Simulation of Wetting and Drying Processes in A Depth Integrated Shallow Water Flow Model by Slot Method

A particular porosity method named ＂slot method＂ is implemented in a depth-integrated shallow water flow model （DIVAST） to simulate wetting and drying processes. Discussed is the relationship between the shape factors of the ＂slot＂ and the preset depth used in ＂wetting-drying＂ algorithm. Two typical tests are conducted to examine the performance of the method with the effect of the shape factors of the ＂slot＂ being checked in detail in the first test. Numerical results demonstrate that： 1 ） no additional effort to improve the finite difference scheme is needed to implement ＂slot method＂ in DIVAST, and 2） ＂slot method＂ will simulate wetting and diying processes correctly if the shape factors of the ＂slot＂ being selected properly.

Study on Flow and Mixing Characteristics of Molten Steel in RH and RH-KTB Refining Processes

The flow and mixing characteristics of molten steel during the vacuum circulation refining, including RH(Ruhrstahl Heraeus) and RH KTB(Ruhrstahl Heraeus Kawasaki top blowing) processes, were investigated on a 1/5 linear scale water model of a 90 t multifunction RH degasser. The circulation rate was directly and more accurately determined, using a new method by which the more reliable results can be obtained. The fluid flow pattern and flow field in the ladle were demonstrated, observed and analyzed. The mixing time of liquid in the ladle was measured using electrical conductivity method. The residence time distribution in the RH model was obtained by tracer response technique. The influence of the main technological and geometric factors, including the gas top blowing (KTB) operation, was examined. The results indicated that the circulation rate of molten steel in the RH degasser can be fairly precisely calculated by the formula: Q lp =0.0333 Q 0.26 g D 0.69 u D 0.80 d(t/min), where Q g-the lifting gas flow rate (NL/min); D u and D d-the inner diameters of the up and down snorkels (cm), respectively. The maximum value of circulation rate of molten steel in the case of the 30 cm diameters either of the up and down snorkels for the RH degasser (the “saturated” rate) is approximately 31 t/min. The corresponding gas flow rate is 900 NL/min. Blowing gas into the vacuum chamber through the top lance like KTB operation does not markedly influence the circulatory flow and mixing characteristics of the RH process under the conditions of the present work. There exist a major loop and a large number of small vortices and eddies in the ladle during the RH refining process. A liquid liquid two phase flow is formed between the descending stream from the down snorkel and the liquid around the stream. All of these flow situation and pattern will strongly influence and determine the mixing and mass transfer in the ladle during the refining. The correlation between the mixing time and the stirring energy density is τ m∝ε -0.50 for the RH degasser. The mixing time rapidly shortens with an increase in the lifting gas flowrate. At a same gas flow rate, the mixing times with the up and down snorkel diameters either of 6 and 7 cm are essentially same. The 30 cm diameters either of the up and down snorkels for the RH degasser would be reasonable. The concentration time curve showed that three circulation cycles are at least needed for complete mixing of the liquid steel in the RH degasser.

Parametric Linear Stochastic Modelling of Benue River flow Process

The dynamics and accurate forecasting of streamflow processes of a river are important in the management of extreme events such as floods and droughts, optimal design of water storage structures and drainage networks. In this study, attempt was made at investigating the appropriateness of stochastic modelling of the streamflow process of the Benue River using data-driven models based on univariate streamflow series. To this end, multiplicative seasonal Autoregressive Integrated Moving Average (ARIMA) model was developed for the logarithmic transformed monthly flows. The seasonal ARIMA model’s performance was compared with the traditional Thomas-Fiering model forecasts, and results obtained show that the multiplicative seasonal ARIMA model was able to forecast flow logarithms. However, it could not adequately account for the seasonal variability in the monthly standard deviations. The forecast flow logarithms therefore cannot readily be transformed into natural flows;hence, the need for cautious optimism in its adoption, though it could be used as a basis for the development of an Integrated Riverflow Forecasting System (IRFS). Since forecasting could be a highly “noisy” application because of the complex river flow system, a distributed hydrological model is recommended for real-time forecasting of the river flow regime especially for purposes of sustainable water resources management.

