Research on characteristics of water motion and influencing factors for the flexible air chamber jig body

The air bag deformation data were obtained by high-speed dynamic videos experiments. Based on gas–liquid flow VOF model, dynamic mesh technique and deformation data, numerical simulations for different structure models were achieved, and the law of water motion and influencing factors were analyzed.The results show that the flow in the length direction of the jig is smooth, and second pulsation appears in the separation time and forms the secondary separation. The installation position of screen and the number of air bags have a great influence on the uniformity of flow and velocity. The screen height cannot be too low to avoid forming the unstable flow. At the same time, the screen height cannot be too high, otherwise water velocity will be too small and was unable to provide enough power. At the height of 1.4m,velocity unevenness is minimum and the best uniform flow can be obtained. Compared with double air bags, there are the following features of single air bag: water flow is not smooth, the time achieving the maximum velocity is too long, maximum velocity is smaller, and overall effect is worse than double air bags.

Numerical Study of Air Chamber for Oscillating Water Column Wave Energy Convertor

Oscillating Water Column （OWC） wave energy converting system is one of the most widely used facilities all over the world. The air chamber is utilized to convert the wave energy into the pneumatic energy. The numerical wave tank based on the two-phase VOF model is established in the present study toinvestigate the operating performance of OWC air chamber. The RANS equations, standard k-ε turbulence model and dynamic mesh technology are employed in the numerical model. The effects of incident wave conditions and shape parameters on the wave energy converting efficiency are studied and the capability of the present numerical wave tank on the corresponding engineering application is validated.

Implications of fine water mist environment on the post-detonation processes of a PE4 explosive charge in a semi-confined blast chamber

The effects of a fine water mist environment in a semi-confined blast chamber on the chemical and thermodynamic processes following detonation of a 20 g PE4 explosive charge have been investigated.The effects were quantified by the analysis of pressure profiles recorded where several parameters including arrival time of the shock at the sensors, peak overpressures, specific impulse of the positive phase, period of the negative phase and the specific impulse of the multiple reflections were quantified.The effect of the fine water mist on the arrival time, peak pressures and the specific impulse of the positive phase agrees with previous findings in literature. In this paper, the focus is on the implications of the fine water mist on the negative phase and the impulse of multiple pressure reflections. The period of the negative phase was found to have increased by 40% and with higher negative peak pressure in the mist condition compared to the atmospheric condition. The activities of the multiple pressure reflections were found to have decreased considerably, both in number and in amplitude leading to lower impulses(by about 60%) for the water mist conditions.

Technology of reinforcement maintenance and blocking against water for large section chamber

The scheme and construction measurement of reinforcement and blocking against water for winder chamber after destroyed by mining influence have been introduced in this paper. The basic principle and advantages of bolting and grouting lining have been also listed. Bolting and grouting lining can increase the integrity and load-carrying capacity of supporting framework and it can assure the stability of supporting framework. It possesses not only the flexible and yielding capacity of bolting and shotcrete lining, but also the effect of rigid support such as metal support and brickwork, forming many kinds of support system, maintaining the stability of roadway together.

深部矿山高承压应急防水闸门设计计算与数值模拟研究——以滇东北毛坪铅锌矿为例

应急防水闸门及其配套工程在水害发生时,能够在短时间内有效控制水害的影响范围和程度,保障机械设备和人员安全。随着矿山开采深度的逐年增加,应急防水闸门及闸门硐室所需要承受的水压也在不断增加,地质条件更加复杂,施工环境也更加恶劣。本文以滇东北大水矿山毛坪铅锌矿为例,在系统评价其310 m中段局部注浆改造前后突水风险的基础上,分析了深部高承压应急防水闸门设计和建造过程中的多项关键技术问题,主要包括防水闸门设计承压值计算、硐室选址、结构类型、关键结构参数、开挖围岩扰动、围岩与结构的水压响应、闸门选型与远程控制系统等。设计计算结果表明,毛坪铅锌矿310 m中段应采用倒截锥形硐室结构,对开型防水闸门,设计承压6.4 MPa。数值模拟结果表明,防水闸门硐室开挖及浇筑后,竖直和水平方向的压应力和拉应力均增大,围岩塑性破坏的范围约为0.38 m,第1个倒截锥形塞的迎水侧承担了超过80%的总水压。最后,探讨了深部高承压应急防水闸门系统的发展趋势,包括防水闸门及硐室结构长期服役的稳定性监测与评价、深部复杂地质条件下的设计与建造技术、配套智能化的水害信息辨识与预警平台等。研究结果可以为深部矿山设计和建造应急防水闸门系统提供参考和借鉴。

化工企业罐区水体污染事故预防与控制

化工企业可燃液体罐区的排水系统应依据罐区排水系统设计规范(标准)中相关规定进行设计。罐区排水系统作为化工企业水体污染事故预防与控制体系的一部分,若设置不当可能引起局部环境污染或安全隐患,应引起设计和管理足够的重视。文章通过设计实践总结了设计要点:罐区排水系统实施清污分流,防火堤外设置阀门井,必要时设置水封井,正常情况下非排水时,阀门处于关闭状态。

