Hydraulic Pipe Research Articles

Chlorination contributes to multi-antibiotic resistance in a pilot-scale water distribution system

Abstract The generation and dissemination of antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs) in the environment has become a critical risk to human health. This study is based on a pilot-scale simulated water distribution system to understand the effects of chlorine disinfection treatment (without free chlorine) on ARB and ARGs in biofilms. The hydraulic parameters and pipe materials of the system were simulated based on a drinking water system. The results of the colony counts showed that bacterial multi-antibiotic resistance could be enhanced 13-fold in the biofilms of the pipeline. The use of high-throughput qPCR (HT-qPCR) indicated that the total relative abundance of ARGs in biofilm samples increased significantly (p < 0.05), while the diversity of bacteria was shown to be reduced via taxonomic analysis of the V3–V4 region of 16S rRNA. The prominent types of ARGs were conferred resistance by aminoglycoside and β-lactam after the chlorine disinfection treatment, and antibiotic deactivation was the main mechanism. Phyla Proteobacteria had the highest abundance in both treatment and control groups but decreased from 70.81% (initial biofilm sample) to 26.09% (the sixth-month biofilm sample) in the treatment groups. The results show that the chlorine disinfection plays a role in the risk of development of bacterial antibiotic resistance in pipe networks owing to bacteria in biofilms. This study was the first to investigate the contribution of chlorination without free chlorine to the bacterial community shift and resistome alteration in biofilms at a pilot-test level.

Investigation of dynamic pressure fluctuations in closed hydraulic circuits as a function of centrifugal pump speed gradients

Electrical consumers, such as pumps, contribute towards the stable operation of the electrical power grid due to active and reactive power consumption. If the consumers are indirectly connected to the grid via power electronic converters, the positive contribution is reduced or non-existent. Consequently, the ability to compensate imbalances within the power grid is greatly reduced. A research project founded by the European Union is focusing on investigations to utilize power converter technology of pump drives for grid stabilization. But in order to stabilize the fluctuating power grid frequency rapid adjustments of the pump speed are required, which can cause major troubles in the hydraulic system. For instance, rapid changes in pump speed are causing the emission of hydro acoustic pressure waves into the pipe system, which are exciting the structure of the hydraulic system and lead to undesirable vibrations and noise emissions. Most critical is the direct excitation of natural frequencies in the entire piping system based on the inherent pressure fluctuations caused by transient fluid flow and pump speed changes. Converter control for grid-adaptive speed adjustment is only possible as long as there is no significant increase in dynamic pressure fluctuations in the whole hydraulic system. For this purpose, a research pump is operated with different rotational speed gradients in a closed hydraulic circuit. Dynamic pressure sensors were used to record the resulting pressure fluctuations at various locations of the hydraulic system. Additionally, an outlook towards an active reduction of the dynamic pressure fluctuations by means of a specially developed hydrodynamic actuator is given. These results are an initial step but of particular interest towards the knowledge of permissible grid adaptive speed control regimes, which can be applied to a pump in a hydraulic piping system.

Numerical and simulation analysis comparison of hydraulic network problem base on higher-order efficiency approach

The hydraulic network study is a real-life engineering problem extensively base on applied and computational approaches. Several numerical schemes are tested for defining of hydraulic pipe networks solution, such as, Hardy Cross Method, Newton Method and Modified Newton method are presented in this paper. Convergence analysis are also compared and deliberated by using a multi-loop hydraulic network. As a novelty, a Modified Newton method tabulated data, graphical results and comparisons are presented with the Hardy-Cross method and 2nd -order Newton–Raphson method. On other hand, we applied Ancient Chinese Algorithm and its modification for value of friction factor by using Colebrook-White relation. Numerical efficiency and comparison of Ancient Chinese Algorithm with Newton method and Bubbfil Algorithm I and Algorthm-II is presented and discussed quantitative approach to demonstrate the feasible result.

