Pipe Flow System Research Articles

Modeling and simulation of xenon storage and supply system for electric propulsion system based on fundamental equation of state

The electric propulsion system (EPS) xenon storage and supply system (SSS) is a complex pipeline network system, which involves the multi-physics coupled fields of transcritical flow, heat transfer, rigid body motion, electromagnetics, and control. Based on the fundamental equation of state, a one-dimensional finite volume model system is proposed for compressible transcritical transient pipe flow. Six typical components of the SSS are modularization modeled by using an object-oriented programming method in Fortran 2018. To evaluate the performance of the algorithm, a simulation model consisting of 77 components is developed for a proportional controlled EPS xenon SSS, and a system-level simulation is performed. Compared with the standard case constructed on the Amesim platform, the model has a pressure rise time error lower than 6%, and the restrictors mass-flow-rate errors of the anode, cathode, and neutralizer are less than 2.8% of the rated flow rate after stabilization. Moreover, the proposed model yields more accurate results at certain operating points. The model system provides an efficient reference for the design and optimization of EPS SSSs, and offers a new approach to simulate complex cryogenic pipe flow systems.

The effect of permeability on the flow structure of porous square cylinders

This study experimentally investigates the wake structure of a porous square cylinder in terms of permeability over two decades of $Da$ (i.e. $2.4 \times 10^{-5} < Da < 2.9 \times 10^{-3}$ ). The porous cylinder, featuring a simple cubic lattice structure, was fabricated using an additive manufacturing technique. This unique method, combined with a periodic and scalable lattice structure, effectively isolates permeability from porosity, making it suitable for an in-depth parametric study. The key parameter, permeability, was directly estimated by measuring the pressure drop and superficial velocity for each porous case in an open-loop pipe flow system. The downstream flow fields were obtained using standard planar particle image velocimetry measurements in an open-loop wind tunnel. Based on the experimental data, structural modifications in the near wake were examined in relation to permeability, leading to the identification of four distinct flow regimes depending on $Da$ . Additionally, the downstream flow adjustment length ( $L_i$ ) was assessed by introducing a permeability-based source term into the momentum equation, facilitating the development of an analytical model for $L_i$ . The present experimental data support this analytical model, and our results further confirmed that $L_i$ plays a crucial role as a characteristic length scale in the near wake.

The analysis of vertex feedback stabilisability of a star-shaped network of fluid-conveying pipes

It is an outstanding problem whether a pipe-flow system on a star-shaped network is stabilisable by a feedback control on the common vertex. In the present paper we deal with this problem. In particular, we study the equation governing the small vibrations of a stretched elastic pipe conveying fluid in a star-shaped network and examine the question of vertex feedback stabilisability of such a system via control moments. Finding an answer to the question is not straightforward, for the system operator associated with the corresponding closed-loop system is unbounded and nonselfadjoint. An approach to the study of the stabilisation problem for the closed-loop system is presented based on the spectral approach previously introduced by the authors for star graphs of stretched elastic beams. When the tension in the pipes is greater than the square of the fluid-flow velocity, we establish a positive result that in fact gives the strong property of uniform exponential stability of the closed-loop system.

An Heat Transfer Coefficient and Pressure Characteristics in a Copper Pipe Flow System: A Preliminary study Utilizing an EG/Water Mixture

An Heat Transfer Coefficient and Pressure Characteristics in a Copper Pipe Flow System: A Preliminary study Utilizing an EG/Water Mixture

A general approach for predicting convective heat transfer coefficients in turbulent systems

A generalized approach for predicting turbulent convective heat transfer coefficients using large eddy simulation is presented. This model is based on semi-empirical transport theory, which links the local convective heat transfer rate to the local energy dissipation rate within the near-wall boundary layer. We apply these approaches to agitated tanks, pipe flow systems, cylinders in crossflow, and tube bundles. We validate the generality and reliability of the theoretical model against expectations from experimentally derived empirical design correlations.

