特种车辆冷却风扇组件失效分析

某特种车辆冷却风扇组件在试车过程中,先后出现了多起风扇组件的失效.分解检查发现,这些风扇组件的失效均是由其主轴承失效所致.为了深入了解该特种车辆风扇组件失效的原因,本文从轴承的工作条件、润滑及支撑结构等影响因素进行了分析.     

井下特种车辆零部件的失效与维护保养

井下作业是油田开发过程中保证油水井正常生产的重要技术手段,其作业工艺主要由作业特种车辆完成。为保证井下作业的顺利进行以及作业质量,因此对井下作业特种车辆的维护与保养十分重要。本文结合生产实际车辆容易出现的一些问题,总结了特种车辆零部件常见的问题与日常维护和保养的要点,为车辆操作与维护人员提供一定指导。     

鼓风机转子叶轮失效分析

通过材质,断口宏微观和腐蚀产物成分分析,确定鼓风机转子叶轮失效模式为腐蚀疲劳,鼓风机转子叶轮上裂纹起源于腐蚀抗,分析结果为防止类似事故的再次发生提供了技术依据。     

空气压缩机钎焊叶轮失效分析

采用金相、ＳＥＭ观察及ＥＤＡＸ能量色散元素定测定等方法，对空气压缩机钎焊叶轮失原因作了全面分析。结果表明，钎焊叶轮失效系统上钎焊缺陷、环境介质引起的钎我裂纹以及使用温度等综合因素所致。严格控制狐焊在５％以下，避免使用温度超过限定值及水蒸气介入，可防叶轮早期失效。     

特种车辆半轴折断分析

半轴的折断失效，其损坏形式为高频率低应力弯曲疲劳损坏。原因为其承受弯矩最大处为９０度尖角，及有车刀切削痕迹，以致产生了严重的应力集中；其次是材料的热处理质量不合格，致使疲劳抗力较低。     

贯流风扇叶轮超声焊接机叶轮定位导杆检测仪

贯流风扇叶轮超声焊接机的叶轮定位导杆垂直度是保证风扇叶轮焊接质量的一项重要性能指标,对定位导杆垂直度检测进行较详细的分析和总结。     

硅油风扇离合器转轴装配断裂失效分析

硅油风扇离合器转轴在装配时发生断裂,通过对断裂的风扇转轴进行宏观分析发现,断裂起源于转轴中心的孔洞,并且在未断裂转轴的底部中心同样存在孔洞。通过金相方法进一步确认了风扇转轴内部孔洞的存在,并分析了孔洞缺陷的性质,从而找到了风扇转轴早期断裂失效与零件内部存在严重的铸造缩孔缺陷有直接关系。另外转轴显微组织异常粗大有过热现象,加剧了转轴早期断裂失效的发生。最后针对导致转轴断裂的原因提出了预防改进措施。     

风扇磨煤机ZGMn13冲击板的失效分析

ZGMn13冲击板的失效方式为不同角度的粒子撞击和冲刷，其表面可以分为三个典型的磨损区域：低角度撞击区、高角度撞击区和冲刷区。详细分析了该三个磨损区域的磨损机理。次表面分析的结果表明，在低负度撞击和冲刷条件下，高锰钢未能充分加工硬化，耐磨性提高有限。     

基于B样条曲线的通风机叶型及特性分析

提出了利用B样条曲线构造风机叶片中线的新方法：以叶栅平面内特定的6个点作为控制点构造3段三次均匀B样条曲线，构成一种新型的叶片中线模型。理论分析表明，利用本方法得到的叶型具有对气流加压强度从零开始逐渐增加然后逐渐降低至零的特点。论文还计算并分析了其加压强度沿叶片中线的分布规律与设计参数的一般关系曲线，结果表明，通过设计参数的合理选取可以获得加压性能良好的轴流风机叶型。     

某型滑油冷却风扇振动特性分析

为避免工作状态下风扇转子由于自身工作转速及相关的激振频率引起的共振现象,通过试验模态分析及数值模态分析结合的方法对转子振动特性进行分析,并与改进前的转子进行对比。结果表明,以静子尾流产生的激振力对应的共振转速与转子的工作转速相接近,改进后的转子各阶固有频率提升但共振裕度减小,因此在风扇使用过程中应保证其完整性,从而避免疲劳断裂等安全隐患。     

基于机器学习的风机叶片开裂预测研究

为了预测风机叶片开裂的状态,使用机器学习的方法对风机叶片状态进行分类预测.首先对SCADA采集的原始数据进行预处理,然后采用逻辑回归与XGBoost集成学习算法对预处理后的数据进行建模,并通过性能度量的评价指标比较两种算法的效果与泛化能力.结果表明,XGBoost在风机叶片开裂的分类预测上有更好的效果,其预测准确率达到...     

