Simultaneous Effect of Convergence and Reducing Slope of Chute Construction on the Economic of the Plan and Cavitation Index (Case Study: Daharan Dam)

The Daharan Dam, like other dams, is subject to concrete surface wear or cavitation in the chute structure. This article looks into the concurrent effects of decreasing the chute angle and slope profile changes from a single slope to a double slope and the simultaneous latitudinal convergence of the chute structure on the cavitation index and the economy of project. In order to perform this research, the geometric specifications were collected of the dam, and the chute structure as well as those of a flood with a return period of 1000 years, which make up the basis of the spillway design. Taking advantage of the numerical WS77 model, different modes were simulated with a single slope, double slope with fixed latitude, double slope with latitudinal convergence, and the cavitation index and the excavation volumes for each option were calculated. The results indicated that a decrease in slope led to a rise in the cavitation index to over 1.2 and that the convergence of the chute structure positively affected the increase in the cavitation index.

Impact of an artificial chute cutoff on the river morphology and flow structure in Sipaikou area of the Upper Yellow River

Artificial chute cutoff can fundamentally eliminate the threat of flood caused by the meandering river,but it significantly changes its morphodynamic characteristics.Channel adjustments after cutoff are rapid,which makes it difficult to study the interaction between river morphology and flow structure only through field measurement.However,numerical simulations can provide insights into the hydrodynamic characteristics after artificial chute cutoffs.In this study,both field measurement and numerical simulation are employed to investigate the flow structure and bed morphology caused by an artificial chute cutoff in Sipaikou area of the Upper Yellow River in 2018.The measured hydrological data provide boundary conditions and initial values for the numerical model.The field measurement results reveal that the concave bank of the study area is severely scoured up to 270 m after the artificial cutoff,and a 20 m deep scour hole and a 2.26 km long pool are formed at the entrance and near the left bank of the chute channel.The numerical simulation results of velocity at typical cross-sections are in good agreement with the measurement results.Flow separation and stagnation zones are observed near the right bank during the low flow conditions(discharge of at least 902 m^(3)/s),but this phenomenon is not seen during larger flow conditions(discharge exceeds 2000 m^(3)/s).Interestingly,flow recirculation zones are also found near the left and right banks of the scour hole.Further,a long flux belt is formed at the scour hole and the pool.Consequently,the impact of the bed topography on the hydrodynamic characteristics is relatively prominent when the discharge is small,while the impact on the river banks and river bed is more noticeable when the water discharge is large.In addition,high shear stress is observed near the left bank at the downstream of the studied area,which indicates that the left bank at the downstream is still being scoured.These results suggest that bank protection measures along the left bank are required to maintain the effectiveness of the artificial chute cutoff.

Particulate flow analysis in inclined pipes and transfer chutes using tomography imaging,discrete element simulations and continuum modeling approaches

In particulate material transfer systems,traditional shear test based steady state analysis can provide some insight into the strength of the bulk material and subsequent resistive frictional forces during flow.For fast flowing transfer points,dynamic flow conditions dominate and additional modelling techniques are required to improve design guidance.The research presented shows the evolution of a design solution which utilises two distinct processes;a continuum method and a discrete element method(DEM). Initially,the internal structure of dense granular flow,down vertical and inclined pipes was investigated using a twin sensor,12 electrode electrical capacitance tomography device.Subsequently,DEM simulations were conducted using the commercial software,PFC3D.Initially,two particle types and their flow behaviours were analysed:plastic pellets and sand.The pipe angle was varied between 0°and 45°to the vertical.For both the plastic pellets and the sand,good qualitative agreement was found with the spatial particle concentration analysis.Generally,the flow had a dense particle region at its core with the particle concentration reducing away from this core.As expected,at 0°, the core was centrally located within the pipe for both the plastic pellets and sand.At pipe angles 5°or greater,the dense core of particles was located on or near the pipe wall.Average flow velocity analysis was also conducted using the results of wall friction test analysis.The velocity comparisons also showed good agreement between the ECT image analysis and the DEM simulations. Subsequently,the DEM method was used to analyse a complex transfer system(or chute) with the continuum method providing comparative flow analysis with the DEM flow analysis.

Investigation on the Structure of Chute-feed and Card Auto-leveller and Their Selection of Technological Processes

Based on the structure of chute - feed and autoleveHer, an analysis of their working principle and the verification of their practical production results have been carried out. Finally, the future investigation direetiom of chute - feed and card autuleveller are put forward.