黄河内蒙古河段水文情势变化及生态效应初探

选择月均流量、日均流量变幅、极端流量和脉冲延时4个水文情势指标,采用IHA-RVA(水文情势变化指标-变化范围法)分析黄河干流内蒙古河段水文情势的时空变化特征,辨析黄河鱼类生态习性与径流组分的响应关系,探讨内蒙古河段流量过程、极端流量变化的生态效应。黄河干流上游河段水利工程运行后,内蒙古河段的水文情势明显改变,进而改变该河段的生态水文联系过程。黄河内蒙古河段枯水期月均流量增加(1、2月份月均流量增幅超过70%)、最小日均流量增加(石嘴山断面最小日流量增幅超过50%),保障了河道流水栖息生境,有利于鱼类越冬。该河段日均流量变幅降低,有利于粘性卵孵化。但是内蒙古河段汛期月均流量减小(7-10月份月均流量降幅接近50%),大、小洪水持续时间缩短,不利于扩展横向栖息地;最大流量出现时间在上游河段延迟超过2个月、在中下游河段提前约1个月,洪水脉冲刺激时间紊乱可能影响鱼类繁殖行为。研究可为黄河内蒙古河段鱼类栖息地保护以及上游水库生态调度提供技术支持。

自动调控畦灌系统中调控要素对水流运动过程的影响

自动调控畦灌是提高灌水质量、减少劳动力需求的重要措施。为探究自动调控畦灌系统如何合理选取调控要素,通过畦灌观测试验获取畦田自然参数,结合WinSRFR模型模拟畦灌过程,分析自动调控畦灌系统中停水距离、停水时间和入畦流量对水流运动过程和土壤水分入渗分布的影响规律。结果表明,停水距离和停水时间在田面水流推进过程、消退过程、土壤水分入渗分布以及灌水质量等方面的调节效果相似。对于100 m畦长的典型试验畦田,七成改水、七五改水、八成改水、八五改水、九成改水的调控效果分别对应灌水量70、80、90、100、110 mm。停水时机对畦田后段的水流推进、消退过程影响较大,而对畦田前段的水流推进、消退过程影响较小,不同改水成数或灌水量并不能显著改变畦田前段的土壤水分入渗分布。调控流量较停水距离和停水时间可以更有效地调控畦田前段的灌水效率和灌水均匀度。因此在优先考虑经济性的自动调控畦灌系统中推荐调控灌水量,而在追求精准调控的自动调控畦灌系统中推荐调控流量。

头部喷气对跨介质航行体入水过程载荷特性的影响

跨介质航行体入水瞬间会受到巨大的冲击载荷,极易导致结构破坏甚至内部器件失灵。为发展有效的降载方法,本文基于VOF(Volume of Fluid)多相流模型,研究头部喷气航行体入水过程的载荷特性和流体动力特性,分析喷气压力、喷气高度对降载效果的影响,并探索头部喷气降载方法有效性的入水速度范围。研究结果表明,头部喷气使自由液面下凹形成空腔,并能极大地降低航行体所受阻力和冲击力,延缓了航行体撞水时间,从而实现冲击载荷控制;喷气压力和喷气高度对入水空泡形态及冲击压力峰值的影响都不大,合理的选择既能达到降载效果又能节约喷气量;入水速度为50 m/s时,降载量高达76.51%,但当入水速度为300 m/s时,降载量仅为39.92%。因此,针对高亚声速跨介质入水问题,需进一步探索主被动相结合的复合降载方法。

