scholarly journals Evaluation of Water Hammer for Seawater Treatment System in Offshore Floating Production Unit

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1041
Author(s):  
Jun Sung Park ◽  
Quang Khai Nguyen ◽  
Gang Nam Lee ◽  
Kwang Hyo Jung ◽  
Hyun Park ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Characteristics ◽  
Water Hammer ◽  
Treatment System ◽  
Closing Time ◽  
Simulation Tools ◽  
Transient Experiments ◽  
Significant Damage ◽  
Seawater Treatment ◽  
1D Numerical Simulation

Water hammer can result in the rupture of pipes, and significant damage to pipe supports is inevitable during the operation of an offshore plant. In this study, the dynamic behaviors of the water hammer caused by closing valves and starting pumps for the seawater treatment system were evaluated by using the 1D numerical simulation model based on the method of characteristics. Before conducting an analysis of a complex piping network, the 1D numerical simulation tools were validated by a comparison between the numerical results and the results from both static and transient experiments that have been conducted in other studies. For the case study, the effects of valve flow characteristics and valve closing time on surge pressure were investigated, and the equal percentage butterfly valve was recommended in order to reduce the surge pressure with a shorter valve closure time and lower weight compared to other valve types.

scholarly journals Progress in Experimental and Theoretical Evaluation Methods for Textile Permeability

2019 ◽  
Vol 3 (3) ◽  
pp. 73 ◽  
Author(s):  
Mohamad Karaki ◽  
Rafic Younes ◽  
Francois Trochu ◽  
Pascal Lafon
Keyword(s):  
Numerical Simulation ◽  
Analytical Methods ◽  
Measurement Techniques ◽  
Analytical Models ◽  
Theoretical Evaluation ◽  
Unidirectional Fiber ◽  
Simulation Tools ◽  
Performance Preparation ◽  
Personal Performance ◽  
Methods Numerical

A great amount of attention has been given to the evaluation of the permeability tensor and several methods have been implemented for this purpose: experimental methods, as well as numerical and analytical methods. Numerical simulation tools are being seriously developed to cover the evaluation of permeability. However, the results are still far from matching reality. On the other hand, many problems still intervene in the experimental measurement of permeability, since it depends on several parameters including personal performance, preparation of specimens, equipment accuracy, and measurement techniques. Errors encountered in these parameters may explain why inconsistent measurements are obtained which result in unreliable experimental evaluation of permeability. However, good progress was done in the second international Benchmark, wherein a method to measure the in-plane permeability was agreed on by 12 institutes and universities. Critical researchers’ work was done in the field of analytical methods, and thus different empirical and analytical models have emerged, but most of those models need to be improved. Some of which are based on Cozeny-Karman equation. Others depend on numerical simulation or experiment to predict the macroscopic permeability. Also, the modeling of permeability of unidirectional fiber beds have taken the greater load of concern, whereas that of fiber bundle permeability prediction remain limited. This paper presents a review on available methods for evaluating unidirectional fiber bundles and engineering fabric permeability. The progress of each method is shown in order to clear things up.

Experimental Investigation and Numerical Simulation of Porous Volcano Rock Hypervelocity Impact on Whipple Shield of Spacecrafts

2010 ◽  
Vol 452-453 ◽  
pp. 385-388
Author(s):  
Bin Jia ◽  
Gao Jian Liao ◽  
Hai Peng Gong ◽  
Bao Jun Pang
Keyword(s):  
Numerical Simulation ◽  
Space Debris ◽  
Geometrical Model ◽  
Hypervelocity Impact ◽  
Rear Wall ◽  
Projectile Impact ◽  
Gas Gun ◽  
Significant Damage ◽  
Speed Range ◽  
Whipple Shield

All spacecrafts in earth orbit are subject to hypervelocity impact by micro-meteoroids and space debris, which can in turn lead to significant damage and catastrophic failure of spacecraft. Porous volcano rock was adopted as one of micro-meteoroid material due to their similar physical and geometric features. Two-stage light gas gun experiments were carried out for a 6mm diameter volcano rock projectile impact on an Al-Whipple shield within the speed range from 1 km/s to 3 km/s. An ANSYS/LS-DYNA software was employed and justified by experimental results, in which a porous geometrical model was established for volcano rock projectile. The higher speed range was extended from 3 km/s to 10 km/s by numerical simulation. The results of experiments and numerical simulation indicated that major damage on rear wall of the Whipple shield impacted by volcano rock projectile is caused by the fragments of bumper of the shield, which is different from that of aluminum projectile. And 5.5km/s is the critical speed of a 6mm diameter volcano rock projectile impact on the Whipple shield investigated.

