Investigations on High-Speed Flash Boiling Atomization of Fuel Based on Numerical Simulations

Flash boiling atomization(FBA)is a promising approach for enhancing spray atomization,which can generate a fine and more evenly distributed spray by increasing the fuel injection temperature or reducing the ambient pressure.However,when the outlet speed of the nozzle exceeds 400 m/s,investigating high-speed flash boiling atomization(HFBA)becomes quite challenging.This difficulty arises fromthe involvement ofmany complex physical processes and the requirement for a very fine mesh in numerical simulations.In this study,an HFBA model for gasoline direct injection(GDI)is established.This model incorporates primary and secondary atomization,as well as vaporization and boilingmodels,to describe the development process of the flash boiling spray.Compared to lowspeed FBA,these physical processes significantly impact HFBA.In this model,the Eulerian description is utilized for modeling the gas,and the Lagrangian description is applied to model the droplets,which effectively captures the movement of the droplets and avoids excessive mesh in the Eulerian coordinates.Under various conditions,numerical solutions of the Sauter mean diameter(SMD)for GDI show good agreement with experimental data,validating the proposed model’s performance.Simulations based on this HFBA model investigate the influences of fuel injection temperature and ambient pressure on the atomization process.Numerical analyses of the velocity field,temperature field,vapor mass fraction distribution,particle size distribution,and spray penetration length under different superheat degrees reveal that high injection temperature or low ambient pressure significantly affects the formation of small and dispersed droplet distribution.This effect is conducive to the refinement of spray particles and enhances atomization.

Understanding the effects of intramuscular injection and feed withdrawal on Salmonella Typhimurium shedding and gut microbiota in pullets

Background:Gut microbiota plays a key role in health,immunity,digestion,and production in layers.Factors such as environment,diet,diseases,stress,and flock management significantly affect gut microbiota;however,it is not known how potential stressors such as intramuscular injections or feed withdrawal alter the composition of gut microbiota that result in increased the shedding level of foodborne pathogens.In the current study,the effects of intramuscular corticosterone injection and feed withdrawal were evaluated to understand their role in Salmonella Typhimurium shedding and changes in the composition of gut microbiota in layers.Results:Salmonella shedding was observed for 8 weeks post-infection.There was a significant increase in Salmonella Typhimurium count after intramuscular injection and feed withdrawal.The Salmonella infected and the negative control groups showed significant differences in the abundance of different genera in gut microbiota at week 1 and up to week 7 post infection.The infected group showed a significant reduction in alpha diversity of gut microbiota.Firmicutes reduced significantly(P<0.05)after intramuscular injection,while the feed withdrawal groups did not cause any significant changes in Proteobacteria-Firmicutes ratio.Furthermore,intramuscular injection resulted in a significant change in alpha diversity of gut microbiota.Conclusions:Exposure of chicks to relatively low dose of Salmonella Typhimurium can lead to persistent shedding in pullets.The Salmonella Typhimurium infection disrupted the gut microbiota composition immediately after infection.The potential stress of intramuscular injection and feed withdrawal significantly increased the Salmonella Typhimurium count in faeces.The intramuscular injection also resulted in a significant alteration of the Proteobacteria-Firmicutes ratio,which could increase the risk of dysbiosis.

Construction of a model of autologous blood intracerebral hemorrhage in rats with a double injection and double needle withdrawal and the characteristics of the operative technique

