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In order to reduce the possibility of structural fatigue and increase the lifetime of conveying fluid pipe, transverse vibration must be effectively eliminated. In this work, using parallel nonlinear energy sinks (NESs), a passive vibration controller is proposed to dissipate the vibration energy of the conveying fluid pipe. A high-order model of the conveying fluid pipe-parallel NESs system, in the form of partial differential equation, is derived and then converted into a quadratic form model containing the gradient information of a convex function. Combining the energy disturbance technique and first order convexity characteristic, the exponential stability of the closed-loop system is proved, which addresses the effectiveness of the proposed parallel NESs. Then, numerical simulations are given to verify the theoretical results and to illustrate the advantages of parallel NESs comparing with single NES. Finally, the reliability of the proposed approach is preliminarily verified through experiment.

Many fundamental studies have indicated that the vibration of conveying fluid pipe is more severe and complex at high subcritical fluid velocity. The control of vibration in this case, however, still remains a challenge for the general vibration absorbers. In this work, the inerter enhanced nonlinear energy sink (NES) is used to solve the severe vibration problem. The partial differential equation form model of the conveying fluid pipe-inerter enhanced NES system is derived and converted to an ordinary differential equation with an easy solution. Global stability of the conveying fluid pipe-inerter enhanced NES system is proved under the Lyapunov stability theory framework and functional analysis technique, to explain the effectiveness of the inerter enhanced NES. The influence of parameters on the conveying fluid pipe is discussed through a sensitivity analysis. The parameters of the proposed controller are optimized based on the energy functional. Finally, numerical examples are provided to verify the control effectiveness and the theoretical results, and also to show the advantages of inerter enhanced NES by comparing with the general NES.

This paper demonstrates the augmentation of nano-fluid heat transfer in circular pipe. In this experimental study, nano-fluid of Al2O3/water flow through the circular tube for different mass flow rate (60LPH, 75LPH, 90LPH) Water was used as base fluid in this experiment. Magnetic stirrer and digital ultrasonic water cleaner were used to prepare the homogeneous mixture to disperse 45 nm of Al2O3 nano particle in the base fluid pipe at a particle concentration of 0.05 per cent. Nano fluid was passed through the copper tube for different mass flow rate. Similarly, Water was also passed through the same tube for the same condition. The outcomes from the both experiment was compared with each other. It revealed that higher heat transfer was achieved by nano fluid compared to water. Rate of heat transfer was 30 percent increased by incorporating nano particles in the base fluid.

The Performance of the Shell and Tube heat exchanger is estimated by its effectiveness. The rate of Heat transfer differs by developing the temperature difference between the entity and the atmosphere, by raising the rate of heat transfer coefficient or the surface area of the entity. The initial two techniques are not monetarily attainable hence the addition of fins to the entity would improve the rate of heat transfer. Thereby, three various cases are taken into account for this study; it includes a base model (without fins) and two different profiles of fins attached to the hot fluid pipe. The surface area of the fins is the same and fitted to the hot fluid pipe so that the heat transfer increased with suitable boundary conditions, as they are examined for the best profile. Initially, the base model is analyzed with suitable boundary conditions, and the required results obtained. This process is repeated for the other two cases to define the optimum fin profile; then the optimum profile is analyzed for the better angle orientation of the fins and results collated for greater effectiveness.

Automatic detection of the presence of intravenous fluids (IVs) and measuring their drip rates are essential for intelligent health care applications. Conventionally, the drip rate is monitored manually by a gravimetric method that suffers from several drawbacks. Some smart commercial drip systems, which mostly work on the optical technique, have inaccuracy due to external light interference, temperature variation, and misalignment of a photodiode and photodetector. The main motivation of this work is to investigate the usefulness of the capacitive sensors for the noncontact detection and measurement of flow rates of IV fluids. There is no previous work on IV drop detection by the capacitive sensors. This article investigated three types of capacitive sensors, such as a cross capacitive, a semicylindrical, and a planar parallel plate to detect the presence of IV droplets in the fluid pipe nondestructively. The sensors are specially designed to fulfill the application needs, and simulated and fabricated with inexpensive double-sided copper-cladded flexible PCB substrates. Experiments are conducted with the sensors for four IV fluids typically used in hospitals to determine their response parameters, such as precision, drift, and drop rate, when the droplet passes through the inner electric field of the sensors. There is an instantaneous change in the value of capacitance due to a sudden change in the dielectric constant of a partially filled air medium. The distinctive capacitance peak enables to count the droplets, drip rate (0.4-m/s cross capacitive) with highly precise (0.036%), and drift-free readings. All the sensors can be used for the target application, but the cross capacitive sensor has single dimension accuracy.