Numerical Simulation Study on the Recovery Process of Autonomous Underwater Vehicle

2021 ◽  
Author(s):  
Weigang Huang ◽  
Donglei Zhang ◽  
Jiawei Yu ◽  
Tao He ◽  
Xianzhou Wang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Autonomous Underwater Vehicle ◽  
Flow Characteristics ◽  
Recovery Process ◽  
Underwater Vehicle ◽  
Hydrodynamic Performance ◽  
Time Step ◽  
Convergence Test ◽  
Motion Paths

Abstract AUV (Autonomous Underwater Vehicle) recovery is considerably influenced by the nearby flow field and simulations of AUV in different motion paths in the wake of a submarine with a propeller are presented in this paper. A commercial CFD solver STAR CCM+ has been used to research the motion and flow characteristics of AUV, which using the advanced computational continuum mechanics algorithms. The DARPA (Defense Advanced Research Projects Agency) SUBOFF Submarine (L1 = 4.356m) propelled with INSEAN (Italian Ship Model Basin) E1619 propeller is used in this study, and the self-propulsion characteristics of the propeller at an incoming flow velocity of 2.75m/s are obtained through numerical simulation and results are compared with the available experimental data to prove the accuracy of the chosen investigation methodology. A grid/time-step convergence test is performed for verification study. AUV (L2 = 0.4356m) is a smaller-scale SUBOFF without a sail, which approaches the submarine in different motion paths in the submarine wake at a relative speed combined with the dynamic overlapping grid technology. The hydrodynamic performance of the AUV when approaching the submarine and the velocity distribution of the surrounding flow field are analyzed, which provides a useful reference for underwater recovery of the AUV.

scholarly journals Numerical and Experimental Investigation of External Characteristics and Pressure Fluctuation of a Submersible Tubular Pumping System

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 949 ◽  
Author(s):  
Yan Jin ◽  
Xiaoke He ◽  
Ye Zhang ◽  
Shanshan Zhou ◽  
Hongcheng Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pressure Fluctuation ◽  
High Efficiency ◽  
Pressure Pulsation ◽  
Guide Vane ◽  
Measurement Data ◽  
Flow Characteristics ◽  
Measuring Point ◽  
Pumping System ◽  
Impeller Outlet

This paper presents an investigation of external flow characteristics and pressure fluctuation of a submersible tubular pumping system by using a combination of numerical simulation and experimental methods. The steady numerical simulation is used to predicted the hydraulic performance of the pumping system, and the unsteady calculation is adopted to simulate the pressure fluctuation in different components of a submersible tubular pumping system. A test bench for a model test and pressure pulsation measurement is built to validate the numerical simulation. The results show that the performance curves of the calculation and experiment are in agreement with each other, especially in the high efficiency area, and the deviation is minor under small discharge and large discharge conditions. The pressure pulsation distributions of different flow components, such as the impeller outlet, middle of the guide vane, and guide vane outlet and bulb unit, are basically the same as the measurement data. For the monitoring points on the impeller and the wall of the guide vane especially, the main frequency and its amplitude matching degree are higher, while the pressure pulsation values on the wall of the bulb unit are quite different. The blade passing frequency and its multiples are important parameters for analysis of pressure pulsation; the strongest pressure fluctuation intensity appears in the impeller outlet, which is mainly caused by the rotor–stator interaction. The farther the measuring point from the impeller, the less the pressure pulsation is affected by the blade frequency. The frequency amplitudes decrease from the impeller exit to the bulb unit.

scholarly journals Modelling of textile composite reinforcements on the micro-scale

2014 ◽  
Vol 14 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Oliver Döbrich ◽  
Thomas Gereke ◽  
Chokri Cherif
Keyword(s):  
Numerical Simulation ◽  
Finite Element Analysis ◽  
Computational Cost ◽  
Textile Composite ◽  
Element Analysis ◽  
Simulation Tools ◽  
Micro Scale ◽  
Generating Method ◽  
Geometrical Effects ◽  
Composite Reinforcements

Abstract Numerical simulation tools are increasingly used for developing novel composites and composite reinforcements. The aim of this paper is the application of digital elements for the simulation of the mechanical behaviour of textile reinforcement structures by means of a finite element analysis. The beneficial computational cost of these elements makes them applicable for the use in large models with a solution on near micro-scale. The representation of multifilament yarn models by a large number of element-chains is highly suitable for the analysis of structural and geometrical effects. In this paper, a unit cell generating method for technical reinforcement textiles, using digital elements for the discretization, is introduced.

Research on Flow Characteristics of Aerostatic Circular Thrust Bearing with a Cone Cavity

2011 ◽  
Vol 308-310 ◽  
pp. 189-192
Author(s):  
Long Xing Chen ◽  
Wen Qi Ma ◽  
He Chun Yu ◽  
Hai Yan Liu ◽  
Hong Wang Du
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Thrust Bearing ◽  
Single Point ◽  
Flow Characteristics ◽  
Simulation Method ◽  
Flow Passage ◽  
Testing Method ◽  
Measurement Results ◽  
Simulation And Experiment

The aerostatic circular thrust bearing was taken as a study subject. The numerical simulation method was used to calculate the flow passage. Meanwhile, the single-point testing method was used to test the pressure distribution. The simulation and experiment measurement results were compared and analyzed. The results show that: The single-point testing method is effective to capture the change of flow characteristics. The overall results of simulation and testing coincide with each other well. In the range of cone cavity, the flow pattern for the gas is turbulent flow, and the flow field should be divided into different zones for simulation.

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