基于Bently-Hammer软件的长距离输水管道水锤防护模拟

基于Bently-Hammer软件对某实际工程中长距离输水系统进行建模,通过实际运行中的不同工况,模拟突发事件在管道与水泵间产生的水锤影响,同时针对系统内突发事件增加液压气动罐、缓闭止回阀等水锤消除措施加以改进,为实际工程提供有效抑制水锤破坏的技术保障。

基于Bentley Hammer的长距离有压管道输水工程的水锤防护研究

【目的】在长距离有压管道输水工程中,因管道内部水流条件复杂而容易产生水锤现象,不仅会影响水流正常输送,还可能导致管道破裂。因此,有必要进行长距离有压管道输水工程的水锤防护研究。【方法】基于台前县城乡供水一体化南水北调配套工程,通过Bentley Hammer软件,在最不利工况下分别建立三种数值模拟模型:无防护措施、加装复合式高速进排气阀水锤防护、气囊式空气罐和复合式高速进排气阀,进行联合水锤防护,对以上三种情况进行水力过渡过程数值模拟分析,研究复合式高速进排气阀与气囊式空气罐联合防护时的水锤防护效果以及气囊式空气罐的防护能力与预设压力和罐体体积之间的关系。【结果】结果表明:复合式高速进排气阀和气囊式空气罐可以很好地消除管道内水锤带来的危害,气囊式空气罐防护能力随着罐体体积和预设压力的增大而增强,罐体体积对其防护能力影响更显著。【结论】选择合理的罐体体积和预设压力可以使水锺防护发挥最好的防护效果,最大化输水工程的经济性。

Digital monitoring of rotary-percussive drilling with down-the-hole hammer for profiling weathered granitic ground

Rock and geotechnical engineering investigations involve drilling holes in ground with or without retrieving soil and rock samples to construct the subsurface ground profile.On the basis of an actual soil nailing drilling for a slope stability project in Hong Kong,this paper further develops the drilling process monitoring(DPM)method for digitally profiling the subsurface geomaterials of weathered granitic rocks using a compressed airflow driven percussive-rotary drilling machine with down-the-hole(DTH)hammer.Seven transducers are installed on the drilling machine and record the chuck displacement,DTH rotational speed,and five pressures from five compressed airflows in real-time series.The mechanism and operations of the drilling machine are elaborated in detail,which is essential for understanding and evaluating the drilling data.A MATLAB program is developed to automatically filter the recorded drilling data in time series and classify them into different drilling processes in sub-time series.These processes include penetration,push-in with or without rod,pull-back with or without rod,rod-tightening and rod-untightening.The drilling data are further reconstructed to plot the curve of drill-bit depth versus the net drilling time along each of the six drillholes.Each curve is found to contain multiple linear segments with a constant penetration rate,which implies a zone of homogenous geomaterial with different weathering grades.The effect from fluctuation of the applied pressures is evaluated quantitatively.Detailed analyses are presented for accurately assess and verify the underground profiling and strength in weathered granitic rock,which provided the basis of using DPM method to confidently assess drilling measurements to interpret the subsurface profile in real time.

基于BentleyHammer的长距离压力输水管道水锤模拟分析

水锤模拟分析在保证工程安全运行、减少事故发生、降低人身财产风险损失等方面具有十分重要的意义。本文利用Bentley Hammer水锤分析软件,以某县城工业园区供水工程为例,模拟长距离压力输水管道工程非正常运行条件下管道水力工况,分析制定安全可靠、合理可行的水锤防护方案,保证供水工程运行安全,为长距离压力输水管道工程水锤防护方案的设计提供参考。

Bentley Hammer V8i软件在城乡一体化供水管道水锤计算中的应用

应用Bentley Hammer V8i软件模拟城乡统筹供水工程中输水和配水管道的稳态工况与事故断电工况的水锤安全性,可以清楚地展示管内水流压力的变化趋势。本文以新和县城乡一体化实际供水工程为研究对象,评估其供水管网水锤安全性。模拟结果显示,虽然该工程在稳态工况与事故断电情况下管道内压力会有剧烈波动,但仍在管道的承载能力之内,可以通过优化关阀时间及相关操作来确保供水的安全稳定。本应用可供类似城乡一体化供水工程管道设计参考。

Water hammer protection for diversion systems in front of pumps in long-distance water supply projects

For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention. In this study, a water hammer protection scheme combined with an overflow surge tank and a regulating valve was developed. A mathematical model of the overflow surge tank was developed, and an analytical formula for the height of the overflow surge tank was derived. Furthermore, a practical water supply project was used to evaluate the feasibility of the combined protection scheme and analyze the sensitivity of valve regulation rules. The results showed that the combined protection scheme effectively reduced the height of the surge tank, lessened the difficulties related to construction, and reduced the necessary financial investment for the project. The two-stage closing rule articulated as fast first and then slow could minimize the overflow volume of the surge tank when the power failure occurred, while the two-stage opening rule articulated as slow first and then fast could be more conducive to the safety of the water supply system when the pump started up.