This paper considers the stability of a conveying fluid pipe with nonlinear energy sink (NES), which is a passive vibration controller. Based on the Galerkin approximation method, the fourth-order partial differential equation (PDE) model of the conveying fluid pipe-NES system is converted into an ordinary differential equation (ODE) form. Then, based on the first order characterization of convexity and energy disturbances technique under the framework of Lyapunov stability theory, global exponential stability of the conveying fluid pipe-NES system is obtained.

Hydrocarbon escape systems can be regionally active on multi-million-year timescales. However, reconstructing the timing and evolution of repeated escape events can be challenging because their expression may overlap in time and space. In the northern Levant Basin, eastern Mediterranean, distinct fluid escape episodes from common leakage points formed discrete, cross-evaporite fluid escape pipes, which are preserved in the stratigraphic record due to the coeval Messinian salt tectonics.The pipes consistently originate at the crest of prominent sub-salt anticlines, where thinning and hydrofracturing of overlying salt permitted focused fluid flow. Sequential pipes are arranged in several kilometers-long trails that were progressively deformed due to basinward gravity-gliding of salt and its overburden. The correlation of the oldest pipes within 12 trails suggests that margin-wide fluid escape started in the Late Pliocene/Early Pleistocene, coincident with a major phase of uplift of the Levant margin. We interpret that the consequent transfer of overpressure from the deeper basin areas triggered seal failure and cross-evaporite fluid flow. We infer that other triggers, mainly associated with the Messinian Salinity Crisis and compressive tectonics, played a secondary role in the northern Levant Basin. Further phases of fluid escape are unique to each anticline and, despite a common initial cause, long-term fluid escape proceeded independently according to structure-specific characteristics, such as the local dynamics of fluid migration and anticline geometry.Whereas cross-evaporite fluid escape in the southern Levant Basin is mainly attributed to the Messinian Salinity Crisis and compaction disequilibrium, we argue that these mechanisms do not apply to the northern Levant Basin; here, fluid escape was mainly driven by the tectonic evolution of the margin. Within this context, our study shows that the causes of cross-evaporite fluid escape can vary over time, act in synergy, and have different impacts in different areas of large salt basins.

Over the years, anomaly detection of fluid pipes has been a focus of water authorities as well as oil and gas operators to advance the operation and management of these mechanical systems. This paper presents a comprehensive review on the development and application of transient wave-based methods for the detection of different anomalies in fluid pipes. A brief introduction of the fundamental physics and mechanism of transient waves in both intact and defective pipes is first presented. Different techniques and principles for transient wave generation and measurement are then discussed. In addition, the signal processing techniques commonly used for feature extraction from the measured signals are summarized. The main focus of this paper is on the comprehensive review of the technological advances and characteristics of five common types of transient wave-based anomaly detection methods for fluid pipe systems, namely (1) reflection-based method; (2) damping-based method; (3) FRF peak pattern-based method; (4) time domain full-waveform inversion method; and (5) frequency domain full-waveform inversion method. Afterwards, two practical applications of transient wave-based methods for anomaly detection in real-life fluid pipe systems are introduced and discussed. Finally, recommendations for future work in this research field are given.

In this paper, we employ the lattice Boltzmann method implemented on compute unified device architecture-enabled graphical processing unit to investigate the multiphase fluid pipe flow. The basics of lattice Boltzmann method as well as the Shan–Chen multiphase model and the fundamentals of graphical processing unit with compute unified device architecture are thoroughly introduced. The procedure of implementation of lattice Boltzmann method on graphical processing unit and the comparison of the computing performance between graphical processing unit and CPU are presented. It is demonstrated that the graphical processing unit-based lattice Boltzmann method has remarkable advantages over CPU especially with selected appropriate parameters. The results of validation cases agree well with previous numerical results or analytical solutions. The vertical and horizontal multiphase pipe flow are simulated and discussed.

