ICONE11-36426 FLOW DISTRIBUTION OF PEBBLE BED HIGH TEMPERATURE GAS COOLED REACTORS USING LARGE EDDY SIMULATION

2003 ◽  
Vol 2003 (0) ◽  
pp. 428 ◽  
Author(s):  
Gokhan Yesilyurt ◽  
Yassin A. Hassan
Keyword(s):  
High Temperature ◽  
Large Eddy Simulation ◽  
Flow Distribution ◽  
Pebble Bed ◽  
Eddy Simulation ◽  
Large Eddy ◽  
High Temperature Gas

Large Eddy Simulation Study of Flow Dynamics in a Multiswirler Model Combustor at Elevated Pressure and High Temperature

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Weijie Liu ◽  
Qian Yang ◽  
Ranran Xue ◽  
Huiru Wang
Keyword(s):  
High Temperature ◽  
Large Eddy Simulation ◽  
Elevated Pressure ◽  
Dominant Frequency ◽  
Flow Dynamics ◽  
Main Stage ◽  
Eddy Simulation ◽  
Precessing Vortex Core ◽  
Flow Interaction ◽  
Large Eddy

Large eddy simulation (LES) of nonreacting turbulent flow in a multiswirler model combustor is carried out at elevated pressure and high temperature. Flow interaction between the main stage and the pilot stage is discussed based on the time-averaged and instantaneous flowfield. Flow dynamics in the multiswirling flow are analyzed using a phase-averaged method. Proper orthogonal decomposition (POD) is used to extract dominant flow features in the multiswirling flow. Numerical results show that the main stage and the pilot stage flows interact with each other generating a complex flowfield. Flow interaction can be divided into three regions: converging region, merging region, and combined region. A precessing vortex core (PVC) is successfully captured in the pilot stage. PVC rotates with a first dominant frequency of 2756 Hz inducing asymmetric azimuthal flow instabilities in the pilot stage. POD analyses for the velocity fields also show dominant high-frequency modes (mode 1 and mode 2) in the pilot stage. However, the dominant energetic flow is damped rapidly downstream of the pilot stage such that it has a little effect on the main stage flow.

scholarly journals Analysis of flow and heat transfer during the impingement of a diesel spray on a wall using large eddy simulation

2018 ◽  
Vol 20 (7) ◽  
pp. 758-764 ◽  
Author(s):  
Hiroshi Kawanabe ◽  
Jun Komae ◽  
Takuji Ishiyama
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
High Temperature ◽  
Large Eddy Simulation ◽  
Diffusion Processes ◽  
Flame Structure ◽  
Outer Region ◽  
Diesel Spray ◽  
Eddy Simulation ◽  
Large Eddy

Numerical calculations were carried out to investigate the formation of a fuel–air mixture as well as ignition and combustion processes associated with a diesel spray impinging on a wall. This was performed by modeling the spray formed by injecting n-heptane into a constant-volume vessel under high temperature and pressure, with the fuel droplets described by a discrete droplet model. The flow and turbulent diffusion processes were calculated based on the large eddy simulation method to simulate the formation of a local non-homogeneous mixture and the accompanying heat release. The flame structure and heat transfer to the wall during impingement were also assessed. The results show that heat transfer to the wall is increased in the peripheral region around the stagnation point, as a result of the high temperature and thin boundary layer. Conversely, in the outer region, the heat transfer decreases as the boundary layer becomes more developed.

Large eddy simulation of a randomly stacked nuclear pebble bed

2014 ◽  
Vol 96 ◽  
pp. 302-321 ◽  
Author(s):  
A. Shams ◽  
F. Roelofs ◽  
E.M.J. Komen ◽  
E. Baglietto
Keyword(s):  
Large Eddy Simulation ◽  
Pebble Bed ◽  
Eddy Simulation ◽  
Large Eddy

Numerical simulation of turbulent flow in microscopic pore scale of pebble bed by large-eddy simulation

2010 ◽  
Vol 85 (7-9) ◽  
pp. 1638-1641 ◽  
Author(s):  
S. Ebara ◽  
T. Yokomine ◽  
A. Shimizu ◽  
H. Hashizume
Keyword(s):  
Numerical Simulation ◽  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Pore Scale ◽  
Pebble Bed ◽  
Eddy Simulation ◽  
Large Eddy

scholarly journals Bypass flow in small absorber sphere channels of the high-temperature gas-cooled reactor pebble-bed module

