Environmental Fatigue Analysis Considering Thermal Stratification in Direct Vessel Injection Piping

2020 ◽  
Author(s):  
Bonghee Lee ◽  
Ilkwun Nam ◽  
Sangyun Park ◽  
Sookyum Kim ◽  
Yongbaek Kim
Keyword(s):  
Thermal Stratification ◽  
Pipe Wall ◽  
Fluid Dynamic ◽  
Check Valve ◽  
Local Stress ◽  
Fatigue Analysis ◽  
Design Stage ◽  
Time Interval ◽  
Bending Moments ◽  
Induced Stresses

Abstract Thermal stratification-induced stresses could lead to a serious failure and fatigue crack on piping systems. U.S. NRC Bulletin 88-08 [1] requires to investigate which unisolable pipings are subjected to the thermal stratification and to demonstrate compliance with applicable code limits during the piping design stage by incorporating the thermal stratification-induced stresses into the fatigue evaluation. In this paper, the computational fluid dynamic (CFD) analyses considering both the out-leakage case by turbulent penetration and the in-leakage case by valve leakage were performed for the unisolable portion of the Direct Vessel Injection (DVI) piping between the reactor vessel nozzle and the first check valve to determine the change of temperature gradient on the pipe wall as a function of time due to the thermal stratification. And then the CFD-based temperature distributions on the pipe wall at each time interval were transformed as input data for the structural analysis to evaluate the stresses induced by the global bending moments and local stresses by the thermal stratification of the DVI piping. The localized thermal stratification stress intensities were directly extracted from the 3-D model using the ANSYS program and were categorized as the three stress terms induced by ΔT1, ΔT2, and Ta - Tb defined in NB-3600 of ASME B&PV Sec. III [2], but including thermal stratification effects herein for the fatigue analysis. To evaluate the air environment- and LWR environment-based fatigue damages for the DVI piping, the bending moments and three local stress terms due to the thermal stratification were incorporated into the fatigue analysis. NB-3200/-3600 of ASME B&PV Sec. III- and Regulatory Guide 1.207-based cumulative usage factors [3, 4] were compared with each other to investigate the effects of fatigue damages considering the thermal stratification in the air and light water reactor (LWR) environments.

Simulation of Unsteady Flow Characteristics of the Reciprocating Pump Check Valve for High Pressure and High Flow Water Medium

2021 ◽  
Vol 144 (3) ◽  
Author(s):  
Jie Dong ◽  
Yinshui Liu ◽  
Hong Ji ◽  
Liejiang Wei ◽  
Defa Wu
Keyword(s):  
High Pressure ◽  
Fluid Dynamic ◽  
Check Valve ◽  
Initial Pressure ◽  
Lower Surface ◽  
Flow Coefficient ◽  
Valve Lift ◽  
Water Medium ◽  
Flow State ◽  
Reciprocating Pump

Abstract The distribution efficiency of the check valve directly affects the performance of the reciprocating pump. The flow coefficient is an important evaluation criterion for the flow capacity of the valve port, and it is of great significance to the design of the valve structure and even the control of cavitation. The traditional design uses flow coefficient as a fixed value, however, the flow state and flow coefficient will change during valve movement. In this study, a three-dimensional transient computational fluid dynamic model for high-pressure and large-flow reciprocating pump valve is established. The dynamic grid simulation method of coupling for the valves and plunger is innovatively proposed, and experimental verification was carried out. The flow state and pressure characteristics for the suction valve under high outlet pressure are analyzed, and the change rule of the suction coefficient is found. The research results show that the initial pressure of the plunger cavity prolongs the negative pressure duration of the plunger cavity when the valve is opened and increases the risk of cavitation of the valve. During the process from valve opening to maximum lift, the suction coefficient first increases and then decreases, and finally remains between 0.5 and 0.6. When the valve lift is large, two-stage throttling occurs, and the flow state will change from cylindrical jet on the lower surface of the valve disk to annular jet, which is beneficial to improve the suction coefficient.

Fatigue Evaluation for Thermally Stratified DVI Piping

2012 ◽  
Author(s):  
Hwan Ho Lee ◽  
Joon Ho Lee ◽  
Dong Jae Lee ◽  
Seok Hwan Hur ◽  
Il Kwun Nam ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Thermal Stratification ◽  
Nuclear Power ◽  
Heat Removal ◽  
Local Stress ◽  
Piping System ◽  
Hydraulic Analysis ◽  
Fatigue Evaluation ◽  
Core Cooling ◽  
Thermal Hydraulic Analysis

A numerical analysis has been performed to estimate the effect of thermal stratification in the safety injection piping system. The Direct Vessel Injection (DVI) system is used to perform the functions of Emergency Core Cooling and Residual Heat Removal for an APR1400 nuclear power plant (Korea’s Advanced Power Reactor 1400 MW-Class). The thermal stratification is anticipated in the horizontally routed piping between the DVI nozzle of the reactor vessel and the first isolation valve. Non-axisymmetric temperature distribution across the pipe diameter induced by the thermal stratification leads to differential thermal growth of the piping causing the global bending stress and local stress. Thermal hydraulic analysis has been performed to determine the temperature distribution in the DVI piping due to the thermal stratification. Piping stress analysis has also been carried out to evaluate the integrity of the DVI piping using the thermal hydraulic analysis results. This paper provides a methodology for calculating the global bending stresses and local stresses induced by the thermal stratification in the DVI piping and for performing fatigue evaluation based on Subsection NB-3600 of ASME Section III.

