STH/CFD Coupled Simulation of the Protected Loss of Flow Accident in the CIRCE-HERO Facility

The paper presents the application of a coupling methodology between Computational Fluid Dynamics (CFD) and System Thermal Hydraulic (STH) codes developed at the University of Pisa. The methodology was applied to the CIRCE-HERO facility in order to reproduce the recently performed experimental conditions simulating a Protected Loss Of Flow Accident (PLOFA). The facility consists of an internal loop, equipped with a fuel pin simulator and a steam generator, and an external pool. In this coupling application, the System code RELAP5 is adopted for the simulation of the internal loop while the CFD code ANSYS Fluent is used for the sake of simulating the pool. The connection between the two addressed domains is provided at the inlet and outlet section of the internal loop; a thermal coupling is also performed in order to reproduce the observed thermal stratification phenomenon. The obtained results are promising and a good agreement was obtained for both the mass flow rates and temperature measurements. Capabilities and limitations of the adopted coupling technique are discussed in the present paper also providing suggestions for improvements and developments to be achieved in the frame of future applications.

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CFD Technique to calculate tube skin peak temperatures in refinery furnaces

CT&F - Ciencia Tecnología y Futuro ◽

10.29047/01225383.230 ◽

2011 ◽

Vol 4 (4) ◽

pp. 73-88

Author(s):

Fabian A. Diaz ◽

Jesús A. Castro

Keyword(s):

Fluid Dynamics ◽

Heat Fluxes ◽

Petroleum Crude ◽

Great Precision ◽

Ansys Fluent ◽

Commercial Code ◽

Computational Fluid Dynamics Cfd ◽

Precision And Accuracy ◽

Skin Temperatures ◽

Good Agreement

Tube skin peak temperature is one of the major parameters in furnaces operation since they determine the life of the tubes and the extent of an operation run. This parameter is very difficult to calculate appropriately in magnitude and location within the furnace and commercial furnace simulators usually fail in its calculation. Computational fluid dynamics (CFD) is the only technique that calculates peak skin temperatures with great precision and accuracy since radiation and convective heat fluxes can be calculated taking into account every singularity of the geometry of the furnace and the burners. In this work is developed a technique to calculate this parameter using CFD commercial code (Ansys Fluent) and an in-house furnace simulator (EcoFursim), results of the simulations are compared with data from different furnaces from Barrancabermeja refinery (Barrancabermeja, Colombia) and good agreement is observed. Refinery furnace is referred in this paper to fired heaters for non reacting heat up of hydrocarbons or petroleum crude.

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A Nonlinear CFD/Multibody Incremental-Dynamic Model for A Constrained Mechanism

Applied Sciences ◽

10.3390/app11031136 ◽

2021 ◽

Vol 11 (3) ◽

pp. 1136

Author(s):

Seyed Mohammadali Rahmati ◽

Alireza Karimi

Keyword(s):

Programming Environment ◽

Aerodynamic Forces ◽

Constraint Force ◽

Ansys Fluent ◽

Force Equation ◽

Dynamic Analyses ◽

Computational Fluid Dynamics Cfd ◽

Nonlinear Dynamic Analyses ◽

Flying Robots ◽

Good Agreement

Numerical analysis of a multibody mechanism moving in the air is a complicated problem in computational fluid dynamics (CFD). Analyzing the motion of a multibody mechanism in a commercial CFD software, i.e., ANSYS Fluent®, is a challenging issue. This is because the components of a mechanism have to be constrained next to each other during the movement in the air to have a reliable numerical aerodynamics simulation. However, such constraints cannot be numerically modeled in a commercial CFD software, and needs to be separately incorporated into models through the programming environment, such as user-defined functions (UDF). This study proposes a nonlinear-incremental dynamic CFD/multibody method to simulate constrained multibody mechanisms in the air using UDF of ANSYS Fluent®. To testify the accuracy of the proposed method, Newton–Euler dynamic equations for a two-link mechanism are solved using Matlab® ordinary differential equations (ODEs), and the numerical results for the constrained mechanisms are compared. The UDF results of ANSYS Fluent® shows good agreement with Matlab®, and can be applied to constrained multibody mechanisms moving in the air. The proposed UDF of ANSYS Fluent® calculates the aerodynamic forces of a flying multibody mechanism in the air for a low simulation cost than the constraint force equation (CFE) method. The results could have implications in designing and analyzing flying robots to help human rescue teams, and nonlinear dynamic analyses of the aerodynamic forces applying on a moving object in the air, such as airplanes, birds, flies, etc.

