scholarly journals Comprehensive Hydraulic Improvement and Parametric Analysis of a Francis Turbine Runner

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 307 ◽  
Author(s):  
Zhe Ma ◽  
Baoshan Zhu ◽  
Cong Rao ◽  
Yonghong Shangguan
Keyword(s):  
Optimization Design ◽  
Internal Flow ◽  
Francis Turbine ◽  
Design System ◽  
Blade Loading ◽  
Operation Conditions ◽  
Wide Range ◽  
Turbine Runner ◽  
Low Head ◽  
Meridional Shape

Hydraulic turbines are usually required to operate in a wide range. The operation at off-design conditions not only reduces the unit efficiency, but also significantly deteriorates the dynamic stability of the turbines. In order to develop a turbine runner with good performances under multi operation conditions, a comprehensive hydraulic improvement has been done of a Francis turbine runner with a multipoint and multi-objective optimization design system. Compared with the initial runner, the runner generated from this method has a satisfactory improvement. In detail, unit efficiencies of the preferred runner are increased by 0.91%, 0.47% and 0.37%, respectively, under the rated head, a high head and the maximum head. The lowest pressure at blade surface is improved by 376.2 kPa under the rated head. CFD calculations are conducted to analyze the flow conditions inside of the preferred runner. In addition, runners with different main design inputs, namely blade lean, blade loading and blade meridional shape are furtherly investigated to reveal their relationship with runner’s internal flow and outer performances. In summary, this optimization system supplies satisfactory results and convincing recommendations to determine the design inputs for low-head Francis turbine runners.

Simulation on Balde Duct Vortex in a Francis Turbine Runner Based on S-A Model

2013 ◽  
Vol 444-445 ◽  
pp. 476-478 ◽  
Author(s):  
Yong Zhong Zeng ◽  
Xiao Bing Liu
Keyword(s):  
Flow Field ◽  
Internal Flow ◽  
Optimal Operation ◽  
Francis Turbine ◽  
Operation Conditions ◽  
Low Load ◽  
Turbine Runner ◽  
Low Specific Speed ◽  
Specific Speed ◽  
Load Conditions

If deviating from the optimal operation conditions, flow separation will occur on the blade of the runner in a low specific speed turbine. At this time, the turbulent flow of flow field in the blade duct will be in a strong non-equilibrium state, and thus the blade duct vortexes will be generated. To further study the mechanism of blade duct vortexes and to control the generation of these vortexes, Spalart-Allmaras (S-A) model was used to numerically simulate and calculate the internal flow in the low specific speed turbine runner under low load conditions. The blade duct vortexes in the turbine runner were accurately predicted. The effect of short blade in eliminating and reducing the vortexes in the low specific speed turbine runner was analyzed and compared.

scholarly journals Automatic Design System with Generative Adversarial Network and Convolutional Neural Network for Optimization Design of Interior Permanent Magnet Synchronous Motor

2021 ◽  
Author(s):  
Yuki Shimizu ◽  
Shigeo Morimoto ◽  
Masayuki Sanada ◽  
Yukinori Inoue
Keyword(s):  
Neural Network ◽  
Prediction Model ◽  
Convolutional Neural Network ◽  
Permanent Magnet ◽  
Optimization Design ◽  
Design System ◽  
Automatic Design ◽  
Wide Range ◽  
Interior Permanent Magnet ◽  
Long Time

The optimal design of interior permanent magnet synchronous motors requires a long time because finite element analysis (FEA) is performed repeatedly. To solve this problem, many researchers have used artificial intelligence to construct a prediction model that can replace FEA. However, because the training data are generated by FEA, it takes a very long time to obtain a sufficient amount of data, making it impossible to train a large-scale prediction model. Here, we propose a method for generating a large amount of data from a small number of FEA results using machine learning. An automatic design system with a deep generative model and a convolutional neural network is then constructed. With its sufficient data, the proposed system can handle three topologies and three motor parameters in a wide range of current vector regions. The proposed system was applied to multi-objective optimization design, with the optimization completed in 13-15 seconds.

