Numerical Prediction of Sediment Erosion on Francis Turbine Blades

2013 ◽  
Vol 662 ◽  
pp. 643-647 ◽  
Author(s):  
Hong Ming Zhang ◽  
Li Xiang Zhang
Keyword(s):  
Turbine Blades ◽  
Three Dimensional ◽  
Suction Side ◽  
Numerical Prediction ◽  
Francis Turbine ◽  
Two Phase ◽  
Sediment Erosion ◽  
Flow Equations ◽  
Sand Erosion ◽  
Simulation Results

The paper presents the numerical prediction of sediment erosion on Francis turbine blades using CFD code. The 3-D turbulent particulate-liquid two-phase flow equations are employed in this study. The computing domain is discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The finite volume method is used to solve the governing equations and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results have shown that the sand erosion rate on pressure side is more than on the suction side of the blade. The numerical simulation results are consistent with the real situation.

Numerical Investigation of Sediment-Laden Flow in a High-Head Francis Turbine Runner

2013 ◽  
Vol 860-863 ◽  
pp. 1542-1546
Author(s):  
Hong Ming Zhang ◽  
Li Xiang Zhang
Keyword(s):  
Erosion Rate ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Suction Side ◽  
Francis Turbine ◽  
Two Phase ◽  
Flow Equations ◽  
Maximum Value ◽  
Sand Erosion ◽  
Turbine Runner

The 3-D turbulent particulate-liquid two-phase flow equations are employed in this study. The computing domain is discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The finite volume method is used to solve the governing equations and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results have shown that the sand erosion rate on pressure side is more than on the suction side of the blade. The maximum value of sand volume fraction and the maximum value of sand erosion rate are at same location.

Numerical Analysis of Erosive Wear on the Guide Vanes of a Francis Turbine

2015 ◽  
Vol 741 ◽  
pp. 531-535
Author(s):  
Hong Ming Zhang ◽  
Li Xiang Zhang
Keyword(s):  
Numerical Analysis ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Erosive Wear ◽  
Francis Turbine ◽  
Two Phase ◽  
Guide Vanes ◽  
Flow Equations ◽  
Sand Erosion ◽  
Volume Method

The paper presents the numerical analysis of erosive wear on the guide vanes of a Francis turbine using CFD code. The 3-D turbulent particulate-liquid two-phase flow equations are employed in this study. The computing domain is discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The finite volume method is used to solve the governing equations and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results have shown that the volume fraction of sand at the top of the guide vanes is higher than others and the maximum of volume fraction of sand is at same location with the maximum of sand erosion rate density. The erosive wear is more serious at the top of the guide vanes.

3D Cavitations Turbulent Transient Calculation in the Francis Turbine Model

2012 ◽  
Vol 479-481 ◽  
pp. 2466-2470
Author(s):  
Dun Zhang ◽  
Yuan Zheng
Keyword(s):  
Model Experiment ◽  
Flow Model ◽  
Three Dimensional ◽  
Francis Turbine ◽  
Two Phase ◽  
Mixture Flow ◽  
Phase Mixture ◽  
Simulation Results ◽  
Accurate Numerical Solution ◽  
Turbine Model

Analysis had been carried out, based on the three-dimensional transient viscous turbulent calculation of a Francis turbine full flow field, the complete cavitations model and the two-phase mixture flow model were combined during the calculation, more accurate numerical solution had been obtained. According to the simulation results, the site and extent of cavitations in the turbine flow were reflected within the specific conditions, and were more consistent with the cavitations phenomenon observed in the model experiment, also provided a reference for the more in-depth research.

scholarly journals Numerical Study of Sediment Erosion Analysis in Francis Turbine

2019 ◽  
Vol 11 (5) ◽  
pp. 1423 ◽  
Author(s):  
Md Rakibuzzaman ◽  
Hyoung-Ho Kim ◽  
Kyungwuk Kim ◽  
Sang-Ho Suh ◽  
Kyung Kim
Keyword(s):  
Erosion Rate ◽  
Cavitation Erosion ◽  
Numerical Study ◽  
Leading Edge ◽  
Suction Side ◽  
Hydraulic Turbine ◽  
Francis Turbine ◽  
Trailing Edge ◽  
Sand Erosion ◽  
Turbine Design

