Journal of Hydroelectric Engineering

水力发电学报

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2026 Vol. 45, No. 1 Published: 2026-01-25

	1	Analysis on influence of upper seal clearance width on operational stability of pump-turbines ^Hot!
		DU Yizhao, LI Xiaobo, TANG Jiawei, YU Yunkuan, ZHENG Yuan, KAN Kan
		DOI: 10.11660/slfdxb.20260101
		This study develops a new three-dimensional multi-scale full-passage model of a pump-turbine that incorporates its millimeter-level sealing clearances, exploring the influence mechanism of its upper clearance width on operational stability. This study conducts numerical simulations of the flows for the five different dimensionless clearance widths for 50%, 80%, and 100% load conditions, focusing on comparison of the characteristics of flow structures, pressure pulsation, and hydrodynamic performance. It was found that wider clearances intensify secondary flow leakage vortices on the pressure suction side of the runner's upper crown. This leads to increasing fluctuations in the radial force on the top cover and higher pressure-pulsating amplitudes, which may rise by up to 15% in the extreme conditions. However, wider clearances reduce the axial thrust of the flow, with a reduction of 0.8% observed for high-load conditions. Conversely, narrower clearances help suppress leakage vortices and stabilize the flow, but result in an increase in the axial thrust at an minimal increment though－less than 0.1% for the full load conditions. Clearance adjustment significantly affects performance for high-load conditions, whereas for medium- or low-load conditions, the strengthening of blade passage vortices tends to induce hydraulic instability. This study has elucidated the mechanism of correlation between clearance widths and dynamic loads, and given a recommendation for engineering application－a moderate reduction of the upper seal clearance in the 0-20% range for enhanced operational stability under the rated conditions. This would lay a basis for optimizing sealing design, balancing axial thrust, and controlling vibration.
		2026 Vol. 45 (1): 1-10 [Abstract] ( 15 ) PDF (5327 KB) ( 15 )

	11	Dry and wet modal characteristics of hydro turbine head covers and fluid added mass effects
		XU Pengbo, WANG Shijian, ZHAO Honglei, LI Peng, HU Hao, MA Zhihao, WU Qinghong
		DOI: 10.11660/slfdxb.20260102
		This paper applies acoustic-solid coupling numerical methods to a systematical analysis on the wet modal characteristics of the top cover of a HLBD993-LJ-407 pumped storage unit at varying fluid-structure conditions, revealing and quantifying the effects of its fluid-induced added mass. Results indicate the added mass reduces the cover's natural frequencies significantly, with the most pronounced attenuation observed in the 1ND mode (natural frequency reduction of 19.6%, corresponding to an added mass coefficient of approximately 0.55). The added mass effect peaks in the water layer within the upper crown gap of the runner, while it diminishes in the flow zones near the inner and outer surfaces of the guide vanes due to boundary connectivity. Meanwhile, it follows the non-linear superposition in the case of multiple fluid domains coexisting. The effect is offset partially by the counter-phase fluid motions in the upper crown gap and guide vane zones; A fully reflective boundary suppresses fluid motions more effectively than a fully absorbing one, increasing the added mass coefficient by more than 20%, and intensifying frequency reduction.. This study has explored the mechanism of added mass influencing the vibration characteristics of the top cover at complicated flow conditions, laying a basis for further study of vibration suppression design and operational optimization.
		2026 Vol. 45 (1): 11-18 [Abstract] ( 13 ) PDF (1966 KB) ( 10 )

