Evaluating the Amount of Erodability and Sedimentation by Comparing Sediment Weight Model and PSIAC Experimental Model (Case Study: Lali Water Catchment, Khuzestan, Iran)

The upstream water catchments are the main source providing sediments in rivers and sedimentary basins. The balance between the erosion phenomenon and the amount of sediment entering into the basin relies on the geometrical specifications and the morphology of the river along the water catchment direction and the amount and type of the sediments. The sedimentary feed of rivers and basins are changed for the sake of natural factors or human disturbances. The river and basin react against this change in that their shape, morphology, plan and profile get changed due to the increase or decrease of the input sediment into the basin. It is essential to know the sediment amount produced by erodability and sedimentation of upstream basins and effects of projects and also to evaluate the amount of sedimentary load in base studies, civil projects, optimizing rivers and dam construction studies specially calculating the amount of sediment amount entering into the dams’ reservoirs in order to take engineering decisions and related alternatives. Sediment Weight Model and PSIAC Experimental Model are recognized as two common methods calculating the amount of the produced sediment caused by erosion applied in this research. Holistically, these methods have been used and compared. Although the results are almost close to one another, more sediment load has been produced in PSIAC method. As more affective parameters are used to cause erosion and produce sediment in PSIAC experimental model, it is recommended to refer to the results of this method because they are closer to reality.

Research on the optimization of tundish by water model

Based on the principle of similarity, water was used to simulate the flow of molten steel to analyze the flow field in a tundish. Several schemes of the tundish＇ s tracer shape were designed and corresponding water model experiments were conducted. During the experiments, a computer automatically collected data. The comparison of the residence time distribution（ RTD ） curves drawn according to the computer-collected data optimized the scheme and photographs originated from the experiments with ink as its tracer. It indicates that the water model can optimize the flow field of the tundish.

Water Modeling of Optimizing Tundish Flow Field

In the water modeling experiments, three cases were considered, i. e, , a bare tundish, a tundish equipped with a turbulence inhibitor, and a rectangular tundish equipped with weirs （dams） and a turbulence inhibitor. Comparing the RTD curves, inclusion separation, and the result of the streamline experiment, it can be found that the tundish equipped with weirs （dams） and a turbulence inhibitor has a great effect on the flow field and the inclusion separation when compared with the sole use or no use of the turbulent inhibitor or weirs （dams）. In addition, the enlargement of the distance between the weir and dam will result in a better effect when the tundish equipped with weirs （dam） and a turbulence inhibitor was used.

Thermodynamic and Experimental Analysis of an Ammonia-Water Absorption Chiller

A single stage ammonia-water absorption chiller with complete condensation is designed, built and tested. The apparatus is designed for a cooling capacity of 2814 W, which is obtained using electric heater as heating source. The thermodynamic models have been derived using the First and Second Laws. Calculated results are compared with experimental data. The results show that the cooling capacity of experimental apparatus is found between 1900 and 2200 W with the actual coefficient of performance (COP) between 0.32 and 0.36. The contribution of the components to internal entropy production is analyzed. It shows that the larger irreversibility is caused by spanning the largest temperature and dissipated thermal energy by heat transfer losses at the generator and evaporator. In the experimentation, the low pressure is lower than the designed value. This is a consequence of a large capacity in the falling film absorber which performs as expected. This decreases the evaporation pressure, and the evaporating temperature could be reduced to the designed value.

Assessment of water depth change patterns in 120° sharp bend using numerical model

In this study,FLUENT software was employed to simulate the flow pattern and water depth changes in a 120° sharp bend at four discharge rates.To verify the numerical model,a 90° sharp bend was first modeled with a three-dimensional numerical model,and the results were compared with available experimental results.Based on the numerical model validation,a 120° bend was simulated.The results show that the rate of increase of the water depth at the cross-section located 40 cm before the bend,compared with the cross-sections located 40 cm and 80 cm after the bend,decreases with the increase of the normal water depth in the 120° curved channel.Moreover,with increasing normal water depth,the dimensionless water depth change decreases at all cross-sections.At the interior cross-sections of the bend,the transverse water depth slope of the inner half-width is always greater than that of the outer half-width of the channel.Hence,the water depth slope is nonlinear at each crosssection in sharp bends.Two equations reflecting the relationships between the maximum and minimum dimensionless water depths and the normal water depth throughout the channel were obtained.

