Study on the Refomation of Francis Turbine Based on CFD

2012 ◽  
Vol 516-517 ◽  
pp. 669-672
Author(s):  
Ying Zheng ◽  
Jiu Ju Cai ◽  
Zhan He Ma
Keyword(s):  
Velocity Vector ◽  
Static Pressure ◽  
Stokes Equations ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Lower Efficiency ◽  
Navier Stokes Equations ◽  
Through Flow ◽  
Mesh Method ◽  
Lower Discharge

Based on CFD software, Navier-Stokes equations, Sparlart-Allmaras turbulence model and the structure mesh method, the whole flow passage of Francis turbine were 3-D numerical simulated. By CFView, the distribution of velocity vector and static pressure in the flow passages through flow field were analyzed, which explained the shortcomings of design and its incidental problems of lower discharge capacity and lower efficiency. Consequently the improvement of the runner alone was promoted, and which could be proved to be good results.

scholarly journals Numerical Investigation on the Water Entry of Several Different Bow-Flared Sections

2020 ◽  
Vol 10 (22) ◽  
pp. 7952
Author(s):  
Qiang Wang ◽  
Boran Zhang ◽  
Pengyao Yu ◽  
Guangzhao Li ◽  
Zhijiang Yuan
Keyword(s):  
Stokes Equations ◽  
Water Entry ◽  
Navier Stokes ◽  
Hydrodynamic Characteristics ◽  
Time Step ◽  
Navier Stokes Equations ◽  
Surface Evolution ◽  
Mesh Method ◽  
The Difference ◽  
Dynamics Method

The bow-flared section may be simplified in the prediction of slamming loads and whipping responses of ships. However, the difference of hydrodynamic characteristics between the water entry of the simplified sections and that of the original section has not been well documented. In this study, the water entry of several different bow-flared sections was numerically investigated using the computational fluid dynamics method based on Reynolds-averaged Navier–Stokes equations. The motion of the grid around the section was realized using the overset mesh method. Reasonable grid size and time step were determined through convergence studies. The application of the numerical method in the water entry of bow-flared sections was validated by comparing the present predictions with previous numerical and experimental results. Through a comparative study on the water entry of one original section and three simplified sections, the influences of simplification of the bow-flared section on hydrodynamic characteristics, free surface evolution, pressure field, and impact force were investigated and are discussed here.

Numerical Calculation on Vortex-Induced Vibration of the Circular Cylinder Using Low Reynolds Model in Hybrid Method

2009 ◽  
Author(s):  
Xingwei Zhang ◽  
Chaoying Zhou
Keyword(s):  
Numerical Calculation ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Turbulence Model ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Vortex Induced Vibration ◽  
Mesh Method ◽  
Volume Method

Fundamental research on interaction between flow and structure is presented for computation the fluid dynamics of different two-dimensional oscillating models. The Navier-Stokes equations are solved using finite volume method. A multigrid mesh method which was applied to the situation of flow past the stagnating or vibrating cylinder is developed to simulate this type of flow. The interactive results between flow and structure rigid cylinders have been present. The computation fluid dynamic codes mainly with low Reynolds RANS solver are used to solve the impressible viscous Navier-Stokes equations. Finite volume method which is coupled with conformal hybrid mesh method is developed to simulate this type of flow. Numerical investigation focused on the response and the fluid forces on the cylinders and also observed the different shedding model in the wake. The numerical results are compared in detail with recent experimental and computational work. Present numerical comparison also showed that solution using different turbulence model will make the result have a little discrepancy and each turbulence model has respective characteristics in numerical solution on the vortex-induced vibration of the cylinder. In addition, the formation of the 2P vortex shedding model through the lock-in region and the beginning of the shedding model transformation in numerical calculation from 2S model to 2P model has been analyzed.

Analyses of Centrifugal Compressor Performance Impacts on Volute and Scroll

2010 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano
Keyword(s):  
Static Pressure ◽  
Stokes Equations ◽  
Single Stage ◽  
Navier Stokes ◽  
Performance Tests ◽  
Peak Efficiency ◽  
Navier Stokes Equations ◽  
Flow Simulations ◽  
Compressor Performance ◽  
Compressor Efficiency

Volute is used to collect and transport swirling gas produced by impeller or diffuser. Design of the volute not only impacts compressor efficiency but also influences the operating ranges of the compressor. In this study, Navier-Stokes equations combined with an algebra turbulence model were used to simulate flows inside a single stage compressor. Detailed flow simulations for a large cut back tongue volute are presented and discussed. A rounded tongue volute was tested in a single stage test rig. The compressor stage performance tests were conducted in the test lab and static pressure taps were used to measure static pressures at volute internal walls at locations of θ = 240° and 360°. Thermal couples and other static pressure probes were instrumented at inlet and outlet of the compressor for performance tests. The numerical results were compared with experiments and good agreements are found. Studies showed that a large cut back rounded tongue volute provided good operating range without dramatically dropping compressor peak efficiency.

scholarly journals Prediction and physical analysis of unsteady flows around a pitching airfoil with the dynamic mesh approah