	19	Study on joint optimal scheduling of Jiaodong Water Transfer Project considering dynamic storage rules of reservoirs
		ZHENG Ying, GU Yu, WANG Chao, WANG Hailong, JIN Pengyu, GAN Tian
		DOI: 10.11660/slfdxb.20260103
		Large-scale inter-basin water transfer projects typically manifest the characteristics of multiple water sources, multiple objectives, multiple users, and multiple dimensions, whereas their different water sources, objectives, and water users are often interconnected yet mutually constraining, leading to new challenges in modeling their joint optimal scheduling and solving the problem. This study constructs a new model for water allocation optimization under the reservoirs' dynamic regulation rules, based on a genetic algorithm (GA) framework, and applied in a case study of the Jiaodong Water Transfer Project. We use this model to determine the system's water flow behaviors through accurate water balance simulations, and then design a fitness function via a comprehensive consideration of the constraints and multi-objective requirements of the project. Finally, its updated solutions are adjusted using a reverse correction strategy. To enhance algorithm efficiency, we have developed three key techniques: adopting a phase identification and division method to reduce decision variable dimensionality; determining the optimization adjustment directions based on reservoir regulation rules; and developing an intelligent mechanism for infeasible solution handling. Application of the new model to the transfer project shows a significant improvement on scheduling performance. Compared with the annual operational plan, a full scheduling period scheme raises the minimum water supply reliability at the diversion outlets by 22%, achieving superior water supply outcomes with reduced diversion flow. In the remaining period scheme, the Jihongtan Reservoir achieves a water supply reliability of 74.17%, with a water shortage of 102.2267 million m3 and a water diversion index utilization rate of 98.43%, meeting all the project requirements. This study helps consider and address optimal operation challenges in complex inter-basin water transfer systems.
		2026 Vol. 45 (1): 19-30 [Abstract] ( 14 ) PDF (4271 KB) ( 4 )

	31	Evaluation of flood control efficacy of reservoir regulation for 1954 flood events in Sishui River System of Dongting Lake
		ZHONG Jiagan, GU Huanghe, DAI Minglong, CHEN Xi, YU Zhiguang
		DOI: 10.11660/slfdxb.20260104
		To evaluate the capacity of a reservoir system operated presently in the Sishui River System of Dongting against historical extreme floods, this study develops a VIC-WUR distributed hydrological model coupled with a reservoir operation module. This model simulates and compares the 1954 basin-wide catastrophic flood events under the scenarios with and without reservoir regulation. The results demonstrate the reservoir group generates significant attenuation to flood peaks, with a maximum peak flow reduction of 62.5% (the Zaoshi Reservoir on the Lishui River), and the longest peak lag of 177.0 hours. The regulatory efficacy features significant spatial variations, subject to the storage capacity, geographical location, and coordinated operation. In the joint operation case of the Zaoshi and Jiangya reservoirs on the Lishui River, the average peak reduction rate is increased up to 56.6%. This study reveals quantitatively the spatiotemporal regulation patterns of reservoir groups against extreme floods, laying a basis critical for managing flood risks in the middle Yangtze and decision making of its collaborative reservoir operation.
		2026 Vol. 45 (1): 31-43 [Abstract] ( 15 ) PDF (7680 KB) ( 4 )

	44	Analysis of cumulative impact of water temperature in lower Jinsha River under dynamic construction of cascade reservoirs
		CAO Guangrong, WANG Haoyu, LIU Xuan, ZHANG Qifan, JIANG Wei, DAI Lingquan, DENG Yun
		DOI: 10.11660/slfdxb.20260105
		Cascade hydropower development is an effective method for fully utilizing hydropower resources, but it inevitably has a cumulative impact on the water temperature rhythm of the watershed. Based on the data series of water temperature monitoring at typical hydrological stations in the lower Jinsha River, this study combines the statistical methods and certain indicators for evaluating cumulative impact, and explores the influence of upstream cascade development on incoming water temperature, focusing on the cumulative impact of water temperature in the dynamic construction process of cascade reservoirs in the lower Jinsha River. Results show the cascade construction in the middle Jinsha River and the Yalong River watershed has imposed a significant impact on water temperature at the inlet section of the lower Jinsha River mainstream. The operation of upstream cascade dams has caused a temperature drop in warming periods and a temperature rise in cooling periods at the tail of the Wudongde Reservoir. As more cascade dams are built and put into operation, a significant difference will emerge in water temperature at the outlet of the lower Jinsha River compared to the natural case, and its influence will become gradually more severe. And the level of hysteresis effect and homogenization of water temperature will be gradually rising. Generally, this cumulative impact manifests different varying trends between months, resulting in an overall process of superposition-stabilization-slowing down-inversion. This study would help deepen our understanding of the impact of water temperature and its cumulative behavior in a reservoir cascade under the changing conditions, and lays a basis for watershed water resource management and regional ecological function maintenance.
		2026 Vol. 45 (1): 44-54 [Abstract] ( 15 ) PDF (3788 KB) ( 14 )

