SKETCH-N/ATHLET steady-state and dynamic coupling scheme verification on Kalinin-3 benchmark results

Efficient thermal design of turbine blade cooling needs to take wall temperature effects on heat transfer into account. This can only be achieved by a coupled calculation of hot gas flow and blade heat conduction. In this paper principle and stability proof of an algorithm are presented that allows to couple a steady state finite element heat conduction solver with a blockstructured steady state finite volume (FV) Navier-Stokes time marching flow solver. The stability of the developed coupling procedure as well as the instability of an alternative algorithm is shown analytically and numerically. The benefits of coupled calculating are shown for a convectively cooled turbine guide vane blade. In the example treated, temperature differences of more than 100 K arise compared to the same calculation performed in an uncoupled way.

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COUPLING OF nTRACER TO COBRA-TF FOR HIGH-FIDELITY ANALYSIS OF VVERs

EPJ Web of Conferences ◽

10.1051/epjconf/202124702008 ◽

2021 ◽

Vol 247 ◽

pp. 02008

Author(s):

Marianna Papadionysiou ◽

Kim Seongchan ◽

Mathieu Hursin ◽

Alexander Vasiliev ◽

Hakim Ferroukhi ◽

...

Keyword(s):

Steady State ◽

High Resolution ◽

Coupling Scheme ◽

High Fidelity ◽

Fuel Temperature ◽

The Cross ◽

Paul Scherrer

Paul Scherrer Institut is developing a high-resolution multi-physics core solver for VVER analysis. This work presents the preliminary stages of the development, specifically the coupling of the 3D pin-by-pin neutronic solver nTRACER to the sub-channel thermal-hydraulic code COBRA-TF for single assembly multi-physics steady state calculations. The coupling scheme and the modifications performed in the codes are described in details. The results of the coupled nTRACER/COBRA-TF calculations are compared to the ones of a standalone nTRACER calculation where the feedbacks are provided by a simplified 1D thermal-hydraulic solver. The agreement is very good with fuel temperature differences around 10 K which can be attributed to the different correlations used in the various solvers. The cross-comparison of the two multi-physics computational routes serves as a preliminary verification of the coupling scheme developed between nTRACER and COBRA-TF.

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Proposed Solution Methodology for the Dynamically Coupled Nonlinear Geared Rotor Mechanics Equations

Journal of Vibration and Acoustics ◽

10.1115/1.3274700 ◽

1985 ◽

Vol 107 (1) ◽

pp. 112-116 ◽

Cited By ~ 4

Author(s):

L. D. Mitchell ◽

J. W. David

Keyword(s):

Steady State ◽

Numerical Simulations ◽

Equations Of Motion ◽

Linear Equations ◽

Three Dimensional ◽

Dynamic Coupling ◽

State Response ◽

Shaft System ◽

Coupling Terms ◽

Solution Methodology

The equations which describe the three-dimensional motion of an unbalanced rigid disk in a shaft system are nonlinear and contain dynamic-coupling terms. Traditionally, investigators have used an order analysis to justify ignoring the nonlinear terms in the equations of motion, producing a set of linear equations. This paper will show that, when gears are included in such a rotor system, the nonlinear dynamic-coupling terms are potentially as large as the linear terms. Because of this, one must attempt to solve the nonlinear rotor mechanics equations. A solution methodology is investigated to obtain approximate steady-state solutions to these equations. As an example of the use of the technique, a simpler set of equations is solved and the results compared to numerical simulations. These equations represent the forced, steady-state response of a spring-supported pendulum. These equations were chosen because they contain the type of nonlinear terms found in the dynamically-coupled nonlinear rotor equations. The numerical simulations indicate this method is reasonably accurate even when the nonlinearities are large.

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Newly Developed Coupling Scheme in RMC With Internal Thermal Feedback and OTF Doppler-Broadening Method

Volume 3: Nuclear Fuel and Material, Reactor Physics and Transport Theory; Innovative Nuclear Power Plant Design and New Technology Application ◽

10.1115/icone25-66519 ◽

2017 ◽

Cited By ~ 1

Author(s):

Ouwen Yexin ◽

Shanfang Huang ◽

Kan Wang

Keyword(s):

Monte Carlo ◽

Steady State ◽

Cross Section ◽

Large Scale ◽

Nuclear Reactor ◽

Simulation Analysis ◽

Coupling Scheme ◽

Monte Carlo Code ◽

Doppler Broadening ◽

Thermal Hydraulics

RMC (Reactor Monte Carlo)[1] is a self-developed Monte Carlo code for nuclear reactor analysis by Reactor Engineering Analysis Lab (REAL), Tsinghua University. On the basis of the self-developed subchannel module (RMC-TH) and Monte Carlo Cell Tally, the internal coupling interface is developed, which combines both input files to one and realizes the fast mesh correspondence process using the cell expansion technology for repeated structure with thermal-hydraulics feedback. It breaks through the bottleneck of geometrical extensibility for coupled code. On-the-fly Doppler broadening method is adopted as the way to consider the temperature effect on microscopic cross section, which only needs the 0 K cross section library so that the memory cost can be apparently reduced. Steady state simulation analysis are performed on PWR fuel pin and 17×17 assembly model, and the results show the feasibility, accuracy and efficiency of the coupling methodology. Therefore, a promising technology roadmap for the large-scale and geometrically universal nuclear reactor in both steady-state and transient conditions with thermal-hydraulic feedback are established. The roadmap can be further applied to neutronics-thermal-hydraulics-depletion coupling in multi-physics simulation process.