Thermal conductivity of cellular rigid polyurethane foam (PUR) increases by time which leads to higher heat energy losses in district heating pipe networks. The main reason for increased thermal conductivity is diffusion of low conductive gases out of the PUR and diffusion of surrounding air into the PUR. However, oxidation of the PUR occurs during the service-life of the PUR and is accelerated by the higher temperatures close the fluid pipe. The effect that oxidation has on the thermal conductivity is not yet fully understood and existing models for prediction of long-term thermal performance of PUR insulation in district heating applications does not take oxidation processes into account. It is possible that the radiative heat transfer is affected by the oxidation and changes over the service-life of the PUR. In order to investigate the influence of oxidation on thermal conductivity, the extinction coefficient was therefore calculated for samples subjected to different levels of ageing. The input data for the calculations were measured by FTIR. The extinction coefficients were then used to calculate the overall thermal conductivity of the PUR with typical gas compositions. Results indicated that the extinction coefficient was 22 % higher in the samples exposed to lower temperatures. However, the effect on the overall thermal conductivity of the same samples was an increase of about 1.8 %. Since the comparison was made between two samples subjected to different levels of ageing, the increase in total thermal conductivity should be interpreted as a minimum if considering the total service lifetime of the PUR insulation.

A new method, electromagnetic incremental tube bulging with casting pipe, has been developed to manufacture corrosion resistant bi-metal pipeline as bulging aluminium alloy tube stuck to the internal surface of casting pipe. By formulating simulation parameters, electromagnetic model and structural model to do numerical simulation. The bulging tube is more homogeneous and closer to a long-straight tube when setting a casting pipe outside the aluminium pipe. Simulation results match well with the experiment. A solenoid coil discharges at different places inside the aluminium alloy tube with casting pipe a few millimetres outside the aluminium alloy tube. The aluminium alloy tube impacts on the internal surface of casting pipe instantaneously under the repulsive electromagnetic forces. The aluminium alloy tube can not be peeled off the casting pipe when tensile force reaches to 1kN. The result demonstrates that it is feasible to produce corrosion resistant bimetallic fluid pipe using electromagnetic incremental forming. The research can provide a certain reference for electromagnetic incremental aluminium alloy tube bulging.

This study presents a method to predict the flow velocity in a fluid-conveying pipe using vibration signals from the pipe surface. The flexural vibration of a fluid pipe is investigated through wave propagation. The wavenumbers and mode shapes of the pipe are determined based on its mechanical properties and flow velocities. The transient components of wavenumbers at low frequencies vary and converge on all values at higher frequencies as the flow velocity is increased. While the stationary fluid pipe exhibits symmetrical mode shapes, pipes with increasing flow velocities exhibit an asymmetric mode shape distribution skewed on one side of the axis. The resonant frequencies shift to the low frequency side as the flow velocity increases. The analytical results of the vibration analysis are used in the transfer function method to predict the flow velocities. To validate the accuracy of the prediction method, numerical vibration signals simulated by the finite element model are used. The actual input flow velocity is compared with the numerical results regarding the same to gauge the accuracy of the prediction method. This method can be used to monitor the flow rate without using flow meters, and thus protect pipelines from sudden malfunction.

High temperature and pressure conditions lead to expanding the pipelines used to transport different types of fluids. A compressive axial force arises if this expansion is prevented. The present work aims to analyze pipelines’ instability due to internal pressure influence by making a simulation using ANSYS - Mechanical APDL 2019 R3. The study presents comparisons between increasing internal pressure from (0 to 10 MPa) on some pipe parameters like a natural frequency and instability for two pined-pined pipe thicknesses, which are 0.5 and 1 mm. It is concluded that the increase in internal pressure will decrease the natural frequency and stability of the vibrated system but will increase the modal damping ratio and total deformation of the tested pipe.

