scholarly journals Erratum to “Weld bead characterization of flat wire electrode in gmaw process part II: a numerical study”

2021 ◽  
Author(s):  
K. Sripriyan ◽  
M. Ramu ◽  
P. R. Thyla ◽  
K. Anantharuban
Keyword(s):  
Numerical Study ◽  
Weld Bead ◽  
Wire Electrode

scholarly journals Characterization of aerodynamic performance of ducted wind turbines: A numerical study

Wind Energy ◽  
2019 ◽  
Vol 22 (12) ◽  
pp. 1655-1666 ◽  
Author(s):  
Vinit V. Dighe ◽  
Gael Oliveira ◽  
Francesco Avallone ◽  
Gerard J. W. Bussel
Keyword(s):  
Wind Turbines ◽  
Numerical Study ◽  
Aerodynamic Performance

Numerical Characterization of Hot Gas Ingestion Through Turbine Rim Seals

2016 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Carl M. Sangan ◽  
James A. Scobie ◽  
Gary D. Lock
Keyword(s):  
Flow Rate ◽  
Numerical Study ◽  
Axial Flow ◽  
Radial Clearance ◽  
Buffering Effect ◽  
Hot Gas ◽  
Numerical Predictions ◽  
Wide Range ◽  
Thermal Buffering

This paper deals with a numerical study aimed at the characterization of hot gas ingestion through turbine rim seals. The numerical campaign focused on an experimental facility which models ingress through the rim seal into the upstream wheel-space of an axial-turbine stage. Single-clearance arrangements were considered in the form of axial- and radial-seal gap configurations. With the radial-seal clearance configuration, CFD steady-state solutions were able to predict the system sealing effectiveness over a wide range of coolant mass flow rates reasonably well. The greater insight of flow field provided by the computations illustrates the thermal buffering effect when ingress occurs: for a given sealing flow rate, the effectiveness on the rotor was significantly higher than that on the stator due to the axial flow of hot gases from stator to rotor caused by pumping effects. The predicted effectiveness on the rotor was compared with a theoretical model for the thermal buffering effect showing good agreement. When the axial-seal clearance arrangement is considered, the agreement between CFD and experiments worsens; the variation of sealing effectiveness with coolant flow rate calculated by means of the simulations display a distinct kink. It was found that the “kink phenomenon” can be ascribed to an over-estimation of the egress spoiling effects due to turbulence modelling limitations. Despite some weaknesses in the numerical predictions, the paper shows that CFD can be used to characterize the sealing performance of axial- and radial-clearance turbine rim seals.

On the crack characterization of reinforced concrete structures: Experimental and data-driven numerical study

Structures ◽  
2021 ◽  
Vol 30 ◽  
pp. 134-145
Author(s):  
Sandeep Das ◽  
Subhrajit Dutta ◽  
Dibyendu Adak ◽  
Shubhankar Majumdar
Keyword(s):  
Reinforced Concrete ◽  
Numerical Study ◽  
Concrete Structures ◽  
Data Driven ◽  
Reinforced Concrete Structures

Numerical Characterization of Flow and Heat Transfer in Pre-Swirl Systems

2017 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Jacopo D’Errico
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Numerical Study ◽  
Physical Phenomenon ◽  
Computational Procedure ◽  
Operating Conditions ◽  
Simulation Techniques ◽  
Numerical Characterization ◽  
Unsteady Simulation

This paper deals with a numerical study aimed at the validation of a computational procedure for the aerothermal characterization of pre-swirl systems employed in axial gas turbines. The numerical campaign focused on an experimental facility which models the flow field inside a direct-flow pre-swirl system. Steady and unsteady simulation techniques were adopted in conjunction with both a standard two-equations RANS/URANS modelling and more advanced approaches such as the Scale-Adaptive-Simulation principle, the SBES and LES. The comparisons between CFD and experiments were done in terms of swirl number development, static and total pressure distributions, receiving holes discharge coefficient and heat transfer on the rotor disc surface. Several operating conditions were accounted for, spanning 0.78·106<Reφ<1.21·106 and 0.123<λt<0.376. Overall the steady-state CFD predictions are in good agreement with the experimental evidences even though it is not able to confidently mimic the experimental swirl and pressure behaviour in some regions. Although the use of unsteady sliding mesh and direct turbulence modelling, would in principle increase the insight in the physical phenomenon, from a design perspective the tradeoff between accuracy and computational costs is not always favourable.

