scholarly journals CFD Optimization of the Resistivity Meter for the IFMIF-DONES Facility

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2543
Author(s):  
Ranieri Marinari ◽  
Paolo Favuzza ◽  
Davide Bernardi ◽  
Francesco Saverio Nitti ◽  
Ivan Di Piazza
Keyword(s):  
Flow Stability ◽  
Electric Resistivity ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Current Configuration ◽  
Resistivity Meter ◽  
Cfd Optimization ◽  
Concentration Of Impurities ◽  
Metallic Impurities ◽  
Resistance Value

A detailed study of lithium-related topics in the IFMIF-DONES facility is currently being promoted and supported within the EUROfusion action, paying attention to different pivotal aspects including lithium flow stability and the monitoring and extraction of impurities. The resistivity meter is a device able to monitor online non-metallic impurities (mainly nitrogen) in flowing lithium. It relies on the variation of the electric resistivity produced by dissolved anions: the higher the concentration of impurities in lithium, the higher the resistivity measured. The current configuration of the resistivity meter has shown different measuring issues during its operation. All these issues reduce the accuracy of the measurements performed with this instrument and introduce relevant noise affecting the resistance value. This paper proposes different upgrades, supported by CFD simulations, to optimize lithium flow conditions and to reduce measurement problems. Owing to these upgrades, a new design of the resistivity meter has been achieved, which is simpler and easier to manufacture.

scholarly journals Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 73 ◽  
Author(s):  
Galih Bangga
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Separation ◽  
Spatial Interpolation ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Correction Terms ◽  
Selection Of ◽  
Blade Element

The present studies deliver the computational investigations of a 10 MW turbine with a diameter of 205.8 m developed within the framework of the AVATAR (Advanced Aerodynamic Tools for Large Rotors) project. The simulations were carried out using two methods with different fidelity levels, namely the computational fluid dynamics (CFD) and blade element and momentum (BEM) approaches. For this purpose, a new BEM code namely B-GO was developed employing several correction terms and three different polar and spatial interpolation options. Several flow conditions were considered in the simulations, ranging from the design condition to the off-design condition where massive flow separation takes place, challenging the validity of the BEM approach. An excellent agreement is obtained between the BEM computations and the 3D CFD results for all blade regions, even when massive flow separation occurs on the blade inboard area. The results demonstrate that the selection of the polar data can influence the accuracy of the BEM results significantly, where the 3D polar datasets extracted from the CFD simulations are considered the best. The BEM prediction depends on the interpolation order and the blade segment discretization.

Effects of Pipe Diameter and Stokes Number on Erosion in Elbows

2020 ◽  
Author(s):  
Soroor Karimi ◽  
Alireza Asgharpour ◽  
Elham Fallah ◽  
Siamack A. Shirazi
Keyword(s):  
Experimental Data ◽  
Oil And Gas ◽  
Learning Algorithm ◽  
Large Diameter ◽  
Stokes Number ◽  
Gas Production ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Oil And Gas Production ◽  
Large Diameter Pipes

Abstract Large diameter pipes and elbows are vastly used in industry especially in mining and oil and gas production. Solid particle erosion is a common issue in these pipelines, and it is important to predict it to avoid failures. Currently, laboratory experiments reported in the literature are limited to diameters less than 4 inches. Therefore, there is not much experimental data available for large diameter elbows. However, the erosion can be predicted by CFD simulations and applying erosion equations in such elbows. The goal of this project is to examine the effects of elbow diameter and Stokes number on erosion patterns and magnitude for various flow conditions for elbow diameters of 2, 4, 8, and 12 inches. The approach of this work is to first perform CFD simulations of liquid-solid and gas-solid flows in 2-inch and 4-inch elbows, respectively, and evaluate the results by available experimental data. Then CFD simulations are carried for 2, 4, 8, and 12-inch standard elbows for various Stokes numbers corresponding to gas dominant flows with the velocity of 30 m/s, and liquid dominant flows with the velocities of 6 m/s. For gas dominant flows erosion in air and for liquid dominant flows erosion in water is investigated. All these simulations are carried for four particle sizes of 25, 75, 150, and 300 microns. The results indicate that Stokes number and diameter of elbows have significant effects on erosion patterns as well as magnitudes in this geometry. This work will have various applications, including validating mechanistic models of erosion predictions in elbows and developing an Artificial Intelligence (machine learning) algorithm to predict erosion for various flow conditions. Such algorithms are limited to the range of conditions they are trained for. Therefore, it is important to expand the database these codes are accessing. Overall, the CFD database of large diameter elbows will reduce the computational costs in the future.

