Pipe Flow Model Research Articles

Effects of internal surface roughness and viscous friction on mass flow rate and conductive heat transfer across a pipe element: Simulink Approach

The study, effects of internal surface roughness and viscous friction on mass flow rate and conductive heat transfer across a pipe element using simulink approach was successfully achieved. Block models were used to represent all the elements of pipe flow model. Pipe element was modeled to retain hydraulic diameter of 0.4 m within a length of 100 m. The shape factor and internal surface roughness were chosen to be 80 and 3e+3m, respectively. Initial temperature and pressure were set to 300k or 27ºC and 1 atm. turbulent regime Nusselt number correlation coefficients were 0.023, 0.8, 0.33, 0, and 0. The mass flow rate from the reservoir had initial value of 0.6 kg/s and signal block was adjusted to 1, 6, 5 for slope, start and maximum respectively. With Ode15s solver, simulation was allowed to run for 15seconds. System model mass flow rate, conductive heat transfer and temperature difference were found to be 0.6kg/s (same with initial value), 5.0346J/s and -80K or 193ºC within 15seconds of simulation. Findings depicted the effects of internal surface roughness and viscous friction on mass flow rate and conductive heat transfer. Also, simulation was run with the shape factor and internal surface roughness chosen to be 64 and 1.5e-5m, respectively. Under viscous friction influence, initial temperature and pressure were set to 298k or 25ºC and 1 atm. turbulent regime Nusselt number correlation coefficients were 0.023, 0.8, 0.33, 0, and 0. The mass flow rate from the reservoir had initial value of 0.6 kg/s. Results also showed that the system model mass flow rate, conductive heat transfer and temperature difference were found to be 0.058kg/s, -275J/s and 100K or -173ºC within 15seconds of simulation. Hence, increasing value of internal surface roughness increases conductive heat transfer at a constant mass flow rate of fluid and increasing value of viscous friction, decreases mass flow rate of fluid as well as conductive heat transfer across the pipe wall.

Wax deposition modeling in oil-water stratified pipe flow

Wax deposition in oil-water stratified flow is commonly encountered onshore and offshore oil production pipe systems, and typically reduces transportation capacity of oil. The accurate predicted model of wax deposition has becomes an indispensable approach to design effective remediation strategies. However, a reliable mechanistic model for wax deposition prediction in oil-water two-phase stratified pipe flow is lacking to validate the deposition process. In this work, a three-dimensional (axial, radial, and angular) robust wax deposit model for oil-water stratified circular pipe flow was developed. The model of formation of a gel deposit based on the first principles of rheology was developed, associated with the results obtained from hydrodynamics and heat/mass transfer simulations. The predictions for wax deposition are found to compare satisfactorily with experimental data with two different oils for single phase and four different water cuts for oil-water stratified pipe flow. It can be seen from the wax gelation mechanism that an increase in water cut can help to reduce the wall/oil-deposit interface shear stress, thereby leading to an increase in the degree of gelation as well as the deposit rate. Furthermore, a local deposit analysis in the circumferential direction was conducted, for water cut 75% and total flow rate 5 m 3 /h, which provided insights to understand that the thickness on pipe wall was roughly uniformly distributed locates near the top of the pipe and the nearer the position gets close to two points, where the oil-water interface contacts the inner wall, the deposition thickness quickly dropped to 0. It was attributed to the fact that a roughly uniformly thickness far away from the oil-water interface contact the inner wall resulted in the slowly changes temperature along the circumferential pipe wall wetted by oil.

Improved Modeling of Flows in Sewer Pipes with a Novel, Well-Balanced MUSCL Scheme

Improved Modeling of Flows in Sewer Pipes with a Novel, Well-Balanced MUSCL Scheme

Design modification of the existing cooling water system of Marsyangdi hydropower station using pipe flow modeling software

Marsyangdi Hydropower Station has adopted the Open Loop Cooling System (also called Once through Cooling System) in which the cooling water extracted from Penstock or the draft tube is circulated throughout the cooling system and discharged back to the draft tube. The water of the Marsyangdi River is muddy and sediment-rich in the rainy season, which causes the choking of tubes of the primary heat exchangers reducing the cooling efficiency and even leading to leakages in the tubes due to erosion. Cleaning and maintenance of the tubes are impossible without dismantling the primary heat exchangers from the Unit assembly. Hence, hours of machine shutdown is required to replace them with new or cleaned one. A Close Loop Cooling System has been modeled in the Software, "AFT Fathom," to overcome the issue in the Existing Cooling System. The modified model was run to observe the performance of the modified system at different river water temperatures and increased heat duty in all the heat exchangers. Further, the System Curve was considering the effect of the increase in surface roughness of pipelines due to aging. The performance capacity of the modified system was justified considering the obtained results from the simulations.

