scholarly journals Research on Unsteady Hydraulic Features of a Francis Turbine and a Novel Method for Identifying Pressure Pulsation Transmission Path

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1216 ◽  
Author(s):  
Shuo Wang ◽  
Liaojun Zhang ◽  
Guojiang Yin ◽  
Chaonian Guan
Keyword(s):  
Pressure Pulsation ◽  
Guide Vane ◽  
Fluid Pressure ◽  
Flow Channel ◽  
Transfer Entropy ◽  
Francis Turbine ◽  
Transmission Path ◽  
Hydropower House ◽  
Entire Flow ◽  
Novel Method

It is of significant value to understand the unsteady hydraulic features and pressure pulsation transmission path in the flow channel through a turbine for providing technical support for turbine design and optimization, as well as laying a foundation for analysis of the stability and the coupled vibration of the hydropower house. In this paper, a three-dimensional mechanics–hydraulics–concrete structure coupled numerical model was established to accurately simulate Francis hydraulic machinery, including the high-rotating turbine runner and fixed guide vane, the unsteady flowing water, the structure of the entire flow channel, as well as the dynamic interaction between them. Turbulent hydraulic features of flow condition and pressure pulsation in design operation were explored using the detached eddy simulation (DES) turbulence model. Then, a novel method was proposed to identify the fluid pressure pulsation transmission path based on the time-delayed transfer entropy method and wavelet theory. On basis of time and frequency analysis of pressure calculation results, investigation into identification of pressure pulsation transmission path was performed using the method of traditional transfer entropy and the method adopted in this paper. The pressure pulsation transmission features in the entire flow channel were revealed during operation of the large-scale Francis turbine. The research method and results could not only lay a basis for exploring the structural vibration regularity of the hydropower house but also provide a scientific reference for vibration reduction design of the hydropower house.

Structure Vibration of Hydropower House Induced by Francis Turbine Basing on CFD

2008 ◽  
Author(s):  
Guangjie Peng ◽  
Liang Qin ◽  
Zhengwei Wang ◽  
Huijing Tian ◽  
Yongyao Luo
Keyword(s):  
Guide Vane ◽  
Flow Simulation ◽  
Fem Analysis ◽  
Francis Turbine ◽  
Test Results ◽  
Hydropower House ◽  
Prototype Test ◽  
Hydraulic Load ◽  
Structure Vibration ◽  
Spiral Casing

The method of CFD is adopted to carry out 3-D unsteady turbulent flow simulation through the whole flow passage of 2# Francis turbine in Wanjiazhai hydropower station. The flow fields of spiral casing, stay vane, guide vane, runner, and tail tube are obtained. The pressure fluctuation of tail tube is also acquired and compared with the prototype test results in time domain and frequency domain. It shows that the numerical results and the experimental results are well identical. On the base, the problems of load distribution in the couple boundary between flow field of turbine and structure field of house and of hydraulic load transferring to machinery foundation by shaft are investigated. Consequently it achieves dynamic analogy of hydraulic load in hydropower house FEM analysis successfully. It provides method of analyzing hydropower house vibration accurately.

Vibration transmission path identification in a hydropower house based on a time-delayed transfer entropy method

2020 ◽  
Vol 26 (15-16) ◽  
pp. 1214-1227
Author(s):  
Liaojun Zhang ◽  
Shuo Wang ◽  
Guojiang Yin ◽  
Chaonian Guan
Keyword(s):  
Information Transmission ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
Scientific Basis ◽  
Entropy Method ◽  
Transfer Entropy ◽  
Vertical Acceleration ◽  
Vibration Transmission ◽  
Transmission Path ◽  
Hydropower House

This article aims to explore the vibration transmission path in the hydropower house using the time-delayed transfer entropy method. A three-dimensional fluid-concrete structure-hydraulic machinery coupling simulation model of the Xiangjiaba hydropower house was established, and the vibration acceleration and equivalent stress of the structure were calculated in the time domain based on the two-way iterative fluid-structure interaction method. The characteristic indexes of information transmission were quantitatively presented, including the rate of information transmission, transmission path contribution, to describe the vibration energy transmission paths and transmission characteristics of different vibration variables as well as different directions of the same variable in the hydropower house. The study indicates that the vertical acceleration can identify more abundant vibration transmission paths, and the lower bracket contributes most to the vibration transmission of the powerhouse. The research outcome can provide a scientific basis for structural optimization, vibration attenuation, and isolation design of the hydropower house.

scholarly journals Analysis of Flow Field Characteristics and Pressure Pulsation in Horizontal Axis Double-Runner Francis Turbine