基于Bentley Hammer的泵站输水系统管道优化前后的水力过渡过程研究

为了研究泵站输水系统管道优化前后事故停泵的水力过渡过程的特性,基于实际工程,运用Bentley Hammer软件,建立泵站输水系统双泵并联机组数学模型,研究两阶段不同关阀方案下管道优化前后对水锤压力、机组转速等最不利水锤参数的影响。结果表明,管道优化后最大水锤压力降低了3.76%~8.85%,最小水锤压力提升了4.89%~8.85%,最大倒转速度提高了1.47%~81.35%;快关时间对最不利水锤参数有显著影响,管道优化后泵站输水系统最不利水锤参数均比优化前提前发生。表明管道优化有效改善了泵站输水系统的水锤特性,提高了泵站输水系统的安全性。

Research on Breeze Vibration Law and Modal Identification Method of Conductor Considering Anti-Vibration Hammer Damage

In the harsh environment,the structural health of the anti-vibration hammer,which suffers from the coupled effects of corrosion and fatigue damage,is significantly reduced.As part of the conductor structure,the anti-vibration hammer is rigidly attached to the conductor,effectively suppressing conductor vibration.The conductor’s breeze vibration law and natural modal frequency are altered damage to the anti-vibration hammer structure.Through built a vibration experiment platform to simulate multiple faults such as anti-vibration hammer head drop off and position slippage,which to obtained the vibration acceleration signal of the conductor.The acceleration vibration signal is processed and analyzed in the time and frequency domains.The results are used to derive the breeze vibration law of the conductor under multiple faults and propose an anti-vibration hammer damage online monitoring technology.The results show that the vibration acceleration value and vibration intensity of the conductor are significantly increased after the anti-vibration hammer damage.The natural frequency increases for each order,with an absolute change ranging from 0.15 to 6.49 Hz.The anti-vibration hammer slipped due to a loose connection,the 1st natural frequency increases from 8.18 to 16.62 Hz.Therefore,in engineering applications,there can be no contact to determine the anti-vibration hammer damage situation by monitoring the modal natural frequency of the conductor.This is even a tiny damage that cannot be seen.This method will prevent the further expansion of the damage that can cause accidents.

Performance of large-diameter pneumatic down-the-hole (DTH) hammers: A focus on influences of the hammer structure

Pneumatic down-the-hole (DTH) hammer has been extensively used in air drillings through hard and ultra-hard geological formations. Numerical modeling can offer close observation on the working behaviors by visualizing internal pressure status as well as provide reliable performance predictions for large-diameter DTH hammers to which conventional empirical and experimental approaches cannot be applied. In this study, CFD simulations coupled with dynamic meshing are utilized to simulate the air flow and piston movement inside the large-diameter DTH hammers. The numerical modeling scheme is verified against a theoretical model published in literature. Effects of structural parameters on hammer performance, including piston mass, piston upper-end diameter, piston groove diameter, and lengths of intake and exhaust stroke in both front and rear chambers, are analyzed in detail by virtue of sets of numerical simulations. The simulations suggest that changing the intake stroke of front chamber has a negligible influence on hammer performance while increasing the piston groove would lower all the four indicators of hammer performance, including impact energy, impact frequency, maximum stroke, and air consumption rate. Changing the other structural parameters demonstrates mixed effects on the performance indicators. Based on the numerical simulations, a large GQ-400 DTH hammer has been designed for reduced air consumption rate and tested in a field drilling practice. The air drilling test with the designed hammer provided a penetration rate 1.7 times faster than that of conventional mud drilling.

钢筋混凝土结构移动式精准检测技术开发

无损检测技术是一种在不损害材料及结构服役性能的前提下,对其性质进行评估和测量的检测技术。然而,随着无损检测技术的发展和实践,结构内部的复杂损伤检测缺乏多层次精准性成为该领域的难点和核心问题。该文旨在结合国内外的研究成果,对无损检测技术的发展、分类和挑战进行梳理和分析,并在此基础上,介绍作者研究团队建立的一套由宏观到细观,再到内部的全面精准检测系统研究成果。针对表面宏观识别与细观定量识别,作者团队开发了表观病害视觉检测技术,包括构建的空间基准点自动追踪融合和亚像素级病害分割的全景图像快速拼接及表观病害厘米级定位方法,以及提出的全景图像中0.05 mm~0.2 mm多尺寸微细裂缝同步识别及真伪判别的人工智能算法。针对结构内部损伤识别,作者团队首创了智能变频敲击声波扫描及各类损伤精准识别新原理,发明建立了自适应激励分布移动敲击声波的损伤检测评估理论方法、声波及声纹图像特征人工智能算法及智能装备关键技术。经过实验验证,裂缝检测中宽度为0.05 mm时最大深度可达40 mm,剥离检测中最大深度可达400 mm,最小识别范围为50 mm。