Numerical Characterization of Hot-Gas Ingestion Through Turbine Rim Seals

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Carl M. Sangan ◽  
James A. Scobie ◽  
Gary D. Lock
Keyword(s):  
Flow Rate ◽  
Numerical Study ◽  
Axial Flow ◽  
Radial Clearance ◽  
Buffering Effect ◽  
Hot Gas ◽  
Numerical Predictions ◽  
Wide Range ◽  
Thermal Buffering

This paper deals with a numerical study aimed at the characterization of hot-gas ingestion through turbine rim seals. The numerical campaign focused on an experimental facility which models ingress through the rim seal into the upstream wheel-space of an axial-turbine stage. Single-clearance arrangements were considered in the form of axial- and radial-seal gap configurations. With the radial-seal clearance configuration, computational fluid dynamics (CFD) steady-state solutions were able to predict the system sealing effectiveness over a wide range of coolant mass flow rates reasonably well. The greater insight of flow field provided by the computations illustrates the thermal buffering effect when ingress occurs: For a given sealing flow rate, the effectiveness on the rotor was significantly higher than that on the stator due to the axial flow of hot gases from stator to rotor caused by pumping effects. The predicted effectiveness on the rotor was compared with a theoretical model for the thermal buffering effect showing good agreement. When the axial-seal clearance arrangement is considered, the agreement between CFD and experiments worsens; the variation of sealing effectiveness with coolant flow rate calculated by means of the simulations displays a distinct kink. It was found that the “kink phenomenon” can be ascribed to an overestimation of the egress spoiling effects due to turbulence modeling limitations. Despite some weaknesses in the numerical predictions, the paper shows that CFD can be used to characterize the sealing performance of axial- and radial-clearance turbine rim seals.

The Effect of Injection and Suction on the Interfacial Mass Transport Resistance in a Proton Exchange Membrane Fuel Cell Air Channel

2014 ◽  
Author(s):  
Mustafa Koz ◽  
Satish G. Kandlikar
Keyword(s):  
Proton Exchange Membrane ◽  
Numerical Study ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Channel Cross Section ◽  
Flow Through ◽  
Air Channel ◽  
Air Channels ◽  
Exchange Membrane

Proton exchange membrane fuel cells are efficient and environmentally friendly electrochemical engines. The present work focuses on air channels that bring the oxidant air into the cell. Characterization of the oxygen concentration drop from the channel to the gas diffusion layer (GDL)-channel interface is a need in the modeling community. This concentration drop is expressed with the non-dimensional Sherwood number (Sh). At the aforementioned interface, the air can have a non-zero velocity normal to the interface: injection of air to the channel and suction of air from the channel. A water droplet in the channel can constrict the channel cross section and lead to a flow through the GDL. In this numerical study, a rectangular air channel, GDL, and a stationary droplet on the GDL-channel interface are simulated to investigate the Sh under droplet induced injection/suction conditions. The simulations are conducted with a commercially available software package, COMSOL Multiphysics.

A numerical study of factors affecting the characterization of nanoindentation on silicon

2007 ◽  
Vol 447 (1-2) ◽  
pp. 244-253 ◽  
Author(s):  
Tong Hong Wang ◽  
Te-Hua Fang ◽  
Yu-Cheng Lin
Keyword(s):  
Numerical Study ◽  
Factors Affecting

Experimental Characterization of Two-Phase Flow Through Valves Applied to Liquid-Assisted Gas-Lift

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Renato P. Coutinho ◽  
Paulo J. Waltrich ◽  
Wesley C. Williams ◽  
Parviz Mehdizadeh ◽  
Stuart Scott ◽  
...  
Keyword(s):  
Water Flow ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Water Flow Rate ◽  
Phase Flow ◽  
Experimental Characterization ◽  
Two Phase ◽  
Flow Through ◽  
Gas Lift