BACKGROUND ： Experimental animal models of intracerebral hemorrhag （ICH） are greatly needed, so the process of establishment should be ideal in hematoma formation and easy to operate. OBJECTIVE ： To construct model of ICH in rats with double injection of autologous blood taken from the cut tail cut and double withdrawal of the needle （shortened as two-step injection model）, and compare with those induced by single and double injections. DESIGN ： A randomized controlled tria SETTING： Department of Neurology, General Hospital of Military Area Command of Chinese PLA. MATERIALS： Thirty male Wistar rats of 10 to 12 months, weighing （400±25） g, provided by the Experimental Center of Medical Animals, General Hospital of Shenyang Military Area Command of Chinese PLA, were divided randomly into 3 groups with 10 rats in each group： two-step injection group, single injection group, double injection group. METHODS ： The experiment was carried out in the Department of Neurology, General Hospital of Military Area Command of Chinese PLA from March to June in 2004. Autologous blood ICH model in rats were established as follows： In the two-step injection group, 50 μL unclotted autologous blood was taken from the rat tail cut, then injected with microsyringe into the caudate nucleus, 10 μL injected at first, paused for 2 minutes, and then the rest 40 μL injected slowly and continuously within 2 minutes. After the injection, the needle was kept immovable for about 4 minutes, withdrawn 2.0 mm, again kept immovable for about 4 minute, and then removed wholly at a slow speed. In the single injection group, 50 μL unclotted tail blood was injected slowly and continuously all within 2 minutes and the needle was slowly removed;（4） In the double injection group, 10 mL blood was injected at first, paused for 2 minutes, the rest 40 μL injected evenly within 2 minutes, and then the needle was withdrawn slowly and uninterruptedly. Neurologic findings were scored in accordance with Longa＇s five-point scale （0-4 scores, the higher the score, the severer the neurological dysfunction）. The rats were killed to remove and sections were prepared, the morphological features of hematomas were grossly observed, the maximal diameter and size of hematomas in each slice were measured with the imaging analytical system, and the volume was calculated. Meanwhile, the conveniences of the techniques were compared. MAIN OUTCOME MEASURES： The morphological features and volume of hematomas, neurologic deficit score （NDS）, and the convenience of the techniques were compared. RESULTS： All the 30 rats were involved in the analysis of results without deletion. （1） Results of the morphological observation of volume of hematoma： In the two-step injection group, hematomas located in the right caudate nucleus area regularly in circular or analogously circular shape in each slice. The formation rate of hematomas in the single injection group and double injection group were lower than those in the two-step injection group [60% （6/10）, 80% （8/10）, 100% （10/10）, P〈 0.01, 0.05]. The volume of hematomas in the single injection group and double injection group were smaller than those in the two-step injection group [（28.5±14.8）, （33.4±7.4）, （41.6±3.9） mm3, P〈 0.01, 0.05]. （2） NDS results： The NDS scores in the single injection group and double injection group were smaller than that in the two-step injection group （0.90±0.83, 1.30±0.78, 1.90±0.57, P〈 0.05）. （3）Comparison of the convenience of the techniques： The double injection method allowed generating reproducible hematomas in rats with shortcomings that it needed autologous arterial blood from femoral artery, and precision instruments such as microinfusion pump. The two-step injection injected fresh unclotting blood taken directly from the tail cut with microsyringe into the rat brain, and it has the advantages of easy operation, no influence on the activity of thrombase, shorter duration for model establishment, and higher rate of hematoma formation, which could generate ideal and economical models of ICH. The two-step injection induced hemotoma regularly in circular or analogously circular shape in each slice, but those induced by single and double injections were mostly in strip or fusiform shapes and extending along the needle tracks or into the ventricle or subarachnoid space. CONCLUSION ： The autologous blood ICH model induced by the two-step injection method is a reproducible and reliable one in regular shape, which is better than those induced by double and single injections.

Large-Scale Carbon Dioxide Storage in Salt Caverns:Evaluation of Operation,Safety,and Potential in China

