A systematic comparative evaluation of mainstream multiphase models for specific hydraulic structures is essential to investigate aerated flow characteristics and promote the models’ application. However, such evaluations remain scarce. In this paper, four multiphase models, namely the VOF, Mixture, and Eulerian models in Ansys Fluent and the aerated flow model in FLOW-3D (AFM-F3D), were comparatively introduced and tested for the aerated flow over stepped spillways. Simulation results, including water surface profiles, inception points of aeration, air concentrations, velocities, and turbulent kinetic energies from four models, are compared with each other and with available experimental data. It is discovered that both the VOF and Mixture models fail to reproduce the self-aeration and subsequent downward transport phenomenon. In contrast, AFM-F3D and the Eulerian models predict reliable aerated water surface profiles. AFM-F3D and the Eulerian model demonstrate superior performance in velocity and air concentration calculations, respectively. Based on overall performance, the Eulerian model is recommended for simulating aerated stepped spillway flows. These insights provide valuable guidance for selecting appropriate multiphase models based on specific engineering requirements.

Aimed at the insufficient energy dissipation inside the deep tail water stilling basin, this paper successively added auxiliary energy dissipators (baffle blocks, T shaped pier and chute sill blocks) inside the stilling basin and then comparatively investigate the corresponding influence upon the energy dissipation on a physical model. Results show that baffle blocks and T shaped piers can only adjust the moving flow in shallow tail water condition but can't exert well effect in view of limited geometrical scale. And chute sill blocks above overflow weir surface can effectively force the moving inflow to deflect and offset in the upper regions of stilling basin, thus significantly shortening hydraulic jump length and increasing energy dissipation inside the deep tail water stilling basin. The common hydraulic jump with water drop is totally eliminated outside the stilling basin.

This paper proposes an improved coupled modeling method for coalbed methane extraction after hydraulic fracturing. Based on the damage mechanics theory, we introduce a state damage variable to record the damage changes at different times and construct the coupling governing equations of the seepage field and solid mechanics field in the hydraulic fracturing process. Then, the results of hydraulic fracturing simulation are used as initial values to perform coupling modeling for coalbed methane extraction. The method is implemented by the combination of different modules in COMSOL to solve the state damage variable, displacement, and pressure. Additionally, two 2D numerical examples are used to verify the precision of this method, and a 3D coalbed methane extraction simulation is performed to analyze the extraction effects and the evolution characteristics of the permeability before and after hydraulic fracturing. Numerical examples show that the proposed coupling modeling method can not only simplify the calculation steps of the CwM method and reduce the numerical errors caused, but also characterize the damage, porosity, permeability, and extraction effect caused by hydraulic fracturing in coal seams with permeability anisotropy.

The problem of slope vibration induced by flood discharge of high dams cannot be ignored. In this paper, this problem is simplified to be the relationship among the fluctuating pressures, the inherent properties of the slope system, and its dynamic responses. The characteristics of fluctuating pressures in the plunge pool during flood discharge are analyzed by the hydraulic model test. And a numerical slope model consisting of the finite element domain and the PML domain is established to study the inherent characteristics and vibration responses by numerical simulation. The results show that the flow fluctuation in plunge pool is a continuous and stable random vibration process. And the fluctuating pressures on the bottom area of the plunge pool are greater than that of the sidewall, but the fluctuation phenomenon at the sidewall is more intense. In addition, the slope displacement vibration intensity caused by fluctuating pressures is small, only at the micron level. The fluctuating pressures on the bottom area of the plunge pool are the dominant factor affecting the kinetic energy density distribution of the slope. This work provides a simple and efficient method for the study of slope vibration induced by high dam flood discharge.

会人溪浆砌石拱坝坝底厚度远小于现行规范及同类工程要求,致使最大拉应力超标,结构安全评定不满足要求,需进行加固处理.为此,基于ANSYS有限元软件编制有限元等效应力计算程序,计算原坝体应力结果,提出了培厚加固、肋墩加固等4种局部加固方案.通过加固后坝体应力分布情况,找到了最优加固方案和加固实施条件.研究表明,在坝体下游侧采用培厚加固、肋墩加固等局部加固方案可显著降低加固区应力,但在初始加固条件下(加固前上游水位139 m),各方案均无法满足拉应力控制标准;坝体上游侧加固区顶部易出现拉应力集中,最大拉应力与加固体型及加固前上游水位相关;对加固前上游水位进行敏感性分析,发现低水位有利于降低坝踵处拉应力,但易导致加固区顶部附近拉应力偏大;在方案2条件下,控制加固前上游水位介于130～134 m时可满足拉应力控制标准,为推荐方案.

