Geometrically-Accurate-Three-Dimensional Simulations of a Used Nuclear Fuel Canister Filled With Helium

2015 ◽  
Author(s):  
Triton Manzo ◽  
Mustafa-Hadj Nacer ◽  
Miles Greiner
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Nuclear Fuel ◽  
Heat Generation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Ansys Fluent ◽  
Model Simulations

This paper presents preliminary results of heat transfer simulations performed in geometrically-accurate-three-dimensional model of nuclear fuel canister filled with helium. The numerical model represents a vertical canister, which relies on natural convection as its primary heat transfer mechanism, containing 24 PWR fuel assemblies. The model includes distinct regions for the fuel pellets, cladding and gas regions within each basket opening. Symmetry boundary conditions are employed so that only one-eighth of the package cross-section is included. The canister is assumed to be filled with helium at atmospheric pressure. A constant temperature of 101.7°C is employed on the canister outer surfaces, assuming the canister to be surrounded with water. These conditions of pressure and temperature were considered, in this paper, for comparison purpose with previous work. The effects of buoyancy-induced gas motion and natural convection, along with radiation and conduction through gas regions and solid are considered. Steady state simulations using ANSYS/Fluent were performed for different heat generation rates in the fuel regions. Simulations that include the effect of natural convection and others that do not include this effect are conducted. The peak cladding temperature and its radial and axial locations are reported. The maximum allowable heat generation that brings the cladding temperatures to the radial hydride formation limit (TRH=400°C) is also reported. The results of the three dimensional model simulations were compared to two dimensional model simulations for the same heat generation rate. The results showed that the two-dimensional simulations overestimate the temperature in the canister by almost 70°C.

Laminar Natural Convection in a Discretely Heated Cavity: I—Assessment of Three-Dimensional Effects

1995 ◽  
Vol 117 (4) ◽  
pp. 902-909 ◽  
Author(s):  
T. J. Heindel ◽  
S. Ramadhyani ◽  
F. P. Incropera
Keyword(s):  
Natural Convection ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Companion Paper ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Nusselt Numbers ◽  
Aspect Ratios ◽  
Laminar Natural Convection

Two and three-dimensional calculations have been performed for laminar natural convection induced by a 3 × 3 array of discrete heat sources flush-mounted to one vertical wall of a rectangular cavity whose opposite wall was isothermally cooled. Edge effects predicted by the three-dimensional model yielded local and average Nusselt numbers that exceeded those obtained from the two-dimensional model, as well as average surface temperatures that were smaller than the two-dimensional predictions. For heater aspect ratios Ahtr ≲ 3, average Nusselt numbers increased with decreasing Ahtr. However, for Ahtr ≳ 3, the two and three-dimensional predictions were within 5 percent of each other and results were approximately independent of Ahtr. In a companion paper (Heindel et al., 1995a), predictions are compared with experimental results and heat transfer correlations are developed.

The Effects of Side-Wall Conduction on Natural Convection in a Slot

1987 ◽  
Vol 109 (2) ◽  
pp. 419-426 ◽  
Author(s):  
G. D. Mallinson
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Radiation Effects ◽  
Three Dimensional ◽  
Side Wall ◽  
Thermal Coupling ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
High Prandtl Number ◽  
Side Walls

A numerical model for the interaction between natural convection in a slot and conduction in the side walls that are parallel to the plane of the slot is described. Two-dimensional equations containing source terms which account for the viscous and thermal coupling between the fluid and the walls are solved by a finite difference method. The model neglects radiation effects. Solutions for a slot of square cross section filled with a high Prandtl number fluid and heated from below are compared with the results of a Galerkin analysis made by Frick [8] and with solutions obtained by a fully three-dimensional model. Solutions for a slot filled with air and heated from the side are also validated by comparison with three-dimensional solutions. The data produced by the model predict that the more conventional Hele Shaw analysis overestimates heat transfer when the slot aspect ratio is greater than 0.05. Perfectly conducting walls are shown to reduce the rate of heat transfer by the fluid but to increase the strength of the flow. Some effects of walls that are neither adiabatic nor perfectly conducting are assessed.

Numerical Simulation of the Aerodynamics and Aerothermal Heating for a Hypersonic Vehicle

2012 ◽  
Vol 429 ◽  
pp. 147-153
Author(s):  
Hai Yong Liu ◽  
Hong Fu Qiang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Mach Number ◽  
Thermal Environment ◽  
Three Dimensional ◽  
Hypersonic Vehicle ◽  
Attack Angle ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model

A hypersonic forebody based on waverider and liftbody concept was presented. The configuration of a new hypersonic vehicle was designed by taking the configuration of X43A. Numerical simulation was conducted on the two-dimensional and three-dimensional models of the vehicle using CFD software of Gambit and Fluent. The effects of Mach number and attack angle on the aerodynamics and heat transfer were considered. The results of simulation investigation showed that: High compressed air was constrained beneath the pre-compressed surface of the forebody. The computational data on central cross section of the three-dimensional model for the vehicle was similar to that of the two-dimensional model. But great pressure gradient existed between the pre-compressed surface and side surface of the forebody which would lead to severe air leakage and pressure loss. The increasing of attack angle and Mach number enforced the stagnation of shock wave on the side walls of the engine. The thermal environment of the vehicle was deteriorated rapidly with increasing Mach number. But the viscous heating was overrated which lead to unbelievable high temperature. The software Fluent was more suitable to predict the aerodynamics than the heat transfer for hypersonic flow.