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CFD modeling of passive autocatalytic recombiners

Nukleonika ◽

10.1515/nuka-2015-0050 ◽

2015 ◽

Vol 60 (2) ◽

pp. 347-353 ◽

Cited By ~ 1

Author(s):

Magdalena Orszulik ◽

Adam Fic ◽

Tomasz Bury

Keyword(s):

Thermal Conductivity ◽

Thermal Conductivity Coefficient ◽

Cfd Modeling ◽

Ansys Fluent ◽

Reactor Technology ◽

Mass Diffusivity ◽

Safety Research ◽

Computational Fluid Dynamics Cfd ◽

Good Agreement ◽

Made In

Abstract This study deals with numerical modeling of passive autocatalytic hydrogen recombiners (PARs). Such devices are installed within containments of many nuclear reactors in order to remove hydrogen and convert it to steam. The main purpose of this work is to develop a numerical model of passive autocatalytic recombiner (PAR) using the commercial computational fluid dynamics (CFD) software ANSYS-FLUENT and tuning the model using experimental results. The REKO 3 experiment was used for this purpose. Experiment was made in the Institute for Safety Research and Reactor Technology in Julich (Germany). It has been performed for different hydrogen concentrations, different flow rates, the presence of steam, and different initial temperatures of the inlet mixture. The model of this experimental recombiner was elaborated within the framework of this work. The influence of mesh, gas thermal conductivity coefficient, mass diffusivity coefficients, and turbulence model was investigated. The best results with a good agreement with REKO 3 data were received for k-ɛ model of turbulence, gas thermal conductivity dependent on the temperature and mass diffusivity coefficients taken from CHEMKIN program. The validated model of the PAR was next implemented into simple two-dimensional simulations of hydrogen behavior within a subcompartment of a containment building.

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STH-CFD Codes Coupled Calculations Applied to HLM Loop and Pool Systems

Science and Technology of Nuclear Installations ◽

10.1155/2017/1936894 ◽

2017 ◽

Vol 2017 ◽

pp. 1-13 ◽

Cited By ~ 12

Author(s):

M. Angelucci ◽

D. Martelli ◽

G. Barone ◽

I. Di Piazza ◽

N. Forgione

Keyword(s):

Numerical Scheme ◽

Research Centre ◽

Ansys Fluent ◽

Reading And Writing ◽

Coupled Calculation ◽

Coupling Procedure ◽

Pool System ◽

Time Required ◽

The University ◽

Good Agreement

This work describes the coupling methodology between a modified version of RELAP5/Mod3.3 and ANSYS Fluent CFD code developed at the University of Pisa. The described coupling procedure can be classified as “two-way,” nonoverlapping, “online” coupling. In this work, a semi-implicit numerical scheme has been implemented, giving greater stability to the simulations. A MATLAB script manages both the codes, oversees the reading and writing of the boundary conditions at the interfaces, and handles the exchange of data. A new tool was used to control the Fluent session, allowing a reduction of the time required for the exchange of data. The coupling tool was used to simulate a loop system (NACIE facility) and a pool system (CIRCE facility), both working with Lead Bismuth Eutectic and located at ENEA Brasimone Research Centre. Some modifications in the coupling procedure turned out to be necessary to apply the methodology in the pool system. In this paper, the comparison between the obtained coupled numerical results and the experimental data is presented. The good agreement between experiments and calculations evinces the capability of the coupled calculation to model correctly the involved phenomena.

