Flow Loads on the Shroud in a Boiling Water Reactor due to a Recirculation Outlet Line Break: A Comparative Study Between Potential Flow and Computational Fluid Dynamics Methodologies

Flow Field ◽

Comparative Study ◽

Potential Flow ◽

Three Dimensional ◽

Dimensional Approximation ◽

Jet Pumps ◽

The Comparative Study

This paper compares two methodologies for estimating the flow loads on the shroud of a typical BWR caused by a Recirculation Outlet Line Break. First, assuming an ideal and irrotational flow field, the complex potential methodology is used to calculate a two dimensional approximation of the flow field by ignoring variations along the radial direction. As a simplification for the comparative study the annulus will be assumed to be devoid of any structural components such as the jet pumps. The flow field derived from the potential flow approach will be used to compute the total lateral and moment loads acting on the shroud. These load values will be compared against similar values derived from a three dimensional and more realistic flow field computed by Computational Fluid Dynamics (CFD). The potential flow based method is computationally simpler as compared to the more time consuming CFD approach.

Comparative Study on Pressure Field of Hydrostatic Thrust Bearing with Different Recess Shapes

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.621.431 ◽

2014 ◽

Vol 621 ◽

pp. 431-436

Author(s):

Xiao Dong Yu ◽

Zhi Qiang Wang ◽

Xiu Li Meng ◽

Qi Hui Zhou ◽

Yan Qin Zhang ◽

...

Keyword(s):

Fluid Dynamics ◽

Comparative Study ◽

Thrust Bearing ◽

Pressure Field ◽

Three Dimensional ◽

Distribution Law ◽

Simulation Results ◽

Volume Method

A comparative study on pressure field of hydrostatic thrust bearing with sector recess, rectangular recess, ellipse recess and I-shaped recess is carried out in order to solve the deformation of the hydrostatic thrust bearing. The Finite Volume Method has been used to compute three-dimensional pressure field of gap oil film between the rotation worktable and the base. This study theoretically analyzes the influence of recess shape on the bearing pressure characteristic according to Computational Fluid Dynamics (CFD) and lubricating theory. It has revealed its pressure field distribution law. The simulation results indicate that an improved characteristic will be affected by recess shape easily. Through this method, the safety of a hydrostatic thrust bearing with different recesses can be forecasted, and the optimal design of such products can be achieved, so it can provide reasonable data for design, lubrication, and experiment and deformation computation for hydrostatic thrust bearing.

Construction Ventilation Scheme Optimization of Underground Main Powerhouse Based on CFD

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.368-370.619 ◽

2013 ◽

Vol 368-370 ◽

pp. 619-623

Author(s):

Zhen Liu ◽

Xiao Ling Wang ◽

Ai Li Zhang

Keyword(s):

Fluid Dynamics ◽

Flow Field ◽

Air Flow ◽

Scheme Optimization ◽

Pressure Distributions ◽

Air Volume ◽

Traditional Construction ◽

Ventilation Scheme

For the purpose of avoiding the deficiency of the traditional construction ventilation, the ventilation of the underground main powerhouse is simulated by the computational fluid dynamics (CFD) to optimize ventilation parameters. A 3D unsteady RNG k-ε model is performed for construction ventilation in the underground main powerhouse. The air-flow field and CO diffusion in the main powerhouse are simulated and analyzed. The two construction ventilation schemes are modelled for the main powerhouse. The optimized ventilation scheme is obtained by comparing the air volume and pressure distributions of the different ventilation schemes.