The Heat Transfer Coefficient in a Copper Pipe Flow System Using a 40/60 Volume Ratio Ethylene Glycol/Water (EG/H2O) Blended Fluid

This study discusses the performance of Ethaline Glycol/water (EG/H2O) fluids at a volume ratio of 40/60. EG/H2O fluids are widely used as basic fluids in cooling and heating system applications. The discussion of EG/H2O fluid performance is focused on the analysis of the heat transfer coefficient and pressure drop. The study used an experimental method using a suction test made of pure copper with an inner diameter, outer diameter and length of 16 mm, 19 mm and 1500 mm respectively. The EG/H2O volume ratio at 40/60 was selected as the input parameter. Other input parameters are variations in the fluid flow rate which are regulated using a control valve at fluid flow rates of 4, 6, 8, 10.12, 14.16 and 18 liters/minute. A 2-unit tubular heater with a total capacity of 2000 W was installed on the sides of the copper pipes. A voltage regulator with a capacity of 3000 W is used to regulate the electric power by regulating the supplied voltage. Ampere pliers are used to measure amperage at the setting used. The experimental results show that the performance of the EG/H2O fluid on the heat transfer coefficient increases as the fluid flow rate increases. The highest heat transfer coefficient rate was obtained at a fluid flow rate of 18 L/minute, while the lowest value was obtained at a fluid flow rate of 4 L/minute. Pressure drops fluctuations occur as the fluid flow rate increases. Even though there is a fluctuating pressure drop, this condition does not significantly affect the friction factor, because the fluid flow characteristics occur in a turbulent manner

CFD modeling of slurry flow erosion wear rate through mitre pipe bend

Erosive wear caused by particulates slurry is one of the major concerns in the pipe bend which may results in the failure of the pipe flow system. In the present work, erosion wear rate through mitre pipe bend caused by silica sand particulates slurry has been investigated using ANSYS Fluent code. The solid spherical particulates of size 125 µm and 250 µm having density of 2650 Kg/m3, were tracked to compute the erosion wear rate using Discrete Phase Method (DPM) model. The particulates were tracked using Eulerian-Lagrange approach along with k-ɛ turbulent model for continuous fluid phase. The silica particulates were injected at solid concentration of 5% and 10% (by weight) from the pipe inlet surface for wide range of velocities viz. 1–8 ms−1. The erosion wear rate was computed through four computational erosion models viz. Generic, Oka, Finnie and Mclaury. Furthermore, the outcomes obtained through Generic models are verified through existing experimental data in the literture. Moreover, the results of DPM concentration, turbulence intensity and particle tracking were predicted to analyze the secondary flow behaviour through the bend cross section. Finally, the effect of particulate size, solid concentration and flow velocity were discussed on erosion wear rate through bend cross section. The findings show that the locality of maximum erosive wear is positioned at the extrados of the bend outlet cross section. Additionally, it is found that Mclaury model offers higher erosion rate as compared to the other models and provides benchmark for designing the slurry pipeline system.

Experimental Study on the Drag Reduction Performance of Clear Fracturing Fluid Using Wormlike Surfactant Micelles and Magnetic Nanoparticles under a Magnetic Field.

This paper examines a new study on the synergistic effect of magnetic nanoparticles and wormlike micelles (WLMs) on drag reduction. Fe3O4 magnetic nanoparticles (FE-NPs) are utilized to improve the performance of viscoelastic surfactant (VES) solutions used as fracturing fluids. The chemical composition and micromorphology of the FE-NPs were analyzed with FT-IR and an electron microscope. The stability and interaction of the WLM-particle system were studied by zeta potential and cryo-TEM measurements. More importantly, the influences of the temperature, FE-NP concentration, magnetic field intensity, and direction on the drag reduction rate of WLMs were systematically investigated in a circuit pipe flow system with an electromagnetic unit. The experimental results show that a suitable content of magnetic nanoparticles can enhance the settlement stability and temperature resistance of WLMs. A magnetic field along the flow direction of the fracturing fluid can improve the drag reduction performance of the magnetic WLM system. However, under a magnetic field perpendicular to the direction of fluid flow, an additional flow resistance is generated by the vertical chaining behavior of FE-NPs, which is unfavorable for the drag reduction performance of magnetic VES fracturing fluids. This study may shed light on the mechanism of the synergistic drag reduction effects of magnetic nanoparticles and wormlike micelles.