Bulk and pipe wall chlorine degradation kinetics in three water distribution systems

ABSTRACT This paper presents a methodology to estimate free residual chlorine concentrations (FRCC) in full-scale water distribution system (WDS) using different degradation kinetics according to pipe material, age and diameter. Intensive field sampling campaigns and laboratory-scale tests were carried out to estimate total and bulk volume FRCC in three WDS. Bulk kinetic constants were estimated for water temperatures typical of different seasons in the Quebec City area (Canada). With field-measured FRCC at all sampling sites and an estimation of travel times through the use of a hydraulic model, total, bulk and pipe wall kinetic constants were obtained with ranges of 10.2 to 130.4, 4.1 to 43.8 and 8.5 to 114.9 10−3/h, respectively. Pipe wall kinetics tend to dominate the total degradation process for older grey and ductile cast-iron pipes, followed by newer ductile iron pipes and then PVC and pre-stressed concrete pipes (mostly installed from 1990). The developed methodology and results will be useful to improve the prediction of FRCC through hydraulic and water quality modelling.

Simulation of thermal perturbation in groundwater caused by Borehole Heat Exchangers using an adapted CLN package of MODFLOW-USG

Simulating heat transfer in an aquifer with one or more vertical Borehole Heat Exchangers (BHEs) of a Ground Source Heat Pump (GSHP) system by means of a finite difference code is difficult because of the square or rectangular geometry grid and computational times thus limiting the types of evaluations that can be performed. The aim of this work is to explore through MODFLOW-USG code (public domain software) a different approach towards simulating a borefield that would be more efficient computationally, in order to enable simulations of larger domains with multiple BHEs. The Connected Linear Network (CLN) package, introduced in MODFLOW-USG, generally simulates 1-D linear computational cells in a 3-D grid, such as hydraulic pipes in subsoil, but for the first time has been adapted to reproduce vertical closed loop U-pipe of a BHE. Therefore, this work evaluates the MODFLOW-USG and CLN package capability to reproduce the yearly operation of one or more BHEs in an aquifer as a simpler and faster approach compared to a very fine finite-difference discretization. Once the CLN package was adapted, a sensitivity analysis on the grid size refinement was performed. There were several findings from this work. The results of the different numerical models were in good agreement with an already validated model, in terms of exchanged energies and aquifer thermal perturbation. Same analyses were carried out for different groundwater flow velocities and it was confirmed that the exchanged energy by a BHE increases with the groundwater flow velocity in accordance with literature studies. At last, a borefield of 7 BHEs was implemented in a numerical model in a more expeditious and efficient way and without any computational effort.

Analysis of joint operation of air-cooling system and peak cooling device in summer

In view of the insufficient condensation capacity of air-cooling island in the summer, this paper proposed joint operation of air-cooling unit and peak cooling device to reduce the turbine back pressure. A joint operation cooling system can be formed by building a separate condenser room, retrofitting hydraulic pipe and adding a peak heat exchanger device. The influence factors on the air-cooling island condensation capacity are analyzed by establishing heat transfer calculation simulation model of the air-cooled condensers (ACCs) and the peak heat exchanger. The simulation results show that the main factor affecting the condensation capacity of air-cooling condenser and peak heat exchanger is ambient temperature, and the condensation capacity decreases significantly with increasing the ambient temperature. When it is hot in summer, the condensation capacity of original air-cooling system can not meet the demand, therefore, a joint operation scheme is determined for temperature above 10 °C: give priority to air-cooling system, peak cooling device as supplement when air-cooling system has insufficient condensation capacity. At the same time, the simulation results show that the joint operation of air-cooling system and peak cooling device can effectively reduce turbine back pressure. In actual power plant, joint operation of air-cooling system and peak cooling device was used at 25 °C and 30 °C under 330 MW, and the turbine back pressure decreased by 6.7 kPa and 6.1 kPa, respectively. The joint operation system has economic benefits and the investment payback period is 4 years.

Low-cost Gent type sampler constructed for urban atmospheric aerosol sampling.

