Flow Across a Butterfly Valve in a Dam Penstock

2017 ◽  
Author(s):  
Dominic Lattouf ◽  
B. P. Huynh
Keyword(s):  
Navier Stokes ◽  
Butterfly Valve ◽  
Maximum Torque ◽  
Ansys Fluent ◽  
Water Head ◽  
Models Comparison ◽  
Flow Through ◽  
Volume Method ◽  
Grid Independence ◽  
Valve Angle

Butterfly valves are typically used as emergency closure devices in dam penstocks; these valves must be capable of closing if a penstock bursts. This paper summarizes a 3D CFD (Computational Fluid Dynamics) study that was conducted on the water flow across a sizable butterfly valve (1.6m in diameter) in a dam penstock with 57m of water head. The main aim is to determine the maximum torque required to close the valve. Thus semi steady flow conditions across the valve at various degrees of closure were investigated and the corresponding torque calculated. A maximum torque of about 87 700 N-m has been obtained, occurring at valve angle 40° (with valve totally closed at 0°, and fully open at 90°). Visual results were analyzed at each valve angle to understand the nature of the flow through the butterfly valve using various 2D contours and streamline images. The CFD software ANSYS Fluent has been used employing a Finite Volume Method. The RANS (Reynolds-Averaged Navier-Stokes) approach with Realizable K-epsilon turbulence model was employed. A grid independence study with up to 10 million cells has also been carried out, resulting in the adoption of 7.5 million cells in all models. Comparison with other available data was also completed, adding to the reliability of the computational results. Distribution of pressure, flow velocity, and turbulence parameters are also presented.

Numerical Analysis of Streamlines in Kaplan Turbine with Different Distributor Fins Design

2020 ◽  
Vol 35 ◽  
pp. 46-54
Author(s):  
Daniele Twardowski ◽  
Diego Alves de Miranda
Keyword(s):  
Stokes Equations ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Flow Profile ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Kaplan Turbine ◽  
Current Lines ◽  
High Level ◽  
Volume Method

With each passing day companies are looking more and more in the initial phase of the project, to understand the phenomena arising, so that in the execution of the project there are no failures, much less when the project is in operation. For this, the numerical simulation has been shown an increasingly efficient tool to assist the engineers and designers of machines and equipment. The Kaplan turbine design requires a high level of engineering expertise combined with a high level of knowledge in fluid mechanics, as poor design of a diffuser fin can lead to disordered turbulent flow which, when mixed with a high pressure drop, can cavitate into turbine blades. The aim of this study is to evaluate different types of diffuser fin profiles in the inlet at Kaplan turbines. For this, numerical computer simulation was used with the aid of the Ansys Fluent software, in which simulations of water flow in a steady state occurred. The software works with the finite volume method for the discretization of the Navier-Stokes equations. The simulations have proved to be efficient in capturing current lines and pointing out the best flow profile in a project, avoiding more complex turbine blade problems.

Calculations of three-dimensional viscous flow in a multiblade centrifugal fan by modelling blade forces

2003 ◽  
Vol 217 (3) ◽  
pp. 287-297 ◽  
Author(s):  
S-J Seo ◽  
K-Y Kim ◽  
S-H Kang
Keyword(s):  
Mathematical Model ◽  
Turbulent Flows ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Centrifugal Fan ◽  
Complex Flows ◽  
Flow Through ◽  
Volume Method ◽  
The Mathematical Model

A numerical study is presented for Reynolds-averaged Navier-Stokes analysis of three-dimensional turbulent flows in a multiblade centrifugal fan. Present work aims at development of a relatively simple analysis method for these complex flows. A mathematical model of impeller forces is obtained from the integral analysis of the flow through the impeller. A finite volume method for discretization of governing equations and a standard k-ɛ model as turbulence closure are employed. For the validation of the mathematical model, the computational results for velocity components, static pressure, and flow angles at the exit of the impeller were compared with experimental data. The comparisons show generally good agreement, especially at higher flow coefficients.

scholarly journals Mathematical Simulation of Drying Process of Fibrous Material

2018 ◽  
Vol 180 ◽  
pp. 02010
Author(s):  
Tomáš Blejchař ◽  
Jiří Raška ◽  
Jana Jablonská
Keyword(s):  
Mathematical Simulation ◽  
Fibrous Material ◽  
Multiphase Model ◽  
Ansys Fluent ◽  
Hot Air ◽  
Porous Element ◽  
Flow Through ◽  
Porous Zone ◽  
Volume Method ◽  
Porous Area

The article describes mathematical simulation of flowing air through porous zone and water vaporisation from mentioned porous area which actually represents dried fibrous material - cotton towel. Simulation is based on finite volume method. Wet towel is placed in pipe and hot air flow through the towel. Water from towel is evaporated. Simulation of airflow through porous element is described first. Eulerian multiphase model is then used for simulation of water vaporisation from porous medium. Results of simulation are compared with experiment. Ansys Fluent 13.0 was used for calculation.