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Thermal Performance Analysis of a Rectangular Longitudinal Finned Solar Air Heater With Semicircular Absorber Plate

Journal of Solar Energy Engineering ◽

10.1115/1.4032010 ◽

2015 ◽

Vol 138 (1) ◽

Cited By ~ 7

Author(s):

Satyender Singh ◽

Prashant Dhiman

Keyword(s):

Thermal Performance ◽

Numerical Solutions ◽

Solar Air Heater ◽

Duct Flow ◽

Balance Equations ◽

Absorber Plate ◽

Ansys Fluent ◽

Air Heater ◽

Glass Cover ◽

Good Agreement

Thermal performance of a single-pass single-glass cover solar air heater consisting of semicircular absorber plate finned with rectangular longitudinal fins is investigated. The analysis is carried out for different hydraulic diameters, which were obtained by varying the diameter of the duct from 0.3–0.5 m. One to five numbers of fins are considered. Reynolds number ranges from 1600–4300. Analytical solutions for energy balance equations of different elements and duct flow of the solar air heater are presented; results are compared with finite-volume methodology based numerical solutions obtained from ansys fluent commercial software, and a fairly good agreement is achieved. Moreover, analysis is extended to check the effect of double-glass cover and the recycle of the exiting air. Results revealed that the use of double-glass cover and recycle operation improves the thermal performance of solar air heater.

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Experimental Methods for Measuring the Viscous Friction Coefficient in Hydraulic Spool Valves

Sustainability ◽

10.3390/su13137174 ◽

2021 ◽

Vol 13 (13) ◽

pp. 7174

Author(s):

Massimo Rundo ◽

Paolo Casoli ◽

Antonio Lettini

Keyword(s):

Friction Coefficient ◽

Viscous Friction ◽

Experimental Tests ◽

Experimental Methods ◽

Displacement Transducer ◽

A Posteriori ◽

Displacement Control ◽

Spool Valves ◽

The University ◽

Good Agreement

In hydraulic components, nonlinearities are responsible for critical behaviors that make it difficult to realize a reliable mathematical model for numerical simulation. With particular reference to hydraulic spool valves, the viscous friction coefficient between the sliding and the fixed body is an unknown parameter that is normally set a posteriori in order to obtain a good agreement with the experimental data. In this paper, two different methodologies to characterize experimentally the viscous friction coefficient in a hydraulic component with spool are presented. The two approaches are significantly different and are both based on experimental tests; they were developed in two distinct laboratories in different periods of time and applied to the same flow compensator of a pump displacement control. One of the procedures was carried out at the Fluid Power Research Laboratory of the Politecnico di Torino, while the other approach was developed at the University of Parma. Both the proposed methods reached similar outcomes; moreover, neither method requires the installation of a spool displacement transducer that can significantly affect the results.

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Experimental and CFD Simulations of the Aerosol Flow in the Air Ventilating the Underground Excavation in Terms of SARS-CoV-2 Transmission

Energies ◽

10.3390/en14164743 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4743

Author(s):

Tomasz Janoszek ◽

Zbigniew Lubosik ◽

Lucjan Świerczek ◽

Andrzej Walentek ◽

Jerzy Jaroszewicz

Keyword(s):

Numerical Calculations ◽

Mining Institute ◽

Ventilation Network ◽

Underground Excavation ◽

In Situ Tests ◽

Ansys Fluent ◽

Aerosol Emission ◽

Ansys Cfx ◽

Computational Fluid Dynamics Cfd

The paper presents the results of experimental and model tests of transport of dispersed fluid droplets forming a cloud of aerosol in a stream of air ventilating a selected section of the underground excavation. The excavation selected for testing is part of the ventilation network of the Experimental Mine Barbara of the Central Mining Institute. For given environmental conditions, such as temperature, pressure, relative humidity, and velocity of air, the distribution of aerosol droplet changes in the mixture of air and water vapor along the excavation at a distance was measured at 10 m, 25 m, and 50 m from the source of its emission. The source of aerosol emission in the excavation space was a water nozzle that was located 25 m from the inlet (inlet) of the excavation. The obtained results of in situ tests were related to the results of numerical calculations using computational fluid dynamics (CFD). Numerical calculations were performed using Ansys-Fluent and Ansys-CFX software. The dimensions and geometry of the excavation under investigation are presented. The authors describe the adopted assumptions and conditions for the numerical model and discuss the results of the numerical solution.