scholarly journals Thermal Examination of a Simplified Exhaust Tube-Heatshield Model

2018 ◽  
Vol 47 (3) ◽  
pp. 190-195 ◽  
Author(s):  
Balázs Vehovszky ◽  
Tamás Jakubík ◽  
Marcell Treszkai
Keyword(s):  
Natural Convection ◽  
Cross Flow ◽  
Exhaust System ◽  
Thermal Conditions ◽  
Forced Flow ◽  
Flow Conditions ◽  
Visualization Technique ◽  
Cfd Simulations ◽  
Critical Part ◽  
Parking Place

Exhaust system and its surrounding is a thermally highly critical part of a vehicle: during forced operation, hottest elements can reach 600 °C. The thermal conditions turn to even more critical if the forced flow leaves off – e.g. when the car stops at a highway parking place. In such a case not only the cooling effect of cross-flow disappears, but the natural convection starts to bring heat toward nearby elements – resulting potential overheating of concerned parts. A measurement setup for modelling such case was built, and different parameters were examined, which have influence on the heating of aluminium heatshield above the exhaust tube. Measurements were complemented by CFD simulations and flow visualization technique aiming the better understanding of evolving thermal and flow conditions.

scholarly journals Modeling of Natural Convection in Electronic Enclosures

2005 ◽  
Vol 128 (2) ◽  
pp. 157-165 ◽  
Author(s):  
Peter M. Teertstra ◽  
M. Michael Yovanovich ◽  
J. Richard Culham
Keyword(s):  
Natural Convection ◽  
Numerical Data ◽  
Composite Model ◽  
Circuit Board ◽  
Flow Conditions ◽  
Transition Flow ◽  
Cfd Simulations ◽  
Wide Range ◽  
Using Data ◽  
Good Agreement

An analytical model is developed for natural convection from a single circuit board in a sealed electronic equipment enclosure. The circuit card is modeled as a vertical isothermal plate located at the center of an isothermal, cuboid shaped enclosure. A composite model is developed based on asymptotic solutions for three limiting cases: pure conduction, laminar boundary layer convection, and transition flow convection. The conduction shape factor and natural convection models are validated using data from CFD simulations for a wide range of enclosure geometries and flow conditions. The model is shown to be in good agreement, to within 10% RMS, with the numerical data for all test configurations.

Numerical Simulations of Flow in Cerebral Aneurysms: Comparison of CFD Results and In Vivo MRI Measurements

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Vitaliy L. Rayz ◽  
Loic Boussel ◽  
Gabriel Acevedo-Bolton ◽  
Alastair J. Martin ◽  
William L. Young ◽  
...  
Keyword(s):  
Flow Fields ◽  
Patient Specific ◽  
Flow Ratio ◽  
Flow Conditions ◽  
Velocity Measurements ◽  
Cfd Simulations ◽  
Specific Flow ◽  
Inlet Flow ◽  
Good Agreement