In this work, the pulsed thermography process applied to inspect and analyze the internal corrosion defect in a pipe. The study carried out in two stages, the first one characterizes the control of the pipe at a standstill by considering the air inside the pipe, and the second one characterizes the control during operation by introducing a turbulent flow of seawater into the simulation. For this purpose, a 3D model of a fluid pipe containing three forms of internal rust defects performed using finite element software. The influence of parameters such as the size and penetration of rust into the tube evaluated by analyzing the contrast of the corresponding thermal images and the temporal and spatial variation of the temperature. The tube thickness introduced as a parameter influencing detection.

Pressure hydraulic pipeline vibration is a type of solid-liquid coupling in fluid-conveying pipes, with obvious instability characteristics in its development. Structural vibration caused by changes in oil flow velocity and pressure in the pressure transmission hydraulic pipeline have significant impact on the efficiency, noise, safety, and many other characteristics of the hydraulic system. Therefore, research in the vibration characteristics of pressure pipe bares important engineering significance. In this paper, an empirical method was used to study the fundamental frequency variation and vibration characteristics of a hydraulic pipe under pressure transmission. Experiments were carried out on a pressure transmission hydraulic pipeline vibration simulation experiment platform. TV400 type vibrometer was used to collect signals. The vibrometer adopts signal processing and fault diagnosis technology, which are characteristics of stringent technical parameters and powerful data management. The natural frequency of the pipeline was obtained by solving the eigenvalues of the fluid pipe vibration correction equation. The influence of flow and pressure on the natural frequency of the pipeline was analyzed, and the vibration characteristics under different rotational speeds and pressures were analyzed. The results show that the natural frequency of pipeline decreased with the increase of flow rate. Under constant flow rate, the natural frequency of the pipeline increased with the increase of pressure at an extremely small magnitude, which was negligible. This is the style of paper required for the Chinese Control Conference. The authors shall and must provide normalized electronic documents to allow convenient search and read by readers.

Highlights: • The Giant Gjallar Vent is still active in terms of fluid migration and faulting. • The Base Pleistocene Unconformity acts as a seal to upward fluid migration. • Seal bypass in at least one location leads to a new phase of fluid venting. The Giant Gjallar Vent (GGV), located in the Voring Basin off mid-Norway, is one of the largest (~ 5 × 3 km) vent systems in the North Atlantic. The vent represents a reactivated former hydrothermal system that formed at about 56 Ma. It is fed by two pipes of 440 m and 480 m diameter that extend from the Lower Eocene section up to the Base Pleistocene Unconformity (BPU). Previous studies based on 3D seismic data differ in their interpretations of the present activity of the GGV, describing the system as buried and as reactivated in the Upper Pliocene. We present a new interpretation of the GGV’s reactivation, using high-resolution 2D seismic and Parasound data. Despite the absence of geochemical and hydroacoustic indications for fluid escape into the water column, the GGV appears to be active because of various seismic anomalies which we interpret to indicate the presence of free gas in the subsurface. The anomalies are confined to the Kai Formation beneath the BPU and the overlying Naust Formation, which are interpreted to act as a seal to upward fluid migration. The seal is breached by focused fluid migration at one location where an up to 100 m wide chimney-like anomaly extends from the BPU up to the seafloor. We propose that further overpressure build-up in response to sediment loading and continued gas ascent beneath the BPU will eventually lead to large-scale seal bypass, starting a new phase of venting at the GGV.

Mechanical seal leakage of centrifugal pumps (especially hot oil pumps) is the main fault reason of the petrochemical equipments. The fuction of the sealing flush system is to maintain the mechanical shaft seal function correctly. The misconduct of flush system settings will directly lead to the failure of mechanical seal. In this paper, the problems are analyzed for the present mechanical seal flushing system. When the centrifugal pump is in a standby state, flushing system may not provide normal flush flow in self-flush plan. This may lead to surface fouling of the hot mechanical shaft seal, resulting in seal failure. Our research focus on solving these problems. The way is to change the source of flush fluid, that is to change the flush plan to external flush plan or toChange the fluid pipe position.

