上倾管内油水两相流流型实验研究

国内多条成品油输送管道在投产和运行过程中,采用"水联运"投产方式所造成的上倾管道低洼处积水现象引起了严重的管道内腐蚀问题。利用上游来油将低洼处积水携出管道能有效缓解内腐蚀。采用0#柴油、去离子水在内径100 mm的上倾管道内观察油水两相流流型并测量油携水临界流速。结果表明,随油流黏性力增大和管道倾角增大,油水两相流依次呈现波状分层流、有水滴的波状分层流和油相占主导的分散流3种流型;同一流型下,油相能将水相携入上倾段的最低临界流速随倾角增大而增大;倾角从20°增大到25°使流型从波状分层流转化为有液滴的波状分层流时,油相能将水相携入上倾段的临界流速从0.203 m/s减小为0.187 m/s;倾角从30°增大至35°时,使初始流型从有液滴的波状分层流转换为水相在油相中的分散流,油相能将水相携入上倾段的临界流速从0.205 m/s减小为0.194 m/s;油相能将水相完全携出上倾段的临界流速随倾角增大而略有增大;发生流型转化的流速随倾角增大而减小。     

管道内污水两相流临界流速浅析

城市排水管道设计中,普遍将污水视为单相流并采用最小流速准则控制排水管道中的泥沙淤积。这种设计准则存在着缺陷,兹将污水视为液-固两相流体,引用著名的克诺罗兹明槽两相流临界流速经验公式以及国内学者费祥俊提出的浆体管道不淤流速公式,根据相似理论,从两相流的角度对有压管道污水的不淤流速进行计算与分析。结论认为,在大多数水质条件及管径范围内最小控制流速设计标准是可行的,但在大型管道和复杂水质条件下有待于进一步修正提出更可靠的设计准则。     

能源塔波纹填料表面液膜流动过程模拟研究

能源塔吸热过程的实质是塔内波纹填料表面液相降膜与逆流气相接触发生热质交换,为探究填料表面液膜流动对能源塔内气液两相热质交换过程的影响机制,文中建立了波纹填料表面液相降膜流动模型,模拟了不同气液相入口参数以及不同波纹结构的填料表面的液膜流动过程,通过对比各工况下填料表面稳定液膜的特性,分析了影响液膜流动的关键因素,从增强气液相接触角度出发,寻求更加合理的气液相入口参数和波纹结构。     

90°弯管内固液两相流临界流速浅析

以90°弯管中固液两相流作为研究范围,并将此特殊水力状况下的固体颗粒假设为随液体一起作沿弯管轴线的圆周运动,速度采用断面平均速度的方式,进行受力分析、求解,来研究管道内固液两相流动的颗粒沉降速度以及流体的不淤流速,并做出了针对物料的性质、流体的性质和管道特性等相关影响因素的分析.     

起伏管内局部油水两相流流动特性实验研究

地形起伏成品油管道积水不仅降低管输效率、加速管道内壁腐蚀,其腐蚀产物还可引起干线设备堵塞,甚至计划外停输。采用0#柴油、自来水在内径50mm的地形起伏透明有机玻璃测试系统上对油流携带积水这一局部油水两相流系统进行了实验研究,发现:随油流剪切作用的增大,积水逐渐呈界面光滑分层流、界面波动分层流以及界面乳化分层流3种形态;一旦积水全部进入上倾管段,其平均运动速度随油相表观速度增大而线性递增,其平均截面含率随油相表观速度增大而线性递减;积水全部进入上倾管段时对应的油相表观速度随上倾倾角增大而增大,而积水量对其影响较小。结果表明采用上游来流可以将积水携带出去。     

球床反应堆气-液两相流阻力特性研究

本文在可视化研究流型观测的基础上,通过对实验过程中所采集的520组压差波动信号进行处理和分析,采用均相流模型对实验数据进行拟合,最终得到了基于气、液两相雷诺数的阻力压降关联式。该关联式包含了影响阻力压降梯度的气相雷诺数、液相雷诺数、填充球直径等参数,相比其他研究者提供的相关关联式,具有更高的预测精度,且物理意义更加清楚,可用于球床反应堆气-液两相流动的阻力压降计算。     