Application of the shock response spectrum method to severity assessment of water hammer loads

Water hammer (WH) is a transient phenomenon which happens to appear in pipe flow systems as an effect of a sudden change in pipe flow conditions. Various origins can be the primary source of WH. They usually come from the liquid (e.g. operation of valves), but when the pipeline system is significantly elastic, WH can be produced by an external impact or transient vibration due to fluid structure interaction (FSI) effect. Hydraulic transients are usually undesired effects as large amplitudes of pressure waves, pipe stresses or vibration accompanying this phenomenon can be the source of pipeline system malfunction. Therefore, many efforts are taken by scientists and engineers to avoid unexpected WH events or to reduce their harmfulness. Systematic protection of pipeline systems requires a reliable method of severity estimation of WH loads. Various ways can be used for evaluation of WH strength. In general, severity of a transient depends on its amplitude, i.e. the maximum value of the liquid pressure. Another important factor is time dependence of the load signal however, a simple observation of its shape in time domain is usually not an effective technique. Instead, frequency domain analysis can be exploited. A specific kind of spectral analysis used in structural mechanics for assessment of shock loads and transients is the shock response spectrum (SRS) method. An original concept of application of this technique to WH events is proposed in this study. The method is shortly presented and its numerical approach developed by the author and applicable to WH loads are described. As an example of use the SRS computations and analysis of own WH experimental results measured at a laboratory pipeline are performed and concluded. Specific preprocessing of WH signal was applied and explained. It is evidenced in the paper that the applied SRS method gives a valuable and effective tool for determination of WH load severity. Therefore, it can also be used for comparison between alternative designs of pipeline system applied for protection from undesired WH events.

Novel Approach for Improving the Flow of Waxy Crude Oil Using Thermochemical Fluids: Experimental and Simulation Study.

This article focuses on the flow assurance of waxy crude oil using an environmentally benign and cost-effective approach involving thermochemical reaction. The study incorporates experimental and simulation works to evaluate heat and pressure generation potentials and heat transfer efficiency of the thermochemical fluids. Experimental results reveal that at the concentration (1 M) of thermochemical fluid (TCF) ranging between 14 and 33% v/wt of the waxy oil, sufficient heat could be generated to raise the temperature of the oil significantly above the pour point (48 °C). In addition, from the bench-top treatment of a damaged tubing, it was observed that more than 95% of the deposited wax could be removed using the thermochemical solutions. Subsequently, a large-scale application of the technology in a long-distance flow assurance of waxy crude oil was confirmed through process simulation. Ultimately, the simulation results revealed the capacity of the method to improve the temperature and pressure profiles of the pipe flow system, and most significantly, to remove wax deposition up to 98%.

A reactive transport approach for modeling scale formation and deposition in water injection wells

Petroleum industry is moving toward enhancing oil recovery methods, especially water-based methods, including low salinity and smart water flooding which water with an optimized composition is injected into the reservoir for improving oil recovery. Injection of water into the target formation is also a common operation in geothermal energy production. As the water is being injected into the reservoir, pressure and temperature change along the well column and cause scale formation. Mineral scale precipitation and deposition is a common problem for water injection wells which reduces the effective radius of the wellbore and affects the injection efficiency.In this paper, modeling scale precipitation and deposition in a pipe flow system by coupling of species transport model and a geochemical software package (PHREEQC) is investigated. The results of the proposed method were matched with experimental data. The model has been used for prediction of scale precipitation and deposition profile along with water injection wells during low salinity waterflooding. The results show deposition of calcium carbonate scale in the bottom section of the water injection wells. Higher temperature, higher salinity and more rate fluctuation cause an increase in scale precipitation and deposition in the wellbore condition.

Detecting Pipeline Anomalies and Variations in Acoustic Velocity in Multiphase Flow Regimes Using Computational Fluid Dynamics

The use of hydrodynamic pressure wave generated from the action of a fast acting valve as well as acoustic reflectometry in the detection of anomalies like leaks, deposits and blockages in a pipe or fluid flow system in the context of the prevailing scientific theories in fluid flow is discussed. The focus of this paper is the application of the theories to more complex scenarios involving multi-phase fluid flow, specifically, two-phase and two-component fluid flow. The principal concern is the determination of acoustic velocity in a two-phase flow regime; which is problematic because it varies with mixture composition along multiphase flowlines. A technique for simulating flow regimes in the laboratory using stacked S-shaped pipes is presented as well as a discussion of the results from a computational fluid dynamics model.

