Numerical Simulation for Effect of Rolling Motion on Thermal Stratification in a Surge Line

2017 ◽  
Author(s):  
Y. L. Shen ◽  
Tao Lu ◽  
Bo Liu
Keyword(s):  
Thermal Stratification ◽  
Fluid Dynamic ◽  
Maximum Temperature ◽  
Rolling Motion ◽  
Fluid Temperature ◽  
Line Pipe ◽  
Static State ◽  
Eddy Simulation ◽  
Surge Line ◽  
Cfd Method

Pressurizer surge lines are essential pipeline structure in NPPs, and the thermal stratification in surge line is recognized as one of the possible cause of thermal fatigue. In this paper, a Computational Fluid Dynamic (CFD) method has been adopted to simulate temperature fluctuations on the process of temperature rising in a pressurizer surge line under rolling motion of single degree of freedom. This work focuses on a fundamental description of differences of thermal stratification between the surge line rolling around the coordinate X-axis condition and that in a static state. The Large-eddy simulation (LES) model is employed to capture the details of temperature change in surge line. Temperature distributions near the inner wall of a surge line pipe with or without swinging were monitored and compared. The temperature differences between the top and bottom of the pipe sections are employed to represent the maximum temperature differences at all the monitored sections. As the surge line swinging, the pattern of temperature distribution and the length of thermal stratification development are different from that in a static. Fluid temperature fluctuation in surge line occur periodically during the fluid temperature rising when the surge line is rotated with the X-axis, and the temperature difference between top and bottom of the surge line is reduced in the same motion mode compared with the static state.

Numerical Analysis of Unsteady Conjugate Heat Transfer and Thermal Stress for a PWR Pressurizer Surge Line Pipe Subjected to Thermal Stratification

2002 ◽  
Author(s):  
Jong Chull Jo ◽  
Young Hwan Choi ◽  
Seok Ki Choi
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Numerical Analysis ◽  
Thermal Stratification ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Analysis ◽  
Stress Distributions ◽  
Line Pipe ◽  
Pipe Model ◽  
Surge Line

This paper addresses three-dimensional numerical analyses of the unsteady conjugate heat transfer and thermal stress for a PWR pressurizer surge line pipe with a finite wall thickness, subjected to internally thermal stratification. A primary emphasis of the present study is placed on the investigation of the effects of surge flow direction on the determinations of the transient temperature and thermal stress distributions in the pipe wall. In the present numerical analysis, the thermally stratified flows (in-surge flow and out-surge flow) in the pipe line are simulated using the standard κ-ε turbulent model and a simple and convenient numerical method of treating the unsteady conjugate heat transfer on a non-orthogonal coordinate system is developed. The unsteady conjugate heat transfer analysis method is implemented in a finite volume thermal-hydraulic computer code based on a non-staggered grid arrangement, SIMPLEC algorithm and higher-order bounded convection scheme. The finite element method is employed for the thermal stress analysis to calculate non-dimensional stress distributions at the piping wall as a function of time. Some numerical calculations are performed for a PWR pressurizer surge line pipe model with shortened length, subjected to internally thermal stratification caused either by insurge or outsurge flow with a specified velocity, and the results are discussed in detail.

Numerical Investigation of Thermal Stratification in the Primary Circuit of VVER-440 Type Reactors

2006 ◽  
Author(s):  
Ildiko´ Boros ◽  
Attila Aszo´di ◽  
Ga´bor Le´gra´di
Keyword(s):  
Thermal Stratification ◽  
Cooling System ◽  
Maximum Temperature ◽  
Primary Circuit ◽  
Operational Experience ◽  
Extensive Evaluation ◽  
Transient Simulations ◽  
Surge Line ◽  
Core Cooling