Clinical experience of using virtual 3D modelling for pre and intraoperative guidance during robotic-assisted partial nephrectomy

2021 ◽  
pp. 205141582110002
Author(s):  
Lorenz Berger ◽  
Aziz Gulamhusein ◽  
Eoin Hyde ◽  
Matt Gibb ◽  
Teele Kuusk ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Partial Nephrectomy ◽  
Surgical Outcome ◽  
Prospective Cohort ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Robotic Assisted ◽  
Robotic Assisted Partial Nephrectomy

Objective: Surgical planning for robotic-assisted partial nephrectomy is widely performed using two-dimensional computed tomography images. It is unclear to what extent two-dimensional images fully simulate surgical anatomy and case complexity. To overcome these limitations, software has been developed to reconstruct three-dimensional models from computed tomography data. We present the results of a feasibility study, to explore the role and practicality of virtual three-dimensional modelling (by Innersight Labs) in the context of surgical utility for preoperative and intraoperative use, as well as improving patient involvement. Methods: A prospective study was conducted on patients undergoing robotic-assisted partial nephrectomy at our high volume kidney cancer centre. Approval from a research ethics committee was obtained. Patient demographics and tumour characteristics were collected. Surgical outcome measures were recorded. The value of the three-dimensional model to the surgeon and patient was assessed using a survey. The prospective cohort was compared against a retrospective cohort and cases were individually matched using RENAL (radius, exophytic/endophytic, nearness to collecting system or sinus, anterior/posterior, location relative to polar lines) scores. Results: This study included 22 patients. Three-dimensional modelling was found to be safe for this prospective cohort and resulted in good surgical outcome measures. The mean (standard deviation) console time was 158.6 (35) min and warm ischaemia time was 17.3 (6.3) min. The median (interquartile range) estimated blood loss was 125 (50–237.5) ml. Two procedures were converted to radical nephrectomy due to the risk of positive margins during resection. The median (interquartile range) length of stay was 2 (2–3) days. No postoperative complications were noted and all patients had negative surgical margins. Patients reported improved understanding of their procedure using the three-dimensional model. Conclusion: This study shows the potential benefit of three-dimensional modelling technology with positive uptake from surgeons and patients. Benefits are improved perception of vascular anatomy and resection approach, and procedure understanding by patients. A randomised controlled trial is needed to evaluate the technology further. Level of evidence: 2b

Blast load simulation using conical shock tube systems

2019 ◽  
Vol 11 (2) ◽  
pp. 135-158 ◽  
Author(s):  
Ahmed Ismail ◽  
Mohamed Ezzeldin ◽  
Wael El-Dakhakhni ◽  
Michael Tait
Keyword(s):  
Shock Tube ◽  
Three Dimensional ◽  
Design Parameters ◽  
Civil Infrastructure ◽  
Two Dimensional ◽  
Blast Loads ◽  
Dimensional Model ◽  
Tube System ◽  
Three Dimensional Model ◽  
Conical Shock

With the increased frequency of accidental and deliberate explosions, evaluating the response of civil infrastructure systems to blast loading has been attracting the interests of the research and regulatory communities. However, with the high cost and complex safety and logistical issues associated with field explosives testing, North American blast-resistant construction standards (e.g. ASCE 59-11 and CSA S850-12) recommend the use of shock tubes to simulate blast loads and evaluate relevant structural response. This study first aims at developing a simplified two-dimensional axisymmetric shock tube model, implemented in ANSYS Fluent, a computational fluid dynamics software, and then validating the model using the classical Sod’s shock tube problem solution, as well as available shock tube experimental test results. Subsequently, the developed model is compared to a more complex three-dimensional model and the results show that there is negligible difference between the two models for axisymmetric shock tube performance simulation; however, the three-dimensional model is necessary to simulate non-axisymmetric shock tubes. Following the model validation, extensive analyses are performed to evaluate the influences of shock tube design parameters (e.g. the driver section pressure and length and the expansion section length) on blast wave characteristics to facilitate a shock tube design that would generate shock waves similar to those experienced by civil infrastructure components under blast loads. The results show that the peak reflected pressure increases as the driver pressure increases, while a decrease in the expansion length increases the peak reflected pressure. In addition, the positive phase duration increases as both the driver length and expansion length are increased. Finally, the developed two-dimensional axisymmetric model is used to optimize the dimensions of a physical large-scale conical shock tube system constructed for civil infrastructure component blast response evaluation applications. The capabilities of such shock tube system are further investigated by correlating its design parameters to a range of explosion threats identified by different hemispherical TNT charge weight and distance scenarios.

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