长庆油田气液两相流量计达到国内领先水平

##正##截至2014年3月6日,长庆油气工艺研究院自主研发的天然气气液两相流量计,在苏里格气田已累计应用160余套。经现场标定和权威机构测试,这种流量计计量精准,达到国内领先水平,而价格仅为国外同类产品的2%。苏里格气田在开发建设过程中,采用井间串接工艺,产液量无法计量。为优化排水采气措施,提高采收率,需要解决单井产液量在线计量问题。国     

滑带在高速剪切条件下的固液两相流问题

在滑坡快速下滑过程中,滑带的剪切运动是某种形式的固液两相流。固相颗粒主要是碎石颗粒,液相则是黏土颗粒和水的混合物。固相颗粒之间的液相,无论是静止、流动还是两相流状态,都会对固相颗粒的粒间作用力产生较大影响。在剪切速率达到一定程度后,固相颗粒的随机碰撞产生的颗粒间作用力将成为颗粒间主要作用力,在此作用力作用下,固相颗粒运动符合Navier-Stokes方程所描述的流体运动。由于滑带特有的边界条件,滑带材料在高速剪切条件下的流体运动,可以用简化的Navier-Stokes方程,即雷诺公式来表示。在一定边界条件下,根据雷诺公式,液相流体产生动压变化,液相的动压变化引起固体颗粒之间的接触应力变化,最终导致滑带整体的抗剪强度的变化。     

气液两相流对气升式管式MBR膜污染的影响

采用计算流体力学(CFD)与实体模型相结合的方法,对气升式管式MBR运行中气液两相流的水力学参数进行计算和验证。CFD模拟结果显示,当单管曝气量>43 L/h时,可得到10.1 Pa以上的膜面剪切力,继续增大曝气量对提高膜面剪切力影响不明显。采用与CFD模型同尺寸的实体模型验证CFD模拟结果,两种方法所得膜面剪切力误差为10%～20%。分析膜面剪切力对气升式管式MBR中膜污染的影响可知,当单膜管曝气量为57 L/h、膜面剪切力为8.7 Pa时,能够得到3.2 kPa/d的膜污染速率,继续增大曝气量反而会加速膜污染速率。     

90°弯管内固液两相流临界流速浅析

以90°弯管中固液两相流作为研究范围，并将此特殊水力状况下的固体颗粒假设为随液体一起作沿弯管轴线的圆周运动，速度采用断面平均速度的方式，进行受力分析、求解，来研究管道内固液两相流动的颗粒沉降速度以及流体的不淤流速，并做出了针对物料的性质、流体的性质和管道特性等相关影响因素的分析。     

Halon 1301 flow in pipelines

An understanding of the mechanism of flow of Halon 1301 is necessary for the proper design of piping systems. Note: The author presented this paper at the 79th Annual Meeting of the National Fire Protection Association held in Chicago, Illinois, May 1975.     

A pedestrian merging flow model for stair evacuation

Pedestrian merging flows on stairs are defined as the confluence of a flow of pedestrians from a stair and pedestrians from each floor of a multi-storey building. This paper introduces a novel simplified mathematical model for the calculation of evacuation times on stairs which takes into account the impact of merging flows. The model allows calculating the impact of merging ratio (people accessing the stair landing from the floor and from the stair) on pedestrian flows and evacuation times at each floor in congested situations. The assumptions and implementation of the model are presented. A hypothetical model case study of a 10-floor building evacuation is investigated, where the results of the new model are compared with the results of an evacuation simulation model using SimTread. Advantages and limitations of the new model in relation to the existing methods adopted for the simulation of merging flows on stairs are discussed.     