Abstract Liquid-assisted gas-lift (LAGL) is a recently developed concept to unload wells using a gas–liquid fluid mixture. The success deployment of the LAGL technology is related to the behavior of two-phase flow through gas-lift valves. For this reason, this work presents an experimental and numerical study on two-phase flow through orifice gas-lift valves used in liquid-assisted gas-lift unloading. To the knowledge of the authors, there is no investigation in the literature on experimental characterization of two-phase flow through gas-lift valves. Experimental data are presented for methane-water flow through gas-lift valves with different orifice port sizes: 12.7 and 17.5 mm. The experiments were performed for pressures ranging from 1.00 to 9.00 MPa, gas flow rates from 0 to 4.71 m3/h, and water flow rate from 0 to 0.68 m3/min. The experimental results are compared to numerical models published in the literature for two-phase flow through restrictions and to commercial multiphase flow simulators. It is observed that some models developed for two-phase flow through restrictions could successfully characterize two-phase flow thorough gas-lift valves with errors lower than 10%. However, it is first necessary to experimentally determine the discharge coefficient (CD) for each gas-lift valve. The commercial flow simulators showed a similar performance as the models available in the literature.

Incorporation of GPR data into characterization of the bitumen filled cracks in pavements: Lab and numerical study

2020 ◽  
Author(s):  
Mezgeen Rasol ◽  
Vega Pérez Gracia ◽  
Mercedes Solla ◽  
Jorge C. Pais ◽  
Francisco M. Fernandes ◽  
...  
Keyword(s):  
Computational Models ◽  
Numerical Study ◽  
Fdtd Method ◽  
Asphalt Pavements ◽  
The Road ◽  
Rigid Pavements ◽  
Temporary Solution ◽  
Ground Penetrating ◽  
Difference Time

&lt;p&gt;Road pavements are subject to a range of problems due to traffic and temperature variations&amp;#160;&lt;/p&gt;&lt;p&gt;producing cracks that propagate to the pavement surface. Cracks need to be assessed to avoid&amp;#160;&lt;/p&gt;&lt;p&gt;deterioration and provide confidence in the functioning of the road system. Cracks are usually&amp;#160;&lt;/p&gt;&lt;p&gt;maintained after visual inspection by filling with bitumen as a first rehabilitation technique to&amp;#160;&lt;/p&gt;&lt;p&gt;avoid further deterioration and absorbing water leakages. Although this temporary solution does&amp;#160;&lt;/p&gt;&lt;p&gt;not extend the pavement life cycle it can help to avoid additional problems occurring within the&lt;/p&gt;&lt;p&gt;pavement. This work is proposed to aid the development of understanding and characterization&lt;/p&gt;&lt;p&gt;of cracks filled with bitumen in both rigid and asphalt pavements.&lt;/p&gt;&lt;p&gt;This study reports on the results of several laboratory experiments that were performed to&amp;#160;&lt;/p&gt;&lt;p&gt;explore the capability of Ground Penetrating Radar (GPR) in the assesment of bitumen-filled&amp;#160;&lt;/p&gt;&lt;p&gt;cracks in both rigid and asphalt pavements, respectively. These tests were focused on the&amp;#160;&lt;/p&gt;&lt;p&gt;analysis of cracking filled with bitumen using a GPR system equipped with a ground-coupled&amp;#160;&lt;/p&gt;&lt;p&gt;antenna with a 2.3 GHz central frequency, and varying the antenna orientation with respect to the&amp;#160;&lt;/p&gt;&lt;p&gt;crack axis.&lt;/p&gt;&lt;p&gt;Results showed the variation in characterization and changes in amplitude that could be expected&amp;#160;&lt;/p&gt;&lt;p&gt;when analysing bitumen-filled cracks in concrete and asphalt specimens, dependent upon the&amp;#160;&lt;/p&gt;&lt;p&gt;antenna orientation being used; GPR B-scans were compared to images from computational&amp;#160;&lt;/p&gt;&lt;p&gt;models using a Finite-Difference Time-Domain (FDTD) method-based software package&amp;#160;&lt;/p&gt;&lt;p&gt;(gprMax2D). Additionally, a field survey carried out provided images consistent with the&lt;/p&gt;&lt;p&gt;comparable conditions of the lab tests. The results of this work proved the capability of the GPR&lt;/p&gt;&lt;p&gt;method to detect and characterize cracks filled with bitumen in pavements across a range of&amp;#160;&lt;/p&gt;&lt;p&gt;crack dimensions and pavement types.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Keywords&lt;/p&gt;&lt;p&gt;GPR, NDT, Rigid pavements, Asphalt Pavements, Cracks, Computational models, Target orientation,&lt;/p&gt;&lt;p&gt;Pavement assessmen&lt;/p&gt;

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