高背压供热机组凝汽器水室结构优化研究

高背压供热机组利用凝汽器回收汽轮机乏汽余热,热网循环水流过凝汽器的水侧来吸收余热。当供热距离较远、管线较长时,热网循环水系统设计压力在2.5 MPa左右,此时凝汽器水侧的设计压力为常规凝汽器水侧设计压力4倍以上。以传统600 MW等级凝汽器水室为例,模拟分析水室在4倍以上设计压力和试验压力下的变形情况,根据模拟结果对传统水室的内部支撑和结构进行优化。

海上油田生产水除气罐水室结构优化研究

在油田生产水处理流程中,生产水除气罐往往作为第一级处理设备,具有重要的除气、除油等功能,但在实际生产运行过程中可能存在处理效果不佳的现象。针对生产水除气罐水室结构的设计缺陷和生产污水流程实际运行状况,停用、检查现场设备,分析查找原因,并设计、制作、安装生产水除气罐水室的收油装置,完善内部结构,实现了生产水除气罐水室收油作业,提高了生产水的处理效果,可为油田类似问题的处理提供参考借鉴。

直流循环凝汽器回水室抽空气改造技术优化及应用

某电厂#1机组、#2机组均采用一次直流供水的开式循环冷却水系统,在机组正常运行的情况下,空气频繁进入凝汽器回水室,使循环冷却水虹吸高度降低,造成机组真空降低,甚至导致凝汽器循环冷却水回水系统虹吸损坏。为此,分析了凝汽器回水室频繁进空气的原因,并通过比较不同类型的凝汽器回水室抽空气改造方案,提出并实施了一种高效分离、全自动控制的凝汽器回水室抽空气改造方案,该方案有效解决了凝汽器回水室频繁进空气的问题。

基于射流点火和气道喷水技术的缸内直喷汽油机稀薄燃烧特性研究

在一台4缸涡轮增压汽油机的基础上,增加预燃室和进气道喷水系统,在最佳油耗工况附近(转速2500 r/min,平均有效压力为0.8~1.2 MPa)开展了试验,研究和分析了汽油机稀薄燃烧特性,以及射流点火和进气道喷水技术对稀薄燃烧性能的影响。结果表明,稀薄燃烧可以将有效热效率从当量燃烧的39.5%提高到42.4%左右,但是当过量空气系数超过1.4以后,燃烧稳定性和碳氢排放变差。采用射流点火技术可以将稳定燃烧的过量空气系数拓展到1.7以上,热效率增加至43.0%以上,燃烧持续期最大缩短37.6%,循环波动不超过1.3%。在此基础上增加进气道喷水,对于平均有效压力在1.1 MPa以上的负荷,抑制爆震效果明显,喷水脉宽达到4 ms时,爆震限制的燃烧重心可以提前到活塞上止点后8°左右,同时最大热效率超过44%,循环波动不超过3%;但是对于平均有效压力低于1.1 MPa的负荷,爆震现象不严重,喷水反而会降低燃烧速率和热效率,同时燃烧稳定性和未燃碳氢排放也随之恶化。

某型柴油机台架试验燃烧室、增压器进水问题分析

某型柴油机在备车过程中,发现燃烧室内存在水分。进一步扩大检查范围,发现增压器底部也有积水现象。该故障导致发动机点火不良,无法正常起动。为了查明原因,对柴油机的内部系统和外部系统进行了故障树分析,最终判断燃烧室及增压器进水的原因为烟气倒灌所致。随后,对烟气中的水蒸气含量以及背压阀的泄漏量进行了计算与分析,并根据分析结果采取了相应的解决措施,经过试验验证,发现该问题已得到解决。

西藏扎拉水电站引水发电建筑物设计

为解决扎拉水电站引水发电建筑物设计过程中存在引水隧洞穿越活动断裂,引水隧洞Ⅳ类、Ⅴ类围岩洞段占比较大,调压室顶部层间密集剪切带,巨型冲击式机组配水环管充水保压浇筑混凝土等重大技术难点,充分论证引水隧洞过活动断裂洞段增加衬砌混凝土厚度、短分节、上部设置排水洞(兼勘探洞、灌浆洞、监测洞)等措施的有效性。通过优化布置和计算线弹性有限元结构,提出了引水隧洞Ⅲ类、Ⅳ类、Ⅴ类围岩分别选取40,60,80 cm厚度衬砌结构设计,调压室选取1.5,1.0 m厚度衬砌结构设计,配水环管选取5.5 MPa的充水保压埋设方式,配水环管分区配置钢筋来优化结构设计。相关设计成果可供同类工程参考。