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2671
Author(s):  
Chunxia Yang ◽  
Jiawei Wu ◽  
Dinge Xu ◽  
Yuan Zheng ◽  
Xueyuan Hu ◽  
...  
Keyword(s):  
Flow Field ◽  
Working Conditions ◽  
Pressure Pulsation ◽  
Guide Vane ◽  
Horizontal Axis ◽  
Francis Turbine ◽  
Back Surface ◽  
Average Efficiency ◽  
Flow Field Characteristics ◽  
The Relationship

Horizontal axis double-runner Francis turbines have great advantages in the development of small hydropower plants, but the arrangement of double runners aggravates the complexity of the water flow between runners, and the mutual influence of the two runners cannot be ignored. In order to explore the relationship between the performance and the internal flow field and investigate the pressure pulsation characteristics of the double-runner Francis turbine, the steady and unsteady numerical analysis of the full flow channel of a prototype turbine was carried out based on the Realizable k-epsilon model and the polyhedral mesh method. The results show that the relationship between the average efficiency of the two runners and the flow difference between the runners is negatively correlated. As the flow rate difference between the runners on both sides increases, the average efficiency of the runners decreases. The draft tube flow of a horizontal-axis turbine has a profound effect on the flow field characteristics in the runner. When the working conditions change, the turning and converging timing of the mainstream at the outlet of the two runners will change. The movement of the mainstream promotes the change in location of the dead water zone. The existence of the vortex zone makes the pressure distribution at the outlet of the runner uneven, which is an important reason for the asymmetry of the flow in the runner. The analysis of pressure pulsation and its frequency spectrum shows that when the working conditions change, the low-frequency, strong pressure pulsation area on the surface of the guide vane will regularly migrate between the two runners, while the high-frequency pressure pulsation that occurs in the bladeless zone will dissipate in the runner. The doubling of the blade frequency on the pressure surface and back surface of the blades gradually attenuates with the increase of frequency. The pressure pulsation attenuation on the surface of the high-position blade conforms to the linear law, and the attenuation of the pressure pulsation on the surface of the low-position blade conforms to the exponential law. The research in this paper provides a certain reference value for revealing the flow field mechanism and pressure pulsation characteristics of the double-runner Francis turbine.

Design and development of guide vane cascade for a low speed number Francis turbine

2016 ◽  
Vol 28 (4) ◽  
pp. 676-689 ◽  
Author(s):  
Biraj Singh Thapa ◽  
Chirag Trivedi ◽  
Ole Gunnar Dahlhaug
Keyword(s):  
Guide Vane ◽  
Francis Turbine ◽  
Design And Development ◽  
Low Speed

scholarly journals Derivation of Global Parametric Performance of Mixed Flow Hydraulic Turbine Using CFD

1970 ◽  
Vol 7 ◽  
pp. 60-64 ◽  
Author(s):  
Ruchi Khare ◽  
Vishnu Prasad Prasad ◽  
Sushil Kumar
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Solutions ◽  
Guide Vane ◽  
Hydraulic Turbine ◽  
Francis Turbine ◽  
Mixed Flow ◽  
Flow Equations ◽  
Laboratory Setup ◽  
Wide Range

The testing of physical turbine models is costly, time consuming and subject to limitations of laboratory setup to meet International Electro technical Commission (IEC) standards. Computational fluid dynamics (CFD) has emerged as a powerful tool for funding numerical solutions of wide range of flow equations whose analytical solutions are not feasible. CFD also minimizes the requirement of model testing. The present work deals with simulation of 3D flow in mixed flow (Francis) turbine passage; i.e., stay vane, guide vane, runner and draft tube using ANSYS CFX 10 software for study of flow pattern within turbine space and computation of various losses and efficiency at different operating regimes. The computed values and variation of performance parameters are found to bear close comparison with experimental results.Key words: Hydraulic turbine; Performance; Computational fluid dynamics; Efficiency; LossesDOI: 10.3126/hn.v7i0.4239Hydro Nepal Journal of Water, Energy and EnvironmentVol. 7, July, 2010Page: 60-64Uploaded date: 31 January, 2011

Comparison of Axial Water and Air Injections in the Draft Tube of a Francis Turbine for RVR Mitigation

2021 ◽  
Author(s):  
Subodh Khullar ◽  
Krishna M. Singh ◽  
Michel J. Cervantes ◽  
Bhupendra K. Gandhi
Keyword(s):  
Pressure Pulsation ◽  
Draft Tube ◽  
Water Injection ◽  
Air Injection ◽  
Flow Instabilities ◽  
Pressure Recovery ◽  
Francis Turbine ◽  
Tube Flow ◽  
Pressure Pulsations ◽  
Jet Injection

