Determination of Surge Tank Diaphragm Head Losses by CFD Simulations

Alligné, Sébastien; Rodic, Primoz; Arpe, Jorge; Mlačnik, Jurij; Nicolet, Christophe

doi:10.1007/978-981-4451-42-0_27

Cited by 5 publications

(7 citation statements)

References 1 publication

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“…Several studies have been performed in the last few years to investigate the performance of throttled surge tanks, and several types and configurations of throttles have been addressed. All these studies have confirmed that placing a throttle is a cost-effective measure to adapt hydroelectric power plants submitted to moderate increase of generation capacity [2,4,6,8,9].…”

Section: Introductionmentioning

confidence: 85%

“…However, changing the surge tank geometry is often a difficult task if it has been already installed; it is also costly because the height of the surge tank directly affects the investment costs [2][3][4]. Throttling the surge tank can help restrain these extreme water levels since it provides a larger damping effect on mass oscillations [3,[5][6][7]. Several studies have been performed in the last few years to investigate the performance of throttled surge tanks, and several types and configurations of throttles have been addressed.…”

Section: Introductionmentioning

confidence: 99%

“…The required throttle head losses in each flow direction are generally evaluated through a transient analysis and 1D numerical simulations of the critical load cases. However, the main issue lies in the design of the throttle itself, finding a geometry that produces the intended losses in each flow direction is often a complex task [2,6]. There exists a considerable body of literature on throttles, where the orifice type is addressed.…”

Section: Introductionmentioning

confidence: 99%

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Holistic Design Approach of a Throttled Surge Tank: The Case of Refurbishment of Gondo High-Head Power Plant in Switzerland

Seyfeddine

Vorlet

Adam³

et al. 2020

Water

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In order to increase the installed capacity, the refurbishment of Gondo high-head power plant required a modification of the existing surge tank by installing a throttle at its entrance. In a previous study, the geometry of this throttle was optimized by physical modeling to achieve the target loss coefficients as identified by a transient 1D numerical analysis. This study complements previous analyses by means of 3D numerical modeling using the commercial software ANSYS-CFX 19 R1. Results show that: (i) a 3D computational fluid dynamics (CFD) model predicts sufficiently accurate local head loss coefficients that agree closely with the findings of the physical model; (ii) in contrast to a standard surge tank, the presence of an internal gallery in the surge tank proved to be of insignificant effect on a surge tank equipped with a throttle, as the variations in the section of the tank cause negligible local losses compared to the ones induced by the throttle; (iii) CFD investigations of transient flow regimes revealed that the head loss coefficient of the throttle only varies for flow ratios below 20% of the total flow in the system, without significantly affecting the conclusions of the 1D transient analysis with respect to minimum and maximum water level in the surge tank as well as pressure peaks below the surge tank. This study highlights the importance of examining the characteristics of a hydraulic system from a holistic approach involving hybrid modeling (1D, 3D numerical and physical) backed by calibration as well as validation with in-situ measurements. This results in a more rapid and economic design of throttled surge tanks that makes full use of the advantages associated with each modeling strategy.

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Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Holistic Design Approach of a Throttled Surge Tank: The Case of Refurbishment of Gondo High-Head Power Plant in Switzerland

Seyfeddine

Vorlet

Adam³

et al. 2020

Water

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“…This model is widely used in ANSYS products but also in connection with other CFD-codes (Yi et al, 2017). Different validations experiments of comparable structures show a very good agreement for comparable investigations with the SST-turbulence model (Adam, 2017;Alligne et al, 2014;Gabl et al, 2014b;Seibl, 2016). The investigated geometry is fully parametrized and the mesh is generated with the tool in ANSYS-Workbench.…”

Section: Generalmentioning

confidence: 91%

Design criteria for a type of asymmetric orifice in a surge tank using CFD

Gabl

Righetti

2018

Engineering Applications of Computational Fluid Mechanics

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An asymmetric orifice can be added to a surge tank of a hydro power plant to dampen the mass oscillation. This allows a reduction of the required volume and a more stable behavior of the overall hydraulic system. In this paper, the advantage of a typical asymmetric orifice is shown in comparison with a sharp-edged geometry with two different pipe diameters. The software ANSYS-CFX is used to investigate the influence of the individual geometry parameters (radius, length, angle at the forefront) on the local head loss coefficients and the ratio of the two flow directions. Furthermore, a coefficient is analyzed based on an equation from the literature for the sharp-edged structure, which can be used comparably for the asymmetric orifice. This allows us to reach preliminary assumptions of the losses at an early state of the design process. The following adaptation can be supported by the presented guidance for the optimization process, so that a suitable geometry for the specific boundary conditions can be found. ARTICLE HISTORY KEYWORDSControl structures; flows in pipes and nozzles; hydraulics of renewable energy systems; hydraulic structure design and management; RANS model

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“…During the study of a hydroelectric plant refurbishment, the first step is generally to simulate the whole waterway with a 1-dimensionnal transient model using either the method of characteristics (Boillat and de Souza 2004) or a similitude between hydraulic behavior and interaction with hydrualic machinery and electro-mechanical equipment (Nicolet 2007, Alligne et al 2014. The results of this step are actually values of head loss coefficients in both direction, i.e.…”

Section: Introductionmentioning

confidence: 99%

Experimental assessment of head losses through elliptical and sharp-edged orifices

Adam¹,

Cesare²,

Schleiss³

2016

Sustainable Hydraulics in the Era of Global Change

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Due to the European electricity market liberalization and the appearance of other renewable electricity producers, an increase of installed peak power capacity is relevant to provide larger amount of electricity in a shorter turbine duration. When the discharge increase is not too large, it is frequently efficient to place an orifice at the entrance of the existing surge tank. Actually, the surge tank modifications have to be designed case-by-case. The introduction of head losses helps to manage maximum and minimum water level following the management of downstream discharge control and transient events. It allows to keep the same safety level. The placed orifice should commonly produce asymmetric losses. It is important to note that target head losses are evaluated with a unidimensional numerical model which performs transient simulation for relevant flow directions in the whole water way system and hydropower plant. A previous study performed by the authors focused on the effects of sharp-edged orifice parameters. This research carries out the analysis of corresponding elliptical orifices to tested sharp-edged orifices. The goal is to evaluate the head loss modification in both directions due to the shape change.

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Determination of Surge Tank Diaphragm Head Losses by CFD Simulations

Cited by 5 publications

References 1 publication

Holistic Design Approach of a Throttled Surge Tank: The Case of Refurbishment of Gondo High-Head Power Plant in Switzerland

Holistic Design Approach of a Throttled Surge Tank: The Case of Refurbishment of Gondo High-Head Power Plant in Switzerland

Design criteria for a type of asymmetric orifice in a surge tank using CFD

Experimental assessment of head losses through elliptical and sharp-edged orifices

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