Springing Responses Analysis and Segmented Model Testing on a 550,000 DWT Ore Carrier

2016 ◽  
Author(s):  
Hui Li ◽  
Di Wang ◽  
Cheng Ming Zhou ◽  
Kaihong Zhang ◽  
Huilong Ren
Keyword(s):  
Natural Frequency ◽  
Design Stage ◽  
Resonant Vibration ◽  
Bending Moments ◽  
Wave Loads ◽  
Regular Waves ◽  
Segmented Model ◽  
Ship Model ◽  
Hull Structure ◽  
Stiffness Distribution

For ultra large ore carriers, springing response should be analyzed in the design stage since springing is the steady-state resonant vibration and has an important effect on the fatigue strength of hull structure. The springing response of a 550,000 DWT ultra large ore carrier has been studied by using experimental and numerical methods. A flexible ship model composed of nine segments was used in the experiment. The model segments were connected by a backbone with varying section, which can satisfy the request of natural frequency and stiffness distribution. The experiments in regular waves were performed and the motions and wave loads of the ship were measured. The experimental results showed that springing could be excited when the wave encounter frequency coincides with half or one-third the flexural natural frequency of the ship. In this paper, the analysis of the hydroelastic responses of the ultra large ore carrier was also carried out using a 3-D hydroelastic method. Comparisons between experimental and numerical results showed that the 3-D hydroelastic method could predict the motions and the vertical bending moments quite well. Based on this numerical method, the fatigue damage was estimated and the contribution of springing was analyzed.

scholarly journals Fatigue life prediction in a door hinge system under uni-axial and multi-axial loading conditions

2021 ◽  
Author(s):  
Sacheen Bekah
Keyword(s):  
Axial Loading ◽  
Fatigue Analysis ◽  
Design Stage ◽  
Fe Model ◽  
Preliminary Design ◽  
Standard Requirement ◽  
Ground Vehicle ◽  
Design Engineers ◽  
Door Hinge ◽  
Preliminary Design Stage

This thesis presents the use of Finite Element (FE) based fatigue analysis to locate the critical point of crack initiation and predict life in a door hinge system that is subjected to both uni-axial and multi-axial loading. The results are experimentally validated. The FE model is further used to obtain an optimum design per the standard requirement in the ground vehicle industry. The accuracy of the results showed that FE based fatigue analysis can be successfully employed to reduce costly and time-consuming experiments in the preliminary design stage. Numerical analysis also provides the product design engineers with substantial savings, enabling the testing of fewer prototypes.

scholarly journals Fatigue life prediction in a door hinge system under uni-axial and multi-axial loading conditions

2021 ◽  
Author(s):  
Sacheen Bekah
Keyword(s):  
Axial Loading ◽  
Fatigue Analysis ◽  
Design Stage ◽  
Fe Model ◽  
Preliminary Design ◽  
Standard Requirement ◽  
Ground Vehicle ◽  
Design Engineers ◽  
Door Hinge ◽  
Preliminary Design Stage

This thesis presents the use of Finite Element (FE) based fatigue analysis to locate the critical point of crack initiation and predict life in a door hinge system that is subjected to both uni-axial and multi-axial loading. The results are experimentally validated. The FE model is further used to obtain an optimum design per the standard requirement in the ground vehicle industry. The accuracy of the results showed that FE based fatigue analysis can be successfully employed to reduce costly and time-consuming experiments in the preliminary design stage. Numerical analysis also provides the product design engineers with substantial savings, enabling the testing of fewer prototypes.

scholarly journals Influence of Geometric Parameters on Aerodynamic and Acoustic Performances of Bladeless Fans

2019 ◽  
Author(s):  
Ang Li ◽  
Jun Chen ◽  
Yangfan Liu ◽  
Stuart Bolton ◽  
Patricia Davies
Keyword(s):  
Cross Section ◽  
Fluid Dynamic ◽  
Geometric Parameters ◽  
Design Stage ◽  
Air Velocity ◽  
Cross Sectional ◽  
Future Design ◽  
Cross Sectional Profile ◽  
The Cross ◽  
Sectional Profile

Abstract In recent years, the bladeless fan that does not have visible impellers have been widely applied in household appliances. Since the customers are particularly sensitive to noise and the strength of wind generated by the fan, the aerodynamic and acoustic performances of the fan need to be accurately characterized in the design stage. In this study, computational fluid dynamic (CFD) and computational aeroacoustics (CAA) are applied to investigate the performances of different designs of a bladeless fan model. The influence of four parameters, namely the airfoil selection for cross-section of the wind channel, the slit width, the height of cross-section and the location of the slit, is investigated. The results indicate the streamwise air velocity increases significantly by narrowing the outlet, but the noise level increases simultaneously. In addition, the generated noise increases while the height of fan cross-section increases, and a 4mm height of the cross section is optimal for aerodynamic performance. When the slit is closer to the location of maximum thickness, the performances of the bladeless fan increases. Moreover, the performance is not changed significantly by changing the cross-sectional profile. Finally, the optimal geometric parameters are identified to guide the future design of the bladeless fan.