渤海低渗油田水处理工艺研究

渤海低渗油田开发是未来产量接替、稳产增产的重要组成部分,但海上现有低渗水处理规模小,工艺流程差异性大。通过总结海上现有低渗水处理工艺流程及应用效果,并对比分析了海上应用的膜过滤及改性纤维球过滤器两种低渗水处理技术的特点,在渤海油田标准化水处理工艺流程基础上,提出了斜板除油器-气浮-核桃壳过滤器-双介质过滤器-膜过滤/改性纤维球过滤器的低渗水处理工艺流程,并对低渗水处理技术发展及流程设计提出了建议,以期为渤海低渗油田的开发设计提供指导借鉴,进一步推动渤海低渗油田的开发利用。

DTRO系统废水浓液减量化研究与应用

本文以某材料有限公司废水减量DTRO装置项目为研究案例,深入探索DTRO系统废水浓液减量化应用情况。在说明项目背景以及废水系统现存问题的基础上,重点阐述了ROR浓液减量化研究,主要包含生化系统工况改善措施与DTRO系统应用中的碟管式反渗透工艺、DTRO组件及膜系统相关内容;并且最终开展了系统运行测试,同时通过优化改进的DTRO系统具有突出性亮点,取得了符合预期目标的改善效果。

长距离输水有压-无压耦合水力瞬变的Godunov格式建模模拟

针对含无压流、倒虹吸有压流联合的长距离输水系统,建立有限体积法Godunov格式的有压-无压耦合水力瞬变数学模型,并对运行水力特性进行模拟研究。对于无压流转变为有压流时,提出考虑有压流水锤效应的Preissmann狭缝法,实现有压流水力瞬变的模拟计算。基于有限体积法Godunov格式对控制方程进行离散求解,采用了虚拟边界法实现了边界与内部单元统一计算,简化了计算的繁琐。结合实际工程,针对稳态运行流态、糙率敏感性、水力过渡过程进行计算分析。结果表明:所建模型模拟结果与精确黎曼解数据基本一致;稳态运行情况下,运行流量越大、糙率越大、下游出水口水位越高,满管率、最大管道充满度、最小管道充满度越大,水面线越高。较高水面线时倒虹吸的惯性振荡可导致瞬变过程出现局部明满交替流波动。

矿井水井下短程直滤处理工艺中试研究

针对当前矿井水井下处理存在处理流程长、占地面积大、运行效果差等问题,提出了以有机金属卷式超滤膜为主要净化核心的井下直滤处理工艺及智能化装备,并在宁东地区某煤矿井下综采工作面进行了中试研究。研究结果表明,在低运行通量条件下,直滤系统运行较为稳定,并未有明显的膜污染情况发生,膜通量衰减不足3%。在初始运行通量为47.4 L/(m^(2)·h),回收率为84.6%条件下,运行48 d后,运行通量衰减9.01%,其膜通量的衰减主要由滤饼层沉积所引起的膜污染导致。同时在恒压运行方式下,提高直滤系统的回收率,进水量随产水量的增加而减小。在进水浊度为10~30 NTU范围内,直滤系统产水水质较为稳定,产水浊度低于0.5 NTU。整体运行效果表明该直滤技术具有处理流程短、产水水质稳定、抗污染性能强等优点,在井下具有较为明显的应用优势。

打造数智竞争优势 提升盐酸合成装置运行品质

氯化氢合成炉投入运行以来,历经两次技术改造,自动化、智能化程度不断提高。通过对各阶段控制模式下运行数据的对比,说明如何实现了合成炉运行质量的飞跃。

Assessment of impact of water diversion projects on ecological water uses in arid region

