Prototype and numerical studies of interference characteristics of two ski-jump jets from opening spillway gates

Xiao, Yexiang; Wang, Zhengwei; Zeng, Jidi; Zheng, jintai; Lin, Jiayang; Zhang, Lanjin

doi:10.1108/ec-04-2013-0104

Cited by 14 publications

(10 citation statements)

References 8 publications

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“…Curvature correction takes the bucket curvature and runner rotation into account. 34 The continuity and momentum equations discretely use a high-resolution scheme with the physical advection terms weighted by a gradient-dependent blend factor while a second-order backward Euler scheme is used for the transient terms.…”

Section: Prototype Pelton Turbine and Numerical Setupmentioning

confidence: 99%

Numerical analysis of a Pelton bucket free surface sheet flow and dynamic performance affected by operating head

Zeng

Xiao

Wang

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part A:

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The present paper aims to find out the influence of operating head on the rotating bucket free surface sheet flow and hydrodynamics performance for a Pelton turbine. Three-dimensional unsteady air-water two-phase flow simulations in the rotating buckets were performed by adopting the shear stress transport curvature correction turbulence model and homogenous model. The sensitivities of the unsteady simulation results to moving mesh resolution and computational fluid dynamics solver time-step have been evaluated to discuss the effect of Courant-Friedrichs-Lewy conditions on the two-phase flow simulation. The accuracy of the numerical predicted flow pattern and the hydrodynamic performance results are reasonable when compared with the experimental data. The simulation results indicate that the remaining kinetic energy carried by the outflow under the nondesigned water head is the main reason for the efficiency loss in the Pelton turbine. Under low water head conditions, jet distortion caused by the Coanda effect and flow interference will lead to more severe efficiency deterioration.

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Section: Prototype Pelton Turbine and Numerical Setupmentioning

confidence: 99%

Numerical analysis of a Pelton bucket free surface sheet flow and dynamic performance affected by operating head

Zeng

Xiao

Wang

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…Hence, dissipation of the energy of flow is the primary issue of spillways. In this way, using the baffles along the chute of the spillway, stepped spillway, ski jump buckets and stilling basin at the toe of spillways have been suggested (Heller et al 2005;Movahedi et al 2019;Xiao et al 2015). Baffles usually are used in the small dam projects.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of energy dissipation on stepped spillway using evolutionary computing

Parsaie

Haghiabi

2019

Appl Water Sci

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In this study, using the M5 algorithm and multilayer perceptron neural network (MLPNN), the capability of stepped spillways regarding energy dissipation (ED) was approximated. For this purpose, relevant data was collected from valid sources. The study of the developed model based on the M5 algorithm showed that the Drop and Froude numbers play important roles in modeling and approximating the ED. The error indices of M5 algorithm in training were R 2 = 0.99 and RMSE = 2.48 and in testing were R 2 = 0.99 and RMSE = 2.23. The study of developed MLPNN revealed that this model has one hidden layer which includes five neurons. Among the tested transfer functions, the great efficiency was related to the Tansing function. The error indices of MLPNN in training were R 2 = 0.97 and RMSE = 3.73 and in testing stages were R 2 = 0.97 and RMSE = 3.98. Evaluation of the results of both applied methods shows that the accuracy of the MLPNN is a bit less than the M5 algorithm. Keywords Energy dissipation • Soft computing • Drop number • Spillways • M5 algorithm Abbreviations ANFIS Adaptive neuro-fuzzy inference system CFD Computational fluid dynamic DN Drop number ED Energy dissipation Fr Froude number g Gravity acceleration GEP Genetic expression programming GMDH Group method of data handling H Total head of flow h s Height of steps L c Length of crest L s Length of steps MARS Multivariate adaptive regression splines Max Maximum Min Minimum MLPNN Multilayer perceptron neural network N Number of steps q Discharge per width y 0 Flow depth over the crest y 1 and y 2 Conjugated depths of hydraulic jump This article is part of the Topical Collection "Water and Energy" guest edited by Enrico Drioli.

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“…In experimental studies, downpull may be determined from direct measurement of the total vertical force by an electronic transducer or by using method of integration of measured pressure distribution. Computational fluid dynamics is widely used in modeling of flow in engineering applications where variances of k-ε turbulence model are used (Xiao et al , 2015; Li, 2011).…”

Section: Introductionmentioning

confidence: 99%

Application of computational fluid dynamics to predict hydrodynamic downpull on high head gates

Köken¹,

Aydin

Sahin

2017

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Purpose High head gates are commonly used in hydropower plants for flow regulation and emergence closure. Hydrodynamic downpull can be a critical parameter in design of the lifting mechanism. The purpose of this paper is to show that a simplified two-dimensional (2D) computational fluid dynamics solution can be used in the prediction of the downpull force on the gate lip by comparison of computed results to experimentally measured data. Design/methodology/approach In this study, ANSYS FLUENT CFD software was used to obtain 2D numerical solution for the flow field around a generic gate model located in a power intake structure which was previously used in an experimental study. Description of the flow domain, computational grid resolution, requirements on setting appropriate boundary conditions and methodology in describing downpull coefficient are discussed. Total number of 245 simulations for variable gate lip geometry and gate openings were run. The downpull coefficient evaluated from the computed pressure field as function of gate opening and lip angle are compared with the experimental results. Findings The computed downpull coefficient agrees well with the previous experimental results, except one gate with small lip angle where a separation bubble forms along the lip, which is responsible from this deviation. It is observed that three-dimensional (3D) effects are confined to the large gate openings where downpull is minimum or even reversed. Research limitations/implications In large gate openings, three dimensionality of the flow around gate slots plays an important role and departure from 2D solutions become more pronounced. In that case, one might need to perform a 3D solution instead. Practical implications This paper presents a very fast and accurate way to predict downpull force on high head gates in the absence of experimental data. Originality/value An extensive amount of simulations are run within the scope of this study. It is shown that knowing its limitations, 2D numerical models can be used to calculate downpull for a wide range of gate openings without the need of expensive experimental models.

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Prototype and numerical studies of interference characteristics of two ski-jump jets from opening spillway gates

Cited by 14 publications

References 8 publications

Numerical analysis of a Pelton bucket free surface sheet flow and dynamic performance affected by operating head

Numerical analysis of a Pelton bucket free surface sheet flow and dynamic performance affected by operating head

Evaluation of energy dissipation on stepped spillway using evolutionary computing

Application of computational fluid dynamics to predict hydrodynamic downpull on high head gates

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