循泵旋网改造进水流道模型试验和分析

循环水系统框架式正面进水旋转滤网,由于其设计结构原因,对机组的安全性、经济性影响较大,文章提出了将旋转滤网结构形式由正面进水改为网内进水侧向出水的布置形式。通过对循环水泵房的进水流道进行建模,并在各工况下进行模型试验,经对比分析发现,侧面旋转滤网若前移到拦污栅井位置,并在网后设置合适的导流墙,基本可以满足循泵正常运行的要求。

XB油田特高含水期油井单管深埋冷输边界条件研究与应用

为了简化集输工艺和降低运行成本,对特高含水期油井单管深埋冷输边界条件进行研究,通过建立单管深埋冷输工艺模型,明确了单管深埋冷输工艺边界条件的计算方法,该方法可指导单管深埋冷输的应用范围。并在XB油田31口采油井开展了现场试验,结果表明,单管深埋冷输工艺适合于现场应用,应用后可有效节约电能及天然气消耗,年节电量11.12×10^(4)kWh,年节气量24.40×10^(4)m^(3),年节约管道维护费用49.6万元,可促进油田绿色低碳高效发展。

Three-phase Fluid Numerical Simulation and Water Modeling Experiment of Supersonic Oxygen Jet Impingement on Molten Bath in EAF

By means of the computational fluid dynamics software Fluent 6.3, a mathematical model of three-dimensional three-phase fluid flow field in the molten bath of electric arc furnace （EAF） with side accessorial oxygen lances was developed to study the transient phenomena of oxygen jet impingement on the molten steel and the molten slag. The water modeling experiment was carried out to verify the simulation results. The impingement of the supersonic oxygen jet caused impact dent on the molten steel surface accordingly. The area of impact dent changed almost in linear relationship to flow rate of oxygen jet, which can be expressed by a deduced mathematical equation. And the relationship between the impact force of oxygen iet and the correspondingly formed apparent static pressure on molten bath was obtained, which was in linear relationship and a direct proportion, and can also be expressed by a deduced mathematical equation.

Water Modeling of Swirling Flow Tundish for Steel Continuous Casting

A conventional turbulence inhibitor is compared with a swirling chamber from the points of view of fluid flow and removal rate of inclusion in the tundish. Comparing the RTD curves, inclusion removals, and the streamlines in water model experiments, it can be found that the tundish equipped with a swirling chamber has a great effect on improving the flow field, and the floatation rate of inclusion is higher than the tundish with a turbulence inhibitor. Because of the introduction of the swirling chamber, the flow field and inclusion removal in a two-strand swirling flow tundish are asymmetrical. Rotating the inlet direction of swirling chamber 60 degree is a good strategy to improve the asymmetrical flow field.

有限水域水下载器推力模型实验壁面效应研究

推力模型实验是水下机器人推进系统设计的重要基础,但是推进系统实验通常伴随壁面效应产生回流,影响推力模型测试结果。为解决静水水池壁面对推进器推力模型测试的影响,通过理论分析建立水下机器人推进器的静水推力模型,通过实验方法,探究水池后壁面距离对推进器推力模型的影响,使用MATLAB对提取的实验结果进行非线性数据拟合,并给出了考虑壁面效应的推进器推力模型修正方法及水池设计的尺寸估计方法。研究发现,由于后壁面的存在,推进器的推力模型被严重低估。本文研究成果对静水实验水池设计及壁面效应下的水下推进器推力模型测试具有重要意义。

无动力潜射导弹运载器出水弹道建模与实验验证

文中建立了无动力潜射导弹运载器出水弹道数学模型,并进行了海上实验验证,仿真计算结果与实验测试数据吻合很好。通过对12条次的实验数据与仿真预报数据的方差分析,表明所建数学模型具有很高的仿真精度,可应用于工程型号的出水弹道预报与仿真研究。

库水浸泡后滑坡体中水分布的实验研究

建立了室内模拟库水浸泡后滑坡体内水润湿的渗流实验装置,根据清江茅坪滑坡的地形、地貌以及岩土混合比例,填制了岩土体实验模型,模拟了水位在涨至模拟坡体凌空面一半高度和水位漫过凌空面达到第一平台高度时,坡体内的水分布情况。在水位降落实验过程中,岩土体部分失稳,证明了润湿滞后在降水期滑坡中起主要作用。

波浪作用下砂质海床孔隙水压力的响应规律实验研究

采用波流水槽模型试验的方法,研究了规则波和不规则波作用下砂质海床的孔隙水压力响应问题,其中主要考虑不同深度、波高及周期对孔隙水压力的影响,从而得出孔压变化规律。当周期和波高不变时,由波浪引起的孔隙水压力随水深的增加而逐渐减小。同一水深和波高条件下,由波浪引起的孔隙水压力随周期变大而变大;当水深和周期固定时,由波浪引起的孔隙水压力随波高的增加而增加。

温度对土壤水分运动影响的研究进展

综述了温度对土壤水分运动的影响 ,温度影响的机理和考虑温度影响的土壤水分运动的数学模型 ,以及目前所用的实验研究方法 ,同时提出了本领域中存在的主要问题及研究展望。