The importance of studying the atmospheric pollution due to its effects on human health and other ecosystems, the inexistence of national production of equipment for air sample collection, and the high cost of the imported equipment (especially in developing countries) led the authors of the present work to construct a low-cost Gent type sampler. The construction of the sampler was carried out by combining low-cost materials with good mechanical strength (such as nylon 6.0), hydraulic piping PVC, and the use of a 3D printer. The innovation of the present work is the employment of a 3D printer using ABS polymer to create the grids that cannot be machined. In addition to the sampler, the system is composed of a vacuum pump, a gas meter, and a rotameter. The total cost of the sampling system amounted at about 1200 USD, and the cost of the manufactured Gent type sampler did not reach 100 USD. The results obtained while using this set for sampling atmospheric aerosol for a period of 11months were compared with the mass concentration of PM10 obtained from the official environmental company, CETESB of São Paulo State, Brazil, showing good correlation with those from CETESB-which confirmed its effectiveness and suitability for use. The low cost, easy operation, and versatility of the built Gent type sampler enable its use for scientific and academic purposes. The equipment can be useful in environmental monitoring networks, in low-income regions, and as an instrument for environmental education used in universities.

Investigation of the influence of dimensions and material of the pipes on the water hammer effect in microbial fuel cells wastewater treatment plants

Water hammer is a transient flow phenomenon generated in a pipeline, when there is a sudden change in velocity, due to the closing of valves. This is particularly important for plants based on complicated hydraulic circuits and piping, to avoid malfunctioning in the urban sewer network. In this study, the effect of a set of parameters: length, diameter and material of the pipe with and without surge tank on transient pressure is investigated by using the software HAMMER V8i. The results show that the maximum Transient Pressure is strongly influenced by an increase of 41.24% of the pipe diameter when the Surge Tank is not present. When the surge tank is inserted the transient pressure increases only of about 12.2%. So the surge tank can have a positive influence on the entire network. Moreover, the increase in the length will lead to a decrease in the Total Pressure of about 10% without Surge Tank and of 8.62% with Surge Tank. While the change in the roughness coefficient of the material used for the pipes will cause a decrease in the Total Pressure of about 42.6%, without Surge tank, and of 12.2% with Surge Tank.

Experimental investigation of critical suction velocity of coarse solid particles in hydraulic collecting

Hydraulic collecting and pipe transportation are regarded as an efficient way for exploiting submarine mineral resources such as the manganese nodules and ores. Coarse particles on the surface of the sea bed are sucked by a pipe during the mining and crushing of the mineral. In this paper, the critical suction velocity for lifting the coarse particles is investigated through a series of laboratory experiments, and the solid–liquid two-phase flow characteristics are obtained. Based on the dimensional analysis, the geometric similarity is found between actual exploitation process and model test with the same kind of material. The controlling dimensionless parameters such as the hydraulic collecting number, the relative coarse particle diameter, the relative suction height, and the density ratio are deduced and discussed. The results show that the logarithm in base 10 of the hydraulic collecting number increases approximately linearly with the increase of the relative suction height, while decreases with the relative particle diameter. A fitting formula for predicting the critical suction velocity is presented according to the experimental results.

A Model-Driven Scheme to Compensate the Strain-Based Non-Intrusive Dynamic Pressure Measurement for Hydraulic Pipe

Strain-based non-intrusive approaches for measuring the pressure of pipes have attracted widespread attention due to their great convenience and ability to avoid destroying the integrity of structures. However, the mentioned method usually measures the dynamic pressure based only on the static strain-pressure sensitivity coefficients (SSSCs) instead of the dynamic strain-pressure sensitivity coefficients (DSSCs) due to its complicated calibration, which will inevitably affect the accuracy significantly. To address this issue, a model-driven scheme with dual stages is proposed in the present study to compensate the dynamic pressure measurement. The DSSCs are analytically derived for the first time from the axial governing equations of the pipe, considering the general boundary conditions for the thin-wall pipe and thick-wall pipe simultaneously. In the first stage, the physical parameters involved in the DSSCs are calibrated by minimizing the residual of the experimental results and the theoretical counterparts. In the second stage, the DSSCs calculated from the calibrated analytical model are utilized to compensate the dynamic pressure based on the relationship between the DSSCs and the SSSCs. The proposed method is applied to an industrial hydraulic pipe system, and the experimental results show that the relative error is reduced greatly after the compensation is implemented, demonstrating the validity of the proposed compensation method.