Effect of Doppler flow meter position on discharge measurement in surcharged manholes

Water Science & Technology ◽

10.2166/wst.2017.563 ◽

2017 ◽

Vol 77 (3) ◽

pp. 647-654 ◽

Cited By ~ 1

Author(s):

Haoming Yang ◽

David Z. Zhu ◽

Yanchen Liu

Keyword(s):

Fluid Dynamics ◽

Flow Field ◽

Flow Regimes ◽

Flow Meter ◽

Flow Meters ◽

Flow Discharge ◽

Doppler Flow ◽

Sewer Systems ◽

Abstract Determining the proper installation location of flow meters is important for accurate measurement of discharge in sewer systems. In this study, flow field and flow regimes in two types of manholes under surcharged flow were investigated using a commercial computational fluid dynamics (CFD) code. The error in measuring the flow discharge using a Doppler flow meter (based on the velocity in a Doppler beam) was then estimated. The values of the corrective coefficient were obtained for the Doppler flow meter at different locations under various conditions. Suggestions for selecting installation positions are provided.

A Three-Dimensional Computational Fluid Dynamics (CFD) Model Analysis of Free Surface Hydrodynamics and Fish Passage Energetics in a Vertical-Slot Fishway

North American Journal of Fisheries Management ◽

10.1577/m05-014.1 ◽

2006 ◽

Vol 26 (2) ◽

pp. 255-267 ◽

Cited By ~ 29

Author(s):

Liaqat A. Khan

Keyword(s):

Fluid Dynamics ◽

Free Surface ◽

Three Dimensional ◽

Fish Passage ◽

Model Analysis ◽

Cfd Model ◽

Vertical Slot ◽

Vertical Slot Fishway

CFD Leakage Predictions of Unworn and Worn Labyrinth Seals With and Without Tooth Axial Offset

Volume 5B: Heat Transfer ◽

10.1115/gt2017-63163 ◽

2017 ◽

Author(s):

Hasham H. Chougule ◽

Alexander Mirzamoghadam

Keyword(s):

Fluid Dynamics ◽

Numerical Modeling ◽

Steady State ◽

Flow Field ◽

Labyrinth Seals ◽

Small Clearance ◽

Total Leakage ◽

Flow Deflection

The objective of this study is to develop a Computational Fluid Dynamics (CFD) based methodology for analyzing and predicting leakage of worn or rub-intended labyrinth seals during operation. The simulations include intended tooth axial offset and numerical modeling of the flow field. The purpose is to predict total leakage through the seal when an axial tooth offset is provided after the intended/unintended rub. Results indicate that as expected, the leakage for the in-line worn land case (i.e. tooth under rub) is higher compared to unworn. Furthermore, the intended rotor/teeth forward axial offset/shift with respect to the rubbed land reduces the seal leakage. The overall leakage of a rubbed seal with axial tooth offset is observed to be considerably reduced, and it can become even less than a small clearance seal designed not to rub. The reduced leakage during steady state is due to a targeted smaller running gap because of tooth offset under the intended/worn land groove shape, higher blockages, higher turbulence and flow deflection as compared to worn seal model without axial tooth offset.

Numerical Analysis of the LCS 2 airwake to understand potential interactions during helipcopter operations

10.5957/wmtc-2015-104 ◽

2015 ◽

Author(s):

Brent S. Paul

Keyword(s):

Fluid Dynamics ◽

Numerical Analysis ◽

Flow Field ◽

Ship Design ◽

It Impacts ◽

Flight Envelope ◽

Potential Interactions ◽

Flight Deck

The successful integration of aviation capabilities aboard ships is a complex endeavor that must balance ship design with the flight envelope of the helicopter. This can be particularly important when considering air wakes and other flow around the superstructure as it impacts the flight deck. This flow can generate unsteady structures that may interfere with safe helicopter operations. Computational fluid dynamics (CFD) is commonly used to characterize the flow field and assess potential impacts to the flight envelope, which can be used to help define an operating envelope for helicopter operations.

Development and Validation of a 3-Dimensional Computational Fluid Dynamics (CFD) Model for Rectangular Settling Tanks in New York City Water Pollution Control Plants

Water Practice & Technology ◽

10.2166/wpt.2009.015 ◽

2009 ◽

Vol 4 (1) ◽

Cited By ~ 2

Author(s):

K. Ramalingam ◽

J. Fillos ◽

S. Xanthos ◽

M. Gong ◽

A. Deur ◽

...