Thermal stratification in the primary loops and in the connected pipes can limit the lifetime of the piping, or lead to penetrating cracks due to the stresses caused by the temperature differences and the cyclic temperature changes. Therefore it is essential to determine the thermal hydraulic parameters of the stratified flow. The determination of the affected pipes can be based on the international operational experience and on engineering consideration. The most affected pipes in PWRs are the pressurizer surge line, the injection pipe of the emergency core cooling systems and the feedwater injection pipe of the steam generators. CFD codes can provide an appropriate tool for the examination of the development and the breaking up of the stratification and the determination of the temperature distribution. However, the challenge of the uncertainty of the boundary conditions has to be faced because of the unknown flow circumstances. According to an extensive evaluation, performed in 1998 by the VEIKI, in the VVER-440/213 units of Paks NPP the most affected pipe is the pressurizer surge line [1]. To find out the possible thermal stratification in the surge line, a temperature monitoring system was installed on the YP20 leg of the surge line of the Unit 1 of the Paks NPP in 2000. The measurements showed that during the heat-up period there is a thermal stratification almost all time in the surge line [2]. The maximum temperature differences reach 140 K (140 °C). The surge line has been modeled with the CFD code CFX-5.7. The performed transient simulations confirmed the existence of a thermal stratification in the surge line, but showed permanent recirculation of colder coolant in the lower layer, caused by the asymmetric arrangement of the surge line legs and the asymmetric connection of the two legs to the main loop. In this paper, the surge line model and the results of the transient simulations are presented. The CFD model of the injection pipe of the high pressure Emergency Core Cooling System and the performed simulations for the analysis of occurrence of thermal stratification are presented as well.

Stress and Fatigue Analysis of Pressurizer Surge Line under Thermal Stratification

2019 ◽  
Vol 795 ◽  
pp. 268-275
Author(s):  
Peng Tang ◽  
Zhi Wei Liu ◽  
Hong Wei Qiao ◽  
Peng Zhou Li
Keyword(s):  
Temperature Distribution ◽  
Temperature Difference ◽  
Thermal Stratification ◽  
Nuclear Power ◽  
Power Plants ◽  
Load Condition ◽  
Maximum Temperature ◽  
Large Temperature ◽  
Maximum Temperature Difference ◽  
Surge Line

Pressurizer surge line is one of the key equipments of nuclear power plants. The thermal stratification due to the intersection of hot and cold fluids inside the pressurizer surge line may affect the safe operation of nuclear power plant. In order to investigate the stress distribution and fatigue characteristics of surge line subjected to long-term thermal stratified loadings, a mechanical model of the surge line was established. And then, according to different temperature distribution assumptions, thermal stress analysis and fatigue assessment were conducted. The results show that the maximum stress appears under the load condition with maximum temperature difference, and finer temperature distribution can obtain more accurate stress and displacement results. The maximum value of fatigue cumulative coefficient appears at the junction of straight pipe and elbow with large temperature difference.

Computational Fluid Dynamics Modeling of an Experimental Thermal-Stratification Flow Case Using ABAQUS/CFD

2019 ◽  
Author(s):  
Daniel Franken ◽  
Subhasish Mohanty
Keyword(s):  
Thermal Stratification ◽  
Cfd Simulation ◽  
The United States ◽  
System Level ◽  
Dynamics Modeling ◽  
Pressurized Water ◽  
Line Pipe ◽  
Surge Line ◽  
Water Reactors ◽  
Abaqus Code

Abstract As the fleet of Pressurized Water Reactors (PWRs) in the United States begin to reach the end of their original lifespan many of them are undergoing assessment to extend their use. In order to investigate the potential for extending the life of the plant, a system level analysis of components needs to be performed in order to ensure that age and degradation of the system will not lead to a potential safety hazard. An area in which this system level investigation is particularly important is in the surge line of the pressurizer. One possible concern is that over the life of the reactor, the surge line pipe will experience thermal stratification many times. Thermal stratification can lead to significant stresses induced on the piping and over time may result in a less than ideal safety standard. Commercially available code Abaqus CFD was used to model the thermal stratification in a pipe. The corresponding experimental results, available in literature were compared. We found there is a good correlation between the experimental and computational results. However, the results discussed in this paper are based on our preliminary effort to study the capability of ABAQUS code for CFD simulation. A detailed parametric study is one of our future work.