Mechanical analysis of carbon fiber reinforced polymer composite using CATIAV5 R14

High performance plastics and composites have become the substitutes for traditional materials, showing improved performance now-a-days. As compared to conventional materials, polymer matrix composites (PMCs) are well- known for their high strength and stiffness at a lower weight. The aim of this paper is to provide information on mechanical analysis of hydraulic flow pipe created utilizing carbon reinforced composites. The effects of test parameters as deformation, equivalent (von-mises) stress and principal stress tensor are discussed. The 3D model of composite cylindrical flow pipe using carbon fiber reinforced with resin epoxy and polypropylene designed, simulated and analysed using CATIA V5 R14 2017workbench. It has been found that carbon fibre reinforced with resin epoxy has shown the total deformation of 2.4788e-013 m which is lesser as compared to Polypropylene having total deformation of 4.7321e-014. Carbon fiber reinforced with resin epoxy composite sample has higher life cycle due to its less total deformation and high stress bearing capacity.

Multiaxial stress mapping and fatigue failure prediction of aircraft hydraulic pipes

Frequent fatigue failures of aircraft hydraulic pipes were caused by a stress concentration site in the form of a circumferential groove at the constrained pipe ends. The grooves were formed as a result of the crimping of a metallic sleeve on the pipes. Internal hydraulic pressure fluctuations during aircraft flight resulted in multiaxial and alternating stresses at the constrained (fractured) end. The complete stress state was found using FEM ‘Frame 3D’ MATLAB® code and analytical stress concentration factors. The calculated stresses not only mapped well with the fractured patterns of a failed pipe but also correlated to the computational stress analysis performed separately in an FEA software. The stress calculations were further utilised for fatigue life estimation of the pipe with and without the presence of circumferential groove. The load spectrum of the pipe was developed using 73 flying hours data of hydraulic fluctuations and converting those into stresses. Various stress amplitudes and load ratios were segregated from the cyclic stresses using the rainflow counting method. A linear constant lifeline diagram and Miner’s rule of damage accumulation were used for fatigue life estimation. A significant decrease (from 12,500 to 165 flying hours) in the service life of the pipe was predicted due to the presence of the stress concentration. The predictions matched well with the observed failure trend (life) of the pipe.

Burst Detection in Water Distribution Systems: The Issue of Dataset Collection

Developing data-driven models for bursts detection is currently a demanding challenge for efficient and sustainable management of water supply systems. The main limit in the progress of these models lies in the large amount of accurate data required. The aim is to present a methodology for the generation of reliable data, which are fundamental to train anomaly detection models and set alarms. Thus, the results of the proposed methodology is to provide suitable water consumption data. The presented procedure consists of stochastic modelling of water request and hydraulic pipes bursts simulation to yield suitable synthetic time series of flow rates, for instance, inlet flows of district metered areas and small water supply systems. The water request is obtained through the superimposition of different components, such as the daily, the weekly, and the yearly trends jointly with a random normal distributed component based on the consumption mean and variance, and the number of users aggregation. The resulting request is implemented into the hydraulic model of the distribution system, also embedding background leaks and bursts using a pressure-driven approach with both concentrated and distributed demand schemes. This work seeks to close the gap in the field of synthetic generation of drinking water consumption data, by establishing a proper dedicated methodology that aims to support future water smart grids.