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DEVELOPMENT AND VERIFICATION OF T-TRACE/PANTHER COUPLED CODE

EPJ Web of Conferences ◽

10.1051/epjconf/202124706027 ◽

2021 ◽

Vol 247 ◽

pp. 06027

Author(s):

A. Abarca ◽

M. Avramova ◽

K. Ivanov ◽

S. Verdebout ◽

D. De Meyer ◽

...

Keyword(s):

Hydraulic System ◽

Nuclear Power ◽

Nuclear Industry ◽

Coupling Scheme ◽

Thermal Hydraulics ◽

Dynamic Coupling ◽

Neutron Kinetics ◽

The Core ◽

Group 3 ◽

Nodal Diffusion

Multi-physics coupled simulations have become increasingly important during the last two decades being one of the major field of application in the nuclear technology. The nuclear reactors themselves are complex systems whose responses are driven by interactions between neutron kinetics, thermal-hydraulics, heat transfer, mechanics and chemistry. Probably, in a nuclear system, the most complex and important feedback effect takes place between the core neutron kinetics and thermal-hydraulics. The development of coupled thermal-hydraulic -neutron kinetics codes is a recurrent field of research for the nuclear industry. This contribution, developed in the Consortium for Nuclear Power (CNP) framework, has the objective of develop a dynamic coupling, using TCP/IP based socket communication, between the thermal-hydraulic system code T-TRACE, Tractebel-ENGIE version of the latest US NRC TRACE release, and the multi-group 3-D nodal diffusion and core physics code PANTHER, developed and maintained by EDF Energy (UK). As a first step of the development, a fully temporally explicit coupling scheme has been developed between TRACE and PANTHER based on a boundary conditions exchange at the core level at each temporal iteration. The OECD TMI MSLB benchmark has been selected as verification scenario for testing the ongoing developing T-TRACE/PANTHER coupled code. The developed coupled code is benchmarked code-to-code against TRACE/PARCS and T-RELAP5/PANTHER.

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Dynamic Coupling of Voltage Sensor and Gate Involved in Closed-State Inactivation of Kv4.2 Channels

The Journal of General Physiology ◽

10.1085/jgp.200810073 ◽

2009 ◽

Vol 133 (2) ◽

pp. 205-224 ◽

Cited By ~ 26

Author(s):

Jan Barghaan ◽

Robert Bähring

Keyword(s):

Steady State ◽

Structural Model ◽

Low Voltage ◽

Large Fraction ◽

Inactivation Kinetics ◽

Dynamic Coupling ◽

Alanine Scanning Mutagenesis ◽

Closed State ◽

Kv4 Channels ◽

Steady State Inactivation

Voltage-gated potassium channels related to the Shal gene of Drosophila (Kv4 channels) mediate a subthreshold-activating current (ISA) that controls dendritic excitation and the backpropagation of action potentials in neurons. Kv4 channels also exhibit a prominent low voltage–induced closed-state inactivation, but the underlying molecular mechanism is poorly understood. Here, we examined a structural model in which dynamic coupling between the voltage sensors and the cytoplasmic gate underlies inactivation in Kv4.2 channels. We performed an alanine-scanning mutagenesis in the S4-S5 linker, the initial part of S5, and the distal part of S6 and functionally characterized the mutants under two-electrode voltage clamp in Xenopus oocytes. In a large fraction of the mutants (>80%) normal channel function was preserved, but the mutations influenced the likelihood of the channel to enter the closed-inactivated state. Depending on the site of mutation, low-voltage inactivation kinetics were slowed or accelerated, and the voltage dependence of steady-state inactivation was shifted positive or negative. Still, in some mutants these inactivation parameters remained unaffected. Double mutant cycle analysis based on kinetic and steady-state parameters of low-voltage inactivation revealed that residues known to be critical for voltage-dependent gate opening, including Glu 323 and Val 404, are also critical for Kv4.2 closed-state inactivation. Selective redox modulation of corresponding double-cysteine mutants supported the idea that these residues are involved in a dynamic coupling, which mediates both transient activation and closed-state inactivation in Kv4.2 channels.

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Studies on Water in the Hydration Chamber of a Modified Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069715 ◽

1970 ◽

Vol 28 ◽

pp. 544-545

Author(s):

R. C. Moretz ◽

G. G. Hausner ◽

D. F. Parsons

Keyword(s):

Thin Film ◽

Thin Films ◽

Electron Microscope ◽

Steady State ◽

Room Temperature ◽

Small Mass ◽

Equilibrium Pressure ◽

Biological Objects ◽

Mechanical Pump ◽

Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

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Continuous hydrogenolysis of acetal-stabilized lignin in flow

Green Chemistry ◽

10.1039/d0gc02928a ◽

2021 ◽

Author(s):

Wu Lan ◽

Yuan Peng Du ◽

Songlan Sun ◽

Jean Behaghel de Bueren ◽

Florent Héroguel ◽

...

Keyword(s):

Steady State ◽

Challenges And Opportunities

We performed a steady state high-yielding depolymerization of soluble acetal-stabilized lignin in flow, which offered a window into challenges and opportunities that will be faced when continuously processing this feedstock.

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