A hybrid model integrating chaos theory, support vector machine (SVM) and the difference evolution grey wolf optimization (DEGWO) algorithm is developed to analyze and predict dam deformation. Firstly, the chaotic characteristics of the dam deformation time series will be identified, mainly using the Lyapunov exponent method, the correlation dimension method and the kolmogorov entropy method. Secondly, the hybrid model is established for dam deformation forecasting. Taking SVM as the core, the deformation time series is reconstructed in phase space to determine the input variables of SVM, and the GWO algorithm is improved to realize the optimization of SVM parameters. Prior to this, the effectiveness of DEGWO algorithm based on the fusion of the difference evolution (DE) and GWO algorithm has been verified by 15 sets of test functions in CEC 2005. Finally, take the actual monitoring displacement of Jinping I super-high arch dam as examples. The engineering application examples show that the PSR-SVM-DEGWO model established performs better in terms of fitting and prediction accuracy compared with existing models.

台阶式溢洪道中凹角水流的循环及能量交换是泄洪消能的关键因素之一,目前台阶式溢洪道的研究多集中在台阶的坡度、尺寸以及与宽尾墩等联合运用方面,鲜有对台阶凹角几何形状进行研究.通过水工模型试验和数值模拟计算,对传统三角形凹角台阶和新型梯形凹角台阶的流态、掺气浓度、压强、流速等水力特性进行研究,结果表明:梯形凹角台阶与三角形凹角台阶水流水力特性分布规律相同,但由于梯形凹角台阶改变了旋涡脱落的形状,漩涡脱落进入主流中,促进水流湍动,使得初始掺气点位置略微前移,增加主流区断面平均掺气浓度,提高虚拟底板处总压强波动强度,降低台阶沿程流速,有利于提高台阶抗空化空蚀能力和促进台阶消能.

清渡河水库溢洪道受下游地形条件限制,存在消力池池长严重不足的工程问题.台阶式消能工可减小入池水流弗劳德数,消力池内加设T型墩辅助消能工可缩短池内水跃长度,两者均有减小消力池所需池长的作用.初步设计采用泄槽满布台阶式消能工后接消力池的基本方案,物理模型试验表明台阶段单宽流量过大导致掺气严重不足,池长仍不足.优化方案比选采用数值模拟进行计算,即先在台阶段前加设掺气挑坎和通气孔进行强迫掺气,在提高台阶段掺气水平的同时减小入池水流弗劳德数,但池长仍不足;之后在消力池内布置T型墩辅助消能工,采用联合消能方案.对推荐体型进行物理模型试验复核,结果表明台阶消能工+消力池内加设T型墩辅助消能工的联合消能方案,可有效解决消力池池长不足的工程问题.

The gentle-slope tunnel has been adopted in many high dams, and aerators are usually required for high operating heads. For such tunnels, the lateral deflector is superior to the traditional bottom aerator, which loses its efficiency due to cavity blockage and fails to aerate the sidewalls. However, unfavorable flow patterns such as water-wings and shock waves are induced by the lateral deflectors. To address this problem, two novel lateral deflectors are proposed, and their hydraulic characteristics are comparatively investigated together with the triangular deflector by means of model test and numerical simulation. The triangular deflector was revealed to form a wide cavity that allows for the free rise up of the water-wings inside the cavity, leading to the development of a buddle-type shock wave, whereas the two-arc deflector yields a jet with a fluctuating surface, which induces water-wings and further develops into diamond-type shock waves. In contrast, the cavity formed behind the two-arc deflector with a straight downstream guiding line is stabler and shorter, thereby restricting the development of the rising flow and preventing the formation of water-wings and shock waves. Moreover, the two-arc deflector with a straight guiding line exhibits higher energy dissipation capacities and thus is recommended in practical engineering design.