Numerical Simulation of Crud Effects on the Flow and Heat Transfer Performance in PWR 17×17 Rod Bundles

2017 ◽  
Author(s):  
Bing Ren ◽  
Fujun Gan ◽  
Yu Dang ◽  
Libing Zhu
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamic ◽  
Flow Characteristics ◽  
Porous Matrix ◽  
Localized Corrosion ◽  
Fluid Temperature ◽  
Fuel Cladding ◽  
Power Shift ◽  
Cfd Method ◽  
Prism Layer

Corrosion products on fuel cladding surface have a significant impact on reactor operation. These types of deposits are defined as Corrosion Residual Unidentified Deposit (CRUD) and are consist of a porous matrix of nickel and iron based oxides deposited on the fuel cladding surface. It is well known that crud deposits may cause potential Crud Induced Localized Corrosion (CILC) risk and Crud Induced Power Shift (CIPS) risk. The paper presents a Computational Fluid Dynamic (CFD) method of predicting the crud effect on the thermal hydraulic performance. The effect of the crud roughness is mainly considered in the simulation, the flow near the wall of the crud is solved by modifying wall function in the prism layer. The simulation object is a span of typical 17×17 rod bundle with a mid grid in PWR, all the structures including grid straps, springs, dimples, mixing vanes and welding spots are included. Thicknesses of grid and fuel cladding are considered in order to precisely simulate the fluid-solid conjugate heat transfer. The crud is set to be covered on the full span downstream of the grid. The simulation is based on the CILC risk pre-analysis and the computed information in the mostly likely crud deposit position is used as boundary condition. Based on the simulation results, the crud effects on the flow characteristics including vortex structures, circulation, turbulent intensity and second flow intensity and the heat transfer characteristics including rod temperature, fluid temperature and heat transfer coefficient are discussed in detail.

Numerical Analysis of Unsteady Conjugate Heat Transfer and Thermal Stress for a Curved Piping System Subjected to Thermal Stratification

2003 ◽  
Vol 125 (4) ◽  
pp. 467-474 ◽  
Author(s):  
Jong Chull Jo ◽  
Young Hwan Choi ◽  
Seok Ki Choi
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Numerical Analysis ◽  
Thermal Stratification ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Analysis ◽  
Stress Distributions ◽  
Line Pipe ◽  
Pipe Model ◽  
Surge Line

This paper addresses three-dimensional numerical analyses of the unsteady conjugate heat transfer and thermal stress for a PWR pressurizer surge line pipe with a finite wall thickness, subjected to internally thermal stratification. A primary emphasis of the present study is placed on the investigation of the effects of surge flow direction on the determinations of the transient temperature and thermal stress distributions in the pipe wall. In the present numerical analysis, the thermally stratified flows (in-surge flow and out-surge flow) in the pipe line are simulated using the standard κ−ε turbulent model and a simple and convenient numerical method of treating the unsteady conjugate heat transfer on a non-orthogonal coordinate system is developed. The unsteady conjugate heat transfer analysis method is implemented in a finite volume thermal-hydraulic computer code based on a non-staggered grid arrangement, SIMPLEC algorithm and higher-order bounded convection scheme. The finite element method is employed for the thermal stress analysis to calculate non-dimensional stress distributions at the piping wall as a function of time. Some numerical calculations are performed for a PWR pressurizer surge line pipe model with shortened length, subjected to internally thermal stratification caused either by insurge or outsurge flow with a specified velocity, and the results are discussed in detail.

Thermal Hydraulic Analysis of Severe Accident in PFBR

2010 ◽  
Author(s):  
K. Velusamy ◽  
P. Chellapandi ◽  
G. R. Raviprasan ◽  
P. Selvaraj ◽  
S. C. Chetal
Keyword(s):  
Atmospheric Pressure ◽  
Fluid Dynamic ◽  
Hydraulic Modeling ◽  
Severe Accident ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
Dynamic Calculation ◽  
Thermal Hydraulic Modeling ◽  
Thermal Hydraulic Analysis ◽  
Design Pressure

