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

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

Applied Sciences ◽

10.3390/app10207032 ◽

2020 ◽

Vol 10 (20) ◽

pp. 7032 ◽

Cited By ~ 3

Author(s):

Pucciarelli Andrea ◽

Galleni Francesco ◽

Moscardini Marigrazia ◽

Martelli Daniele ◽

Forgione Nicola

Keyword(s):

Thermal Stratification ◽

Outlet Section ◽

Experimental Conditions ◽

Ansys Fluent ◽

Internal Loop ◽

Fuel Pin ◽

Mass Flow Rates ◽

Computational Fluid Dynamics Cfd ◽

The University ◽

Good Agreement

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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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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Analytical study of special girder moment frames using a mixed shear–flexural link element

Canadian Journal of Civil Engineering ◽

10.1139/l07-037 ◽

2007 ◽

Vol 34 (9) ◽

pp. 1119-1130 ◽

Cited By ~ 10

Author(s):

M T Kazemi ◽

S Erfani

Keyword(s):

Stiffness Matrix ◽

Analytical Study ◽

Kinematic Hardening ◽

Moment Frames ◽

Moment Frame ◽

Element Analysis ◽

Dynamic Analyses ◽

Roof Level ◽

Nonlinear Dynamic Analyses ◽

Good Agreement

The present paper introduces a mixed shear–flexural (VM) link element that is capable of modelling shear yielding, flexural yielding, and their interaction under monotonic and cyclic loadings. The inelastic deformations are modelled using the multisurfaces approach with dissimilar yield surfaces and a stiffness matrix with nonzero off-diagonal components in shear–flexural space. A new kinematic hardening and new non-associated flow rules are employed. A special girder, which has an open web in the middle, is introduced and modelled using the developed VM link element. It is shown that the results of analyses using the VM link element are in good agreement with those from a finite element analysis. Nonlinear dynamic analyses are performed on a benchmark ordinary moment frame (OMF) and its improved versions with special girders. The special girder moment frame (SGMF), which consists of special girders at the lower storeys and ordinary girders at the roof level, has better seismic performance.Key words: mixed shear–flexural (VM) link element, inelastic zone, shear–flexural interaction, cyclic loading, multisurface, special girder, special girder moment frame (SGMF), ordinary moment frame (OMF).

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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 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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Mechanism and Flow Control on the Mismatching of Impeller and Vaned Diffuser Caused by Inlet Prewhirl for Centrifugal Compressors

Volume 2D: Turbomachinery ◽

10.1115/gt2016-56244 ◽

2016 ◽

Cited By ~ 1

Author(s):

Qiangqiang Huang ◽

Xinqian Zheng ◽

Aolin Wang

Keyword(s):

Flow Control ◽

Control Method ◽

Three Dimensional ◽

Navier Stokes ◽

Vaned Diffuser ◽

Inlet Distortion ◽

Computational Fluid Dynamics Cfd ◽

Stagger Angle ◽

Good Agreement ◽

Matching Relation

Air often flows into compressors with inlet prewhirl, because it will obtain a circumferential component of velocity via inlet distortion or swirl generators such as inlet guide vanes. A lot of research has shown that inlet prewhirl does influence the characteristics of components, but the change of the matching relation between the components caused by inlet prewhirl is still unclear. This paper investigates the influence of inlet prewhirl on the matching of the impeller and the diffuser and proposes a flow control method to cure mismatching. The approach combines steady three-dimensional Reynolds-averaged Navier-Stokes (RANS) simulations with theoretical analysis and modeling. The result shows that a compressor whose impeller and diffuser match well at zero prewhirl will go to mismatching at non-zero prewhirl. The diffuser throat gets too large to match the impeller at positive prewhirl and gets too small for matching at negative prewhirl. The choking mass flow of the impeller is more sensitive to inlet prewhirl than that of the diffuser, which is the main reason for the mismatching. To cure the mismatching via adjusting the diffuser vanes stagger angle, a one-dimensional method based on incidence matching has been proposed to yield a control schedule for adjusting the diffuser. The optimal stagger angle predicted by analytical method has good agreement with that predicted by computational fluid dynamics (CFD). The compressor is able to operate efficiently in a much broader flow range with the control schedule. The flow range, where the efficiency is above 80%, of the datum compressor and the compressor only employing inlet prewhirl and no control are just 25.3% and 31.8%, respectively. For the compressor following the control schedule, the flow range is improved up to 46.5%. This paper also provides the perspective of components matching to think about inlet distortion.

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Effect of Pitch Parameters on Aerodynamic Forces of a Straight-Bladed Vertical Axis Wind Turbine with Inclined Pitch Axes

Applied Sciences ◽

10.3390/app11031033 ◽

2021 ◽

Vol 11 (3) ◽

pp. 1033

Author(s):

Jia Guo ◽

Timing Qu ◽

Liping Lei

Keyword(s):

Wind Turbine ◽

Vertical Axis ◽

Speed Ratio ◽

Incline Angle ◽

Asymmetric Distribution ◽

Vertical Axis Wind Turbine ◽

Power Performance ◽

Aerodynamic Forces ◽

Ansys Fluent ◽

Pitch Regulation

Pitch regulation plays a significant role in improving power performance and achieving output control in wind turbines. The present study focuses on a novel, pitch-regulated vertical axis wind turbine (VAWT) with inclined pitch axes. The effect of two pitch parameters (the fold angle and the incline angle) on the instantaneous aerodynamic forces and overall performance of a straight-bladed VAWT under a tip-speed ratio of 4 is investigated using an actuator line model, achieved in ANSYS Fluent software and validated by previous experimental results. The results demonstrate that the fold angle has an apparent influence on the angles of attack and forces of the blades, as well as the power output of the wind turbine. It is helpful to further study the dynamic pitch regulation and adaptable passive pitch regulation of VAWTs. Incline angles away from 90° lead to the asymmetric distribution of aerodynamic forces along the blade span, which results in an expected reduction of loads on the main shaft and the tower of VAWTs.

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