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

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3440
Author(s):  
Mona Seyfeddine ◽  
Samuel Vorlet ◽  
Nicolas Adam ◽  
Giovanni De Cesare
Keyword(s):  
Power Plant ◽  
Transient Flow ◽  
Holistic Approach ◽  
Head Loss ◽  
Surge Tank ◽  
3D Numerical Modeling ◽  
Head Loss Coefficient ◽  
Loss Coefficients ◽  
High Head ◽  
Modeling Strategy

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.

Design of a Throttled Surge Tank for Refurbishment by Increase of Installed Capacity at a High-Head Power Plant

2018 ◽  
Vol 144 (2) ◽  
pp. 05017004 ◽  
Author(s):  
N. J. Adam ◽  
G. De Cesare ◽  
C. Nicolet ◽  
P. Billeter ◽  
A. Angermayr ◽  
...  
Keyword(s):  
Power Plant ◽  
Surge Tank ◽  
High Head ◽  
Installed Capacity

scholarly journals Experimental and simulation‐based investigations on throttle’s head loss coefficients of a surge tank

2020 ◽  
Vol 8 (8) ◽  
pp. 2722-2733 ◽  
Author(s):  
Jianxu Zhou ◽  
Sunit Palikhe ◽  
Fulin Cai ◽  
Yuefei Liu
Keyword(s):  
Head Loss ◽  
Surge Tank ◽  
Simulation Based ◽  
Loss Coefficients

Internal Flow Losses: A Fresh Look at Old Concepts

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Bastian Schmandt ◽  
Heinz Herwig
Keyword(s):  
Flow Field ◽  
Entropy Generation ◽  
Mechanical Energy ◽  
Internal Flow ◽  
Second Law Of Thermodynamics ◽  
Head Loss ◽  
Local Entropy ◽  
Flow Losses ◽  
Loss Coefficients ◽  
Local Entropy Generation

Losses in a flow field due to single conduit components often are characterized by experimentally determined head loss coefficients K. These coefficients are defined and determined with the pressure as the critical quantity. A thermodynamic definition, given here as an alternative, is closer to the physics of flow losses, however. This definition is based upon the dissipation of mechanical energy as main quantity. With the second law of thermodynamics this dissipation can be linked to the local entropy generation in the flow field. For various conduit components K values are determined and physically interpreted by determining the entropy generation in the component as well as upstream and downstream of it. It turns out that most of the losses occur downstream of the components what carefully has to be taken into account when several components are combined in a flow network.

Influence of Surge Tank and Relief Valve on Transient Flow Behaviour in Hydropower Stations

2011 ◽  
Author(s):  
Alireza Riasi ◽  
Ahmad Nourbakhsh
Keyword(s):  
Power Plants ◽  
Transient Flow ◽  
Flow Analysis ◽  
Internal Boundary ◽  
Transient Condition ◽  
Maximum Pressure ◽  
Surge Tank ◽  
Small Hydropower ◽  
Relief Valve ◽  
Hydropower Stations

Unsteady flow analysis in water power stations is one of the most important issues in order to predict undesirable pressure variations in waterways and also probable changes in rotor speed for the power plants safe operation. Installation of surge tank and relief valve is the two main methods for controlling of hydraulic transient. The relief valve is used in several medium and small hydropower stations instead of the surge tank and mounted on the penstock near the powerhouse. The recent generation of relief valves are reliable and beneficial and consist of fully control system that directly conducted by governor. This paper presents a numerical method for transient flow in hydropower stations using surge tank and relief valve. For this purpose the governing equations of transient flow in closed conduit are solved using the method of characteristics (MOC) using unsteady friction. Hydraulic turbine, surge tank and relief valve are considered as internal boundary conditions. The influence of surge tank and also relief valve on the maximum pressure in spiral case and turbine over speed has been studied for a real case. The results show that the transient condition is considerably improved by using a relief valve and this device can be mounted in lieu of an expensive surge tank.

Characterization of surge superposition following 2-stage load rejection in hydroelectric power plant

2016 ◽  
Vol 43 (9) ◽  
pp. 844-850 ◽  
Author(s):  
Sheng Chen ◽  
Jian Zhang ◽  
Xichen Wang
Keyword(s):  
Power Plant ◽  
Analytical Formula ◽  
Hydroelectric Power Plant ◽  
Hydroelectric Power ◽  
Surge Tank ◽  
Time Intervals ◽  
Interval Time ◽  
Unexpected Phenomenon

When calculating the maximum upsurge in surge tank due to load rejection in a hydroelectric power plant, it has been natural and customary to believe that the maximum surge amplitude occurs in simultaneous load rejection of all units at 100% load. As 2-stage load rejection (2-stage LR), involving a step-wise reduction in load, is not considered since it is assumed to produce less severe surge conditions. This study formulates the surge superposition associated with 2-stage LR and shows, surprisingly but significantly, that such 2-stage LR sometimes produces more severe surge conditions than simultaneous and complete load rejection (SCLR). The results indicate that this unexpected phenomenon is ascribable to the resistant effect of throttled surge tank, whose increase will lead to a greater difference in the maximum upsurges between 2-stage LR and SCLR conditions. Different time intervals during 2-stage LR correspond to different maximum upsurges. The analytical formula predicting the worst interval time is derived exactly and verified with two numerical cases.

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