During a core disruptive accident (CDA), the amount of primary sodium that can be released to Reactor Containment Building (RCB) in Prototype Fast Breeder Reactor (PFBR) is estimated to be 350 kg/s, by a transient fluid dynamic calculation. The pressure and temperature evolutions inside RCB, due to consequent sodium fire have been estimated by a constant burning rate model, accounting for heat absorption by RCB wall, assuming RCB isolation based on area gamma monitors. The maximum pressure developed is 7000 Pa. In case RCB isolation is delayed, then the final pressure inside RCB reduces below atmospheric pressure due to cooling of RCB air. The negative pressure that can be developed is estimated by dynamic thermal hydraulic modeling of RCB air / wall to be −3500 Pa. These investigations were useful to arrive at the RCB design pressure. Following CDA, RCB is isolated for 40 days. During this period, the heat added to RCB is dissipated to atmosphere only by natural convection. Considering all the possible routes of heat addition to RCB, evolution of RCB wall temperature has been predicted using HEATING5 code. It is established that the maximum temperature in RCB wall is less than the permissible value.

scholarly journals The Design and Implementation of Fan Chips as Cooling for Milling Process on Aluminum Alloy 5086 to Increase Tool Life

2021 ◽  
Vol 2 (1) ◽  
pp. 29-42
Author(s):  
Agus Sifa ◽  
Dedi Suwandi ◽  
Tito Endramawan ◽  
Alam Aulia Rachman
Keyword(s):  
Aluminum Alloy ◽  
Tool Life ◽  
Experimental Testing ◽  
Fluid Dynamic ◽  
Milling Process ◽  
Machining Process ◽  
Central Character ◽  
Spindle Rotation ◽  
Cfd Method ◽  
Increase Tool Life

In the metal machining process, especially in the milling process, the parameters that affect the quality milling process results are cooling media because it affects the tool life used. This paper aims to determine the performance of using fan chips as the coolant in the dry milling process area. The method used is the computational fluid dynamic (CFD) method and the experimental milling process on a workpiece made from aluminum alloy 5086. In experimental testing using a variation of the milling machine spindle rotation. The simulation test results on the fluid flow character on fan chips with a protector producing a central character with a small area. In contrast, fan chips without a protector make a central character with a broader area. The wind speed data in simulation testing and experimental testing produced the same trend graph. The results of the performance of fan chips after experimented with variations in spindle rotation, cooling process on area occurs when the motor spindle rotates above 1120 Rpm on the fan chips with a protector, and the engine spindle rotates above 770 Rpm on the fan chips without a protector. The effect of fan chips on tool life affects increasing tool life by 8 minutes on installing fan chips with a protector and increasing tool life by 12 minutes on installing fan chips without a protector.

Computational study of the cavity flow over sharp nose cone in supersonic flow

2020 ◽  
Vol 31 (06) ◽  
pp. 2050079 ◽  
Author(s):  
F. Pish ◽  
Tran Dinh Manh ◽  
M. Barzegar Gerdroodbary ◽  
Nguyen Dang Nam ◽  
Rasoul Moradi ◽  
...  
Keyword(s):  
Computational Study ◽  
Fluid Dynamic ◽  
Thermal Characteristic ◽  
Main Body ◽  
Cavity Depth ◽  
Nose Cone ◽  
Sst Turbulence Model ◽  
Mach 3 ◽  
Cfd Method ◽  
Supersonic Vehicles

Heat and drag reduction on the nose cone is a significant issue for increasing the speed of the supersonic vehicles. In this paper, computational fluid dynamic method is applied to investigate the thermal and drag coefficient on the sharp nose cone with different cavity shapes. In order to simulate our model, the CFD method with SST turbulence model is applied to study the flow feature and temperature distribution in the vicinity of the nose body. The effect of depth and length of the cavity on the thermal characteristic of the nose cone is comprehensively investigated. In addition, the influence of the number of the cavity in the thermal performance of the main body is studied. According to our results, increasing the length of the cavity highly efficient for the reduction of the drag at Mach = 3. As the Mach number is increased to 3, the number of the cavity becomes a significant role and it is observed that case 9 with four cavities is more efficient. Obtained results also show that increasing the cavity depth declines the temperature on the main body. Our findings confirm that the main source of the expansion is the edge of the cavity.

Sign in / Sign up

Export Citation Format

Share Document