Quantification of annular flow in lined pipelines

This paper attempts to quantify the amount of flow within the annular space that could exist between a polymeric liner and a deteriorated host pipe. Inadequate fit of the liner within sewer line segments is likely to cause annular flow that will result in a higher flow rate within the wastewater collection system. The results of full-scale field tests performed by the authors on 12 pipelines lined with four different deformed/reformed or fold-and-form (DR/FF) and cured-in-place-pipe (CIPP) liner products indicated that gaps of different sizes existed in all of the tested pipelines. These gaps have resulted in variable annular flow in the tested pipelines. Based on the results of the full-scale tests, a mathematical relationship was established between the annular flow in a lined pipeline and the annular space. The relationship between the annular flow rate and the average annular gap size depends on the difference in head between the entry and exit points along the pipeline. In turn, the average annular gap size depends on many factors including tolerances and imperfections in the host pipe and liner, conditions of the host pipe and the quality of liner installation. A third-order polynomial equation was found to best describe the relationship between the annular flow and average gap size under high differential heads (up to 3.0 m or 10 ft); whereas, a logarithmic relationship fits best under low differential heads for wider range of annular gap sizes (up to 17.8 mm or 0.70 in.). Based on the results of the full-scale tests, this is believed to be more representative of typical liner installations.     

高层建筑疏散过程分析

<正>本文分析了人员及时安全疏散的方法,提出了利用楼梯和电梯分阶段从高层写字楼疏散人群的算法。世界高层建筑发展趋势表明:目前世界最高建筑是508m的台湾101大楼,到2010年最高的建筑是迪拜塔,设计高度为807m。这种高层建筑一旦发生火     

浅析成吉思汗的伦理思想

12世纪末、13世纪初,成吉思汗顺应蒙古社会历史发展趋势,统一蒙古诸部落,建立了大蒙古国。成吉思汗作为这一时期的统治者是我们研究这一时期蒙古民族伦理道德的关键。千百年来,成吉思汗的至诚、重义、守信、孝亲、平等等伦理道德思想渗透到蒙古族的精神世界中,形成一种独具民族特色的文化。     

Flow characteristics of Halon 1301 in pipelines

Halon systems are designed to deliver specific agent concentrations. The author discusses the effects of temperature, pressure, and two-phase flow on the flow characteristics of Halon 1301.     

Pressure measurements with valve-induced transient flow in water pipelines

Pressure measurements provide valuable insights for managing water supply systems by tracking time-dependent hydraulic transients. In this study, we report on two pressure-monitoring issues – sampling location and sampling interval – by analyzing a valve-induced transient event that was not recorded in the 1-min timestamp pressure generated by the existing supervisory control and data acquisition (SCADA) system of a real water transmission line in the southern part of Korea. Field measurement data show that the measured pressure magnitude is influenced by the sampling location, which depends on pipe connectivity and distance from automatic control valve, and by the sampling interval, which is sensitive to network size for wave propagation. Based on the findings of the field experiments, a pressure-measurement method is proposed by employing numerical transient simulation and spectral analysis of pressure waves.     

A fast flow control algorithm for real-time emergency evacuation in large indoor areas

Evacuation in an emergency is always an important issue for shopping malls, subway stations and other populous indoor places. The purpose of evacuation is to evacuate people from the danger zone through exits within the shortest possible time. To help evacuation missions to be carried out efficiently and effectively by rescuers, a fast evacuation approach is needed.     

海底管道失稳过程的模型试验研究

直接铺设于砂质海床上的管道的失稳是一“流-管-土”耦合问题。本文利用U形水槽产生的振荡流对管道的失稳过程进行了模拟 ,通过改变管道水下重量、管径和加载历史研究管道失稳的条件。在试验结果的基础上 ,初步得到了管道失稳的临界Fr数与管重无量纲参数之间的关系曲线 ,并发现不同的加载历史对管道稳定性的影响程度不同     

The effect of occupant characteristics on crawling speed in evacuation

The movement of occupants is a key element in the development of evacuation models, which estimate the required evacuation time to reach an exit. The deterioration of environmental conditions influences occupants to adopt new responses. This study investigates crawling movement as a physical response to environmental conditions during a fire. The study investigates occupant crawling speed compared with walking speed, and the effect of occupant characteristics; gender and body composition (BMI), on crawling during an evacuation. Eighteen subjects (nine males and nine females) within the 19–29 age stratum participated in the study (normal, overweight, and obese body composition). The findings indicate a statistical significance between normal walking and crawling speeds. Further, the study statistically demonstrates that both gender and body composition significantly impact individual crawling speed as they are unique individual characteristics. More research is needed to better understand the effect of age group, mobility capabilities, and fatigue on crawling speed. The study concludes that the development of crawling data and its representation in evacuation models will enhance the accuracy of evacuation models, and better evaluate the safety of evacuees.