An Efficient Framework for Multi-Objective Risk-Informed Decision Support Systems for Drainage Rehabilitation

Combining multiple modules into one framework is a key step in modelling a complex system. In this study, rather than focusing on modifying a specific model, we studied the performance of different calculation structures in a multi-objective optimization framework. The Hydraulic and Risk Combined Model (HRCM) combines hydraulic performance and pipe breaking risk in a drainage system to provide optimal rehabilitation strategies. We evaluated different framework structures for the HRCM model. The results showed that the conventional framework structure used in engineering optimization research, which includes (1) constraint functions; (2) objective functions; and (3) multi-objective optimization, is inefficient for drainage rehabilitation problem. It was shown that the conventional framework can be significantly improved in terms of calculation speed and cost-effectiveness by removing the constraint function and adding more objective functions. The results indicated that the model performance improved remarkably, while the calculation speed was not changed substantially. In addition, we found that the mixed-integer optimization can decrease the optimization performance compared to using continuous variables and adding a post-processing module at the last stage to remove the unsatisfying results. This study (i) highlights the importance of the framework structure inefficiently solving engineering problems, and (ii) provides a simplified efficient framework for engineering optimization problems.

Research on fluid flow mechanism of fracture-cave carbonate reservoirs based on fluid mechanics

ABSTRACT Facture-cave carbonate reservoir has not formed mature development theory and method up to now, and the development is world-class difficult problems, which are caused by that it is not clear to understand the particularity of reservoir characteristics and fluid flow mechanism. Because karst caves are the dominant reservoir space and production contributor, porous flow mechanics is not applicable. Reservoir body belongs to neither porous media nor continuum as a whole, hence fluid flow belongs to the research category of fluid mechanics. Contrary to widely adopted coupling method, this paper will focus on the fluid flow mechanism by only applying the theory of fluid mechanics and ignoring porous flow on the basis of analyzing the particularity of reservoir characteristics. Both capillary pores in carbonate matrix and slender dissolved cavities can be regarded as hydraulic long pipe, and fluid flow conforms to pipe flow law. Fluid flow in fracture belongs to parallel plate clearance differential pressure flow, which is similar to pipe flow. Fluid is static under gravity and fluid flow conforms to hydrostatics law in approximately equiaxed karst caves, and fluid flow out of karst cave is orifice outflow. Porous flow in reservoirs is unified with pipe flow. The essence of porous flow is the macro performance of pipe flow in countless capillary pores, which manifests as Darcy’s law under laminar condition. Porous flow in carbonate matrix can be completely ignored because it is extremely difficult to occur and the effect is very tiny. In dissolved-cavity reservoir body of millimeter scale, fluid flow is mainly slight pipe flow and gravity effect is significant, which leads to tiny production pressure differential and pressure drop funnel. In karst-cave reservoir body of meter scale, there is no fluid flow nor pressure drop in horizontal direction and the displacement of oil by water is piston-like displacement vertically upward in karst caves, hence pressure drop funnel does not exist at all. The production pressure differential generated by orifice outflow at the outlet of karst cave is very tiny and can be ignored. The new fluid flow mechanism based on fluid mechanics will provide theoretical basis for solving the difficult problems of developing fracture-cave carbonate reservoirs.

Stress response of the hydraulic composite pipe subjected to random vibration

In this paper, the stress response characteristics of the hydraulic composite pipe subjected to random vibrations were studied. Based on 3D-anisotropy elasticity, the motion equation of the hydraulic composite pipe was established by utilizing the Hamilton principle subjected to random vibration, and takes into account the fluid-structure interaction (FSI). The discrete analysis method of random vibration is employed to solve the random vibration under the excitation of white noise. Also, the effects of different parameters including external excitation, fluid velocity, fluid pressure and structural parameters on the stress response of composite pipe are investigated. Experimental results agreed with the simulation results, demonstrating that the analytical method could provide theoretical reference for the design, improved efficiency, and fatigue reduction of the composite pipe subjected to random vibration.