Active Optimum Control of Orthotropic Plates Using Piezoelectric Stiffeners

1993 ◽  
Author(s):  
Victor Birman ◽  
Sarp Adali
Keyword(s):  
Time Interval ◽  
Short Time Interval ◽  
Bending Moments ◽  
Optimum Control ◽  
Orthotropic Plates ◽  
Time Intervals ◽  
Control Forces ◽  
Short Time ◽  
Alternating Voltage ◽  
Over Time

Abstract Active control of orthotropic plates subjected to an impulse loading is considered. The dynamic response is minimized using in-plane forces or bending moments induced by piezoelectric stiffeners bonded to the opposite surfaces of the plate and placed symmetrically with respect to the middle plane. The control forces and moments are activated by a piece-wise constant alternating voltage with varying switch-over time intervals. The magnitude of voltage is bounded while the switch-over time intervals are constantly adjusted to achieve an optimum control. Numerical examples presented in the paper demonstrate the effectiveness of the method and the possibility of reducing the vibrations to very small amplitudes within a short time interval which is in the order of a second.

Load Factors for Concrete Wall Pipe Penetrations With a Wall Mounted Welded Plate

2017 ◽  
Author(s):  
Samuel R. Costanzo ◽  
Chee W. Mak ◽  
Phuong H. Hoang
Keyword(s):  
Stress Analysis ◽  
Parametric Study ◽  
Steel Plate ◽  
Pipe Wall ◽  
Bending Moments ◽  
Normal Reaction ◽  
Concrete Wall ◽  
Structural Evaluation ◽  
Load Factors ◽  
Anchor Bolts

The bending moments imposed on welded plate anchors that are part of embedded pipe wall penetrations are often overestimated in the structural evaluations of these penetrations. For this type of restraint, the pipe is embedded in a concrete wall penetration with a welded plate mounted on the surface of the wall. This penetration is typically modeled with a single 6 degree of freedom (DOF) restraint at the plate in the pipe stress analysis. This approach can lead to overestimated loads on the welded plate and the mounting anchor bolts because no credit is taken for reaction on the embedded portion of the pipe. A significant portion of the bending moments from piping on both sides of the penetration is transferred directly to the concrete wall by the normal reaction on a fully grouted pipe, thus reducing loads on the steel plate and the mounting anchored bolts. The objective of this study is to determine load factors for bending moments from both sides of the pipe penetration on the anchored steel plate. A parametric study is performed using ANSYS models of a pipe fully embedded in a concrete wall penetration with a welded plate mounted on one side of the wall by anchor bolts. Various pipe diameters, concrete wall thicknesses and plate thicknesses are considered. For each model, the loading on the plate is compared to the loading applied at the free end of the pipe. Load factors are developed for use in the structural evaluation of the welded plate and the mounting anchor bolts. The maximum compressive bearing pressure at the concrete wall is also calculated for use in the structural evaluation of these types of pipe supports.

Analysis of Thermal Stratification and Fatigue Stress for Pressurizer Surge Line

2010 ◽  
Author(s):  
Xiaofei Yu ◽  
Yixiong Zhang
Keyword(s):  
Cross Section ◽  
Thermal Stratification ◽  
Thermal Stresses ◽  
Structural Integrity ◽  
Bending Moments ◽  
One Dimensional ◽  
Pipe System ◽  
Pipe Cross Section ◽  
Fatigue Stress ◽  
Surge Line

Thermal stratification of pressurizer surge line induced by the inside fluid brings on global bending moments, local thermal stresses, unexpected displacements and support loadings of the pipe system. In order to confirm the structural integrity of pressurizer surge line affected by thermal stratification, this paper theoretically establishes thermal stratified transient and studies the calculation method of thermal stratified stress. A costly three-dimensional computation is simplified into a combined 1D/2D technique. This technique uses a pipe cross-section for computation of local thermal stresses and represents the whole surge line with one-dimensional pipe elements. The 2D pipe cross-section model is used to compute elastic thermal stresses in plane strain condition. Symmetry allows half the cross-section to be considered. The one-dimensional pipe elements model gives the global bending moments including effects of usual thermal expansion and thermal stratification of each model nodes. This combined 1D/2D technique has been developed and implemented to analyze the thermal stratification and fatigue stress of pressurize surge line in this paper, using computer codes SYSTUS and ROCOCO. According to the mechanical analysis results of stratification, the maximum stress and cumulative usage factor are obtained. The stress and fatigue intensity of the surge line tallies with the correlative criterion.

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