scholarly journals PHENOMENOLOGICAL ANALYSIS OF A CONCEPTUAL WATERJET PROPULSOR BASED ON THE COANDA EFFECT

2019 ◽  
Vol 18 (1) ◽  
pp. 03
Author(s):  
R. L. Lemos ◽  
C. H. Marques ◽  
L. A. Rocha ◽  
L. A. Isoldi ◽  
E. D. dos Santos
Keyword(s):  
Physical Phenomenon ◽  
Transient State ◽  
Water Jet ◽  
Coanda Effect ◽  
Ansys Fluent ◽  
Marine Propulsion ◽  
Flow Through ◽  
Coandǎ Effect ◽  
Mechanical Devices ◽  
Volume Method

This work is part of a research project conceived at the Federal University of Rio Grande. The project aims to create and develop mechanical devices that use the Coanda effect to enhance their overall efficiency. The focus herein is analyzing the physical phenomenon occurring in a conceptual water-jet propulsor. In the proposed concept, a water-jet propulsor has its impeller replaced by injectors that produce the so-called Coanda effect, increasing thereby the mass flow rate. In order to simulate the flow through the propulsor, a numerical model was developed. In this model the time-averaged conservation equations of mass and momentum were solved numerically by the finite volume method, more precisely with the commercial package ANSYS FLUENT (version 14.0). For the closure of the constitutive equations, the k-ω URANS turbulence model was employed. The simulation was performed for a transient state with a timestep of ∆t = 1×10-3 s and a total physical time of t = 6.0 s. Static pressure fields, streamlines and speed profiles are used to analyze the equipment performance and the phenomenon occurrence. The results show that the Coanda Effect is able to generate thrust in a waterjet propulsion device without impeller. The study suggests that the employment of this principle has promising applicability in marine propulsion and deserves attention on future works.

A LES Study of Ventilation Flow Through a 3-D Room Fitted With Solar Chimney

2020 ◽  
Author(s):  
B. Phuoc Huynh
Keyword(s):  
Solar Radiation ◽  
Natural Ventilation ◽  
Boussinesq Approximation ◽  
Scale Model ◽  
Navier Stokes ◽  
Solar Chimney ◽  
3 Dimensional ◽  
Fluid Properties ◽  
Flow Through ◽  
Volume Method

Abstract Solar chimney (thermal chimney) is a device which absorbs solar radiation to heat the air. The heated air, becoming buoyant, rises through the chimney’s passage and induces further air currents. When fitted to a building, solar chimney can thus induce fresh outside air to flow through the building for ventilation. Because only natural means (solar radiation here) are involved to cause the air flow, solar chimney is considered a natural-ventilation device. This work investigates computationally natural ventilation induced by a roof-mounted solar chimney through a real-sized 3-dimensional room, using a commercial CFD (Computational Fluid Dynamics) software package which employs the Finite Volume Method. A LES (Large-Eddy Simulations) formulation with Smagorinsky SGS (Sub-Grid Scale) model is used. All fluid properties are assumed to be constant and corresponding to those of air at 300K (27°C, constant ambient temperature) and standard pressure at sea level (101.3kPa); but Boussinesq approximation (wherein temperature change affects only the fluid density pertaining to buoyancy force) is also assumed. Comparison is made with computational results obtained from a RANS (Reynolds-Averaged Navier-Stokes) formulation. Agreement between LES and RANS results indicate the trustworthiness of CFD methods used.

scholarly journals Validation and Verification of CFD Prediction of Fluid Flow of a Submerged Vertical Round Jet

2018 ◽  
Vol 3 (2) ◽  
pp. 113-121
Author(s):  
Nurul Hasan ◽  
Ahmed Oliur Rahman ◽  
Md. Shah Alam
Keyword(s):  
Symmetric Domain ◽  
Navier Stokes ◽  
Computational Error ◽  
Navier Stokes Equation ◽  
Validation And Verification ◽  
Fluent Software ◽  
Computational Fluid Dynamics Cfd ◽  
Volume Method ◽  
Grid Independence ◽  
Better Than

This paper presents a step by step verification and validation process of a vertical round submerged jet into a cylindrical bath. Taking advantage of the axi-symmetric domain, Navier-Stokes equation of primary is solved by finite volume method (FVM) using commercial computational fluid dynamics, CFD (Fluent) software. For verification and to minimise the computational error, step by step grid independence tests were performed. For validation, experimental data was produced using laser Doppler velocimetry (LDV). Among the turbulence model,  SST was found to predict the flow behaviour better than k-e-  realization or RSM models. 

scholarly journals Atmospheric Flow at Alcântara Launch Center

2020 ◽  
Vol 42 ◽  
pp. e35
Author(s):  
Karine Klippel ◽  
Elisa Valentim Goulart ◽  
Gilberto Fisch ◽  
Neyval Costa Reis Junior ◽  
Cayo Prado Fernandes Francisco
Keyword(s):  
Wind Direction ◽  
Reynolds Stress Model ◽  
Navier Stokes ◽  
Neutral Atmosphere ◽  
Ansys Fluent ◽  
Atmospheric Flow ◽  
Freestream Velocity ◽  
Coastal Cliff ◽  
Computational Fluid Dynamics Cfd ◽  
Volume Method