In this article a novel piezo-hydraulic actuator exploiting resonance effects is presented. The operation of the proposed resonant fluid actuator (RFA) relies on the significant pressure raised in a fluid pipe during wave resonance. The piston of the actuator houses a valve, which rectifies the wave's motion into direct mechanical motion. A state-space model, derived from the compressible Navier-Stokes equations, is formed by linearizing these equations and then discretizing them using the Chebyshev collocation method. In order to track the deformable control space, the resulting equations are reformed in an Arbitrary Lagrangian Eulerian framework. The fluid model is augmented with the valve and piezo dynamics, and, therefore, the final model is capable of capturing the performance of the RFA. The overall model is formulated in a time-variant state-space form and an optimal controller is designed to maximize the differential pressure across the piston. Experimental studies are used to investigate the efficacy of the proposed modeling approach, via utilization of a wavelet transform and finite element analysis. Simulation studies and experimental data are offered for verification of the actuator's principle of operation.

International audience; An exploration 3D seismic data set from the Gjallar Ridge off mid-Norway images a giant fluid seep structure 3 × 5 km wide, which connects to late Palaeocene magmatic sills at depth. Two of the pipes that have developed as hydrothermal vents reach all the way to the modern seafloor implying that they either were active much longer than the original hydrothermal activity or have been reactivated. We combine detailed seismic analysis of the northern pipe and sandbox modeling to constrain pipe initiation and propagation. Although both the seismic data and the sandbox models suggest that fluids at depth are focused through a vertical conduit, sandbox models show that fluids ascend and reach a critical depth migration where focused migration abruptly transforms into distributed fluid flow through unconsolidated sediments. This indicates that at this level the sediments are intensely deformed during pipe propagation, creating a V-shaped structure, i.e. an inverted cone at depth and a positive relief anomaly, 5 to 10 m high, at the seafloor, which is clearly identified on 3D seismic data. Comparison of the geometries observed in sandbox modeling with the seismically observed geometries of the Giant Gjallar Vent suggests that the Giant Gjallar Vent may be a proto-fluid seep at an early stage of its development, preceding the future collapse of the structure forming a seafloor depression. Our results imply that the Gjallar Giant Vent can be used as a window into the geological processes active in the deep parts of the Vøring Basin.

Biofilms form an irregular network matrix that is surrounded by extracellular polymeric substrate (EPS). The architecture of biofilm plays an important role in protecting bacteria under physical, chemical, and biological stress. The shear stress is one of the major factors to construct stable bioflim. The experimental observation of biofilm formation on large-scale water flow has been limited because most of fluid pipe are water and sewer lines. This study presents the biofilm formation in a PDMS-based microfluidic channel which is able to simulate fluid pipes at small scale. We could characterize the hydrodynamics of the growth of single-species bacteria between biofilm formation and the external environmental factors. Particularly, the dynamics of biofilm formation confirms that biofilm, under the optimum shear stress, efficiently form a stable EPS structure which provides a mechanical shield against high-pressure fluidic flow.

The stratification of two fluid phases, namely gas and liquid, within flow distribution devices, such as headers, that have side or bottom oriented fluid pipe connections, or discharges, has shown relevance to loss-of-coolant accidents in nuclear power plants. Under critical conditions the gas phase could entrain into the predominantly liquid discharge flow causing the fluid quality to be dramatically affected. This condition is referred to as the onset of gas entrainment (OGE) phenomenon and it occurs at a specific critical liquid height which changes with the Froude number. The liquid velocity field at the OGE is of importance, for example, to theorists who may find a semi-empirical approach to model this phenomenon. Stereoscopic particle image velocimetry (PIV) technique is an excellent candidate for non-intrusively investigating the velocity field. The liquid-phase velocity field was investigated for three discharge Froude numbers at the OGE. It was found that the stereoscopic PIV could be used to extract the velocity field experimentally, yet a high degree of error was found in the region closest to the discharge. The relative error was determined through conservation of mass by comparing the flow rate obtained with the PIV data to that obtained using a flow meter. In summary it was found that the number of image planes used, the resolution of the image planes, and consequently the number of vectors used to calculate the flow rate, all contributed a great deal to the relative error.