Impacts of urban development on urban water management – Limits of predictability

This study evaluates how random variations in urban development affect projections of urban water management over long time horizons, based on combined simulations of urban development and water management. The urban development was simulated based on existing procedural tools; however, novel procedures were implemented to allow the simulation of re-development in existing areas. The urban layout was parameterised based on the characteristics of existing building stock. A state-of-the-art hydraulic simulation tool was applied to simulate urban water systems. Experiments were conducted based on different degrees of random variation in the projections of urban development. These ranged from simply shuffling the sequences of urban developments foreseen in planning documents, to simulating urban growth with fixed growth rates but without zoning regulations, to simulations where both the growth rates and urban development locations were selected based on past development characteristics. Odense (a city in Denmark) was analysed using this paradigm. The impacts on the annual flow volumes, combined sewer overflows, exceedances of hydraulic pipe capacity, and surcharge volumes were evaluated. In general, the projections of the urban water management parameters were strongly affected by the random variations in the locations of urban development. In addition, most trends resulting from changing population growth rates could only be identified on spatial scales above 10 km2. Projections on longer time horizons were less affected by the random variations in urban development locations, as bounded simulation areas were considered. In conclusion, conceptual models are considered sufficient for performing combined simulations of urban development and urban water management in exploratory assessments.

Three-dimensional model of an external gear pump with an experimental evaluation of the flow ripple

A three-dimensional model of an external gear pump and a new application of an algorithm for the measurement of the unsteady flow rate in hydraulic pipes are presented. The experimental delivery flow ripple was compared with the outcomes of a simulation under different operating conditions. A comprehensive computational fluid dynamics model of the pump and of the high-pressure delivery circuit was developed in SimericsMP+®. The pump model considers the clearances, which vary according to the shaft angle, between the tip of the tooth and the inner surface of the stator, as well as between the flanks of the teeth that are in contact. The pump delivery circuit is constituted by a straight pipe with a fixed orifice at the end to generate the load. The model of the entire system was preliminarily validated in terms of delivery pressure ripple. Subsequently, the simulated flow ripple was contrasted with the instantaneous flow rate, measured by means of an innovative flow meter. It was found that the proposed flow meter is reliable in assessing the flow oscillations under the various working conditions.

In-plane dynamic response of a hydraulic pipe subjected to random vibration

PurposeTo improve the transmission efficiency and reduce the damage to pipes in the hydraulic systems of tunnel boring machine subjected to random vibration, this paper aims to propose a novel dynamic characteristic analysis method that considers random vibration.Design/methodology/approachA fluid-structure interaction motion equation of the pipe is established by using Hamilton’s principle. The finite element method and discrete analysis method of random vibration are used to construct a model of the dynamic behavior of the pipe.FindingsThe influences of fluid parameters and external excitation parameters on the dynamic characteristics of pipes are analyzed. The experimental results are found to be in good agreement with the simulation results, which demonstrates that the proposed analytical method can provide a theoretical reference for the design and selection of hydraulic pipes subjected to random vibration.Originality/valueThe proposed method can be regarded as a future calculation method for pipes subjected to random vibration, and the transmission efficiency of the pipe can be improved.

Axial Vibration Characteristics of Fluid-Structure Interaction of an Aircraft Hydraulic Pipe Based on Modified Friction Coupling Model

This paper aims at studying the axial vibration response characteristics of Fluid-Structure Interaction (FSI) vibration of aircraft hydraulic pipe when considering the friction coupling. Based on the Brunone empirical model and the Zielke weighting function, an expression of fluid shear stress of the hydraulic pipeline is presented for a wide range of Reynolds number, and the friction model of the FSI 14-equation for high-speed and high-pressure hydraulic pipeline is modified. On this basis, a left-wing hydraulic pipeline of the C919 airplane is taken as the verification object and modeled, then the FSI vibration 14-equation is solved using frequency-domain transfer matrix method in MATLAB to analyze the modal and the axial vibration characteristics of the pipeline. Ultimately, a test experiment is given and discussed by being compared with the numerical simulation results, which confirmed the correctness of the friction model and demonstrated that the analytic accuracy of axial velocity response of FSI vibration could be improved by considering the friction coupling.