	55	Analysis of river regime adjusting in plateau braided reaches. Case study of upper Yellow River reach in Gannan
		MA Feng, CAO Yuqin, XIANG Yujie, SHI Xi, XIA Junqiang
		DOI: 10.11660/slfdxb.20260106
		The Hequ-Machang reach of the upper Yellow River in the Gannan Tibetan Autonomous Prefecture, a typical plateau braided reach, is characterized by a wide-shallow channel and its significant bed deformation and frequent bank erosion, threatening the safety of local infrastructure. Based on flow and sediment data, remote sensing images, and other multi-source datasets, new calculation methods are developed to quantify the channel width swept by mainstream migrating and the degree of channel planform braiding. We examine the process of river regime adjustment that occurred in the years of 2006-2021, focusing on a discussion on the impacts of flow-sediment regime. Results show the main channel in this reach manifested an equal shifting frequency in both left and right directions, with the average annual migration width of 60.6 m/a. However, at certain typical cross-sections, the width exceeded 100 m/a with the mainstream scouring the locations of the proposed bank revetment projects, which needs a special attention. The reach featured a moderate braiding intensity (an average braiding index = 1.9), but significant longitudinal variations occurred with stronger braiding intensity in the upper and lower sections. Hydrodynamic conditions and sediment concentration are two major factors that affect the main channel migration and braiding intensity, respectively; their variations are reflected using certain combined flow-sediment indexes (e.g., fluvial erosion intensity and incoming sediment coefficient). These indexes should also be suitable for revealing overall river regime adjustments in plateau braided reaches.
		2026 Vol. 45 (1): 55-65 [Abstract] ( 7 ) PDF (1920 KB) ( 2 )

	66	Approximate analytical method for landing locations of random splashing water droplets
		ZHANG Yuchen, ZHANG Hua
		DOI: 10.11660/slfdxb.20260107
		A large number of water droplets are splashed out after a water jet nappe impinging into the free surface of a water body downstream of the dam. To address the low computational efficiency in solving the random water droplet splashing mathematical model, this paper describes an approximate analytical method for calculating the landing locations of the splashed droplets, based on two-dimensional projectile motions against secondary resistance. We compare the calculations of landing locations and probability density distributions with those of the fourth-order Runge-Kutta method. Notably, given the same number of water droplets and initial information, our new method achieves an accuracy comparable to the Runge-Kutta and a significant reduction in computational cost—only 1/30 of the latter one, thus offering an efficient approach for analysis of the motions of randomly sprayed water droplets.
		2026 Vol. 45 (1): 66-75 [Abstract] ( 8 ) PDF (1611 KB) ( 3 )

	76	Study on strength and failure mode of Xiyu conglomerate after infiltration and dissolution
		YANG Gui, GAO Jiaxuan, ZHU Jin, DENG Weijie
		DOI: 10.11660/slfdxb.20260108
		Aiming at seepage-mechanical instability caused by the weakening of Xiyu conglomerate when it meets water, we conduct seepage dissolution tests and mechanical tests on the conglomerate under different seepage pressures－for the Momoke water control project in Kashgar, Xinjiang－focusing on the influence of seepage pressures and loading paths on the seepage characteristics and strength evolution of rock mass. The results show time variations in permeability coefficients feature two stages: In initial stage, the water absorption and expansion of clay minerals lead to a sudden drop in the rock mass￠s permeability (41% - 52% within 48 h at 0.05 MPa); in later stage, dissolution of its calcium cement leads to significant adjustment in its pore structure with permeability approaching a stable value (2.40 - 6.45 mD). Variations in calcium ion concentration confirms the characteristics of water-rock reaction in the two stages. Direct loading causes a sudden drop in the conglomerate￠s permeability and a continuous damage to its structure, while step-by-step loading promotes its dynamic pore erosion-siltation balance, resulting in a smaller attenuation range of its mechanical parameters. The coupling effect of infiltration and dissolution generates nonlinear deterioration in the conglomerate￠s mechanical properties, and an increase in infiltration pressure causes a nonlinear decrease in a number of its parameters－such as compressive strength, elastic modulus, residual strength, and tensile strength. Damage to its microstructure makes the failure mode shift from brittle splitting to tensile-shear composite failure. This study lays a basis of multi-field coupling analysis for stability prediction of Xiyu conglomerate strata.
		2026 Vol. 45 (1): 76-86 [Abstract] ( 17 ) PDF (3732 KB) ( 5 )