Numerical Simulations of Liquid-Solid Flows in A Vertical Pipe by MPS-DEM Coupling Method

In the process of deep-sea mining, the liquid-solid flows in the vertical transportation pipeline are very complex. In the present work, an in-house solver MPSDEM-SJTU based on the improved MPS and DEM is developed for the simulation of hydraulic conveying. Firstly, three examples including the multilayer cylinder collapse, the Poiseuille flow and two-phase dam-break are used to validate the precision of the DEM model, the pipe flow model and MPS-DEM coupling model, respectively. Then, the hydraulic conveying with coarse particles in a vertical pipe is simulated. The solid particle distribution is presented and investigated in detail. Finally, the coupling method is successfully applied for the simulation of the liquid-solid flows in a vertical pipe with rotating blades, which shows the stability of the solver under rotating boundary conditions. This fully Lagrangian model is expected to be a new approach for analyzing hydraulic conveying.

Generating a physics-based quantitatively-accurate model of an electrically-heated Rijke tube with Bayesian inference

We perform 7000 experiments at 175 stable operating points on an electrically-heated Rijke tube. We pulse the flow and measure the acoustic response with eight probe microphones distributed along its length. We assimilate the experimental data with Bayesian inference by specifying candidate models and calculating their optimal parameters given prior assumptions and the data. We model the long timescale behaviour with a 1D pipe flow model driven by natural convection into which we assimilate data with an Ensemble Kalman filter. We model the short timescale behaviour with several 1D thermoacoustic network models and assimilate data by minimizing the negative log posterior likelihood of the parameters of each model, given the data. For each candidate model we calculate the uncertainties in its parameters and calculate its marginal likelihood (i.e. the evidence for that model given the data) using Laplace’s method combined with first and second order adjoint methods. We rank each model by its marginal likelihood and select the best model for each component of the system. We show that this process generates a model that is physically-interpretable, as small as possible, and quantitatively accurate across the entire operating regime. We show that, once the model has been selected, it can be trained on little data and can extrapolate successfully beyond the training set. Matlab code is provided so that the reader can experiment with their own models.

The Mathematical Model of Integrated Coupling of Gas Reservoir-Wellbore-Choke in Sulige Gas Field, China

The tight sandstone gas has huge objective reserves in China and great potential for development. The Sulige gas field is the largest tight sandstone gas field in China. To prevent hydrates and reduce surface pipeline pressure, downhole throttling technology has been widely used in the Sulige gas field, China. Since gas wells in the Sulige gas field are prone to liquid accumulation during production, the installation of downhole chokes makes the liquid accumulation phenomenon of gas wells more complicated, and traditional methods are difficult to simulate and predict production performance. In order to solve this problem, based on the establishment of the gas reservoir seepage model, the wellbore pipe flow model, and the choke nozzle flow model, the gas reservoir-wellbore-choke integrated coupling mathematical model and its solution method were proposed. The case calculation of the choke well in the Sulige gas field is presented. The research results show that the new integrated coupled mathematical model can fully reflect the impact of choke installation and fishing on fluid accumulation and is effectively used for the production performance simulation of choke wells in the Sulige gas field.

A New Method for Piping Risk Evaluation on Unconfined Aquifers under Dewatering of Deep Foundation Pits

This paper presents a new method to evaluate the piping risk of unconfined sandy cobble aquifers during the dewatering of deep foundation pits. Firstly, the possibility of piping is judged according to the particle size distribution and pore diameter of the sandy cobble stratum. Secondly, the critical hydraulic gradients of particles with different sizes are calculated according to the pipe flow model. Thirdly, the hydraulic gradient around the foundation pit during the dewatering process is calculated by numerical method. Then, combined with the distribution of hydraulic gradient around the foundation pit and the critical hydraulic gradients of particles with different sizes, the range of moveable particles with different sizes in the surrounding stratum is evaluated. Finally, according to the sandy cobble aquifers conditions and the influence of particle movement on the stratum, the level of piping risk is determined. This method was successfully applied to evaluate the piping risk of Tawan Station in Luoyang Metro Line No.1, and according to the risk evaluation the pensile curtain was recommended for the retaining structure in this case. From the satisfied applications, this method is a reference for the evaluation of piping risk and selection of retaining structure when considering the impact of the dewatering in deep foundation pit with unconfined aquifers on the surrounding stratum.