基于改进突变级数法的引水隧洞施工安全综合评价

为保障引水隧洞施工安全,构建了改进的突变级数法的引水隧洞施工安全评价模型。首先分析引水隧洞施工安全突变特征,构建了引水隧洞施工安全评价指标体系;然后利用ISM-ANP组合赋权方法,获取定性和定量的评价指标,提升评价数据的可靠性;进一步基于ISM-ANP组合赋权结果和突变级数理论构建改进的突变级数综合评价模型。最后以某引水隧洞工程作为评价对象,运用模型对引水隧洞施工安全状态进行评价分析。结果表明:某引水隧洞工程施工安全评价等级为一般,引水隧洞施工过程中存在一定安全隐患;提出的改进突变级数安全评价方法精度较高,可为引水隧洞安全评价提供理论参考。

大断面地下综合管廊--水信仓综合管线安装技术研究

结合某工程实例,阐述了大断面地下综合管廊多种管线立体交叉安装技术,以及施工期间的重要技术措施,尤其是在管廊较长、空间狭小、管线分布密集的地下空间内,研究各种管线的安装技术尤为重要,不仅可以减少交叉施工影响,合理组织施工工序,而且可以提高安装施工效率。

CO_(2)浓度升高对农田生态系统水分利用效率的影响效应——基于气候箱控制性试验的Meta分析

选取1985—2020年21篇与气候箱控制性试验有关的文献,利用Meta分析法研究CO_(2)浓度升高对农田生态系统水分利用效率(WUE)的影响。结果显示,在气候箱的控制下CO_(2)浓度升高对水分利用效率有正面影响,增加的比例为20%,对碳积累和蒸散发分别有正面和负面的效应,影响的效应分别为34%和-4%,但都存在显著的异质性(P<0.05)。研究还发现,CO_(2)浓度升高对WUE的影响效应与对碳积累的影响效应有显著的正相关关系(P<0.05),而与对蒸散发的影响效应没有显著的相关关系(P>0.05)。异质性分析结果显示,CO_(2)浓度升高对WUE的影响效应在不同物种间具有显著的差异,其中对大豆和番茄的影响效应显著高于对小麦的影响效应(P<0.05)。此外,CO_(2)浓度升高对WUE的影响效应与光照强度、温度和土壤相对含水量都有显著的相关关系(P<0.05),其中与光照强度有负相关关系,与温度和土壤含水量有正相关关系;而与CO_(2)富集程度没有显著的相关关系。

张仲景“血不利则为水”学术思想在治疗良性前列腺增生中的应用探析

从张仲景《金匮要略》“血不利则为水”观点出发,基于该理论所体现的“血”与“水”的关系,探讨该理论在良性前列腺增生治疗中的指导作用。良性前列腺增生的主要表现为“水病”,其病因病机也与“血瘀”密切相关。“血不利”作为前列腺增生疾病过程中的重要因素,贯穿于病程始终,临证须重视其存在,根据患者的临床症状表现,抓住病机主要矛盾和次要矛盾,运用补肾化瘀、益气化瘀、行气化瘀、清热化瘀等法,使“血利”,终求“症消”。

Ionization Chamber Dosimetry for Conventional and Laser-Driven Clinical Hadron Beams

The practice of using the direct ionization radiation (electrons, protons, antiprotons, pions, ions, etc) or of the indirect ionization radiation (photons, neutrons, etc) in economy and social life has led to the introduction of the absorbed dose magnitude (ICRU 1953) defined as the energy absorbed per mass unit of the irradiated substance. This is a fundamental magnitude valid for any type of ionizing radiation, any irradiated material and any radiation energy. In case of clinical hadron beams generated by conventional accelerators or those controlled by lasers, IAEA TRS 398 recommends the absorbed dose to water. This may be determined employing the calorimeter method with water or graphite, chemical method, fluence based measurements as Faraday cups or activation measurements, and the ionization chamber method. In this paper the selected method was the thimble air filled ionization chamber method for determination of absorbed dose to water.

Research Progress of Buckling Propagation Experiment of Deep-Water Pipelines

In recent years, the extraction of fossil resources, especially oil and gas in deep and ultra-deep water areas has been playing a more important role and been paid more attention to. For this reason, the working depth of submarine pipelines, which are used for the transportation of oil and gas, has been increasing sharply. As the main failure pattern of deep-water pipelines, buckling and its propagation problem have drawn more attention of many research institutions and engineering units around the world. Based on the existing research, the summary of experiments and their outcomes of deep-water pipeline buckling failure is made in this paper. Research status and developing prospects of the experiments of buckling propagation and buckle arrestor are discussed in detail.

医用电子束水吸收剂量测量及其不确定度讨论

目前医用电子束水吸收剂量测量不确定度超过3%,很难满足临床治疗和医用电子加速器辐射源检定规程的要求。中国计量科学研究院采用水量热法开展了电子束辐射剂量学的研究,实现了电子束水吸收剂量绝对测量相对标准不确定度为0.35%,同时也开展了医用电子束的同质溯源工作,总结了电子束水吸收剂量测量的5个方案,相对标准不确定度包含最高的3.7%和最低的1.4%。为方便临床电子束水吸收剂量测量,给出了电离室剂量计选取、送检和使用不同校准系数的注意事项。