基于前缘锯齿形叶片的多翼离心风机数值分析与实验研究

为减少叶片附近的涡流,降低多翼离心风机流场的流动损失和气动噪声,设计了一种具有锯齿形前缘的空调器用离心风机叶片。与常见改型叶片不同,并未从整个叶片宽度方向进行改进,仅从叶轮前盘沿叶片前缘的1/3叶轮宽度处开设锯齿结构。基于几何相似原理和FLUENT软件,对计算得出的不同锯齿结构进行数值模拟,结果显示:锯齿结构主要对聚集在靠近前盘的涡流进行破坏,蜗舌、叶片后缘和叶间涡流较原型叶片也明显减少,且降低了基频噪声。结果表明:在不同转速下,前缘锯齿形叶片多翼离心风机的整机风量较原型机基本不变,噪声值降低0.9～1.2 dB(A),输入功率降低2.75～3.55 W。说明具有锯齿形前缘结构的叶片,不仅能优化风机的风道性能,还能起到节能降噪的作用。     

叶型改进对离心通风机内部气动激励影响机理的数值分析研究

叶片是离心通风机核心部件,为研究叶型改进对离心通风机振动的影响,对某型离心通风机进行气动激励的仿真计算;通过定常计算,发现叶型改进能够推迟流动分离,减小诱发振动的激励因素;通过非定常计算,发现叶型改进对离心通风机气动激励的影响主要体现在压力脉动的改善,尤其是叶频脉动的降低;用计算分析结果对通风机振动变化进行预估,样机试验结果表明,叶型改进能够降低叶频振动,同时也表明气动激励分析可为通风机低噪声改进效果提供判断依据。     

Failure Analysis of a Vehicle Engine Crankshaft

An investigation of a damaged crankshaft from a horizontal, six-cylinder, in-line diesel engine of a public bus was conducted after several failure cases were reported by the bus company. All crankshafts were made from forged and nitrided steel. Each crankshaft was sent for grinding, after a life of approximately 300,000 km of service, as requested by the engine manufacturer. After grinding and assembling in the engine, some crankshafts lasted barely 15,000 km before serious fractures took place. Few other crankshafts demonstrated higher lives. Several vital components were damaged as a result of crankshaft failures. It was then decided to send the crankshafts for laboratory investigation to determine the cause of failure. The depth of the nitrided layer near fracture locations in the crankshaft, particularly at the fillet region where cracks were initiated, was determined by scanning electron microscope (SEM) equipped with electron-dispersive X-ray analysis (EDAX). Microhardness gradient through the nitrided layer close to fracture, surface hardness, and macrohardness at the journals were all measured. Fractographic analysis indicated that fatigue was the dominant mechanism of failure of the crankshaft. The partial absence of the nitrided layer in the fillet region, due to over-grinding, caused a decrease in the fatigue strength which, in turn, led to crack initiation and propagation, and eventually premature fracture. Signs of crankshaft misalignment during installation were also suspected as a possible cause of failure. In order to prevent fillet fatigue failure, final grinding should be done carefully and the grinding amount must be controlled to avoid substantial removal of the nitrided layer. Crankshaft alignment during assembly and proper bearing selection should be done carefully.     

Failure Analysis of Fan Motor Shafts of a Tunnel Dryer

This article details the analysis of two conducting shafts operating on blowers of a tunnel dryer. A deductive analysis was applied looking toward a successful recognition of root cause(s), where based on knowledge of background, and failure characteristics, multiple hypothesis are exposed that are further confirmed or rejected according to different tests, material analysis or maintenance history. In both shafts, failure arises from inadequate repairing. In order to confirm this, the failure analysis methodology included the following steps: technical review, visual inspection, fractography, penetrating inks, metallography, optic microscopy and stress analysis. Evidence obtained through these techniques indicates a fatigue failure induced by inadequate repairing procedures; therefore, main recommendation is to take the necessary precautions in order to guarantee minimal alterations on shaft geometry or material microstructure.     

中央空调系统中冷却塔风机变频节能的可行性分析

借助于冷水机组和冷却塔的选型软件,并通过迭代计算的结果表明:以控制恒定逼近度的逻辑方法,在冷却塔风机上能够实施变频的运行范围因为受到冷量、湿球温度和冷水机组的效率影响而非常小;而且如果将冷水机组与冷却塔的综合能耗一起考虑的话,可能达不到所设计的节能效果.