Underground salt cavern CO_(2) storage(SCCS)offers the dual benefits of enabling extensive CO_(2) storage and facilitating the utilization of CO_(2) resources while contributing the regulation of the carbon market.Its economic and operational advantages over traditional carbon capture,utilization,and storage(CCUS)projects make SCCS a more cost-effective and flexible option.Despite the widespread use of salt caverns for storing various substances,differences exist between SCCS and traditional salt cavern energy storage in terms of gas-tightness,carbon injection,brine extraction control,long-term carbon storage stability,and site selection criteria.These distinctions stem from the unique phase change characteristics of CO_(2) and the application scenarios of SCCS.Therefore,targeted and forward-looking scientific research on SCCS is imperative.This paper introduces the implementation principles and application scenarios of SCCS,emphasizing its connections with carbon emissions,carbon utilization,and renewable energy peak shaving.It delves into the operational characteristics and economic advantages of SCCS compared with other CCUS methods,and addresses associated scientific challenges.In this paper,we establish a pressure equation for carbon injection and brine extraction,that considers the phase change characteristics of CO_(2),and we analyze the pressure during carbon injection.By comparing the viscosities of CO_(2) and other gases,SCCS’s excellent sealing performance is demonstrated.Building on this,we develop a long-term stability evaluation model and associated indices,which analyze the impact of the injection speed and minimum operating pressure on stability.Field countermeasures to ensure stability are proposed.Site selection criteria for SCCS are established,preliminary salt mine sites suitable for SCCS are identified in China,and an initial estimate of achievable carbon storage scale in China is made at over 51.8-77.7 million tons,utilizing only 20%-30%volume of abandoned salt caverns.This paper addresses key scientific and engineering challenges facing SCCS and determines crucial technical parameters,such as the operating pressure,burial depth,and storage scale,and it offers essential guidance for implementing SCCS projects in China.

综放工作面停采期间防灭火方案设计及应用

高瓦斯煤层的开采面临瓦斯与煤炭自然发火并存及耦合的问题,尤其是在工作面停采回撤期间,自然发火风险成倍增长,本文针对8306综放工作面停采期间所面临的防灭火工作难题,首先分析出采空区遗煤多、工作面漏风隐患大、工作面推采放缓甚至停滞等防灭火难题,然后针对性制定了防止采空区漏风、采空区注氮惰化、液压支架后方喷洒阻化剂,以及加强监测监控及预测预报等综合防灭火方案,有效抑制了采空区遗煤的自燃进程,保障了矿井安全生产。

Optimal design of the gas storage surface pipeline system with injection and withdrawal conditions

Underground natural gas storage(UNGS)is an important part of the natural gas supply system to ensure a balanced energy supply.The surface system,as an important part of the gas storage,undertakes the functions of gas injection and gas production of the gas storage,and its investment economy is of vital importance.In fact,the UNGS surface pipeline network has two-way injection and production characteristics,which is different from the one-way production characteristics of conventional oil&gas gathering and transportation systems.This paper takes the minimum investment of the pipeline network as the objective function,considers the gas injection and gas withdrawal flow conditions and esablishes a mixed integer non-linear programming model(MINLP)for the surface pipeline network of the UNGS to optimize its pipeline layout and diameter parameters.Constraints including the well affiliation,the number of stations,the gathering radius,the processing capacity and the flow/pressure equilibrium equations,are also taken into consideration.Taking an UNGS in China as an example,the results of the optimal structure and diameter of the pipeline network,as well as the pipe flow,node pressure,and maximum/minimum flowrate during gas injection and gas withdrawal are obtained.Finally,the effects of constraints such as processing capacity and radius on the structure layout and investment of the UNGS are analyzed,verifying the reliability and effectiveness of the model.

欧盟食品动物注射部位兽药残留指南概述

2022年3月25日,欧盟药品管理局(EMA)兽医药品委员会(CVMP)发布了食品动物注射部位兽药残留指南,并于2022年8月1日正式生效。该指南代替旧版的注射部位兽药残留指南(EMA/CVMP/542/03-FINAL)。本文就新发布指南的背景、适用范围、法律依据、评价方法、残留研究及相关定义等内容进行介绍。