2007 ◽  
pp. 451-476
Author(s):  
Sébastien Bourdet ◽  
Marianna Braza ◽  
Yannick Hoarau ◽  
Rajah El Akoury ◽  
Arif Ashraf ◽  
...  
Keyword(s):  
Compressible Flows ◽  
Stokes Equations ◽  
Dynamic Mesh ◽  
Navier Stokes ◽  
Physical Analysis ◽  
Navier Stokes Equations ◽  
Pitching Airfoil ◽  
Eddy Simulation ◽  
Mesh Method ◽  
High Reynolds

The fluid structure interaction due to the pitching motion of a NACA0012 aerofoil has been studied numerically at moderate and high Reynolds numbers. The dynamic mesh method has been employed in the code ICARE/IMFT solving the Navier-Stokes equations in compressible flows. At high Reynolds number, the phase-averaged Navier-Stokes equations have been solved, coupled with advanced URANS modelling in the NSMB code. The vortex dynamics and especially the stall are physically captured by the dynamic mesh method and by the URANS/Organised Eddy Simulation approach.

The Interaction Between the Impeller and Casing in a Small-Size Turbo-Compressor

2002 ◽  
Author(s):  
D.-W. Kim ◽  
Youn J. Kim
Keyword(s):  
Static Pressure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Reference Method ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Pressure Distributions ◽  
Loss Coefficients ◽  
Compressible Turbulent Flow ◽  
Turbo Compressor

The effects of casing shape on the performance and the interaction between the impeller and casing in a small-size turbo-compressor are investigated. Numerical analysis is conducted for the compressor with circular and single volute casings from inlet to discharge nozzle. In order to predict the flow pattern inside the entire impeller, vaneless diffuer and casing, calculations with multiple frames of reference method between the rotating and stationery parts of the domain are carried out. For compressible turbulent flow fields, the continuity and three-dimensional time-averaged Navier-Stokes equations are employed. To evaluate the performance of two types of casings, the static pressure and loss coefficients are obtained with various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load. To prove the accuracy of numerical results, measurements of static pressure around casing and pressure difference between the inlet and outlet of the compressor are performed for the circular casing. Comparison of these results between the experimental and numerical analyses are conducted, and reasonable agreement is obtained.

A note on Milne-Thomson's general solution of Navier–Stokes equations

1965 ◽  
Vol 61 (4) ◽  
pp. 915-916
Author(s):  
G. D. Nigam
Keyword(s):  
General Solution ◽  
Force Field ◽  
Velocity Vector ◽  
Stokes Equations ◽  
Scalar Potential ◽  
Compressible Fluids ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
External Force Field ◽  
Image Position

The Navier–Stokes equations governing the motion of viscous compressible fluids arewhere ρ is the density, q is the velocity vector, V is the scalar potential of the external force field, I is the idemfactor and Φ is the stress-tensorMilne-Thomson ((l)) has given a general solution of (1) and (2) in the form

Numerical Study on the Flow Characteristics of the Francis Turbine With Various Blade Profiles

2013 ◽  
Author(s):  
J.-H. Jeon ◽  
S.-S. Byeon ◽  
Y.-J. Kim
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Ansys Cfx ◽  
Commercial Code ◽  
Sst Turbulence Model

The Francis turbine is a kind of reaction turbines, which means that the potential energy of water converted to rotational kinetic energy. In this study, the flow characteristics have been investigated numerically in a Francis turbine on the 15 MW hydropower generation with various blade profiles (NACA 65 and NACA 16 series) and discharge angles (14°, 15°, 17°, and 18°), using the commercial code, ANSYS CFX. The k-ω SST turbulence model is employed in the Reynolds averaged Navier-Stokes equations. The computing domain includes the spiral casing, guide vanes, and draft tube, which are discretized with a full three-dimensional mesh system of unstructured tetrahedral shapes. The results showed that the change of blade profiles and discharge angles significantly influenced the performance of the Francis turbine.

Investigation of the Flow in Centrifugal Compressor Volute

2008 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano
Keyword(s):  
Static Pressure ◽  
Stokes Equations ◽  
Single Stage ◽  
Navier Stokes ◽  
Performance Tests ◽  
Test Rig ◽  
Peak Efficiency ◽  
Navier Stokes Equations ◽  
Flow Simulations ◽  
Compressor Efficiency

Volute is used to collect and transport swirling gas produced by impeller or diffuser. Design of the volute not only impacts compressor efficiency but also influences the operating ranges of the compressor. In this study, Navier-Stokes equations combined with an algebra turbulence model were used to simulate flows inside a single stage compressor. Detailed flow simulations for a large cut back tongue volute are presented and discussed. A rounded tongue volute was tested in a single stage test rig. The compressor stage performance tests were conducted in the test lab and static pressure taps were used to measure static pressures at volute internal walls at locations of θ = 240° and 360°. Thermal couples and other static pressure probes were instrumented at inlet and outlet of the compressor for performance tests. The numerical results were compared with experiments and good agreements are found. Studies showed that a large cut back rounded tongue volute provided good operating range without dramatically dropping compressor peak efficiency.

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