In arid regions, large-scale water diversion from rivers leads to significant changes in river flow regimes, which may have large impacts on ecological water uses of river-dependent ecosystems, such as river, lake, wetland, and riparian ecosystems. To assess the integrated impact of water diversion on ecological water uses, we proposed a hierarchy evaluation model composed of four layers representing the evaluation goal, sub-areas of the influenced region, evaluation criteria, and water diversion schemes, respectively. The evaluation criteria for different types of ecological water uses were proposed, and the analytical hierarchy process was used for the integrated assessment. For a river ecosystem, the percentage of mean annual flow was used to define the grade of environmental flow. For a lake ecosystem, water recharge to the lake to compensate the lake water losses was used to assess the ecological water use of a lake. The flooding level of the wetland and the groundwater level in the riparian plain were used to assess the wetland and riparian ecological water uses, respectively. The proposed model was applied to a basin in northern Xinjiang in northwest China, where both water diversion and inter-basin water transfer projects were planned to be carried out. Based on assessment results for the whole study area and two sub-areas, an appropriate scheme was recommended from four planning schemes. With the recommended scheme, ecological water uses of the influenced ecosystems can be maintained at an acceptable level. Meanwhile, economical water requirements can be met to a great extent.

Seismic geomorphology and main controls of deep-water gravity flow sedimentary process on the slope of the northern South China Sea

The Quaternary continental slope of the Baiyun Sag in northern South China Sea is characterized by a complex topography and abundant gravity flow sedimentation.High-resolution 3-D seismic data in this area allow for a detailed study of the seismic geomorphology and deep-water gravity flow depositional process.The Quaternary continental slope in the northern South China Sea is an above-graded slope.An intraslope basin lies within the above-grade continental slope.Slump,erosion,and deposition processes tend to develop a gentle topography and consequently a graded slope.The upper continental slope,which is above the slope equilibrium profile,is dominated by erosion and slumping.Slides,slumps and erosional channels are developed within this continental slope.The intraslope basin is located below the slope equilibrium profile and is potential accommodation space where sediments transported by gravity flows could be deposited,forming lobe aprons.Under the influence of gravity flow supply,gravity flow duration,continental slope topography,equilibrium profile,and accommodation,a slump-erosional channel-lobe depositional system is developed in the Quaternary continental slope in the Baiyun Sag.The deep-water gravity flow depositional process and the distribution of gravity flow sediments are greatly influenced by the continental slope topography,while the continental slope topography at the same time is reshaped by deep-water gravity flow depositional process and its products.The study of the interplay between the continental slope and gravity flow is helpful in predicting the distribution of the deep-water gravity flow sediments and the variation of sediment quality.

深水重力流沉积油气勘探中的几个基础沉积学问题与研究展望

深水重力流沉积物中多蕴含着丰富的油气资源,但现阶段对深水重力流沉积砂体分布及优质储集层分布规律认识还存在较多问题,制约了油气勘探与开发。超临界浊流与亚临界浊流之间的相互转化和浊流向泥质碎屑流的转化是形成重力流沉积物分布新认识的2个核心热点问题。深水重力流沉积存在水道—堤岸、水道—朵叶转换带和朵叶等多种沉积构型要素,对其沉积识别标志的精细解析是明确砂体分布的重要依据。深水超临界浊流向亚临界流转化过程中强烈的水力跳跃作用侵蚀基底沉积物是形成重力流水道的最新认识。构造活动、沉积物供给和海(湖)平面变化是控制重力流沉积砂体分布的盆外因素;沉积盆地水体密度、盆底地貌和地形坡度则是决定重力流沉积砂体分布的盆内因素。深水重力流沉积砂体埋藏成岩演化过程中的砂泥协同成岩作用对相对高孔隙度和渗透率的优质储集层发育起到重要控制作用。野外露头与现代观测并重的沉积过程研究、深水重力流沉积构型要素与内幕结构研究、深水重力流成因细粒沉积与页岩油气研究、深水重力流沉积砂体成岩作用研究有望成为下一步深水重力流沉积油气勘探沉积学研究的重点。

布尔台选煤厂末煤系统分析与优化

针对布尔台选煤厂末煤系统存在的问题,提出对末煤系统进行选前脱粉、煤泥水流程改造与板框压滤机更新。通过一系列的优化改造,末煤系统煤泥含量降低1.6%,品种煤预计每年可以增加150万t/a。为煤泥浮选入料性质优化、粗煤泥分选项目奠基,保证煤炭产品质量实现稳定化、均质化、优质化,提高了企业经济效益。