Realizing the green recycling of sludge is an important link to effectively solve the problem of sludge disposal. In this paper, sewage sludge (SS) and rice husk (RH) were utilized as raw materials in preparing novel ceramsite (SRC) for the treatment of lead-containing wastewater, and its adsorption mechanism was explored. The results showed that the optimal preparation conditions were 40% RH + 60% SS mixture, a sintering temperature of 1190 °C, and a sintering time of 20 min. The basic properties of SRC met Chinese artificial ceramsite filter material standards for water treatment (CJ/T 299-2008). Under optimum adsorption conditions (pH = 6, 1 g/L SRC dosage, 20 mg/L Pb(NO)3 concentration, 18 h), the removal rate of Pb2+ reached 94.7%, and the equilibrium adsorption capacity was 18.94 mg/g. The adsorption process was more consistent with the pseudo-second-order kinetic model and the Langmuir isotherm model, indicating that the adsorption process was dominated by chemisorption. Thermodynamic parameters (ΔH0 > 0, ΔG0 < 0, ΔS0 > 0) indicated that the adsorption reaction was spontaneous and endothermic. The possible adsorption mechanisms are as follows: (1) SRC is rich in layered mesoporous structure, which provides sufficient reaction sites for Pb adsorption; (2) the sintered lawsonite and muscovite can strongly attract Pb and then form a new phase (Pb10[Si2O7]3(OH)2); (3) Pb2+ can bond with the Si–O- bond in aluminosilicates, and the introduction of Pb elevates the degree of polymerization of aluminosilicates in turn, indicating that the adsorption process is stable.

The establishing of an accurate and reliable dam deformation prediction model is an important content of dam safety evaluation. To this end, a dam deformation prediction method based on support vector machine (SVM) with optimal parameters selected by improved grey wolf optimization algorithm (IGWO) is proposed by introducing the crossover and mutation operators of the differential evolution algorithm into the GWO algorithm. The initial population is enriched by the differential evolution algorithm, an IGWO is proposed, and the penalty factor and kernel function of SVM are optimized by the IGWO algorithm, then a dam deformation prediction model based on the SVM-IGWO algorithm is established. The results will be compared with those of the SVM and SVM-GWO models through the measured data of Xiluodu super high arch dam. The research shows that the proposed SVM-IGWO model can effectively improve the accuracy of dam deformation prediction.

建立准确可靠的大坝变形预测模型是大坝安全评价的重要内容,为此,将差分进化算法的交叉和变异算子引入灰狼优化算法(GWO),提出一种基于改进灰狼算法(MGWO)优化支持向量机(SVM)的大坝变形预测方法.通过差分进化算法丰富初始种群,提出改进灰狼优化算法(MGWO),并采用MGWO算法优化SVM的惩罚因子和核函数,建立基于MGWO-SVM算法的大坝变形预测模型.以锦屏一级特高拱坝实测数据为例,将MGWO-SVM模型与SVM、GWO-SVM模型的预测结果进行比较.结果表明,MGWO-SVM模型可以有效提高大坝变形预测精度.

在修山水电站枢纽工程原设计方案的基础上,通过整体水工模型和泄水闸断面模型试验研究,对枢纽的导墙及上下游导航墙提出优化调整,并对下游消能防冲设计提出试验推荐方案.实验研究成果可供类似工程参考.

针对大坡度、紧凑型溢流坝中墩尾部水翅问题,基于某水库工程实例,采用物模试验和数值模拟方法对3种中墩体型进行了对比研究.结果表明,两孔水流在体型1传统中墩后交汇对冲形成了大尺度偏向左岸的水翅和墩尾空腔;体型2消减大坡度、紧凑型溢流坝中墩尾部水翅作用有限,且墩后空腔有所增大;体型3中斜尾墩采用大侧收缩角、小顶面夹角结构设计,有效消减了墩后横向流速峰值和水翅规模,下泄水流更加平顺,溢流坝面和消力池入池流态显著改善,可供类似工程参考.

高速水流消能是高水头水利水电枢纽中最重要的水工水力学问题,目前工程上还未出现将沿程不连续束缩式内消能工应用在高流速无压隧洞中的先例.采用束窄过流断面的方法,利用Flow-3D软件对某水电站溢洪道进行数值模拟,验证高流速溢洪道无压隧洞内沿程布置内消能工可行性.初期采用结构简单的三角墩体型,以分析不同束窄度及倾角的消能墩的消能效果.针对三角墩体型的缺陷,提出驼峰型消能墩解决方案.最终确定隧洞段沿程布置束窄度为10％的对称驼峰墩组,并建立比尺为1:80的溢洪道物理模型,对Flow-3D软件计算结果进行验证.实验结果表明,无压隧洞沿程布置驼峰墩组消能效果理想,但驼峰型消能墩仍存在过墩水翅及峰顶存在较大负压的问题,需要进一步进行体型优化.贴合水流流线优化后的驼峰型消能墩的空蚀空化及水翅问题可得到有效改善.