Effect of cross-section shape of rotating chute on particle movement and distribution at the throat of a bell-less top blast furnace

Rotating chutes are widely used to control the burden distribution and enhance the gas distribution in a blast furnace.The chute cross-section shape has a significant effect on the particle movement and distribution.Therefore,this study developed a three-dimensional model of a blast furnace top with rotating chute using the discrete element method.The effect of different chute shapes on the particle movement and radial burden distribution was then investigated.The results showed that the burden stream height at the chute discharge agrees well with the burden stream thickness at the burden surface.A semicircular chute had the largest main striking point,where the chute discharge joins the burden surface,and trapezoidal and rectangular chutes had successively smaller MSPs.The semicircular chute helped to obtain a uniform radial size distribution.The trapezoidal chute helped form an aggregated burden stream at low rotating speeds,while the rectangular shape chute achieved this at higher rotating speeds and different chute angles.

Effect of Chute Rotation on Particles Movement for Bell-less Top Blast Furnace

For the bell-less top blast furnace, when particles move along the chute, the particlesr motion direction and the frictional force acting on them will change due to the chute rotation, which consequently influences the velocity at the tip of chute, changes the burden flow width and impact point, and finally affects the stock profile and gas f[ow distribution. So the influence of chute rotation needs to be considered when calculating the burden trajectory with a mathematical model. The mathematical model was established to analyze the influence of Coriolis force on particle velocity at chute tip as well as height and width of burden flow in chute, and to summarize the effect of Coriolis force on burden distribution, thereby making the calculation result more accurate.

End wall effect on particle motion in a chute flow

The influence of the end wall of a chute on the rotation of internal characteristic particles is mainly on the z-axis.A measurement device based on inertial measurement technology does not require the assistance of external information;hence,it is especially suitable for measuring the angular and translational velocities of internal characteristic particles.To study the influence of the end wall of the chute on the motions of the internal characteristic particles,the z-axis rotational and translational velocities of the internal characteristic particles in the chute were measured,and it was found that the rotational velocity about the z-axis differs according to the initial position.The z-axis angular velocity of a characteristic particle at the centre fluctuates near 0,and the average value approaches 0.The z-axis angular velocity of a characteristic particle at the left end wall is typically negative.This phenomenon is due to the influence of the end wall on the rotational motions of particles with initial positions that are near the end wall.In addition,the average translational velocity of the characteristic particles is also affected by the end wall.The distributions of the average z-axis angular velocity and the average translational velocity are quantitatively analysed,and the correlation between the tilt angle of the chute and the end wall effect is studied.

EFFECT OF AERATOR ON HYDRAULIC DRAG ACTING ON A CHUTE

The formulae used to calculate the friction in the non uniform flow chute were examined with the experimental data, and the results show that the accuracy of the formula is enough for engineering applications. A comparison between the results of friction respectively from the uniform flow assumption and the non uniform flow approximation indicates that the former is an order of magnitude larger than the latter in the case of steep chute. The hydraulic drag on a steep chute with aerators was measured on the hydraulic model directly and the coefficient of the aerator effect on the drag was obtained. The variation patterns of the wall shear just downstream of the aerators were investigated and the mechanism of the increase in the drag by aerator were analyzed qualitatively with the measured water depths just downstream the aerators.

Air entrainment and detrainment downstream a chute aerator

The chute aerators separate the flow from the chute bottom,and the air can enter into the flow through the lower surface.In this study,the air concentration and the pressure along the chute bottom are investigated systematically by a series of model tests with the upper aeration effect being eliminated.The chute downstream the aerator is partitioned into four zones:the cavity zone,the impact zone,the equilibrium zone,and the far zone.It is found that a large amount of air entrained in the cavity zone is only partially entrained into the flow finally.Furthermore,the lower air discharge is decreased sharply in the impact zone,and the detrainment disappearsonthe section of x= Lm.In the equilibrium zone,the lower air discharge is kept unchanged.With the in crease of the flow Froude number and withthe other parameters kept unchanged,it is found that the dimensionless value of K has a significant increase.Meanwhile,a formula to calculate K is proposed,with results in good agreement with the model and prototype data.

