure is considered in analyzing the current density distribution of the fuel cells and, subsequently, of liquid water generation. A serpentine gas flow channel is assumed, and its two‐dimensional arrangement is considered in the different gas channel numbers and its length. Four inlet pressure variations and four geometrical shape variations also are considered in analyzing the fuel cells' current density and water generation distributions. The results obtained from this research can be utilized in identifying the fuel cells' optimal operating pressure and designing their gas channel number and arrangement. Copyright © 2011 John Wiley & Sons, Ltd.     

直列六缸柴油机燃油泵齿轮系噪声优化研究

建立了燃油泵齿轮系的简化弹性质量体模型,仿真分析得到其扭转振动响应。结果表明:燃油泵工作频率和发动机着火频率不一致,引起燃油泵齿轮轴扭振幅值较大且峰值波动较大,是燃油泵齿轮系声音异常的主要因子。通过优化燃油泵速比和初始相位,其扭振幅值降低60%,峰值无波动;噪声试验验证优化后的燃油泵齿轮系异响消失,噪声声压级水平总体降低了0.9 dB(A)。     

Spray characteristics of biodiesel fuel in constant volume chamber using multi-response optimization technique

This study discusses about the optimization of spray characteristics of biodiesel fuel in a spray chamber. Three factors namely, fuel injection pressure, fuel temperature and fuel blends were chosen as the influencing factor for the set objective. Four levels were chosen in each factor and spray tip penetration, spray cone angle and Sauter mean diameter (SMD) were taken as the response variables. Experiments were designed by employing design of experiments method and Taguchi full factorial array was used to conduct the tests with different levels of the chosen factors. Multi Response Signal to Noise ratio (MRSN) was calculated for the response variables and the optimum combination level of factors was obtained simultaneously using Taguchi’s parametric design. Confirmation experiments were conducted for the obtained optimum combination level of factors and the results were compared with the normal operating conditions and significant improvement were observed in the response variables.     

柴油喷射系统的发展现状及潜力（上）

车用柴油机现在正面临降低有害排放和优化燃油经济性的重大挑战。对于柴油机技术来说 ,喷油系统技术的发展已成为柴油机达到排放指标的决定性因素。喷射压力已从 5 0MPa逐步增加到了 2 0 0MPa ,高控制柔性的喷油系统必须能够进行多次喷射和喷油规律控制。喷油系统本身具有高的效率是非常重要的。为了喷油系统的进一步发展 ,新技术如变喷孔面积的喷油嘴技术和新的执行器技术等等是关键的因素。用柔性控制的喷油系统 ,就有可能获得最佳的排放组合和燃油经济性的折中