Lethality Calculation of Particulate Liquid Foods during Aseptic Processing

In the past two decades, aseptic processing has been implemented in the food industry to sterilize particulate liquid food mixtures. To ensure that particulates in the liquid receive sufficient heating, mathematical modeling is employed to evaluate the temperature and lethality level in the particles. We developed a model for the thermal processing of liquid foods containing cubic particles in a continuous laminar pipe flow system, comprising a tubular heat exchanger. In our simplified approach, heat transfer equations for particulate liquid foods were solved analytically and numerically to evaluate the effect of certain process parameters on the time temperature profiles of particles and the lethality value in the products. A comparison of the particles’ lethality values was made between the experiment and simulation for two different particle residence times in a case study, and the model predictions were in good agreement with experimental data. Based on modeling studies, it was found that within the range of parameters studied, an increase in flow rate and particle size resulted in a decrease in the lethality value of the particles, while an increase in particle concentration and holding tube length resulted in the opposite effect.

Development of modeling approaches to describe mineral scale deposition kinetics in porous medium and pipe flow system

Mineral scale deposition is among the most significant water-associated operational issues in oilfield operations. Scale deposition can lead to severe damages both in reservoir and in production systems. However, most of the existing studies and the developed computer models only consider the thermodynamics of scale formation process without taking into account of the kinetic aspect of the issue. Thus, it is difficult to estimate the time frame for scale deposition. In this study, modeling approaches have been developed to describe scale deposition kinetics during fluid flow in a porous medium and in a pipe flow system. The focus is given to the identification of limiting equations in brine chemistry calculations related to scale deposition kinetics. Mathematical equations were obtained to relate the brine chemistry change due to scale deposition with the pressure change over distance and also to relate the fractional change in medium porosity with scale deposition kinetics. Both radial and linear flow geometries were considered and the scenarios with and without a CO2 gas phase were studied for each flow geometry. This study demonstrates that incorporation of kinetics into a thermodynamics-based model can expand our capacity in obtaining an in-depth understanding of the kinetic aspect of scale deposition process and in estimating the limits on reaction rates. This information can be very useful in evaluating potential operational problems related to scale deposition and in optimizing oilfield scale treatment strategies.

A novel attach-and-release mineral scale control strategy: Laboratory investigation of retention and release of scale inhibitor on pipe surface

A novel “attach-and-release” approach has been experimentally evaluated as an alternative scale control strategy for pipe flow system. Phosphonate scale inhibitor was initially attached to calcium carbonate medium on the surface of the pipe. Subsequently, the retained inhibitor was released into the flowing fluid for scale control. A plug-flow tube reactor apparatus was adopted in laboratory studies. It shows that formation of calcium-inhibitor precipitate accounts for the attachment of inhibitor and brine chemistry can considerably impact the amount of inhibitor retained. This proposed strategy has the potential to be applied in a pipe flow system to control scale deposition threat.

Intelligent identification of steam jet condensation regime in water pipe flow system by wavelet multiresolution analysis of pressure oscillation and artificial neural network

On-line recognition of condensation regime of vapor jet in pipe flow systems is a promising approach for flow assurance and intellectualization of industrial processes. However, the selection of distinguishable characteristics from pressure signals associated strongly with various condensation regimes is essential and challenging for satisfactory recognition purpose. Accordingly, an artificial neural network technique using wavelet multiresolution analysis of pressure oscillation signals for objective identification of jet condensation regimes is presented in this paper. The recognition procedure was carried out in two major steps. Statistical features of wavelet multiresolution analysis of pressure signals, i.e., mean of absolute and percentage of energy of each wavelet scale, were chose first. And then artificial neural network was adopted to construct classifiers for forecasting the condensation regimes automatically. The recognition results illustrated that the proposed method is feasible and effective for identifying vapor jet condensation regime in pipe flow system. Furthermore, it is suggested that statistical features of mean of absolute and percentage of energy at least four or more particular wavelet scales, and also sample length longer than 1.5 s could guarantee a satisfactory recognition rate above 90%.