2017 ◽  
Vol 10 (3) ◽  
pp. 128-139 ◽  
Author(s):  
Ziping Liu ◽  
Zeguang Li ◽  
Jun Sun
Keyword(s):  
High Temperature ◽  
Network Model ◽  
Reactor Core ◽  
Flow Distribution ◽  
Maximum Temperature ◽  
Bypass Flow ◽  
Pebble Bed ◽  
Flow Network ◽  
Control Rod ◽  
High Temperature Gas

In the high-temperature gas-cooled reactor pebble-bed module, the helium bypass flow among graphite blocks cannot be ignored due to its effect on the temperature distribution as well as the maximum temperature in the reactor core. Bypass flow was previously analyzed in the discharging tube, in vertical gaps between graphite reflectors, and in control rod channels. The focus of this study is on the bypass flow that connects the small absorber sphere channels. Different from bypass flow connecting the control rod channels, there was no evident inlet or outlet flow paths into or out of the small absorber sphere channels at the top or bottom of the reactor core. Therefore, the bypass flow connecting the pebble bed with the small absorber sphere channels was mainly caused by the horizontal gaps, in which those gaps would also be irregular due to installation, thermal expansion, or irradiation of the graphite reflectors. After clarifying the resistant coefficients of those gaps by computational fluid dynamic tools, the bypass flow distribution was calculated by the flow network model including the flow in the reactor core, small absorber sphere channels, as well as horizontal gaps. Cases with various size combinations of gaps were adopted into the flow network model to test the sensitivity of bypass flow distribution to those parameters. Finally, the bypass flow in the small absorber sphere channels was concluded to be not significant in the reactor core.

Large Eddy Simulation of Mixing in the Outlet Plenum of a High Temperature Reactor: A Benchmark Exercise

2004 ◽  
Author(s):  
Jan-Patrice Simoneau ◽  
Julien Champigny
Keyword(s):  
High Temperature ◽  
Large Eddy Simulation ◽  
Unsteady Flows ◽  
Simulation Technique ◽  
Eddy Simulation ◽  
Large Eddy ◽  
High Temperature Reactor

This paper is related to the validation of the CFD codes in the frame of High Temperature Reactor studies. A code to code benchmark involving complex unsteady flows in the outlet plenum is proposed and the Large Eddy Simulation technique is retained. The paper presents the benchmark conditions, the results obtained by the Star-cd software used in Framatome-ANP and the comparison with the Trio-U code (from CEA) and the literature. It presents the advantages of such fine unsteady calculations and mainly highlights the coherence between both analyses.

scholarly journals Large Eddy Simulation of a Swirl-Stabilized Pilot Combustor from Conventional to Flameless Mode

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Ehsan Fooladgar ◽  
C. K. Chan
Keyword(s):  
High Temperature ◽  
Large Eddy Simulation ◽  
Turbulent Flame ◽  
Combustion Model ◽  
Lean Premixed Combustion ◽  
Eddy Simulation ◽  
Stirred Reactor ◽  
Wide Range ◽  
Large Eddy ◽  
One Step

This paper investigates flame and flow structure of a swirl-stabilized pilot combustor in conventional, high temperature, and flameless modes by means of a partially stirred reactor combustion model to provide a better insight into designing lean premixed combustion devices with preheating system. Finite rate chemistry combustion model with one step tuned mechanism and large eddy simulation is used to numerically simulate six cases in these modes. Results show that moving towards high temperature mode by increasing the preheating level, the combustor is prone to formation of thermalNOxwith higher risks of flashback. In addition, the flame becomes shorter and thinner with higher turbulent kinetic energies. On the other hand, towards the flameless mode, leaning the preheated mixture leads to almost thermalNOx-free combustion with lower risk of flashback and thicker and longer flames. Simulations also show qualitative agreements with available experiments, indicating that the current combustion model with one step tuned mechanisms is capable of capturing main features of the turbulent flame in a wide range of mixture temperature and equivalence ratios.

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