Keyword(s):

Water Pollution ◽

Fluid Dynamics ◽

New York ◽

New York City ◽

Pollution Control ◽

York City ◽

Three Dimensional ◽

Cfd Model ◽

New York City provides secondary treatment to approximately 78.6 m3/s among its 14 water pollution control plants (WPCPs). The process of choice has been step-feed activated sludge. Changes to the permit limits require nitrogen removal in WPCPs discharging into the Long Island Sound. The City has selected step feed biological nitrogen removal (BNR) process to upgrade the affected plants. Step feed BNR requires increasing the concentration of mixed liquors, (MLSS), which stresses the Gould II type rectangular final settling tanks (FSTs). To assess performance and evaluate alternatives to improve efficiency of the FSTs at the higher loads, New York City Department of Environmental Protection (NYCDEP) and City College of New York (CCNY) have developed a three-dimensional computer model depicting the actual structural configuration of the tanks and the current and proposed hydraulic and solids loading rates. Using Computational Fluid Dynamics (CFD) Model, Fluent 6.3.26TM as the base platform, sub-models of the SS settling characteristics as well as turbulence, flocculation, etc. were incorporated. This was supplemented by field and bench scale experiments to quantify the co-efficients integral to the sub-models. As a result, a three-dimensional model has been developed that is being used to consider different baffle arrangements, sludge withdrawal mechanisms and loading alternatives to the FSTs.

Effect of Rib Width of Flow Field Plate on the Performance of a PEMFC: a Computational Fluid Dynamics (CFD) Study

ECS Meeting Abstracts ◽

10.1149/ma2007-02/3/188 ◽

2007 ◽

Keyword(s):

Fluid Dynamics ◽

Flow Field ◽

Field Plate ◽

The Design of Refinement Criteria for Dynamic Grid Adaptation Applied to Airfoil Flow Modeling

Emerging Technology in Fluids, Structures, and Fluid Structure Interactions ◽

10.1115/pvp2003-1952 ◽

2003 ◽

Author(s):

Melih Demir ◽

Govert de With ◽

Arne E. Holdo̸

Keyword(s):

Fluid Dynamics ◽

Flow Field ◽

Unsteady Flow ◽

Mesh Refinement ◽

Research Centre ◽

Shear Stresses ◽

Wall Region ◽

Grid Adaptation ◽

At present a large number of fluid dynamics applications are found in aerospace, civil and automotive engineering, as well in medical related fields. In many applications the flow field is turbulent and the computational modelling of such flows remains a difficult task. To resolve all turbulent flow phenomena for flow problems where turbulence is of key interest is a priori not feasible in a Computational Fluid Dynamics (CFD) investigation with a conventional mesh. The use of a Dynamic Grid Adaptation (DGA) algorithm in a turbulent unsteady flow field is an appealing technique which can reduce the computational costs of a CFD investigation. A refinement of the numerical domain with a DGA algorithm requires reliable criteria for mesh refinement which reflect the complex flow processes. At present not much work has been done to obtain reliable refinement criteria for turbulent unsteady flow. The purpose of the work is to implement a new refinement technique for the boundary layer in the vicinity of the wall. It is aimed to model the flow around an airfoil with a LES turbulence model and a new DGA algorithm. In addition to that several simulations have been carried out for parametric studies. In these studies the incompressible solver in REACFLOW has been used. This Computational Fluid Dynamics (CFD) code REACFLOW was developed in collaboration with the joint Research Centre (JRC) in Italy. The following aims are aspired: • A new mesh refinement criteria method suitable for boundary layers; • To carry out LES simulations to establish the performance of the refinement criteria. The new criteria which are created in this work are for the near wall region. This criteria uses the wall shear stresses for the refinement technique. For the main flow stream the refinement criteria proposed by de With et al [6] will be used.