基于单井注抽试验的增强型地热系统储层近井渗透率原位测试方法研究

储层压裂阶段,对近井渗透率的高效评估是分析压裂效果、更新压裂方案的重要环节。但受技术或成本制约,目前仍然缺少深部储层近井渗透率原位测算方法。借助于压裂施工过程的间歇性注入和返排泄压环节,提出一种依托压裂施工过程的单井注抽示踪试验工艺,以及基于数值求解和解析解的2种渗透率估算方法,实现了低成本条件下深部储层渗透率原位测试。将该套方法体系应用于实际增强型地热系统场地,结果显示:在单井注抽试验示踪剂突破曲线不完备条件下,通过数值方法仍然能够合理地估算近井渗透率(0.8 D),但方法计算效率较低;而在示踪剂突破曲线相对完备条件下(即监测得到示踪剂浓度峰值),可采用解析法快速估算渗透率(0.25 D);但由于解析法中未能精确考虑井筒内部长距离示踪剂迁移过程和储层内部弥散作用对示踪剂突破曲线的影响,计算精度相对较低。然而,通过数值方法和解析方法估算近井渗透率处于同一数量级,表明解析法仍可以作为渗透率原位快速估算的一种有效手段。文章提出的单井注抽试验工艺和数据解释方法体系为深部储层渗透率原位测试提供了一种新的途径。

复方甘草酸苷对SARS患者激素撤药综合征的影响

目的 :探讨复方甘草酸苷 (GL)在SARS患者减激素治疗过程中的作用。方法 :采用回顾性分析方法 ,观察GL对SARS患者的激素撤药综合征 (HWS)相关症状和指标的影响。结果 :应用GL后可使HWS症状发生率降低 ,其中SARS患者的主要症状气短、胸闷的发生率分别由24 5 %和22 6 %降低至3 6 %(P≤0 01)和7 1 %(P≤0 05) ;乏力、肌肉关节痛、头痛的发生率分别由13 2 %、15 1 %、10 4 %降至7 2 %、14 3 %、0 %;SARS患者ALT升高例数减少 (P≤0 01)。结论 :激素撤药过程中应用GL ,可以降低HWS的发生率。

中国地下储气库现状及技术发展方向

中国地下储气库建设经过多年探索,已经进入一个新的发展阶段。已经投产的11座地下储气库群设计工作气量达到180×10~8 m^3,在国内天然气调峰安全保供中发挥了重要作用。但国内地下储气库建设仍面临不少困难:①储气库工作气量增长速度慢,落后于调峰需求量增长的速度;②建设工程技术难度大,投资成本高;③安全运行压力大,风险识别和控制困难;④库址资源少,建库条件复杂;⑤尤其是在现有天然气价格体制下,储气库难以通过自身运营获得经营效益。究其原因,主要是已经形成的运营方式和建库技术尚不足以应对市场和复杂地质条件所带来的挑战。为破解这一系列难题,在开展市场化运作模式探索的同时,更需要加大技术攻关力度,加强研究地质评价与气藏工程、钻井完井工程、储气库注采工程、地面配套工艺及储气库完整性评价等多个方面的核心技术,大幅提高储气库建库效率,以促进我国地下储气库的可持续发展。

鞘内氯诺昔康对正常大鼠痛阈的影响

目的探讨鞘内注射氯诺昔康对正常大鼠的机械痛阈及热痛阈的影响。方法雄性SD大鼠18只,用于机械痛阈测定,随机平均分为3组,鞘内溶剂组(S组,鞘内注射氯诺昔康注射用水20μL)、肌注组(IM组,肌注氯诺昔康120μg/20μL)、实验组(IT组,鞘内注射氯诺昔康120μg/20μL)。另取雄性SD大鼠18只,用于热痛阈测定,动物分组及处理同前。分别于注射前(痛阈基础值)和注射后10、30、60、90、120、150min采用足底力学感觉测量仪和足底温觉测量仪对机械痛阈和热痛阈进行测定。结果S组在鞘内注射前后的机械痛阈和热痛阈值无明显变化。IM组在肌注后30min,机械痛阈值〔(31.1±4.05)g〕和热痛阈值〔(20.82±2.15)s〕出现高峰(P<0.05或P<0.01);分别于60min和90min恢复至基础水平。IT组在鞘内注射后10min,机械痛阈值〔(35.0±2.76)g〕和热痛阈值〔(26.72±3.75)s〕均大于基础值(P<0.01);分别于90min和120min恢复至基础水平。3组机械痛阈和热痛阈的基础值差异无统计学意义。在10、30、60min,IT组的机械痛阈值高于S组(P<0.01或P<0.05);在10、30min,IT组高于IM组(P<0.05)。在10、30、60、90min,IT组的热痛阈值均高于S组和IM组(P<0.01或P<0.05)。结论鞘内注射氯诺昔康可以提高正常大鼠的机械痛阈和热痛阈,与全身系统给药相比,该作用起效快,维持时间长。