Effective hydraulic turbine design prevents sediment and cavitation erosion from impacting the performance and reliability of the machine. Using computational fluid dynamics (CFD) techniques, this study investigated the performance characteristics of sediment and cavitation erosion on a hydraulic Francis turbine by ANSYS-CFX software. For the erosion rate calculation, the particle trajectory Tabakoff–Grant erosion model was used. To predict the cavitation characteristics, the study’s source term for interphase mass transfer was the Rayleigh–Plesset cavitation model. The experimental data acquired by this study were used to validate the existing evaluations of the Francis turbine. Hydraulic results revealed that the maximum difference was only 0.958% compared with the CFD data, and 0.547% compared with the experiment (Korea Institute of Machinery and Materials (KIMM)). The turbine blade region was affected by the erosion rate at the trailing edge because of their high velocity. Furthermore, in the cavitation–erosion simulation, it was observed that abrasion propagation began from the pressure side of the leading edge and continued along to the trailing edge of the runner. Additionally, as sediment flow rates grew within the area of the attached cavitation, they increased from the trailing edge at the suction side, and efficiency was reduced. Cavitation–sand erosion results then revealed a higher erosion rate than of those of the sand erosion condition.

scholarly journals Prediction and Measurement of Film Cooling Effectiveness for a First-Stage Turbine Vane Shroud

1990 ◽  
Author(s):  
D. Granser ◽  
T. Schulenberg
Keyword(s):  
Secondary Flow ◽  
Film Cooling ◽  
Three Dimensional ◽  
Suction Side ◽  
Computer Code ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Flow Equations ◽  
Numerical Predictions ◽  
Numerical Effort

After compressor discharge air has initially been used to cool the heat shields of the hot gas inlet casing, it can subsequently be employed for film cooling of the first-stage vane shrouds. Since the flow field near these shrouds is three-dimensional, the film cooling effectiveness cannot be predicted correctly by common two-dimensional codes. The secondary flow transports the film from the pressure side to the suction side where it can even climb up the airfoil to cool its trailing section. Such film cooling effectiveness was first investigated experimentally in a linear vane cascade at atmospheric pressure. The temperatures and static pressure levels at the adiabatic shrouds, as well as the temperature measurements within the vane cascade, are reported for different cooling film blowing rates. In addition, the secondary flow was analysed numerically using a partially-parabolic computer code for 3D viscous flows. It involves mutual interaction of the boundary layer with the mainstream. The secondary flow can also be modelled with this algorithm, which requires less numerical effort than solving the fully 3D elliptic flow equations. The numerical results of the experiment and numerical predictions are compared. In addition, the application of these results to a high-temperature gas turbine is presented.

Numerical Prediction of Cavitation Erosion on a Francis Turbine Runner

2013 ◽  
Vol 655-657 ◽  
pp. 449-456
Author(s):  
Hong Ming Zhang ◽  
Li Xiang Zhang
Keyword(s):  
Cavitation Erosion ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Numerical Prediction ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Transfer Model ◽  
Cavitation Damage ◽  
Turbine Runner

The paper presents numerical prediction of cavitation erosion on a Francis turbine runner using CFD code. The SST turbulence model is employed in the Reynolds averaged Navier–Stokes equations in this study. A mixture assumption and a finite rate mass transfer model were introduced. The computing domain is discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The finite volume method is used to solve the governing equations of the mixture model and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators(PISO) procedure. Comparison the numerical prediction results with a real runner with cavitation damage, the region of higher volume fraction by simulation with the region of runner cavitation damage is consistent.

The Aerodynamic Mixing Effect of Discrete Cooling Jets With Mainstream Flow on a Highly Loaded Turbine Blade

1996 ◽  
Vol 118 (3) ◽  
pp. 468-478 ◽  
Author(s):  
G. Wilfert ◽  
L. Fottner
Keyword(s):  
Boundary Layer ◽  
Film Cooling ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Suction Side ◽  
Horseshoe Vortex ◽  
Surface Flow ◽  
Experimental Investigations ◽  
Turbine Cascade ◽  
Mixing Processes

For the application of film cooling to turbine blades, experimental investigations were performed on the mixing processes in the near-hole region with a row of holes on the suction suction side of a turbine cascade. Data were obtained using pneumatic probes, pressure tappings, and a three-dimensional subminiature hot-wire probe, as well as surface flow visualization techniques. It was found that at low blowing rates, a cooling jet behaves very much like a normal obstacle and the mixing mainly takes place in the boundary layer. With increasing blowing rates, the jet penetrates deeper into the mainstream. The variation of the turbulence level at the inlet of the turbine cascade and the Reynolds number showed a strong influence on the mixing behavior. The kidney-shaped vortex and as an important achievement the individual horseshoe vortex of each single jet were detected and their exact positions were obtained. This way it was found that the position of the horseshoe vortex is strongly dependent on the blowing rate and this influences the aerodynamic mixing mechanisms. A two-dimensional code for the calculation of boundary layer flows called GRAFTUS was used; however, the comparison with the measurements showed only limited agreement for cascade flow with blowing due to the strong three-dimensional flow pattern.