scholarly journals Automatic Design System with Generative Adversarial Network and Convolutional Neural Network for Optimization Design of Interior Permanent Magnet Synchronous Motor

2021 ◽  
Author(s):  
Yuki Shimizu ◽  
Shigeo Morimoto ◽  
Masayuki Sanada ◽  
Yukinori Inoue
Keyword(s):  
Neural Network ◽  
Prediction Model ◽  
Convolutional Neural Network ◽  
Permanent Magnet ◽  
Optimization Design ◽  
Design System ◽  
Automatic Design ◽  
Wide Range ◽  
Interior Permanent Magnet ◽  
Long Time

The optimal design of interior permanent magnet synchronous motors requires a long time because finite element analysis (FEA) is performed repeatedly. To solve this problem, many researchers have used artificial intelligence to construct a prediction model that can replace FEA. However, because the training data are generated by FEA, it takes a very long time to obtain a sufficient amount of data, making it impossible to train a large-scale prediction model. Here, we propose a method for generating a large amount of data from a small number of FEA results using machine learning. An automatic design system with a deep generative model and a convolutional neural network is then constructed. With its sufficient data, the proposed system can handle three topologies and three motor parameters in a wide range of current vector regions. The proposed system was applied to multi-objective optimization design, with the optimization completed in 13-15 seconds.

scholarly journals Characteristic analysis of the efficiency hill chart of Francis turbine for different water heads

2017 ◽  
Vol 9 (2) ◽  
pp. 168781401769007 ◽  
Author(s):  
Pengcheng Guo ◽  
Zhaoning Wang ◽  
Longgang Sun ◽  
Xingqi Luo
Keyword(s):  
Incidence Angle ◽  
Suction Side ◽  
Francis Turbine ◽  
Small Range ◽  
Characteristic Analysis ◽  
Wide Range ◽  
Low Head ◽  
Model Efficiency ◽  
Hydraulic Turbines ◽  
High Head

According to several model test results of Francis turbines, complete model efficiency hill charts were constructed. The formation and inevitability of diversified hydraulic phenomena on model efficiency hill chart for typical head range were analyzed and the difference is compared, as well as characteristics and commonness toward the curves are discussed and summarized. Furthermore, hydraulic performance and geometric features are presented by particularly analyzing the efficiency hill charts. The inherent characteristics of Francis turbine is expressed by all kinds of curves on the model efficiency hill charts, and these curves can be adjusted and moved in a small range but cannot be removed out. Due to wide range of unit speed in terms of medium-low-head hydraulic turbines, incipient cavitation curve on suction side can be observed and it is positioned close to the operation zone; however, it fails to be visualized for the high-head turbine. The blade channel vortex curves are in the vicinity of optimum region for low-head hydraulic turbines, while high-head shows reverse trend. The interaction between zero incidence angle and zero circulation curve has a significant influence on isoefficiency circles. All comparisons and analyses could provide hydraulic design basis and retrofit references.

Based on CFX Numerical Simulation of Francis Turbine Runner

2013 ◽  
Vol 456 ◽  
pp. 207-210
Author(s):  
Fang He
Keyword(s):  
Numerical Simulation ◽  
Guide Vane ◽  
Prediction Method ◽  
Internal Flow ◽  
Francis Turbine ◽  
Flow State ◽  
Hydro Turbine ◽  
Runner Blade ◽  
Vibration Prediction ◽  
Turbine Runner

This paper presents a vibration prediction method for Francis turbine: Provided with advanced CFX software, Numerical simulation of movable guide vane and Turbine runner’s internal flow state. From the source of hydraulic vibration, Focus on numerical analysis, numerical simulation for the cutting thickness of the runner blade. After analysis of the influence of the blade of hydraulic vibration. To explore new ways for the hydro turbine control hydraulic vibration.