水驱气藏型储气库运行指标动态预测

针对水驱型气藏储层特征,通过归类分析揭示水驱气藏型储气库注、采运行规律,确定边水运移、岩石骨架应力敏感性及储层展布特征是此类气库运行效果的主要影响因素,并进一步完善水驱气藏型储气库渗流模型。从储层流体非稳态渗流理论出发,采用循环迭代的方式实现了水驱气藏型储气库运行指标动态预测,建立一种针对水驱气藏型储气库运行的参数分析方法。

孔隙介质毛细滞回简化模型研究

土-水特征曲线的研究是非饱和孔隙介质研究的重要部分。完整的土-水特征曲线包括初始脱湿曲线(IDC)、主吸湿线(MWC)和主脱湿线(MDC)3部分。传统的土-水特征曲线实验需要花费较长的时间和精力。以文献中的试验数据为依据,对非饱和土土-水特征关系和岩石的汞注入抽出试验的滞回现象进行了深入研究,提出一个经验模型来模拟MDC曲线。如果已根据试验得到了孔隙介质的IDC和MWC,此模型只需要一个参数,即可得到增量形式的MDC。通过与试验结果相比较,验证了模型对MDC模拟的有效性。

大港油田地下储气库可行性研究

通过对大港油田已枯竭的板８２０气藏的更加深入的地质研究，重新评价了该气藏的储集层和盖层，论证了作为地下储气库的地质可行性；通过对开发史分析研究，论证了作为地下储气库的开发可行性，并计算了气藏开发动态储量。根据多年来对天津市供气规律，确定了储气库调峰周期和基本参数。设计了注采井生产能力和注采方案。根据经济评价，认为利用废弃气藏作为地下储气库经济效益显著。图２表１（郭海莉摘）

气藏型储气库注采运行物理模拟研究与应用

气藏型地下储气库运行过程中常出现实际库容量小于设计库容量及运行效率低等问题。为此,研发了物理模拟实验系统,定量研究了气藏型储气库建库与注采运行机理。以水侵砂岩气藏储气库为例,采用该系统针对储气库高速反复注采的工况,研究了建库气驱机理、多周期注采过程气水渗流规律及其对库容量和注采能力的影响,确定了影响气库运行效率的主控因素;并与矿场生产实际运行效果进行了对比分析。结果表明:1储层受边水运移影响,孔隙空间可利用程度逐步降低,气相渗流阻力逐步增加,从而影响气库扩容及注采效果;2储层的可动含气孔隙空间比例随注采周期增加呈上升趋势,由于受储层孔喉分布非均质性、驱替压力梯度限制以及细小孔喉较强的毛细管力作用,扩容所增加的可动孔隙空间有限,使可动孔隙空间利用效率较低,约为45%;3物理模拟孔隙空间利用率与储气库实际运行过程变化趋势相同,误差在5%以内。结论认为:该物理模拟实验系统所得结果的可靠度较高,有助于制定合理的运行制度,最大限度地提高储气库运行效率。

易燃大倾角厚煤层综放面停采撤架期间综合防灭火技术

针对崔木煤矿21302综放工作面在停采撤架期间出现回撤面CO浓度超限以及发生停采线架后遗煤自燃的问题,从工作面地质构造、遗煤量、漏风等方面分析了回撤面遗煤自然发火的原因,针对该工作面的实际情况和各种防灭火技术的特点采取了中段修建密闭墙后双通道回撤技术,在工作面封闭后提出了在架前钻孔灌注胶体材料、封闭注氮、高位钻孔注水相结合的降温、降氧的防灭火方案,有效降低了该工作面在火区启封后的CO气体浓度和温度,保证了工作面支架的安全撤出。