Experimental and Numerical Research on Flow-Induced Vibration in Valves

Abstract 
 All central air conditioning systems contain piping system with various components, sizes, material, and layouts. If such systems in operating mode, the flow in piping system and its component such as valves can produce severe vibration due to some flow phenomenon’s. In this research, experimental measurements and numerical simulation are used to study the flow-induced vibration in valves. Computational fluid dynamics (CFD) concepts are included with one-way and two-way fluid-structure interaction concepts by using finite element software Package (ANSYS 14.57). Detection analysis is performed on flow characteristics under operation conditions and relations with structural vibration. Most of real geometrical, operational, and boundary conditions are simulated to obtain best similarity with real operation conditions. Comparisons performed between experimental data and numerical results (one-way and two-way simulation) to verify the results. The main conclusion was drawn from the study that the dominant source of vibration for valve is the water pulsation in addition to amount of water hammering. In addition, the main source of water pulsation in globe valve is the vortex shedding and pressure difference between upstream and downstream of valve. The vibration amplitude was increased with increasing flow rate until to be maximum when the flow rate around 30% and then decreased until flow rate reaches to around 85% and then trends to be constant.
 Keywords: Flow-induced vibration, vortex shedding, pressure pulsation, valve, finite element, ANSYS, fast Fourier transform (FFT).

Investigation on transient behavior of residual heat removal pumps in 1000 MW nuclear power plant using a 1D-3D coupling methodology during start-up period

Residual heat removal pumps (RHRPs) are the key equipment in nuclear power plants, and their transient performances can sensitively affect the stability and reliability of pump system. A 1D-3D coupling methodology has been developed to investigate the instantaneous flow characteristics of the pump system during start-up period. In this methodology, the flow in the RHRPs was considered to be three-dimensional (3D) flow and the flow in pipe system was simplified to be one-dimensional (1D) flow. Due to the influence of the impeller structure displacement was taken into account, the SST k-ω turbulence model was selected to calculate the 3D flow field in the RHRPs. At the same time, the structure response caused by the flow loads was also obtained by using Fluid-structure interaction method. The 1D flow in the pipe system was calculated by Euler equations. The boundary condition at the shared interface was properly updated by the code MpCCI which was used to exchange the information between the two domains. Meanwhile, the head of the RHRP, the stress of impeller structure and the displacement of impeller were also obtained. The results show that the transient head is distinctly impacted during the startup period. Additionally, the stress of impeller structure rapidly increases with the increase of the rotating speed, and then the impact effect is found. These imply that instability phenomenon occurring during the startup process. Furthermore, the total displacement of impeller is increasing and its distribution is asymmetrical along the impeller radial. Finally, the maximum displacement occurs at the impeller hub where which is near the rim between two blades, due to the centrifugal force at the rim is larger than that in other regions and the relative low impeller rigidity.

A dual grid method for the compressible two-fluid model which combines robust flux splitting methodology with high-resolution capturing of incompressible dynamics

The speed of sound in two-phase pipe flow systems is often several orders of magnitude greater than the travelling speed of hydraulic information (volume fractions). Dynamically simulating such flows requires resolution of acoustic and hydraulic waves existing at vastly different spatial and temporal scales. If simulated on the same numerical grid, the need for accuracy in hydraulic waves will necessitate an exaggerated resolution of acoustic waves. Likewise, time steps restricted by the speed of sound are small compared to the time scales active in hydraulic waves. This constitutes a waste of computational potential. The method proposed herein decouples the hydraulic and acoustic scales, greatly improving computational efficiency.The proposed dual grid method solves a four-equation compressible two-fluid model on a principal grid which robustly accounts for the pressure evolution and conserves mass and momentum. An incompressible two-equation model is at the same time solved on a finer grid, resolving the details of the hydraulic evolution. Information from both model formulations is coupled through the terms of the governing transport equations, providing consistency between the grids. Accurate and finely resolved schemes can then be employed for the incompressible two-fluid model without suffering from the time and stability restrictions otherwise enforced by acoustic waves. At the same time, the Hybrid Central-Upwind flux splitting scheme of Evje and Flåtten (2005a) allows for an explicit and numerically robust treatment of the acoustic waves without losing hydraulic accuracy.The dual grid method is tested against four dissimilar problems: A shock tube problem, the water faucet problem, a surge wave and pressure wave problem and a roll-wave case. In all problems, the proposed scheme provided significant increases in computational efficiency and accuracy as compared with a single grid arrangement.

Numerical Analysis of Oil-Water Two-Phase Flow in Pipe Systems

Numerical Analysis of Oil-Water Two-Phase Flow in Pipe Systems