A Novel Surge Damping Method for Hydraulic Transients with Operating Pump Using an Optimized Valve Control Strategy

Hydraulic transients may pose a critical threat to process operation due to devastating surge waves. This paper investigates hydraulic surge and damping control associated with pipe flow modeling and valve optimization. A one-dimensional transient model was developed using the modified instantaneous accelerations-based (IAB) model, considering energy dissipation, referred to as the compression–expansion effect, which was then solved by the Method of Characteristics (MOC). Analogous to solving valve operation by means of the traveling salesman problem (TSP), a novel surge damping strategy was proposed by applying an improved artificial fish swarm algorithm (AFSA). After validating the unsteady model and the optimization algorithm, wave surge damping effectiveness was evaluated on the basis of case studies in different pump running scenarios. The results showed that the proposed nonlinear optimized control method was able to reduce surge amplitude by 9.3% and 11.4% in pipe systems with and without running centrifugal pump, respectively, and was able to achieve a 34% time margin or a maximal 75.2% surge reduction in the case of using an positive displacement pump. The optimized nonlinear valve closure presents different shapes in fast closing and slow closing situations. The strategy proposed in the present study is beneficial for guiding valve real-time control, as well as providing a reference for valve design for the purpose of wave surge protection.

Numerical Simulation of Choke Size Optimization in a Shale Gas Well

To optimize the flowback system of shale gas horizontal wells after fracturing and to maximize the production capacity of gas wells, pipe flow and flowback models of shale gas multistage fractured horizontal wells were established based on the actual geological engineering conditions and the fracture parameters inverted from automatic history matching by combining experimental and numerical simulation methods. Optimization of the maximum choke size, reasonable opening choke size, replacement stages, and choke replacement frequency were studied. The research results show that the larger the production pressure difference in the early period, the higher the initial gas production rate but the easier the migration of proppant and the higher its stress sensitivity, which increases the permeability damage and weakens the reservoir recovery ability. Thus, the fracture conductivity gets worse and the later gas production rate and liquid production rate get lower. Specifically, the research results mainly include the following: (1) The laboratory experiment results show that the effective stress exceeding 19 MPa caused a proppant breakage and embedding phenomenon, leading to difficult recovery from reservoir permeability damage. Therefore, the maximum production pressure difference corresponding to the single-well maximum choke size shall not exceed 19 MPa. (2) A small opening choke size of a shale gas well is superior to the large one, and according to the numerical simulation, the choke size of 3 mm is recommended to be the reasonable opening choke size. (3) Under the drainage and production systems of replacing the choke size from small to large, the simulation results indicate that the production effect under the drainage and production systems of increasing the choke size incrementally stage by stage with an increase in amplitude of 1 mm is much better than that under the drainage and production systems of increasing the choke size by skipping the stage. (4) When the choke size is increased stage by stage, the research results indicate that the optimal duration of each grade of choke size is 3 days, beyond which, the increase of EUR will not be remarkable. The application of the proposed fine choke system research method in Well-CN001 indicates that the influence amplitude of the reasonable choke system on the daily gas production of Well-CN001 is in the range of 65.96%–121.67% and that on single-well EUR increase amplitude in 20 years is in the range of 5.2%–22.27%. The research results provide technical support for understanding the influence of different choke systems on the productivity of shale gas wells and optimizing the reasonable drainage and production systems of shale gas wells after fracturing.

Numeričke simulacije hidrauličkih tranzijenata u crpnoj hidroelektrani Fužine

Hydraulic transients in pumping hydroelectric power plant (PHPP) Fužine were simulated with 1D unsteady pipe flow model. High accuracy of the model was accomplished with the use of nonconservative formulation of unsteady pipe flow model incorporating unsteady friction model and second order flux limited numerical scheme. Simulation results show very good agreement between the computed and measured piezometric heads, both in amplitude and frequency of the oscillation.