The atmospheric flow at Alcântara Launch Center (CLA) was studied using Computational Fluid Dynamics (CFD) techniques. To characterize the region were considered the coastal cliff and the Integration Mobile Tower, called TMI, both within the launching and preparation area (SPL). In this study, the cliff was represented by a step of 90° with 40 meters of height. The inlet velocity profile was elaborate according to the power law, with exponent of 0.11, freestream velocity of 20 m/s and Reynolds number of 4.3 x 105, adopting neutral atmosphere. Three wind directions were considered, 90º, 125º and 135°. The numerical model used was the Reynolds Stress Model (RSM), based on the Reynolds-Averaged Navier-Stokes (RANS) equations. The solution of the equations was obtained by ANSYS FLUENT 19, which uses the finite volume method. The results showed good agreement with the wind tunnel tests especially for wind direction perpendicular to the cliff. The incident wind direction strongly influences the flow dynamics in the SPL forming a helicoidal vortex over the coastal cliff the higher the wind slope.

scholarly journals Computational hydrodynamic analysis of a highly skewed marine propeller

2019 ◽  
Vol 16 (1) ◽  
pp. 21-32
Author(s):  
Houari Hussein ◽  
Kadda Boumediene ◽  
Samir Belhenniche ◽  
Omar Imine ◽  
Mohamed Bouzit
Keyword(s):  
Open Water ◽  
Navier Stokes ◽  
Marine Propeller ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Ship Wake ◽  
Sliding Mesh ◽  
Wide Range ◽  
Volume Method ◽  
Thrust And Torque

 The objective of the current paper is to study the flow around Seiun Maru Highly Skewed (HSP) marine propeller by assessment of blade forces and moments under non-cavitating case. The calculations are performed in open water (steady case) and non-uniform ship wake (Unsteady case). The governing equations based on Reynolds Averaged Navier-Stokes Equation (RANSE) are solved using Finite Volume Method. Ansys Fluent 14.0 is used to implement the simulation. For the steady case, Moving Reference Frame (MRF) is selected while sliding mesh technique is adopted for the unsteady case. Calculated open water performances in terms of thrust and torque coefficients fit very well with experimental data for a wide range of advance ratio. In the unsteady calculations, axial velocities, deduced from the nominal wake, are introduced in the Ansys fluent code. To locate suitably the non-uniform wake in the propeller front plane, three positions of inlet wake have been taken into account to determine their effects on the accuracy of the results. Obtained results show that computed performances are improved compared to panel method when the inlet is close to the propeller.  

scholarly journals OPTIMIZATION TO INCREASE ENERGY EFFICIENCY OF A SIROCCO CENTRIFUGAL FAN USING COMPUTATIONAL FLUID DYNAMICS (CFD)

2017 ◽  
Vol 16 (1) ◽  
pp. 52
Author(s):  
L. B. Kothe ◽  
A. P. Petry ◽  
T. D. J. Vecina ◽  
J. L. R. Luz
Keyword(s):  
Energy Efficiency ◽  
Flow Rate ◽  
Navier Stokes ◽  
Centrifugal Fan ◽  
Ansys Fluent ◽  
Increase Energy Efficiency ◽  
Commercial Code ◽  
Centrifugal Fans ◽  
Sst Turbulence Model ◽  
Volume Method

This paper presents a numerical and experimental study on the aerodynamic performance of Sirocco centrifugal fans seeking an increase in energy efficiency. Numerical simulations are performed by the Finite-Volume Method commercial code ANSYS Fluent. Characteristics such as flow rate at the outlet, consumed power and sound pressure levels emitted by centrifugal fans with the original model of 16 blades and the optimized models of 16 and 14 blades are compared. Numerical calculations are performed by the continuity equation, the Reynolds Averaged Navier- Stokes (RANS) equations and the k-ω SST turbulence model. The quality of the mesh is evaluated for three different mesh densities. Results demonstrate that it was possible to obtain an increase of flow rate up to 22.7%, and reductions in the noise levels without increasing the consumption of the electric motor.

scholarly journals On Numerical Solution of the Incompressible Navier-Stokes Equations with Static or Total Pressure Specified on Boundaries

2009 ◽  
Vol 2009 ◽  
pp. 1-26 ◽  
Author(s):  
N. P. Moshkin ◽  
D. Yambangwai
Keyword(s):  
Boundary Conditions ◽  
Incompressible Flow ◽  
Total Pressure ◽  
Stokes Equations ◽  
Computational Method ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Viscous Incompressible Flow ◽  
Flow Through ◽  
Volume Method

The purpose of this article is to develop and validate a computational method for the solution of viscous incompressible flow in a domain with specified static or total pressure on the flow-through boundaries (inflow and outflow). The computational algorithm is based on the Finite Volume Method in nonstaggered boundary-fitted grid. The implementations of the boundary conditions on the flow-through parts of the boundary are discussed. Test examples illustrate the main features and validity of the proposed method to study viscous incompressible flow through a bounded domain with specified static pressure (or total pressure) on boundary as a part of well-posed boundary conditions.

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