通过两孔平底泄洪闸物理模型试验,对比研究了非对称平行水跃和传统水跃的水跃特性,揭示了非对称平行水跃的消能机理,探究了其能量耗散、共轭水深比、水跃旋滚长度与闸门开度比之间的关系.结果表明,非对称平行水跃中水流横向扩散增大了平行射流面积,除形成大幅度横轴旋滚外,还激起局部立轴旋滚,增强了相邻水股剪切紊动,加剧了能量耗散;相较于传统水跃,非对称平行水跃能显著降低跃后水深及缩短水跃长度;结合试验数据提出共轭水深比、水跃旋滚长度计算经验公式,经验公式拟合效果较好,精度较高,可为同类工程设计提供参考依据.

The deformation prediction of the dam in the initial stage of operation is very important for the safety of high dams. A hybrid model integrating chaos theory, support vector machine (SVM), and an improved Grey Wolf Optimization (IGWO) algorithm is developed for deformation prediction of dam in the initial operation period. Firstly, the chaotic characteristics of the dam deformation time series will be identified, mainly using the Lyapunov exponent method, the correlation dimension method, and the Kolmogorov entropy method. Secondly, the SVM-IGWO model based on phase space reconstruction (PSR) is established for deformation forecasting of the dam in the initial operation period. Taking SVM as the core, the deformation time series is reconstructed in phase space to determine the input variables of SVM and the GWO algorithm is improved to realize the optimization of SVM parameters. Finally, take the actual monitoring displacement of Xiluodu super-high arch dam as an example. The engineering application example shows that, compared with the existing models, the prediction accuracy of the PSR-SVM-IGWO model established in this paper is improved.

为使鱼道模型中进口流场与试验鱼类的游泳能力相匹配,在以往变态模型相似性研究的基础上,将变态相似理论应用于鱼道建筑物,使模型变率小于1.利用计算流体动力学(computational fluid dynamics,CFD)软件对3种变率方案下的鱼道建筑物进行数值模拟计算,根据计算结果量化变率对物理模型中水流特性的影响,得到变率对横向、纵向、平面速度的影响规律以及建筑物中流量对变态相似误差产生的影响,并给出了可参考的变率范围.

Schizothorax oconnori Lloyd is a local endemic species, one of the most frequently observed species in the Tibet plateau, China, and the representative species of cold-water fish in the Yarlung Zangbo River basin. Knowing the flow velocity preference of fish is essential for understanding the mechanics of their locomotion, and part of the biological foundation required for habitat restoration. The flow velocity preference of Schizothorax oconnori swimming upstream was investigated using a four-channel flume. The flow fields in each channel were nearly uniform, but the flow velocity varied by channel. Test fish swam upstream, of their own volition, into a channel and were recorded by PIT (Passive Integrated Transponder) antennas as they entered the channel. The proportion of fish entering each channel was recorded and changes in activity level during the experiment were analyzed to detect diurnal and nocturnal cycles of activity. The choice among channels made by the test fish differed significantly, indicating that Schizothorax oconnori display a preference for flow velocity. Furthermore, it was demonstrated that the preference for flow velocity varied by season, with a preference for relatively high velocity in late July and a relatively low velocity in late August. This variation in preference may be attributed primarily to different feeding strategies in the two seasons and to differing maximum flow velocities in the two experiments. Due to fatigue, or acclimation to the constant flow field, fish activity decreased significantly after 10 h. Schizothorax oconnori was more active at night than during the day, attributed to its benthic nature and the relatively high light level in the shallow flume. Based on our findings, we make the following recommendations for fish passage design: (1) The flow field should be non-uniform to accommodate a flow preference that varies with season, and which helps prevent fatigue; (2) Avoid excessively long fish passageways and provide a combination of water depth and shading that provides a satisfactory light level.

针对超服役期渡槽结构运行的安全性问题,基于东村超服役期U形薄壳渡槽工程实例,提出考虑局部破损情况下的有限元分析方法,结合原型充水试验成果和ANSYS有限元分析结果对超服役期U形薄壳渡槽的结构性能进行分析研究.对比分析原型充水试验与有限元计算结果可知,渡槽结构应力分布规律近似符合简支梁受弯规律,考虑局部破损情况下的有限元分析结果与现场实测结果吻合较好,基本规律一致,数值接近,考虑局部破损下的有限元分析方法可行且结果较准确;现场试验成果及数值模拟计算结果中,渡槽在不同水位下产生的应力与变形均较小,小于规范及设计要求的允许限值,验证了超服役期渡槽的安全性和可靠性;提出了渡槽加固的建议,可为同类工程分析研究提供参考.