	87	Study on digital competence of project legal entities in major water conservancy projects
		DING Jiyong, SHI Qinhan, ZHANG Zhaobo, DING Zhuqing
		DOI: 10.11660/slfdxb.20260109
		The traditional management of major water conservancy projects and their owners￠ capabilities have become inadequate to fully address new challenges, as digital technology application expands in width and depth in construction and management. This brings about an urgent need for project owners to develop high-level capability, namely digital competence. In this work, we compile a digital competence dictionary based on a systematic review and synthesis of literature in the classical competence theory framework, and refine the key factors to characterize the digital competence of a project owner through behavioral event interviews. Applying the dynamic capability theory, we establish a digital competence model that integrates three dimensions－sensing capability, integrating capability, and reconfiguring capability. This model clarifies the distinguishing competence elements of the project owners in the digital transformation of engineering projects, helping to promote the capacity building and digital governance of project owners in major water conservancy projects.
		2026 Vol. 45 (1): 87-98 [Abstract] ( 10 ) PDF (523 KB) ( 2 )

	99	Prediction of injection volume in curtain grouting using hybrid optimized stacking ensemble learning algorithm
		ZHANG Pengcheng, MA Chao, GU Xiqian
		DOI: 10.11660/slfdxb.20260110
		For a dam curtain-grouting project, accurate prediction of its unit grout injection volume is crucial to engineering cost control and effective mitigation of its seepage-related risks. To address the complicated nonlinear relationship between its evaluation indicators and unit cement consumption, this paper presents a novel prediction model based on stacking ensemble learning, and compares it with the models of Random Forest (RF), XGBoost, and Support Vector Machine (SVM). We optimize the hyper-parameters of these models using a Newton-Raphson-based optimizer (NRBO), and test their predictive performance based on both training sets and validation sets. Results show the stacking model markedly outperforms the single-method models, with R2 = 0.998 and RMSE = 0.350 achieved on the training sets, and R2 = 0.971 and RMSE = 1.224 on the validation sets. By contrast, validation-set R2 values of the three single-method models are 0.905, 0.930 and 0.728 respectively, and RMSEs are 2.219, 1.896 and 3.748 respectively. Ensemble-learning models (Stacking, RF, and XGBoost) feature a stronger fitting capacity and robustness in the case of high-dimensional nonlinear data, while the stacking model, by leveraging the strengths of multiple base learners, further enhances predictive accuracy and robustness to outliers. Thus, our NRBO-Stacking model offers high accuracy, effective solutions, and better generalization performance for dam curtain-grouting projects.
		2026 Vol. 45 (1): 99-108 [Abstract] ( 18 ) PDF (3494 KB) ( 5 )

	109	Localized full-scale test and shear key parameter analysis of grouted connections in offshore wind turbine jacket foundations
		LIAN Jijian, LI Xinyu, GUO Yaohua, WANG Haijun, LIU Yuhui, CUI Hao, WANG Jinge
		DOI: 10.11660/slfdxb.20260111
		This study adopts a combined approach of full-scale local test and numerical simulations to clarify our understanding of the axial damage modes of grouted connections. A modified finite element model is used to examine the influence of shear key height and spacing on the overall mechanical performance and failure patterns of grouted connections, aimed to provide a basis for optimized designs. The results indicate that the axial ultimate bearing capacity manifests limited variation with the shear key spacing, but vertical displacement is more sensitive to it. A small spacing tends to induce localized inclined cracks, while a large one may lead to brittle damage. Shear key height significantly influences the load-bearing mechanism and stiffness of the connection structure; at its minimum, the bearing capacity is relatively low. Its variation imposes a considerable effect on damage distribution and damage modes, but little on primary damage angles, reducing the performance of the connection structure if it is excessively small or excessively large. With a comprehensive consideration of the strength, ductility, failure mode, stress distribution, and construction cost, we recommend the shear key spacings suggested by API and HSE, and the shear key height ranges by NORSOK and ISO.
		2026 Vol. 45 (1): 109-120 [Abstract] ( 11 ) PDF (7348 KB) ( 4 )