引汉济渭工程初期运行调水区河道生态流量优化研究

针对跨流域调水工程等强人类活动对河道生态造成严重影响的实际问题,以引汉济渭工程为研究对象,建立并求解了工程运行初期多年调节水库三河口的中长期调度模型,设定了不同生态需水下的调度方案集,量化与评估了工程初期运行对供水与生态的满足情况,并推荐了最佳的调度方案与优化的生态流量过程。研究表明:(1)在生态需水为生态基流时(设计方案),供水与生态基流保证率均满足设计要求,验证了模型与方法的合理性;(2)在生态需水为适宜生态流量时,供水与生态基流保证率分别为65%、98%,表明供水与生态两者间呈竞争关系;(3)在生态需水为修正的生态流量时,供水与生态基流保证率分别为95%、100%,在满足供水目标的同时,河道内月平均流量较设计方案提高了47%,推荐该调度方案与生态流量过程为最佳方案与最优生态流量过程。研究成果对构建生态流域、提高跨流域调水工程的综合效益具有实际意义和应用价值。

底板破碎条件下高承压水快速堵水技术研究

底板高度破碎条件下快速堵水是煤矿防治水的难点。孟津煤矿通过突水水源快速判定、科学布置堵水钻孔,注非水溶性聚氨酯将管道流改造成渗流,结合合理的注浆工艺,实现了堵水率高、用时短、成本低的良好堵水效果,对孟津煤矿保护地下水资源、消除矿井安全隐患具有重要的意义,为其他矿井类似堵水工程提供经验借鉴。

水利工程水闸施工工艺流程与质控对策分析

水闸是重要的基础水利设施,其质量控制是水利工程全寿命周期管理的关键。为从源头加强质量控制、保证水闸施工质量,延长水利工程使用寿命,文章阐述了水利工程水闸施工工艺流程,分析了水利工程水闸施工质控对策,包括水闸总体施工质控对策和闸室施工质控对策,旨在为有关人员提供参考。

A^(2)/O+MBR+潜流湿地在南方小流域环境综合整治中的应用

受制于该流域用地指标及用地性质的影响,结合流域环境整治的景观需求,采用了灰绿结合的A^(2)/O+MBR+潜流湿地组合工艺形式作为流域治理的水质净化处理工艺对流域收集的污水进行处理。工程运行四年来,出水主要指标稳定达到《地表水环境质量标准》(GB3838-2002)Ⅳ类水质标准(TN≤10 mg/L),其中再生水厂COD、BOD5、NH_(3)-N、TN、TP、SS平均去除率分别达到91.18%、98.27%、97.83%、62.74%、91.29%和99.04%;潜流湿地NH_(3)-N、TN、TP平均去除率分别达到38.44%、12.15%和33.04%。工程实践表明,该组合工艺不仅满足了流域水质要求、节约占地,同时也起到了很好的景观效果。

FPSO油-水旋流分离器模拟分析及应用研究

旋流分离器因其紧凑高效在海上平台污水处理单元中被广泛应用。基于巴西某海上油田的污水实况,根据该油田FPSO的污水处理工艺及设计特点,通过对比分析常见的几种含油污水处理方法,并运用FLUENT软件,建立油-水旋流器几何模型,研究旋流分离器内部流场分布特性,综合分析分离性能随来液流速的变化规律。根据运行工况,当旋流器入口流速为3 m/s时,分离效率低于70%,分离效果不理想;当入口流速为7 m/s时,分离效率高于90%,分离后污水含油质量浓度低于100 mg/L。流速过高时,分离效率下降,这是由于流速过大,导致油滴破裂,甚至加剧乳化。这一规律可为今后海上平台污水处理工艺设计提供参考。在实际运用时,应根据油田污水性质、实际环境要求、油滴变形破裂及能耗,选择合适的处理工艺及最优的入口流速。