Performance Prediction by Viscous Flow Analysis for Francis Turbine Runner

1994 ◽  
Vol 116 (1) ◽  
pp. 116-120 ◽  
Author(s):  
T. C. Vu ◽  
W. Shyy
Keyword(s):  
Viscous Flow ◽  
Computational Algorithm ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Francis Turbine ◽  
Turbine Runner ◽  
Current Design ◽  
Low Head ◽  
High Head

Validation of a three-dimensional computational algorithm for viscous flow analysis has been conducted for two types of Francis turbine runner geometry, one low head and one high head, using experimental measurement. Assessment has been made for both qualitative features of flow behavior, as well as quantitative distribution of blade pressure and head loss. The influence of the grid size on the accuracy of the numerical solution is also discussed. Effort has been made to address some of the design issues, and to demonstrate that the present computational algorithm can make useful contributions to help improve the current design practices.

Suppression of Cavitation in a Francis Turbine Runner by Application of 3D Inverse Design Method

2002 ◽  
Author(s):  
Hidenobu Okamoto ◽  
Akira Goto
Keyword(s):  
High Efficiency ◽  
Static Pressure ◽  
Design Method ◽  
Three Dimensional ◽  
Inverse Design ◽  
Francis Turbine ◽  
Blade Loading ◽  
Static Pressure Distribution ◽  
Turbine Runner ◽  
Inverse Design Method

This paper describes a new design method of blade geometry for a Francis turbine runner by using a three-dimensional inverse design method and the Computational Fluid Dynamics (CFD) technique. The design objectives are the suppression of cavitation by reducing the area in which static pressure is lower than the vapor pressure while keeping the efficiency high. In the inverse design method, it is possible to optimize the static pressure distribution in the runner by controlling blade loading parameters and/or stacking condition, which is related to a blade lean angle, for the same design specification. A Francis turbine runner was re-designed by the inverse design method for different blade loading and stacking conditions, and the flow fields were evaluated by applying CFD. It was confirmed that the present design method is very practical and effective to control low pressure region and achieve high efficiency for Francis turbine runners.

scholarly journals Study on Friction in Automotive Shock Absorbers Part 1: Friction Simulation Using a Dynamic Friction Model in the Contact Zone of an FEM Model

Vehicles ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 212-232
Author(s):  
Ludwig Herzog ◽  
Klaus Augsburg
Keyword(s):  
Ride Comfort ◽  
Viscous Friction ◽  
Simulation Method ◽  
Friction Model ◽  
Model Parameters ◽  
Dynamic Friction ◽  
Friction Modeling ◽  
Shock Absorbers ◽  
Operation Conditions ◽  
Wide Range

The important change in the transition from partial to high automation is that a vehicle can drive autonomously, without active human involvement. This fact increases the current requirements regarding ride comfort and dictates new challenges for automotive shock absorbers. There exist two common types of automotive shock absorber with two friction types: The intended viscous friction dissipates the chassis vibrations, while the unwanted solid body friction is generated by the rubbing of the damper’s seals and guides during actuation. The latter so-called static friction impairs ride comfort and demands appropriate friction modeling for the control of adaptive or active suspension systems. In this article, a simulation approach is introduced to model damper friction based on the most friction-relevant parameters. Since damper friction is highly dependent on geometry, which can vary widely, three-dimensional (3D) structural FEM is used to determine the deformations of the damper parts resulting from mounting and varying operation conditions. In the respective contact zones, a dynamic friction model is applied and parameterized based on the single friction point measurements. Subsequent to the parameterization of the overall friction model with geometry data, operation conditions, material properties and friction model parameters, single friction point simulations are performed, analyzed and validated against single friction point measurements. It is shown that this simulation method allows for friction prediction with high accuracy. Consequently, its application enables a wide range of parameters relevant to damper friction to be investigated with significantly increased development efficiency.

scholarly journals Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1182
Author(s):  
Seung-Jun Kim ◽  
Yong Cho ◽  
Jin-Hyuk Kim
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Air Injection ◽  
Low Flow ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Vortex Rope

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

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