In this paper, the vibration suppression mechanism of a nonlinear fluid pipe via nonlinear energy sink (NES) is studied for the first time. The fluid pipe is simply supported under harmonic foundation excitation. The complexification-averaging method combined with the arc-length continuation method is used to predict the response of the system. The analytical solution is supported by the numerical result. The trend of interaction between liquid speed and NES parameters are investigated by comparison of parameters optimization. It is especially pointed out that the change of stiffness has a very complicated influence on the response. The parameters optimization is investigated at the resonance frequency. It is noted that the liquid speed has an important effect on the vibration suppression of the fluid pipe. Besides, the system is evaluated from the point of view of energy. The distribution of the input energy is calculated and the instantaneous transaction of the energy is examined by considering the energy transaction measure (ETM). The numerical simulations demonstrate that the target energy transfer (TET) leads to a very efficient vibration suppression.

A one-dimensional mathematic model is presented which describes pressure fluctuations behavior of liquid-filled pipes. The model is based on conventional two-equations water hammer theory. Here is multi-water-hammer occurring simultaneously and coupling together. The differences are obvious when taking into account coupled water hammer and just single water hammer in Fluid pipe system by comparing the numerical simulation. The pressure characteristics located where water hammer takes place is investigated by numerical simulation and experiment. Then the factors of influencing on the coupled water-hammer pressure and frequency are considered, the result shows that system parameters effecting on it are critical and should be detailedly analyzed.

During the pigging operation of a certain oil depot mixed transmission pipeline, there was a π-type compensator under significant stress, resulting in apparent displacement of the bent pipe. For this problem, the OLGA software was used to simulate the pigging process of the mixed pipeline, and the impact of the fluid on the π-compensator bend pipe during the occurrence of slug flow inside the pipeline was calculated and analysed. The calculation results showed that when made a pigging for the liquid-phase fluid pipe, the pipeline pressure declined along the pipeline; and for the gas-liquid two-phase flow pipe, there would be gas accumulation at the bottom of the compensator riser, and then the slug flow was formed. Pipeline pressure at the slug flow increased suddenly, causing pressure fluctuations in the pipeline to increase, pressure drop along the pipeline decreased sharply, and pressure loss occurred at downstream; pressure fluctuations caused by slug flow generated strong fluid shock, resulting in pipeline's jump and relative displacement, which destroyed the pipe system. The research results are of guiding significance for solving the problem of pigging operation in the multiphase pipeline and provide reference for other similar pigging operations.

This paper describes progress on a new technique to detect pipeline features and leaks using signal processing of a pressure wave measurement. Previous work (by the present authors) has shown that the analysis of pressure wave reflections in fluid pipe networks can be used to identify specific pipeline features such as open ends, closed ends, valves, junctions, and certain types of bends. It was demonstrated that by using an extension of cross-correlation analysis, the identification of features can be achieved using fewer sensors than are traditionally employed. The key to the effectiveness of the technique lies in the artificial generation of pressure waves using a solenoid valve, rather than relying upon natural sources of fluid excitation. This paper uses an enhanced signal processing technique to improve the detection of leaks. It is shown experimentally that features and leaks can be detected around a sharp bend and up to seven reflections from features/leaks can be detected, by which time the wave has traveled over 95 m. The testing determined the position of a leak to within an accuracy of 5%, even when the location of the reflection from a leak is itself dispersed over a certain distance and, therefore, does not cause an exact reflection of the wave.

Corrosion and deposition in Refineries and Petrochemicals is becoming one of the most critical and serious obstacle, and also can cause reduce the efficiency, performance, and analysis accurate of industrial instrument such as turbines, power plants, boilers, and especially sampling tube lines, because of increasing the pressure drop due to build-up deposits. To limit and minimize these deposits in sampling pipe lines would be uses a specially sampling system that design and discuss in this article. This kind of sampling system includes: isokinetic sampling, rapid condensation and cooling, pressure reduction, and process indicators, as well as safety devices to protect online instruments and plant personnel. All in all, by increasing the outer and inner diameter of sampling tube lines, wall thickness, Reynolds number, and required sampling rate, the pressure drop of flowing sample is decreasing and also with increasing the volume annual, the amount of deposits are significantly reduce, because of decreasing the pressure drop.