scholarly journals Towards a model for structured mass movements: the OpenLISEM hazard model 2.0a

2021 ◽  
Vol 14 (4) ◽  
pp. 1841-1864
Author(s):  
Bastian van den Bout ◽  
Theo van Asch ◽  
Wei Hu ◽  
Chenxiao X. Tang ◽  
Olga Mavrouli ◽  
...  
Keyword(s):  
Mass Movement ◽  
Three Dimensional ◽  
Dynamical Behaviour ◽  
Material Point ◽  
Mass Movements ◽  
Complex Flow ◽  
Flume Experiments ◽  
Stress Strain ◽  
Two Phase ◽  
Flow Equations

Abstract. Mass movements such as debris flows and landslides differ in behaviour due to their material properties and internal forces. Models employ generalized multi-phase flow equations to adaptively describe these complex flow types. Such models commonly assume unstructured and fragmented flow, where internal cohesive strength is insignificant. In this work, existing work on two-phase mass movement equations are extended to include a full stress–strain relationship that allows for runout of (semi-)structured fluid–solid masses. The work provides both the three-dimensional equations and depth-averaged simplifications. The equations are implemented in a hybrid material point method (MPM), which allows for efficient simulation of stress–strain relationships on discrete smooth particles. Using this framework, the developed model is compared to several flume experiments of clay blocks impacting fixed obstacles. Here, both final deposit patterns and fractures compare well to simulations. Additionally, numerical tests are performed to showcase the range of dynamical behaviour produced by the model. Important processes such as fracturing, fragmentation and fluid release are captured by the model. While this provides an important step towards complete mass movement models, several new opportunities arise, such as application to fragmenting mass movements and block slides.

scholarly journals Towards a model for structured mass movements: the OpenLISEM Hazard model 2.0a

2020 ◽  
Author(s):  
Bastian van den Bout ◽  
Theo W. J. van Asch ◽  
Wei Hu ◽  
Chenxiao Tang ◽  
Olga Mavrouli ◽  
...  
Keyword(s):  
Dynamical Behavior ◽  
Mass Movement ◽  
Three Dimensional ◽  
Material Point ◽  
Mass Movements ◽  
Complex Flow ◽  
Flume Experiments ◽  
Stress Strain ◽  
Two Phase ◽  
Flow Equations

Abstract. Mass movements such as debris flows and landslide differ in behavior due to their material properties and internal forces. Models employ generalized multi-phase flow equations to adaptively describe these complex flow types. However, models commonly assume unstructured and fragmented flow after initiation of movement. In this work, existing work on two-phase mass movement equations are extended to include a full stress-strain relationship that allows for runout of (semi-) structured fluid-solid masses. The work provides both the three-dimensional equations and depth-averaged simplifications. The equations are implemented in a hybrid Material Point Method (MPM) which allows for efficient simulation of stress-strain relationships on discrete smooth particles. Using this framework, the developed model is compared to several flume experiments of clay blocks impacting fixed obstacles. Here, both final deposit patterns and fractures compare well to simulations. Additionally, numerical tests are performed to showcase the range of dynamical behavior produced by the model. Important processes such as fracturing, fragmentation and fluid release are captured by the model. While this provides an important step towards complete mass movement models, several new opportunities arise such as ground-water flow descriptions and application to fragmenting mass movements and block-slides.

Simulations and Measurements of Pressure Oscillations Caused by Vortex Ropes

2006 ◽  
Vol 128 (4) ◽  
pp. 649-655 ◽  
Author(s):  
Zhengwei Wang ◽  
Lingjiu Zhou
Keyword(s):  
Stokes Equations ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Suction Side ◽  
Rotational Frequency ◽  
Francis Turbine ◽  
Pressure Oscillations ◽  
Hydraulic Unit ◽  
Load Conditions

Pressure oscillations caused by vortex rope were measured in the draft tube of a prototype Francis turbine. The three-dimensional, unsteady Reynolds-averaged Navier-Stokes equations with the RNG κ−ϵ turbulence model were solved to model the flow within the entire flow path of the prototype hydraulic unit including the guide vanes, the runner, and the draft tube. The model was able to predict the pressure fluctuations that occur when operating at 67–83% of the optimum opening. The calculated frequencies and amplitudes of the oscillation show reasonable agreement with the experiment data. However, the results at 50% opening were not satisfactory. Pressure oscillations on the runner blades were found to be related to the precession of vortex ropes which caused pressure on the blades to fluctuate with frequencies of −fn+fd (fn is the rotational frequency and fd is vortex procession frequency). The peak-to-peak amplitudes of the pressure oscillations on the blades at the lower load conditions (67% opening) were higher than at higher load conditions (83% opening). Fluctuations on the suction side tended to be stronger than on the pressure side.

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