Smoothed Particle Hydrodynamics with Unsteady Friction Model for Water Hammer Pipe Flow

Smoothed Particle Hydrodynamics with Unsteady Friction Model for Water Hammer Pipe Flow

Energy Efficient Hop-by-Hop Retransmission and Congestion Mitigation of an Optimum Routing and Clustering Protocol for WSNs

In the past few decades, wireless sensor networks, which take a growing number of applications in the surroundings further than the human reach, have risen in popularity. Various routing pseudo codes have been suggested for network optimization, emphasizing energy efficiency, network longevity, and clustering processes. To the existing load balancing energy-efficient sleep awake, aware smart sensor network routing protocol, the modified load-balancing efficient-energy sleep active alert smart routing system for wireless sensor networks is presented in this paper, which takes network homogeneity into account. The modified protocol is the optimum clustering and routing protocol in wireless sensor networks (OCRSN), which simulates an enhanced network coupled node pair model. Our suggested modified approach studies and enhances factors such as network stability, network lifetime, and cluster monitor mechanism choice. The significance of typically combining sensor endpoints is applied to maximize energy efficiency. The proposed protocol significantly improved network parameters in simulations, showing that it could be a valuable option for WSNs. In wireless sensor networks, in addition to memory considerations and dependable transportation, this paper presents a hop-by-hop re-transmission strategy and congestion mitigation, which is the major contribution of this paper. It is a very consistent method based on a pipe flow model. After performing additional optimized overhead to improve the network lifespan of wireless sensors networks, the current algorithm can be paralleled to the less energy adaptive clustering hierarchy protocol. The optimal clustering in multipath and multihop technique intends to minimize the energy consumption highlighted for a circular area enclosed by a sink by replacing one-hop communication with efficient multihop communication. The optimum quantity of clusters is determined, and the energy consumption is reduced by splitting the network into clusters of nearly equal size. The obtained simulation results will demonstrate the increase in the network lifetime compared to previous clustering strategies such as Low Energy Adaptive Clustering Hierarchy.

The Grease Worker and Its Applicability to Study Mechanical Aging of Lubricating Greases for Rolling Bearings

Mechanical degradation by shear is one of the mechanisms that limits the life-time of lubricating grease in a rolling bearing. It results in a change of the micro-structure of the thickener–oil system, leading to a change in bleed and consistency. The resistance to degradation can be quantified using a grease worker. In this article, a novel approach is described, where the grease worker is used to measure the rheological properties of a grease in situ, while aging the grease. Mechanical energy and pressure losses are calculated using the measured force that is required to push the plate with holes through the grease in the cylinder of the grease worker. A pipe flow model in combination with a power law rheology model are used to analytically determine the power law fluid consistency index and exponent while aging the grease. The model validity is verified using computational fluid dynamics simulations and measurements using a rheometer with plate–plate geometry.

In-situ pumping tests and numerical simulations of seepage wells in the Yellow River valley, China

Abstract Seepage wells that can convert surface water into groundwater are often constructed near river valleys to obtain more water and lead to smaller drawdown compared with traditional wells. Seepage wells have been widely used, whilst the groundwater and river-level variations caused by seepage wells are still unclear, and numerical models are rarely verified due to the lack of in-situ observational data, which may lead to results that are quite different from the actual conditions. To address those limitations, a large-scale pumping test was carried out near the Yellow River valley in China and a coupled seepage–pipe flow model was established using the exchange yield between the aquifer and pipe as the coupling key in this research. The coupled model was evaluated with in-situ measurement. The field observation showed that both the river and groundwater had a positive response to the pumping of the seepage wells. The simulation results indicated that our model can well estimate the pumping rate and drawdown with root-mean-square deviations of 158.235 m3/d and 0.766 m, respectively. Further, it is also found that the groundwater showed the obvious characteristics of three-dimensional flow under the influence of seepage wells and the maximum drawdown should be less than 15 m to ensure exploitation efficiency. These findings provide important information that can guide the design and construction of seepage wells to improve the rational exploitation of groundwater.

A comprehensive model for simulating supercritical water flow in a vertical heavy oil well with parallel double tubes

At present, there is no research on parallel double pipe injection of supercritical water. The research on the process of SAGD supercritical water injection is insufficient. This paper first established a mathematical model of parallel twin-pipe injection supercritical water pipe flow. On this basis, the SAGD supercritical water injection development numerical model was established using numerical simulation software, and the variation characteristics of the temperature field, crude oil viscosity field and oil saturation field in the reservoir were analyzed. The main conclusions obtained are as follows: (a) the high temperature area first developed from the lower part of the vertical well. (b) After 150 days, the temperature in the reservoir gradually increased. (c) When the injection time reaches 210 days, the viscosity of the heavy oil between the vertical wells has been sufficiently reduced. (d) Condensed water occupies a lot of pore space, resulting in a decrease in oil saturation.