Computational fluid dynamics (CFD) methods can be used to compute the velocity field in patient-specific vascular geometries for pulsatile physiological flow. Those simulations require geometric and hemodynamic boundary values. The purpose of this study is to demonstrate that CFD models constructed from patient-specific magnetic resonance (MR) angiography and velocimetry data predict flow fields that are in good agreement with in vivo measurements and therefore can provide valuable information for clinicians. The effect of the inlet flow rate conditions on calculated velocity fields was investigated. We assessed the internal consistency of our approach by comparing CFD predictions of the in-plane velocity field to the corresponding in vivo MR velocimetry measurements. Patient-specific surface models of four basilar artery aneurysms were constructed from contrast-enhanced MR angiography data. CFD simulations were carried out in those models using patient-specific flow conditions extracted from MR velocity measurements of flow in the inlet vessels. The simulation results computed for slices through the vasculature of interest were compared with in-plane velocity measurements acquired with phase-contrast MR imaging in vivo. The sensitivity of the flow fields to inlet flow ratio variations was assessed by simulating five different inlet flow scenarios for each of the basilar aneurysm models. In the majority of cases, altering the inlet flow ratio caused major changes in the flow fields predicted in the aneurysm. A good agreement was found between the flow fields measured in vivo using the in-plane MR velocimetry technique and those predicted with CFD simulations. The study serves to demonstrate the consistency and reliability of both MR imaging and numerical modeling methods. The results demonstrate the clinical relevance of computational models and suggest that realistic patient-specific flow conditions are required for numerical simulations of the flow in aneurysmal blood vessels.

Unsteady 360 CFD Validation of a Turbine Stage Mainstream/Disc Cavity Interaction

2014 ◽  
Author(s):  
A. V. Mirzamoghadam ◽  
S. Kanjiyani ◽  
A. Riahi ◽  
Reddaiah Vishnumolakala ◽  
Lavan Gundeti
Keyword(s):  
Fluid Velocity ◽  
Swirling Flows ◽  
Time Dependent ◽  
Cover Plate ◽  
Turbine Stage ◽  
Flow Conditions ◽  
Unstable Flow ◽  
Cfd Simulations ◽  
Cfd Validation ◽  
Purge Flow

The amount of cooling air assigned to seal high pressure turbine rim cavities is critical for performance as well as component life. Insufficient air leads to excessive hot annulus gas ingestion and its penetration deep into the cavity compromising disc or cover plate life. Excessive purge air, on the other hand, adversely affects performance. Experiments on a rotating turbine stage rig which included a rotor-stator forward disc cavity were performed at Arizona State University. The turbine rig has 22 vanes and 28 blades, while the cavity is composed of a single-tooth lab seal and a rim platform overlap seal. Time-averaged static pressures were measured in the gas path and the cavity, while mainstream gas ingestion into the cavity was determined by measuring the concentration distribution of tracer gas (carbon dioxide) under a range of purge flows from 0.435% (Cw = 1540) to 1.74% (Cw = 6161). Additionally, particle image velocimetry (PIV) was used to measure fluid velocity inside the cavity between the lab seal and the rim seal. The data from the experiments were compared to time-dependent CFD simulations using FLUENT CFD software. The CFD simulations brought to light the unsteadiness present in the flow during the experiment which the slower response data did not fully capture. An unsteady RANS, 360-degree CFD model of the complete turbine stage was employed in order to increase the understanding of the swirl physics which dominate cavity flows and better predict rim seal ingestion. Although the rotor-stator cavity is geometrically axisymmetric, it was found that the interaction between swirling flows in the cavity and swirling flows in the gas path create non-periodic/time-dependent unstable flow patterns which at the present are not accurately modeled by a 360 degree full stage unsteady analysis. At low purge flow conditions, the vortices that form inside the cavities are greatly influenced by mainstream ingestion. Conversely at high purge flow conditions the vortices are influenced by the purge flow, therefore ingestion is minimized. The paper also discusses details of meshing, convergence of time-dependent CFD simulations, and recommendations for future simulations in a rotor-stator disc cavity such as assessing the observed unsteadiness in the frequency domain in order to identify any critical frequencies driving the system.

Unsteady 360 Computational Fluid Dynamics Validation of a Turbine Stage Mainstream/Disk Cavity Interaction

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
A. V. Mirzamoghadam ◽  
S. Kanjiyani ◽  
A. Riahi ◽  
Reddaiah Vishnumolakala ◽  
Lavan Gundeti
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Swirling Flows ◽  
Time Dependent ◽  
Cover Plate ◽  
Turbine Stage ◽  
Flow Conditions ◽  
Unstable Flow ◽  
Cfd Simulations ◽  
Purge Flow