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Ground Flutter Simulation Test Based on Reduced Order Modeling of Aerodynamics by CFD/CSD Coupling Method

International Journal of Applied Mechanics ◽

10.1142/s175882511950008x ◽

2019 ◽

Vol 11 (01) ◽

pp. 1950008

Author(s):

Binwen Wang ◽

Xueling Fan

Keyword(s):

Aerodynamic Force ◽

Test System ◽

Simulation Test ◽

Robust Controller ◽

Test Technique ◽

Reduced Order ◽

Aerodynamic Model ◽

Flutter Boundary ◽

Computational Fluid Dynamics Cfd ◽

Good Agreement

Flutter is an aeroelastic phenomenon that may cause severe damage to aircraft. Traditional flutter evaluation methods have many disadvantages (e.g., complex, costly and time-consuming) which could be overcome by ground flutter test technique. In this study, an unsteady aerodynamic model is obtained using computational fluid dynamics (CFD) code according to the procedure of frequency domain aerodynamic calculation. Then, the genetic algorithm (GA) method is adopted to optimize interpolation points for both excitation and response. Furthermore, the minimum-state method is utilized for rational fitting so as to establish an aerodynamic model in time domain. The aerodynamic force is simulated through exciters and the precision of simulation is guaranteed by multi-input and multi-output robust controller. Finally, ground flutter simulation test system is employed to acquire the flutter boundary through response under a range of air speeds. A good agreement is observed for both velocity and frequency of flutter between the test and modeling results.

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Analysis of Late Phase Severe Accident Phenomena in CANDU Plant

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4035416 ◽

2017 ◽

Vol 3 (2) ◽

Cited By ~ 4

Author(s):

D. Dupleac

Keyword(s):

Heat Transfer ◽

Fluid Dynamics ◽

Late Phase ◽

Severe Accident ◽

Ansys Fluent ◽

Water Depletion ◽

Sources Of Uncertainty ◽

Parametric Studies ◽

Computational Fluid Dynamics Cfd ◽

Containment Pressure

The paper overviews the analytical studies performed at Politehnica University of Bucharest on the analysis of late phase severe accident phenomena in a Canada Deuterium Uranium (CANDU) plant. The calculations start from a dry debris bed at the bottom of calandria vessel. Both SCDAPSIM/RELAP code and ansys-fluent computational fluid dynamics (CFD) code are used. Parametric studies are performed in order to quantify the effect of several identified sources of uncertainty on calandria vessel failure: metallic fraction of zirconium inside the debris, containment pressure, timing of water depletion inside calandria vessel, steam circulation in calandria vessel above debris bed, debris temperature at moment of water depletion inside calandria vessel, calandria vault nodalization, and the gap heat transfer coefficient.

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Modeling of Compressor Drum Cavities With Radial Inflow

Volume 5A: Heat Transfer ◽

10.1115/gt2016-56505 ◽

2016 ◽

Author(s):

D. Amirante ◽

Z. Sun ◽

J. W. Chew ◽

N. J. Hills ◽

N. R. Atkins

Keyword(s):

Thermal Stratification ◽

Turbulence Modeling ◽

Navier Stokes ◽

Inflow Rate ◽

Cfd Models ◽

Flow And Heat Transfer ◽

Rotating Discs ◽

Computational Fluid Dynamics Cfd ◽

Inlet Conditions ◽

Cooling Air

Reynolds-Averaged Navier-Stokes (RANS) computations have been conducted to investigate the flow and heat transfer between two co-rotating discs with an axial throughflow of cooling air and a radial bleed introduced from the shroud. The computational fluid dynamics (CFD) models have been coupled with a thermal model of the test rig, and the predicted metal temperature compared with the thermocouple data. CFD solutions are shown to vary from a buoyancy driven regime to a forced convection regime, depending on the radial inflow rate prescribed at the shroud. At a high radial inflow rate, the computations show an excellent agreement with the measured temperatures through a transient rig condition. At a low radial inflow rate, the cavity flow is destabilized by the thermal stratification. Good qualitative agreement with the measurements is shown, although a significant over-prediction of disc temperatures is observed. This is associated with under prediction of the penetration of the axial throughflow into the cavity. The mismatch could be the result of strong sensitivity to the prescribed inlet conditions, in addition to possible shortcomings in the turbulence modeling.

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