Abstract The conventional approach to submarine pipeline stability design considers interactions between water and pipeline (fluid-pipe) and pipeline and seabed (pipe-soil). The seabed is typically assumed hydrodynamically stable in this approach. Interactions between the water and the seabed (fluid-soil) are generally considered only as an afterthought. A new approach for assessing the stability of submarine pipelines is under development and is aimed at including seabed stability (or mobility) as a key aspect of the design analysis. An overview of this approach is presented in this paper. A practical method for utilising this design approach has also been developed, and is based on a combination of numerical analysis and physical model testing. Background On-bottom Stability On-bottom stability design of submarine pipelines is based on assessing the effects of the environment, namely the ocean and the seabed, on the pipeline. In short, a 'stable' pipeline does not displace (or displaces only by a small and allowable distance) when subjected to any environmental loading that may occur - in particular steady-state and oscillatory (wave-induced) on-bottom currents. This approach is known as 'absolute stability' design. As this method has evolved, the criteria for defining pipeline stability have loosened, and now extend to allowing the pipeline to displace a significant predefined distance laterally - up to tens of pipe diameters - under a given loading condition. Whether the distance is arbitrary, based on the operational constraints or the mechanical strength of the pipeline depends on the design approach and the code of practice utilised. This approach is known as 'dynamic stability' design, reflecting that a full dynamic analysis of the structural response is required to predict the displacement of the pipeline during a design storm event. There are three main interactions that affect the stability of a submarine pipeline. They are the interactions between the water and the pipeline (fluid-pipe); the interactions between the pipeline and the seabed (pipe-soil); and the interactions between the water and the seabed (fluid-soil). Fluid-pipe interactions result in hydrodynamic loading of the pipeline. Pipe-soil interactions result in the mobilization of soil resistance - which is often treated as two independent components, arising respectively from ‘friction’ between the pipeline and the seabed, and passive resistance to pipeline movement provided by the soil that is ahead of the embedded part of the pipe. Strictly these two components are not separate mechanisms, but it is common practice, and a reasonable simplification, to consider them in this way. Fluid-soil interactions result in seabed instabilities such as scour, fluctuations and potential build-up of excess soil pore pressure, and potentially liquefaction of the seabed soil. Pipe-soil interactions such as pipeline displacement may also lead to excess pore pressure generation. Each of the interactions outlined above are dependent on the other interactions and their effect on certain parameters. For example, the degree of pipeline embedment is affected by scour and liquefaction (fluid-soil), and in turn affects the hydrodynamic loads acting on the pipeline (fluid-pipe), as well as the passive resistance provided by the soil (pipe-soil). Figure 1 summarises these interactions that affect subsea pipeline stability.

Thermal stratification introduces thermal shock effect which results in local stress and fatique problems that must be considered in the design of nuclear power plant components. Local stress and fatique calculation were performed on the Pressurize Surge Line piping system of the Pressurize Water Reactor of the Nuclear Power Plant. Analysis was done on the operating temperature between 177 to 343° C and the operating pressure of 16 MPa (160 Bar). The stagnant and transient condition with two kinds of stratification model has been evaluated by the two dimensional finite elements method using the ANSYS program. Evaluation of fatigue resistance is developed based on the maximum local stress using the ASME standard Code formula. Maximum stress of 427 MPa occurred at the upper side of the top half of hot fluid pipe stratification model in the transient case condition. The evaluation of the fatigue resistance is performed on 500 operating cycles in the life time of 40 years and giving the usage value of 0,64 which met to the design requirement for class 1 of nuclear component. The out surge transient were the most significant case in the localized effects due to thermal stratification.