直膨式太阳能热泵热水器的仿真分析

基于直膨式太阳能热泵热水器的热力循环,在建立太阳集热器/蒸发器和冷凝器的分布参数数学模型、压缩机和热力膨胀阀的集总参数数学模型的基础上,用能量平衡和质量平衡等约束条件将四大部件结合起来并进行求解。理论计算结果与若干典型工况下的实验数据对比表明:集热器平均集热效率的平均相对误差为4.6%,热水得热量、压缩机功耗、COP等指标的平均相对误差都在1%以内;热水温度、COP和集热器集热效率的理论和实验值的瞬时变化规律吻合良好,从而验证了此仿真数学模型的准确性。

竖直平板间液桥形状的观测与预测模型开发

了解析湿工况下液桥对管翅式换热器性能的影响,需要对液桥形状进行实验研究并建立描述液桥形状的方法。通过搭建可视化实验台观察了液桥在竖直平板间的形状,并测量了液桥的接触线和接触角。实验研究了不同体积、不同平板间距、不同平板材料间形成的液桥,并通过实验数据开发了能够描述液桥形状的关联式,包括接触线伸长比和接触角分别与Bond数的关联式。还根据关联式建立了描述液桥形状的方法并将结果与实验数据进行对比,对比结果显示接触线的描述方法平均误差为3.4%,接触角的描述方法平均误差为7.9%。

振动诱导微结构粗糙表面水滴Wenzel-Cassie状态转变特性

以聚二甲基硅氧烷(PDMS)基底采用光刻蚀技术制备了微方柱结构粗糙表面。采用高速摄影对液滴在垂直振动作用下的动态浸润状态进行了图像采集。通过对水滴振动过程中的动态浸润特性分析,研究了粗糙表面水滴的Wenzel-Cassie浸润状态转变特征。结果表明,对于一定尺寸的Wenzel状态水滴,只有当施加的振动能量超过某一阈值时,微方柱粗糙表面Wenzel状态液滴才可以发生向Cassie状态的完全转变,且存在发生Wenzel-Cassie浸润转变的阈值范围;此外,当外加振动频率和液滴固有频率一致时,即在共振频率时,液滴发生Wenzel-Cassie状态转变需要的能量最小。外加振动频率偏离液滴固有频率越远,发生Wenzel-Cassie状态转变需要的能量最大。基于表面化学和振动力学理论,建立了液滴发生Wenzel-Cassie转变时的物理模型。

煤矿井下水仓水位的灰色动态预测

为实现煤矿井下可靠、节能自动排水的需要,根据不同季节和时段井下涌水量的差异引起水位不同变化,基于灰色理论的分析和几种灰色预测模型的比较,提出了煤矿井底水仓水位的灰色动态预测方法,采用新信息模型作为煤矿井底水仓水位动态预测的渐进模型,并采用实测的实验数据加以验证,证明具有良好的符合度。为科学、合理的确定排水时段及水泵启停控制策略、数字化监控提供了依据。

孔隙水压力传感器的改装设计

以模型实验的方法,根据孔隙水压力计的工作原理,将微型土压力传感器改装成孔隙水压力传感器,用于模型实验中的实际监测,以验证改装后的孔压计的有效性,为实验提供可靠数据。将土压力传感器和由其改装的孔压计埋置于同一深度的砂土中,测得的土压力值略高于孔隙水压力值,这完全符合有效应力原理,定性地说明了改装后的孔压计有一定的工作效果;实验测得的孔压值与由Putnam得出的理论值基本吻合,其平均误差约为5%,最大误差不超过10%。由此定量地表明,改装后的孔隙水压力传感器是有效的,可以用于实际监测。

斥水性土壤水分入渗试验和模型

为研究斥水性土壤水分入渗规律,并探寻适用于斥水性土壤水分入渗的数学模型,以妫水河流域亲水性和斥水性土壤为研究对象,开展室内一维垂直土柱入渗试验;分别采用Kostiakov分段函数、Fourier级数、一阶Gaussian函数以及Gaussian分段函数对斥水性土壤入渗率进行拟合。试验结果表明:亲水性土壤入渗率随时间呈单调减小变化趋势,斥水性土壤入渗一段时间后累积入渗量会出现翘尾现象,入渗率为先增大后减小的单峰曲线。模型图形分析表明:Kostiakov分段函数入渗率在拐点处同时存在一个极大值和极小值,Fourier级数存在多个波峰,一阶Gaussian函数不能反映入渗率在拐点后大于拐点前的试验现象,因而均难以真实反映斥水性水分入渗过程。忽略水分开始快速入渗过程,Gaussian分段函数模型不仅能够反映入渗率在拐点前的单调增以及拐点后的单调减过程,同时也能够体现入渗率在拐点后大于拐点前的试验现象。