Rheological behavior of alcohol-resistant foam concentrates and its impact on pipe flows

The rheological behavior of alcohol-resistant foam concentrates and its impact on pipe flows play critical roles in the scientific design of foam fire-extinguishing systems. In the present work, the equilibrium flow curve, yield stress and thixotropy of alcohol-resistant foam concentrates are experimentally studied, and the effects of the yield stress and thixotropy on pipe flows are theoretically analyzed. The results show that the equilibrium flow curves of alcohol-resistant foam concentrates conform to the Herschel-Bulkley model, and the thixotropic behavior can be well represented by a structural kinetics model that we have established. Ignoring the yield stress or thixotropy of alcohol-resistant foam concentrates will result in an overoptimistic calculated pressure loss in pipe flows. When the thixotropy of alcohol-resistant foam concentrates is incorporated in pipe flow modeling, the nominal shear rate at the pipe wall is no longer a fixed value but gradually increases with time until it reaches a steady-state value. The steady-state value depends on the equilibrium flow curve of the alcohol-resistant foam concentrate and the shear stress at the pipe wall. Based on the initial structural strength and equilibrium flow curve of alcohol-resistant foam concentrates, a method for estimating the design pressure loss in pipe flows is proposed.

Experimental study of a single elongated bubble in liquid in under 10-degree upwardly inclined pipes

Two phase flow is of great interest in chemical and petroleum industries, and multiphase pipe flow models with closure relationships require experimental data for their development and validation. However, only little experimental information is available for slightly upward inclined pipes. Experimental investigations of single elongated bubble in marginally upwardly inclined pipes less than 10° have therefore been performed. Observations of the bubble drift velocity along the pipe has been highlighted. The drift velocity data presented here can contribute to improve knowledge of pipe inclination and viscosity dependency in drift velocity correlations. The new data on the bubble characteristics - shape, length, fraction and drift velocity may also provide useful information for the development and validation of numerical models. The measured drift velocity data have therefore been compared with some recently developed bubble velocity correlations.

Sensitivity Analysis of a Groundwater Infiltration Model and Sea-Level Rise Applications for Coastal Sewers

Groundwater elevations in coastal cities will be affected by climate-change-induced sea level rise (SLR) and wastewater collection systems will experience increased groundwater infiltration (GWI) due to greater submergence of sewer pipes. Commercial sewer hydraulics models consider GWI to be a constant quantity estimated via a low-flow monitoring campaign and are incapable of predicting future flows due to changes in GW elevations. A global sensitivity analyses conducted for a two-dimensional GWI pipe flow model found the most important input parameters are groundwater head and surrounding soil hydraulic conductivity. Two case studies were conducted considering a range of pipe defect severity to estimate increases in GWI associated with predictions of future SLR. The findings are that SLR will begin to have noticeable impacts in terms of increased average dry weather flow (ADWF) as soon as 2030 (3–10%) and will increase dramatically in the future (10–29% by 2050, and 50% or more by 2100). Daily and seasonal tide ranges affect the normal diurnal flow variations by between 3% and 10%. The estimation methodology and case studies described here illustrate the coming future importance of SLR effects on GWI in coastal collection systems that should be included in facilities planning and design.

Effect of hydraulic gradient on the permeability characteristics of foam-conditioned sand for mechanized tunnelling

Low permeable soil is important for stabilising the tunnel face during mechanized tunnelling in sandy soils under water level. Foam is one of the most common conditioning agents to achieve low permeability of the excavated soil. This study investigates the effect of hydraulic gradient on the permeability characteristics of foam-conditioned sand in various conditioning states, according to a series of experimental permeability tests under different hydraulic gradients. With an increase in the hydraulic gradient, the duration of the initial stable stage of the permeability coefficient either gradually decreases or completely disappears. In the rapid growth period, the permeability coefficient increases greatly. The pipe flow model is introduced to analyse time-dependent permeability characteristics of conditioned sand under different hydraulic gradients. The results shows that as hydraulic gradient increases, the time required for water to penetrate throughout the foam plugs decreases and the enlargement rate of the assumed pipe diameter increases in the rapid growth period. Finally, changes in the conditioning parameters for EPB shield tunnelling and EPB pipe-jacking under the influence of hydraulic gradient are discussed. With an increase in the hydraulic gradient, the range of conditioning parameters of the soil that satisfies the shield tunnelling permeability requirement gradually narrows and moves towards a low water content (w) and high foam injection ratio (FIR). The results show that an increase in the hydraulic gradient poses a more serious challenge for foam-dominant soil conditioning during mechanized tunnelling.