In this article, a novel piezo - hydraulic actuator exploiting resonance effects is presented. The proposed actuator relies its operation on the significant pressure built up in a fluid pipe during resonance. The actuator's piston houses a valve which rectifies the wave's motion into direct mechanical motion. Since pressure waves are to be examined, a model capable of capturing the wave dynamics and fluid motion is derived. A state space model derived from the compressible Navier - Stokes equations is formed by linearizing these equations followed by a discretization using the Chebyshev collocation method. The model parameters are identified using a simple adaptive algorithm based on experimental data. A feature extraction technique, incorporating the wavelet transform on the experimental and simulated data, is used to calculate the resonance frequency and damping factor of the system. Experimental studies are used to investigate the efficiency of the proposed modeling approach.

The basic principle of EMF (electromagnetic flow meter) is the Faraday electromagnetic induction law. An induced voltage EMF for measuring flow rate of single phase in pipes has been used successfully in many industrial areas. But the measurement of volumetric flow rate of multiphase flow is not understood poor, especially the measurement of the continuous phase velocity profile in multiphase flows where the continuous phase is electrical conductive. This paper tries to investigate the characteristic of induced electric potential or potential drop, which can reflect the velocity distribution of the conductive continuous phase in the flow pipe. A predefined fluid velocity distribution, vz=5+200y, that means the component z of fluid velocity varies with the coordinate value of axis y and the components x and y of the fluid velocity are 0, was applied in the investigation. The numerical simulation model with geometry and physical preconditions was built. The analysing methodology adopting multiple virtual electrodes that could be arranged at any position of the internal circumference of fluid pipe to meet the requirement of signals picking for induced potential was proposed. Finally, the characteristics of induced potential that varies with the electrodes position are analysed clearly in different figures

Symplectic mathematics is introduced into the thermoacoustic network model. The transferring matrix of thermoacoustic system is analyzed, and the transferring matrix of working gas in isothermal fluid pipe of thermoacoustic system is a symplectic matrix. The transferring matrix of working gas in regenerator of thermoacoustic system is not a symplectic matrix, but it can be converted into a symplectic matrix by variable transformation. With variable transformation, the whole transferring matrix of thermoacoustic system can be represented by a symplectic matrix. The form of symplectic matrix is conducible to analyzing and calculating the thermoacoutic network model.

Pipelines carry fluids important to modern civilization. Many cross seismically active regions where they may be subjected to damage from earthquake induced ground shaking. The pipe motion may be in the lateral or axial directions, or both. The current note is an attempt to answer the question of fluid pipe interaction when the only mechanism for coupling is the fluid viscosity. As such, the results are not applicable to situations where frequent bens or changes in cross section give rise to coupling mechanisms related to motion normal to the surface.

This paper deals with transient characteristics of a valve-controled hydraulic driving system consisting of actuator, fluid pipe and operation valve, especially with pressure surge generation in a pipe due to sudden valve closure. Pressure variation was measured under various system and operating parameters, such as valve closure time, valve closure process, valve orifice shape, etc., and compared with theoretical results of the preceding paper. Consequently, the following matters became evident. (1) The theoretical results which were obtained by employing a wave equation of two-dimensional viscous flow for an unsteady pipe flow agree well with experimental results in any system parameters and valve closure process. (2) An approximate solution which was obtained by considering only the compressibility of fluid in pipe is accurate enough for practical usage in case of very slow valve closure. (3) Variation of discharge coefficient of valve depending on Reynolds number, saturation of valve flow at large opening and leakage flow through valve orifice after closure can not be disregarded in case of gradual valve closure.

This paper studies the prototype development of the vibro-impact capsule system aiming for autonomous mobile sensing for pipeline inspection. Self-propelled progression of the system is obtained by employing a vibro-impact oscillator encapsuled in the capsule without the requirement of any external mechanisms, such as wheels, arms, or legs. A dummy capsule prototype is designed, and the best geometric parameters, capsule and cap arc lengths, for minimizing fluid resistance forces are obtained through two-dimensional and three-dimensional computational fluid dynamics analyses, which are confirmed by wind tunnel tests. In order to verify the concept of self-propulsion, both original and optimized capsule prototypes are tested in a fluid pipe. Experimental results are compared with computational fluid dynamics simulations to confirm the efficacy of the vibro-impact self-propelled driving.