CFRP加固损伤钢筋混凝土梁抗冲击性能试验研究

对采用碳纤维增强复合材料(CFRP)加固的不同损伤程度的钢筋混凝土梁进行落锤冲击试验,以冲击高度、加固层数为试验参数分析CFRP加固损伤试件的裂缝发展、破坏形态及抗冲击性能,并研究试件在冲击荷载下的动力性能。结果表明:试件损伤程度越高,其斜向裂缝发展越密集,试件的破坏程度越严重;落锤冲击高度越高,裂缝发展越趋近于跨中局部化;当采用多层CFRP布加固损伤试件时,试件在落锤冲击作用下保持较好的完整性,仅外部混凝土粉碎掉落;随着CFRP布粘贴层数的增加,试件整体产生弯剪破坏,损伤试件加固修复后的抗冲击能力及刚度相较于完好试件得到显著提升,提升幅度为70%~72%,但增加CFRP布粘贴层数对试件的加固修复效果提升作用有限,且加固效果与抗冲击能力并非呈线性关系;基于有效应变计算的结果可知,采用CFRP布加固修复不仅仅具有加固补强的作用,同时能够在一定的程度上改善试件的整体抗冲击性能。

水击补气式压力罐及水力瞬变仿真

空气阀常常安装在输水管检修孔侧壁,进气后部分气体就会存留在检修孔上部产生气垫式压力罐的水击防护作用。据此,提出了水击补气式压力罐装置的设计方法,即利用泵站事故断电产生的水击负压现象,通过真空破坏阀或空气阀给压力罐补气,以防止输水管发生液体汽化现象并削减水击最大压力。然后,建立了水击补气式压力罐水力瞬变数值仿真数学模型。最后,以一个实际输水工程为例,计算比较了分别设置空气阀、空气阀调压室及真空破坏阀补气式压力罐时的水击防护效果,结果表明,补气式压力罐水击防护效果最好。

钻井利器的故事之“液动潜孔锤”

在各种钻探方法中,液动冲击回转钻进具有效率高、质量好、回次长、事故少、成本低等优点,而液动潜孔锤又是液动冲击回转钻进的技术核心。本文梳理了各种液动潜孔锤的结构特点及其与绳索取心钻具、孔底动力钻具相结合衍生的各种钻具,简要介绍了这一技术的典型应用案例,总结归纳了其下一步发展方向和技术难点,以期普及液动锤的应用,促进液动冲击回转钻进技术的进步。

液压破碎锤活塞横裂机理分析与工艺优化

针对破碎锤中的活塞横裂现象,分析了活塞产生横裂的机理,并提出了一种新的活塞热处理制造工艺。采用硬度计和金相组织显微镜对活塞材料进行分析,得出发生活塞横裂故障部位的材料成分和金相组织符合设计要求,而硬度和硬化层深度低于设计要求。利用ANSYS求解活塞“卡死”情况下的最大应力为1229.8 MPa,超出材料的屈服极限850 MPa,最大应力的位置在活塞横裂处;利用Fluent求解活塞所受的径向不平衡力,在活塞的回油槽中受到的最大径向力为3408 N,最小径向力为10 N,在活塞的进油槽中,最大径向力为15675 N,最小径向力为73 N。结果表明,活塞在径向不平衡力作用下形成的“卡死”现象是活塞发生横裂的主要原因。提出延长活塞的渗碳时间、增加活塞在热处理过程中的校直次数等热处理新工艺,经耐久实验验证,所提工艺可以有效解决活塞横裂问题。

空气锤钎头的结构优化及疲劳寿命研究

空气锤钎头在钻井过程中表现的低疲劳寿命,大大降低钻井效率,提高了钻井成本。为此,研究空气锤钎头的疲劳寿命并对其结构优化,以提高空气锤钎头的服役寿命。在12.25 in(1 in=2.54 cm)空气锤钎头的基础上,考虑防掉结构,对空气锤钎头整体结构进行设计。提出微型钎头概念并完成了微型钎头样品疲劳寿命实验,使用Ansys/Ls-Dyna和nCode DesignLife软件对微型钎头进行动力学与疲劳寿命分析并与实验结果相验证,对钎头基本结构和材料进行确定。将仿真过程运用到钎头本体,考虑钎头本体尺寸和活塞冲击速度等问题对钎头疲劳寿命的影响,对钎头本体进行结构优化。研究表明,采用40CrMnSiMoV的钎头疲劳寿命最佳;钎头本体基本尺寸中,直径对钎头疲劳寿命影响最大;当冲击功变化时,钎头疲劳寿命随末速度的增加而减小;冲击功恒定情况下,当钎头末速度的平方与钎头质量接近时,钎头疲劳寿命最佳。