基于VB和HYSYS的地下储气库地面井筒一体化压力计算系统

已有HYSYS软件本身没有井筒模块,不能在HYSYS中实现对地下储气库注采气井筒部分压力系统的模拟。为此,通过分析地下储气库注采气井井筒压力传递机理,建立了井筒压力计算数学模型;在此基础上,基于VB软件开发平台,利用HYSYS模拟软件的Extension模块扩展功能,将地下储气库注采气井井筒压力传递模型嵌入HYSYS新的单元模块,由此可方便地实现注采气井井口压力与井底压力之间的数值关联计算与压力模拟传递,并且在HYSYS的PFD模拟流程图中可以直接调用扩展开发的井筒模型。仿真计算结果表明,采用开发出的井筒压力传递模块模拟计算出的压力数据与实测数据偏差很小,能满足现场模拟计算的需求。此外,基于VB与HYSYS模拟平台对地下储气库注采气井井筒模块的成功开发使得地下储气库地面井筒压力模拟更加便捷,操作过程简化,实现了地下储气库地面管网压力系统与注采井筒压力系统的一体化模拟。

气顶油藏型地下储气库注采动态预测方法

气顶油藏型地下储气库建设及运行在我国刚刚起步,尚缺乏现场实用的运行注采动态分析与预测方法。为此,根据气顶注采气过程中气相与油相的压力响应特征,引入了周期可变动用剩余油量与地层压力的关系,真实还原了剩余油量在注采气过程中对地下储气库运行的影响,建立了周期注采气动态预测数学模型,得到了一个完整注采周期内气顶自由气、地层剩余油的动用量以及与之相对应的库容参数预测指标。实例计算结果表明:(1)一方面,周期可动用剩余油量对气顶自由气动用量的影响不能忽略,可动剩余油的弹性作用使气顶内部压力响应特征产生了较为复杂的改变,有可能导致气顶油藏型地下储气库建库周期较气藏型地下储气库长;(2)另一方面,随着注采周期的延长,储气库内动用自由气、剩余油的动用量逐步增长,但趋势渐缓,从而使注入气向剩余油溶解扩散造成的损耗气量始终保持在较低水平,不会对储气库的稳定运行造成负面影响。

复杂断块油藏水平井二氧化碳吞吐注采参数优化研究

水平井是冀东油田浅层复杂断块油藏的主要开发方式,随着水平井的持续开发,含水快速上升,严重影响了开发效果。采用CO_2吞吐可进一步提高增油效果和产能,降低含水上升速率。为优化CO_2吞吐的注采参数、提高现场试验效果,利用矿场岩屑设计制作了CO_2吞吐三维物理模型(尺寸30 cm×30 cm×12 cm,水测渗透率1.160μm^2,孔隙度31%),使用该模型开展了注入量、焖井时间等注采参数优化研究。结果表明,CO_2吞吐增油效果明显,采收率较衰竭开采增加幅度为1.97%~9.47%,换油率为1.14~3.62 m^3/m^3;为达到最佳的增油效果,宜采用的CO_2吞吐注采参数为:注入量0.3~0.4 PV、焖井时间12~15 h、注入速率4~6 mL/min、采液速率480~600 mL/h。

多层非均质低流度油藏稳油控水技术研究与应用

针对大港南部油田具体地质和开发生产特征,提出以水治水、提速开采、以水促油、高效注水的开发思路和技术措施,在前人精细油藏地质研究基础上,针对不同的油藏类型及所处开发阶段,结合油藏微观渗流特征、剩余油分布规律,通过Logistic旋回数学模型、开发动态分析法和经验公式法确定最大采液量、合理注采比、合理采油速度等开发参数,最终使得大港南部油田水驱开发效果得到明显改善,并对多层段低流度油藏减缓层间及平面矛盾起到重要作用,也为国内同类型的低流度复杂断块油藏注水开发开拓了一条捷径。