音频数据驱动的洗煤厂溜槽堵塞检测

溜槽堵塞作为工业生产中的一种常见问题,不仅影响生产效率还可能导致安全隐患,因此实时准确地检测溜槽堵塞状态具有重要意义。然而传统的检测方法在实际应用中存在诸多问题与挑战,如精度不高、依赖人工干预等。文章基于音频信息构建结合了WaveNet和GRU的WaveGNet深度网络模型,通过提取分析声音信号寻找溜槽堵塞的特征,以实现准确的堵塞检测。WaveNet能够提取高质量的声音信号特征,而GRU网络则能够捕获声音序列中的时间关系。通过将两者融合以更好地理解声音信号,在时间和频率维度上进行更准确的分析,揭示与堵塞状态相关的模式从而提高检测的准确性和鲁棒性。通过声音信息直接捕获堵塞状态,减少了人工干预的需求且具备实时性。该方法有望为工业生产中的溜槽堵塞检测提供一种创新、高效且可靠的解决方案,在实际应用中具有重大潜力。

李官集铁矿溜井三维激光扫描测量及稳定性分析

溜井是矿石运输的主要通道,溜井内部的精细测量是评估井筒健康的重要步骤。为精细测量李官集铁矿0 m中段8#采场溜井内壁的破损情况,通过翼目神HM100型三维激光扫描仪对其进行扫描测量,进行点云数据采集处理、模型建立、成果分析和溜井健康状况评估;进一步通过Rhino-FLAC3D耦合建模分析方法,开展溜井在自重应力及地应力作用下的稳定性分析;最后基于分析结果提出了符合实际的溜井放矿管理和修复措施。结果表明:溜井在自重应力及地应力作用下相对稳定,溜井井壁破损的主要原因为矿石放矿过程中的冲击及磨损作用,为李官集铁矿溜井的安全运行提供基础依据。

基于CFD-DEM耦合的梯级溜槽的设计与分析

针对传统物料转运过程中溜槽和输送带磨损严重、出口处粉尘浓度过高的问题,建立含臂架的梯级溜槽几何模型,采用基于计算流体力学与离散单元法(CFD-DEM)耦合的数值模拟方法,分析了臂架对转运溜槽的磨损以及对其出口处粉尘排放浓度的影响。仿真结果表明:含臂架的梯级溜槽可以有效控制物料流的速度和方向,降低对溜槽内表面的冲击磨损,降低出口处的粉尘量。

溢洪道弯道段流态改善试验研究和应用

溢洪道泄槽弯道泄流时,弯道段内易产生横向冲击波,水流紊乱,流态较差,会不同程度地影响溢洪道的正常运行。该文根据广东省部分水库陡槽溢洪道水力模型试验研究成果,介绍改善溢洪道泄槽弯道段流态的断面超高、斜向高低坎、纵向导流墙、阶梯跌坎、弯道前设置消力池等工程措施,并对各种工程措施的适用性进行分析,研究成果可供类似工程设计和运行参考。

储煤筒仓内钢制螺旋溜槽脱落事故分析

螺旋溜槽是块煤仓防碎的重要手段,但在其应用过程中,事故的发生却屡见不鲜。针对某储煤筒仓内钢制螺旋溜槽脱落事故,在现场踏勘的基础上,通过检测、有限元分析和理论计算,分析了钢制螺旋溜槽脱落的原因。结果表明:荷载取值不当是造成此次事故的直接原因,而框架和溜槽结构选型和连接构造不合理是间接原因。溜槽支架宜采用多边形框架结构,也可加设框架间支撑体系;其结构宜选用底板宽度较小的U形或L形;计算时,应取溜槽底板投影一个螺距范围内的全部贮料重力且应考虑放料时的动压;螺旋溜槽计算模型应按空间螺旋曲梁计算,并充分考虑扭矩的影响。

刮板输送机中部溜槽焊接研究现状及展望

刮板输送机在综采煤工作面中担负运煤、采煤机运行导向以及液压支架推移支撑的重要作用。中部溜槽是刮板输送机的重要部件,由于采煤工作面工作条件恶劣,中部溜槽的耐磨性和可靠性变得尤其重要,而实现中部溜槽高耐磨性和可靠性的关键是使用更耐磨的材料与更高质量的中部溜槽焊接。阐述了目前中部溜槽焊接材料的更新过程、焊接工艺的发展与改善提高过程、中部溜槽焊接质量的分析、焊接方法的改进等方面的研究进展,展望了BTW中锰钢作为未来中部溜槽焊接材料的可能性。

高深溜井矿石阶段性流动规律对溜井生产的影响

基于对高深溜井生产实践的长期观察,归纳总结出矿石在高深溜井中的流动规律,提出垂直全断面阶段性流动是高深溜井区别于短溜井特有的工程现象。运用散体材料结构自组织力链和搭拱效应理论,分析了井筒内矿石阶段性流动产生的原因,揭示了高深溜井矿石阶段性流动对溜井生产过程中常见的滞流、堵塞、磨损和片帮现象以及溜井内矿石的混合和分级的影响;分析了溜井内空气气流对散体流动的影响,在正常放矿过程中,流动气体的存在有利于矿石流动和临时平衡拱的破坏;同时,由于受气体的曳力作用,溜井内矿石产生块、粉分级集中现象,助推了井筒内矿石的滞流和堵塞。研究提出矿石的粒级成分、密度、含水量、黏结性及溜井直径、井壁粗糙程度是造成溜井滞流和堵塞的基础因素,垂直全断面阶段性矿石流动特性是造成高深溜井滞流和堵塞的重要原因。