配筋率与质量比对FRP-RC梁冲击响应与损伤的影响

基于考虑应变率效应的三维数值模型,对玄武岩纤维增强复材筋混凝土(BFRP-RC)梁的抗冲击性能进行了研究.分析了冲击体与FRP-RC梁质量比、配筋率等因素对冲击响应的影响规律.结果表明,随着质量比增大,FRP筋混凝土梁的破坏模式从弯曲破坏转变为剪切破坏,但是配筋率的改变并不影响梁的破坏模式.由于BFRP筋弹性模量低,并且没有屈服阶段,故即使在梁损伤比较严重的情况下,BFRP筋的应变和BFRP筋梁的位移也会发生较大恢复.在冲击过程中,冲击力时程曲线的形状与质量比之间的规律不随配筋率而改变.此外,以剩余承载力为基准,建立了以频率变化、损伤因子和峰值位移为指标的损伤评估方法,为实际工程中FRP筋混凝土梁构件的灾后处置提供理论基础.

有机玻璃管道直接水锤压力特性试验研究

为了了解黏弹性管道的水锤压力特性,文中通过搭建水库-管道-阀门系统模型,进行了系列关阀水锤试验,针对有机玻璃管道中末端阀门初始开度分别为30%,100%时关阀产生的直接水锤压力变化规律进行了研究,从黏弹性材料的本构关系角度分析了关阀时间对黏弹性材料直接水锤的影响机理,并对2种不同初始开度下阀门附近的流场进行了三维数值模拟.研究结果表明:黏弹性管道中直接水锤压力变化规律与传统的水锤理论不符,直接水锤压力不仅与阀门的关闭时间有关,还与阀门的初始开度有关,满足“阀门关闭越快,直接水锤压力越大”与“阀门初始开度越小,直接水锤压力越大”的规律.

多级压缩机气阀寿命评估与极限含水量预测

针对目前油田天然气回注具有介质含水多、压力高且变化范围宽等特点,多级往复式压缩机容易产生水击破坏,如何预测极限含水量以有效防止水击是亟需解决的关键问题。采用计算流体力学方法,数值模拟并分析了多级压缩机注入湿气条件下各级气阀阀片的动力学特性,得到了不同天然气含水量的气阀阀片载荷分布。进一步结合nCode计算疲劳,预测了多级压缩机气阀服役寿命与极限含水量。JGC-4型压缩机模拟计算结果表明:随着进气含水量增大,压缩机排气压力提高,气缸内不断析出水滴,致使水击产生,且对高压级影响更为显著,压缩机整机进气含水体积分数上限为0.43%。研究结果可为多级往复式压缩机的应用提供技术支撑。

长距离多支线有压输水系统起动水锤防护

为研究同时包含重力流输水管线与泵站加压提水管线的长距离多支线有压输水系统开启运行时的水锤问题,基于瞬变流分析的特征线法建立了输水系统过渡过程计算的数学模型,结合实际工程计算了输水系统开启运行时调节阀与水泵及其出口阀不同的开启时间与控制策略对水锤的影响,并在此基础上提出了空气阀联合阀门开启的水锤防护方案。结果表明:采取提水泵站滞后调节阀开启运行,且各提水泵站相继开启的策略可有效改善输水系统沿线的内水压力分布;采用空气阀联合阀门开启的水锤防护方案可在不影响输水系统反应速度的情况下以较小尺寸的空气阀达到较好的水锤防护效果。

汉麻秆芯粉体制备方法的研究进展

由于汉麻本身具有天然的杀菌成分和良好的透湿透气性能,使其在纺织界逐渐受到重视。传统汉麻的外层韧皮纤维利用率较高,但汉麻秆芯则会被当做燃料焚烧或直接作为农业废物填埋掉,这部分大概占汉麻纤维产量的70%~80%。对汉麻秆芯能源的开发利用需要进行粉碎加工处理,以便进一步应用。以汉麻秆芯粉体制备理论、制备方法为研究对象,讨论了锤式粉碎、气流式粉碎、振动式粉碎等工艺技术,为汉麻秆芯粉体的转化利用做好前期处理工序准备。