The amount of cooling air assigned to seal high pressure turbine (HPT) rim cavities is critical for performance as well as component life. Insufficient air leads to excessive hot annulus gas ingestion and its penetration deep into the cavity compromising disk or cover plate life. Excessive purge air, on the other hand, adversely affects performance. Experiments on a rotating turbine stage rig which included a rotor–stator forward disk cavity were performed at Arizona State University (ASU). The turbine rig has 22 vanes and 28 blades, while the cavity is composed of a single-tooth lab seal and a rim platform overlap seal. Time-averaged static pressures were measured in the gas path and the cavity, while mainstream gas ingestion into the cavity was determined by measuring the concentration distribution of tracer gas (carbon dioxide) under a range of purge flows from 0.435% (Cw = 1540) to 1.74% (Cw = 6161). Additionally, particle image velocimetry (PIV) was used to measure fluid velocity inside the cavity between the lab seal and the rim seal. The data from the experiments were compared to time-dependent computational fluid dynamics (CFD) simulations using fluent CFD software. The CFD simulations brought to light the unsteadiness present in the flow during the experiment which the slower response data did not fully capture. An unsteady Reynolds averaged Navier–Stokes (RANS), 360-deg CFD model of the complete turbine stage was employed in order to increase the understanding of the swirl physics which dominate cavity flows and better predict rim seal ingestion. Although the rotor–stator cavity is geometrically axisymmetric, it was found that the interaction between swirling flows in the cavity and swirling flows in the gas path create nonperiodic/time-dependent unstable flow patterns which at the present are not accurately modeled by a 360 deg full stage unsteady analysis. At low purge flow conditions, the vortices that form inside the cavities are greatly influenced by mainstream ingestion. Conversely at high purge flow conditions the vortices are influenced by the purge flow, therefore ingestion is minimized. The paper also discusses details of meshing, convergence of time-dependent CFD simulations, and recommendations for future simulations in a rotor–stator disk cavity such as assessing the observed unsteadiness in the frequency domain in order to identify any critical frequencies driving the system.

A Single-Stage Centripetal Pump—Design Features and an Investigation of the Operating Characteristics

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Mihael Sekavčnik ◽  
Tine Gantar ◽  
Mitja Mori
Keyword(s):  
Single Stage ◽  
Flow Conditions ◽  
Operating Characteristics ◽  
Cfd Simulations ◽  
Pump Design ◽  
Flow Channels ◽  
Performance Curves ◽  
Computational Fluid Dynamics Cfd ◽  
Working Media ◽  
Inflow Conditions

In this paper, we present an experimental and numerical investigation of a single-stage centripetal pump (SSCP). This SSCP is designed to operate in the pump regime, while forcing the working media through impeller-stator flow channels in the radial inward direction. The measured performance curves are characterized by a hysteresis, since the throttle-closing performance curves do not correspond to the throttle-opening performance curves throughout the whole operating range. A computational fluid dynamics (CFD) model was developed to establish these throttle-closing and throttle-opening performance curves. The flow conditions obtained with the CFD simulations confirm that the hydraulic behavior of the SSCP is influenced by the partial circumferential stall that occurs in the impeller-stator flow channels. It was shown that the inflow conditions to the impeller-stator assembly considerably influence the flow rate of the stall cessation, the size of the hysteresis, and the head generated during part-load operations.

scholarly journals Experimental and numerical investigation of thermal and flow conditions inside a large pharmaceutical storage after the ventilation system failure

2021 ◽  
pp. 346-346
Author(s):  
Ilija Tabasevic ◽  
Rastko Jovanovic ◽  
Dragan Milanovic
Keyword(s):  
Temperature Distribution ◽  
Flow Field ◽  
Flow Rate ◽  
Ventilation System ◽  
Pharmaceutical Products ◽  
System Failure ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Depth Analysis ◽  
Good Agreement

Safe storage of pharmaceutical products is of great importance due to potential hazards for human health. The aim of this study was to assess the ability of pharmaceutical storage to recover design temperature during ventilation system recovery. The performed CFD simulations showed good agreement with experimental temperature measurements. Numerical results allowed in-depth analysis of flow field and temperature distribution inside the storage. It was discovered that the flow field is highly non-uniform, which consequently leads to an uneven temperature distribution of pallets with products. However, a high inlet mass flow rate ensured that all pallets reach the designed temperature.

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