服役环境下动车车底装备滑槽疲劳载荷谱的编制与验证

随着动车组向更高速度发展,对列车轻量化的需求愈发迫切。在现有的动车组平台中,将没有横梁底架的车体改为底架滑槽吊挂能够显著减轻设备框架的质量和体积,实现列车轻量化目的。然而,滑槽吊挂引起的最为关切的问题是结构的疲劳强度能否满足需求。为了了解结构的疲劳强度性能,基于服役中动车组车下设备振动加速度,结合现有标准体系,采用服役全周期内工况组合和载荷外推方法,采用累积损伤原理和疲劳试验加速法,编制107次循环次数下的等效振动幅值,并开展滑槽结构疲劳强度试验。研究结果表明:与既有标准体系相比,考虑服役环境的车下设备垂向载荷小于标准值,横向和纵向载荷大于标准值;当轻量化高速动车组大质量车下设备采用滑槽吊挂方式时,结构可以满足30年设计寿命要求。

湿陷性黄土地区明渠陡槽加墩消能工优化试验

明渠陡槽加墩是一种高效消能工布置方式,在特定条件下具有很高的技术竞争优势,但目前国内相关研究甚少。针对甘肃庆阳小崆峒沟雨水下塬排放工程的明渠陡槽加墩段进行了1∶30大比尺水工模型试验研究,试验发现初步方案沿程水流流态不稳定,存在向外泼溅溢出现象,危及黄土边坡的结构稳定。为此对初步方案进行了优化研究,试验发现,通过缩短消能墩排距,可以显著减小水面波动,使沿程水深分布均匀,流速降低,沿程不再出现水流向外泼溅溢出现象。消能墩排距由H/i缩短至0.5H/i后,在最大设计流量工况下,水面波动减小72.5%,平均流速降低40.1%,总消能率由87.9%提高至94.6%。

气流强化末精煤溜槽脱水流场数值模拟

为提高选煤厂工业生产废能回收利用,将加压过滤机压风机运行过程产生的废热用于末精煤溜槽进一步脱水,在末精煤离心机出料溜槽设置矩形进风口(风刀),将废热引入溜槽中干燥精煤。通过SolidWorks建立模型并导入ICEM CFD中进行网格划分,然后导入Fluent中进行边界条件设置后进行数值模拟计算。系统研究了风刀位置、风刀数量、风刀角度和热风速度等因素对于溜槽内部流场的影响,结果表明:在双风刀、风速45 m/s、角度0°、高度600 mm条件下,可以明显优化气流在溜槽内的分布,中心平面Y轴右侧(靠近单风刀侧)距离200 mm处轴向未出现气流速度为0的区域,气流流场的作用较全面且均匀,为利用选煤厂废能提供了基础支撑。

灰岩矿溜井开挖支护与降段爆破参数优化

“贮矿降段法”是溜井口在露天矿中随露天开采向下进行而延伸的一种溜井降段方法,常用多孔爆破方式进行溜井降段。目的降段过程中,维持溜井井壁的稳定性是生产过程中的重要环节,但溜井内部状态具有不可视性,因此,研究溜井爆破降段前井口的合理支护方式和爆破降段时更优的爆破参数对溜井井壁稳定性尤为重要。方法基于某灰岩矿溜井,对溜井井壁稳定性影响进行理论分析,研究溜井降段前与爆破降段时井壁稳定性,通过数值模拟手段研究溜井掘进后不同支护条件下及多次爆破降段时井壁稳定性。结果研究结果揭示了爆破产生的扰动对井口和井壁影响程度与井筒距爆破中心距离呈负相关关系,明确了掘进后和爆破降段时溜井的应力分布和井壁破坏规律,确定了更为合理的井口支护方式。结论在此灰岩矿溜井井口进行C40级混凝土支护,可有效削弱日常爆破开采产生的震动对井口围岩的破坏,确定爆破辅助孔底盘抵抗距3.5 m,孔距3.5 m,排距3.5 m时更加合理,为爆破降段过程的安全性提供理论依据和参考价值。