基于Workbench的某转子发动机偏心轴强度分析

以某转子发动机的偏心轴为研究对象,对偏心轴的振动及最大爆发压力下的瞬态冲击应力进行了分析。运用CATIA软件建立偏心轴三维模型,将模型输入ANSYS Workbench进行模态和强度分析,得出了输出偏心轴的前6阶固有频率和及偏心轴在最高爆发压力下的瞬态冲击应力。结果表明,偏心轴的最低阶固有频率高于偏心轴的激励频率,最大爆发压力下的极限应力发生在轴承段与主轴颈的过渡圆角处。     

Grass silage for biorefinery—A meta‐analysis of silage factors affecting liquid–solid separation

This meta‐analysis based on 19 studies from Finland comprising 43 grass silages was undertaken to evaluate the effect of silage quality on liquid yield, liquid composition and retained compounds in liquid using four different liquid–solid separation methods. Silages were classified according to species (grass, clover or a mixture of them), additive treatment (no, biological or formic acid‐based additive) and harvest (primary growth or regrowth). A mixed model regression analysis with random study effect was used to evaluate the impact of silage characteristics on biorefinery efficiency. There was a large variation in silage quality in the data set. Silage dry‐matter concentration was the characteristic most highly correlated with liquid yield for all separation methods, and when used as an independent variable in the model, it resulted in the best predictions. The liquid–solid separation methods presented a great variation in the liquid yield, ranging from 0.26 to 0.56 when silage dry‐matter concentration was standardized to 250 g/kg. There was no effect of additive treatment and harvest in the estimation of the biorefinery potential, but species was a significant variable in predicting liquid yield for the laboratory‐scale presses with higher liquid yield for mixed grass and legume. The high correlation between silage quality and liquid yield and liquid composition provides potential to predict the biorefinery potential based on equations developed for each separation method. This information can be used to modify the silage production systems so that they best meet the requirements of a green biorefinery process.     

含气率对小流量下混流式混输泵轴系振动的影响

振动是反映混输泵运行稳定性的关键指标,液体含气率对混输泵的振动强度有重要影响.为探究小流量工况下含气率变化对混输泵轴系振动的影响规律,该研究以某3级混流式气液混输泵为研究对象,采用建立的多通道振动测试系统采集小流量工况下混输泵输送不同含气率的水时主轴和轴承座的振动信号,然后分析水中含气率对主轴和轴承座振动特性的影响规律...     

次生盐渍土暗管+竖井排水控盐技术模式筛选及效果评价

[目的]评价暗管、竖井工程在新疆南疆次生盐渍化土上的排盐效果,筛选出适宜的暗管布设间距.[方法]以新疆南疆垦区兵团第二师38团撂荒地次生盐渍化土为对象,于2016～2019年设置暗管+竖井田间排水控盐试验,选取3个相邻地块,暗管布设间距分别为6、8和10 m(依次记为T1、T2、T3),每个地块暗管埋深1.2 m,竖井...     

迷宫螺旋泵气液两相流场的数值模拟及试验

基于混合物多相流模型、RNGk-ε湍流模型和SIMPLEC算法,应用CFD软件Fluent对迷宫螺旋泵内气液两相流场进行数值模拟并通过试验进行验证.通过分析流道内不同截面上的压力、速度以及含气率分布,研究泵内气液两相流场的流动情况.模拟结果表明,压力分布从进口到出口沿螺旋槽逐渐升高,增压效果明显,速度分布在环形腔的外侧比在内侧稍大,螺旋部分含气率分布比较均匀,进出口处出现含气率分布不均匀现象,局部含气率较高,在此要防止气堵现象的发生.试验结果表明所采用的计算模型基本符合泵内部流动的实际情况,这说明模拟结果一定程度上揭示了迷宫螺旋泵内部气液两相流场的流动规律,可为迷宫螺旋泵气液两相流研究提供理论依据,试验结果同时表明迷宫螺旋泵进行气液混输时具有良好的曝气效果,可作为传统曝气设备的替代产品.     

基于APDL参数化建模的轴系可靠性

运用大型通用有限元软件ANSYS提供的PDS模块,以泵轴的几何尺寸、载荷、应力、弹性模量以及强度极限等参数作为随机输入变量,根据应力-强度干涉理论,建立极限状态函数;通过APDL参数化设计语言,建立泵轴参数化三维实体模型,根据实际受载情况,对泵轴进行静应力分析,生成概率分析文件,选用蒙特卡罗有限元方法和拉丁抽样法对泵轴进行可靠度设计,得到比传统设计方法精度高、易于实现的泵轴失效概率及可靠度.以HS1K型碱泵的泵轴为例进行计算,获得了碱泵的应力概率分布特征,在置信度为95%时,该泵的可靠度为99.75%.实践表明,利用ANSYS/PDS模块对泵轴进行可靠性分析,能为生产厂家改进设计提供理论依据,具有一定的工程应用价值.     

二维码技术在发动机主轴瓦分选系统中的应用

介绍了二维码技术特性和优点,以及CFTEC发动机主轴瓦装配技术要求,然后阐述了发动机装配线主轴瓦分选系统的工作原理,体现了二维码技术在发动机主轴瓦分选系统中的应用优点。     

自动采集转轮及其在鱼类资源调查中的应用

介绍了一种自动采集转轮的结构、工作原理及其在鱼类资源调查中的应用。自动采集转轮特别适合在小河流及溪流中自动采集小型鱼类,并且选择性小、活体采样、对鱼类无大的损伤、可长期自动运行、成本低廉。     

Mechanical and physical screw withdrawal properties behavior of agglomerated panels reinforced with coir and pejibaye fibers

The screw withdrawal resistance and the mechanical behavior of agglomerated panels reinforced with coir and pejibaye fibers were evaluated using through and non-through screw withdrawal tests. Widespread commercially materials, such as Pinus solid wood, Medium Density Fiberboard (MDF) and plywood, were also tested in order to compare the behavior and results obtained with the lignocellulosic-reinforced agglomerated panels. Among the conventional materials tested, the highest maximum withdrawal load/thickness ratio was measured in solid wood. Panels reinforced with natural fibers showed lower withdrawal resistance than conventional materials. However, panels reinforced with coir fibers reached about 74% of the maximum strength achieved by MDF samples. Panels reinforced with pejibaye showed the worst mechanical performance. Hybridization between pejibaye and coir fibers resulted, however, in a performance improvement of approximately 50% in the maximum withdrawal load comparing with panels reinforced only with pejibaye fibers. The behavior along screw withdrawal was analyzed and could be split into four different steps. Each of these steps was correlated to the screw withdrawal rate, and also with the interactions between the material and the screw. The mechanisms involved in each step are presented and discussed.     

基于CFD的全金属单螺杆泵非稳态流场计算及性能预测

为了得到螺杆泵内非稳态流场特性及间隙泄漏规律,采用CFD的动网格技术,针对油田使用的全金属单螺杆泵进行三维瞬态流场数值模拟,在此基础上预测计算了不同转速、压头和流体黏度条件下螺杆泵的流量、功率及总效率并与试验结果进行了对比.结果显示,螺杆泵在运行中具有显著的非稳态特性,在1个旋转周期内,流量出现的脉动次数与螺杆泵定子转子导程的比值相一致,高压头工况下的泄漏量和流量值的脉动幅度明显大于低压头工况下的情况;在计算高压头螺杆泵输入功率时,机械及容积损失不应忽略.基于CFD的性能预测和实测数据的趋势较为一致,误差在工程允许范围内,表明采用的模拟计算方法是切实可行的.