Hydraulic Performance of a Francis Turbine with a Variable Draft Tube Guide Vane System to Mitigate Pressure Pulsations

Joy, Jesline; Raisee, Mehrdad; Cervantes, Michel

doi:10.3390/en15186542

Cited by 8 publications

(4 citation statements)

References 26 publications

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“…The numerical simulation results indicated that reducing the height of the guide vane hub could improve the head and efficiency of the axial flow pump. Jesline Joy et al [26] proved this concept by introducing a variable guide vane system into the draft tube of the high-head Francis turbine. A variable guide vane structure was added to the draft tube of the hydraulic turbine.…”

Section: Computational Modelmentioning

confidence: 99%

Angle-Regulating Rule of Guide Vanes of Variable Geometry Turbine Adjusting Mechanism

et al. 2023

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In recent years, more and more attention has been paid to research on variable geometry turbine engines with the increasing requirement of engine performance. Variable geometry turbine technology can significantly improve the operating performance of aero engines. Adjusting the working angle of the turbine guide vane can change the thermodynamic cycle of the engine operation, so that the turbine can respond to different engine operating conditions. Variable geometry turbines work in harsh environments. Therefore, the design of the variable geometry turbine needs to consider the effect of thermal deformations of the mechanism on operational stability. There are few research studies on variable geometry turbine adjusting mechanisms. This paper established the numerical calculation models of two adjusting mechanisms by integrating fluid mechanics, heat transfer, and dynamic theories, which are paddle and push–pull rod mechanisms. The models were applied to study the effects of components’ thermal deformations and flexible bodies on the motion characteristics of the adjusting mechanism. Furthermore, the performance of the two adjusting mechanisms was compared. The calculation results show that the paddle rod adjusting mechanism can accurately adjust the angles of guide vanes. The paddle rod adjusting mechanism has a larger driving stroke and smaller driving force than the push–pull rod adjusting mechanism. The paddle adjustment mechanism was better suited to the operational requirements of the variable geometry turbine. The research results of this paper are relevant to the design of variable geometry turbine regulation structures.

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Section: Computational Modelmentioning

confidence: 99%

Angle-Regulating Rule of Guide Vanes of Variable Geometry Turbine Adjusting Mechanism

et al. 2023

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“…Unlike the fluid-based methods, geometry-based RVR mitigation methods are various in their design and diverse in their impact. Some of the more widely studied methods in this realm include the installation of fins, baffles, j-grooves, and guide vanes in the draft tube [27][28][29][30][31][32][33][34]. More recently, more novel techniques have been proposed, such as the inclination of the draft tube, adjusting the diffuser outlet cross section using a diaphragm, triggering RVR dissipation with the installation of a perforated conical obstacle inside the draft tube, and the installation of a free-spinning runner downstream of the main runner cone [35][36][37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%

“…They observed that the installation of the guide vanes restricts the RVR motion to the center of the draft tube. In another study, the impact of the draft tube guide vanes with variable angles was experimentally investigated on the turbine performance [34]. The results showed a minimal efficiency loss of below 0.6% while achieving complete mitigation of the RVR.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Part Load Vortex Rope Mitigation With Rod Protrusion in an Axial Turbine

Shiraghaee,

Sundstrom,

Raisee

et al. 2024

Journal of Fluids Engineering

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The present paper investigates the rotating vortex rope (RVR) mitigation on an axial turbine model by the radial protrusion of four cylindrical rods into the draft tube. RVR mitigation is of particular interest due to the unfavorable pressure pulsations it induces in the hydraulic circuit that can affect turbine life and performance. The protrusion lengths, which were the same among the four rods, were varied according to a pre-defined sequence. The experiments were performed under four part-load regimes ranging from upper part load to deep part load. Time-resolved pressure measurements were conducted at two sections on the draft tube wall along with high-speed videography and efficiency measurement to investigate the effect of the mitigation technique on the RVR characteristics and turbine performance. The recorded pressure data were decomposed and studied through spectral analyses, phase-averaging, and statistical analyses of the RVR frequency and peak-to-peak pressure amplitude distributions. The results showed different levels of pressure amplitude mitigation ranging from approximately 10% to 85% depending on the operating condition, protrusion length, and the method of analysis. The hydraulic efficiency of the turbine decreased by a maximum of 3.5% that of the best efficiency point (BEP) with the implementation of the mitigation technique. The variations in the obtained mitigation levels and efficiencies depending on protrusion length and operating condition indicate the need for the implementation of a feedback-loop controller. Thus, the protrusion length can be actively optimizes based on the desired mitigation target.

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“…With this background,the research consortium HydroFlex was started. The aim of HydroFlex was to develop technologies, for instance, a Francis turbine runner (Joy, Raisee, & Cervantes, 2022; Trivedi, Iliev, & Dahlhaug, 2020), permitting very flexible hydropower production while simultaneously investigating how an increase in hydropeaking frequency might affect the hydraulics in the downstream reaches. The scenarios of interest included as many as 60 flow changes (30 starts and stops) per day (HydroFlex, 2022).…”

Section: Introductionmentioning

confidence: 99%

Hydraulic classification of hydropeaking stages in a river reach

Burman

Andersson

Hellström

2023

River Research & Apps

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Hydropower is an important tool in the struggle for low-emission power production.In the Nordic countries, hydropower operating conditions are expected to change and work more in conjunction with intermittent power production. This in turn might increase the amount of hydropeaking events in the reaches downstream of hydropower plants. The current work investigates the influence of highly flexible, highfrequency hydropeaking on the hydrodynamics in the downstream reach. By quantifying four different dynamic stages in the study reach, the influence of the hydropeaking frequencies was investigated in the bypass reach of the Stornorrfors hydropower plant in the river Umeälven in northern Sweden. The hydrodynamics in the study reach were numerically modelled using the open source solver Delft3D.Eight different highly flexible future hydropeaking scenarios, varying from 12 to 60 flow changes per day, were considered. A method for identifying four hydropeaking stages-dewatering, dynamic, alternating and uniform -was introduced. The hydropeaking frequency directly decided the stage in most of the study reach.Furthermore, a Fourier analysis showed a significant difference between the stages and their corresponding power spectra. The classification of stages put forward in this work provides a novel, simple method to investigate the hydrodynamics due to hydropeaking in a river reach.

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Hydraulic Performance of a Francis Turbine with a Variable Draft Tube Guide Vane System to Mitigate Pressure Pulsations

Cited by 8 publications

References 26 publications

Angle-Regulating Rule of Guide Vanes of Variable Geometry Turbine Adjusting Mechanism

Angle-Regulating Rule of Guide Vanes of Variable Geometry Turbine Adjusting Mechanism

Experimental Investigation of Part Load Vortex Rope Mitigation With Rod Protrusion in an Axial Turbine

Hydraulic classification of hydropeaking stages in a river reach

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