Abstract The presence of excessive swirl at the runner outlet in Francis turbines operating at part load leads to the development of flow instabilities such as the rotating vortex rope (RVR). The presence of RVR causes severe pressure pulsations, power swings, and fatigue damage in the turbine unit. Air and water injection in the draft tube have been reported to reduce the detrimental effects of RVR formation in the Francis turbines. Air injection is one of the oldest and most widely used methods. In contrast, water jet injection is a relatively new methodology. The present work reports the numerical simulations performed to compare the respective effectiveness of these methods to mitigate the RVR and the related flow instabilities. The efficacy of the two methods has been compared based on the pressure pulsations and pressure recovery in the draft tube cone. The results show that the air and water injection influence the draft tube flow field in different ways. Both air and water injection led to a reduction in pressure pulsation magnitudes in the draft tube cone. However, the air injection led to a negative pressure recovery while the water injection improved the draft tube action.

scholarly journals Influence of guide vane clearance on internal flow of medium-specific speed Francis turbine

2019 ◽  
Vol 240 ◽  
pp. 022056
Author(s):  
Gnanasekaran Kishor Kumar ◽  
Tadachika Tanaka ◽  
Naoki Yamaguchi ◽  
Toui Taniwaki ◽  
Kazuyoshi Miyagawa ◽  
...  
Keyword(s):  
Guide Vane ◽  
Internal Flow ◽  
Francis Turbine ◽  
Specific Speed

scholarly journals Fluid–structure interaction analysis of fluid pressure pulsation and structural vibration features in a vertical axial pump

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401982858
Author(s):  
Liaojun Zhang ◽  
Shuo Wang ◽  
Guojiang Yin ◽  
Chaonian Guan
Keyword(s):  
Pressure Pulsation ◽  
Interaction Analysis ◽  
Equivalent Stress ◽  
Fluid Structure Interaction ◽  
Fluid Pressure ◽  
Structural Vibration ◽  
Interaction Method ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Axial Pump

Current studies on the operation of the axial pump mainly focus on hydraulic performances, while the coupled interaction between the fluid and structure attracts little attention. This study aims to provide numerical investigation into the vibration features in a vertical axial pump based on two-way iterative fluid–structure interaction method. Three-dimensional coupling model was established with high-quality structured grids of ADINA software. Turbulent flow features were studied under design condition, using shear–stress transport k-ω turbulence model and sliding mesh approach. Typical measure points along and perpendicular to flow direction in fluid domain were selected to analyze pressure pulsation features of the impeller and fixed guide vane. By contrast, vibration features of equivalent stress in corresponding structural positions were investigated and compared based on fluid–structure interaction method. In order to explore fluid–structure interaction vibration mechanism, distribution of main frequencies and amplitudes of the measure points was presented based on the Fast Fourier Transformation method. The results reveal the time and frequency law of fluid pressure pulsation and structural vibration at the same position in the vertical axial pump while additionally provide important theoretical guidance for optimization design and safe operation of the vertical axial pump.

scholarly journals Numerical and Experimental Investigation of External Characteristics and Pressure Fluctuation of a Submersible Tubular Pumping System

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 949 ◽  
Author(s):  
Yan Jin ◽  
Xiaoke He ◽  
Ye Zhang ◽  
Shanshan Zhou ◽  
Hongcheng Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pressure Fluctuation ◽  
High Efficiency ◽  
Pressure Pulsation ◽  
Guide Vane ◽  
Measurement Data ◽  
Flow Characteristics ◽  
Measuring Point ◽  
Pumping System ◽  
Impeller Outlet

This paper presents an investigation of external flow characteristics and pressure fluctuation of a submersible tubular pumping system by using a combination of numerical simulation and experimental methods. The steady numerical simulation is used to predicted the hydraulic performance of the pumping system, and the unsteady calculation is adopted to simulate the pressure fluctuation in different components of a submersible tubular pumping system. A test bench for a model test and pressure pulsation measurement is built to validate the numerical simulation. The results show that the performance curves of the calculation and experiment are in agreement with each other, especially in the high efficiency area, and the deviation is minor under small discharge and large discharge conditions. The pressure pulsation distributions of different flow components, such as the impeller outlet, middle of the guide vane, and guide vane outlet and bulb unit, are basically the same as the measurement data. For the monitoring points on the impeller and the wall of the guide vane especially, the main frequency and its amplitude matching degree are higher, while the pressure pulsation values on the wall of the bulb unit are quite different. The blade passing frequency and its multiples are important parameters for analysis of pressure pulsation; the strongest pressure fluctuation intensity appears in the impeller outlet, which is mainly caused by the rotor–stator interaction. The farther the measuring point from the impeller, the less the pressure pulsation is affected by the blade frequency. The frequency amplitudes decrease from the impeller exit to the bulb unit.

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