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The drilling process requires real-time measurement of drill string vibration, which is crucial for drilling and downhole safety. However, the traditional power supply mode used for downhole vibration sensors has been found to increase drilling costs and reduce drilling efficiency. Therefore, sensors with self-powered capabilities are considered more suitable for practical conditions. A downhole arrayed self-powered deformable vibration sensor was proposed based on the principle of triboelectric nanogenerators. Experimental results demonstrate that the sensor synchronized measurements of amplitude and frequency. The vibration frequency is measured within a range of 0 Hz to 11 Hz, with a measurement error of less than ± 4% . Additionally, the sensor is able to measure three discrete amplitude values (10, 25, 40 mm) with a measurement error of ± 3 mm. The sensor can working normally within a temperature range of 0 ℃ to 85 ℃. Furthermore, the sensor has power generation capabilities, with experiments revealing a maximum output power of 8. 3 × 10-7 W. Notably, when multiple sensors are used in parallel, the power generation capacity is significantly enhanced. These research findings provide new insights for the development of downhole sensors and downhole generators. [ABSTRACT FROM AUTHOR]

Pipe vibration induced by water hammer frequently emerges in water conveyance system, especially in the hydropower plant or pumped storage power station with long diversion pipelines. This vibration in turn affects the hydraulic pulsation so that undesired fluid-structure interaction (FSI) arises. In this research, attention is given to a pipeline embedded in concrete. A six-equation model was derived to describe the fluid-pipe-concrete interaction considering Poisson coupling and junction coupling. With the elastic and homogeneous hypotheses, an iterative approach was proposed to solve this model, and the results were validated by experiment and classical water-hammer theory. Then dynamic FSI responses to water hammer were studied in a reservoir-pipe-valve physical system. Hydraulic pressure, pipe wall stress and axial motion were discussed with respect to different parameters of concrete. Results obtained by the two-equation model, four-equation model and six-equation model show characteristics of pressure wave and stress wave separately with and without FSI.

[Display omitted] • A novel mechanism of standpipe vibration of CFB boiler was proposed, which was also proven in engineering. • The influence of several factors on standpipe vibration of CFB boiler was analyzed by calculation. • Engineering solutions to the standpipe vibration of CFB boiler were proposed, especially for large-capacity CFB boiler. Standpipe vibration of circulating fluidized bed (CFB) boiler will threaten its safe and stable operation. In order to solve the standpipe vibration, the mechanism of standpipe vibration was discovered based on the type B choking theory in the CFB system and the Ledinegg instability criteria for the gas-liquid flow. And the influence of several factors on the gas-solid flow, especially the reverse flow in the standpipe, was qualitatively analyzed according to the pressure and mass balance in the whole loop. The standpipe vibration is caused by the mismatch between the driving pressure and the resistance pressure drop in the whole loop. To suppress the standpipe vibration, it is necessary to optimize the flow and pressure parameters under stable working conditions, which can be achieved by four main methods of reducing the resistance of the returning valve and cyclone, increasing the circulating rate and the solid height in the standpipe. In engineering application, these four methods can be realized by appropriately increasing the aerated air velocity and the sectional area ratio between the riser and the standpipe, reducing the length of the passage and the height of the weir, increasing the effective material fraction and the inlet area of the cyclone. This paper theoretically analyzes the mechanism of standpipe vibration and proposes corresponding engineering solutions to guide the operation and design of CFB boilers. [ABSTRACT FROM AUTHOR]

[Objectives]The fluid-conveying pipes may vibrate under external excitation. In order to reduce the vibration of the fluid-conveying pipes and study the vibration-reduction characteristics of the Dynamic Vibration Absorber(DVA),[Methods]the receptance matrix of the multi-degree-of-freedom (DOF)system of the additional spring-mass system was derived based on the passive modification method in the receptance method,and the zero assignment of the target DOF in the multi-DOF system was performed to suppress the corresponding vibration under the target DOF. On this basis,a DVA was designed and applied to the fluid-conveying pipes for experiments to verify its vibration-reduction effect.[Results]The results show that the designed DVA can well absorb the vibration at the target frequency, and the vibration reduction is better for a larger tuned mass when the target frequency is the same.[Conclusions]Such DVA is convenient to install and has a wide application range,which can provide a certain reference for pipe vibration reduction research.

Abstract Natural characteristics of thin-wall pipe of the compressor under uniformly distributed pressure were presented in this paper based on a cylindrical shell model. In the traditional method, the beam model was usually used to analyze the pipe system. In actual fact, the pipe segment of the compressor was always broken in the form of a long crack or a partial hole and the phenomenon was hardly explained by beam model. According to the structure characteristic of compressor pipe segment, whose radius is large and thickness is little, shell model shows the advantage in this kind of pipe problem. Based on Sanders’ shell theory, the vibration differential equation of pipe was established by applying the energy method. The influences of length to radius ratio (L/R), thickness to radius ratio (h/R), circumferential wave number (n) and pressure (q) on the natural frequencies of pipe were analyzed. The study shows: Pressure and structural parameters have a great effect on the natural characteristics of the pipe. Natural frequency increases as the pressure increases, especially for the higher mode. The sensitivity of natural frequency on pressure becomes stronger with h/R ratio increases; when L/R ratio is greater than a certain critical value, the influence of the pressure on natural frequency will no longer be obvious. The value of n corresponding to the minimum natural frequency also depends on the value of pressure. In the end, analysis of the forced vibration of a specific pipeline model was given and the modal shapes were illustrated to understand the break of the pipe. The research here will provide the theory support for the dynamic design of related pressure pipe and further experiment study should be employed.

Copyright of Nuclear Safety is the property of Nuclear & Radiation Safety Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The simulation model of flow-vibration-radiation noise was established for the throttling pipe used in the nuclear reactor. The mechanism of generating radiation noise and the influence of throttling hole diameter and flow rate on the vibration and noise were studied by the experiment and simulation. The radiation noise generates because of the wake vortices in the flow field of throttling pipe. When the frequency of the periodically exciting force generated on the pipe wall by the fluid in the pipe approaches that of the corresponding pipe modal， the vibration is enhanced， resulting in the radiation noise. Moreover， the vibration and radiation noise reduce with the increase of the throttling hole diameter， and enhance with the increase of the inlet flow rate. [ABSTRACT FROM AUTHOR]

Aiming at the vibration problem of the outlet pipeline of super high pressure compressor, the application of damping technology in pipeline vibration reduction was studied. Combined with the vibration of the first-grade outlet pipe of a super high pressure compressor in a chemical plant, the modal analysis was carried out by using ANSYS finite element software, and the main reason of pipeline vibration was determined by combining the vibration of the site pipeline. SAP2000 software was used to simulate the vibration reduction of the damping. The effect of the number and location of dampers on the vibration reduction of pipelines was discussed, and a feasible installation scheme was formulated. The results indicate that the vibration energy of the outlet pipeline of the super high pressure compressor can be absorbed mostly by installing two viscous dampers at the maximum vibration position of the pipeline without changing the original structure of the pipeline and shutting down the compressor. At the same time, the vibration speed and amplitude of pipelines are reduced by more than 70% , and the vibration of adjacent pipelines will not be caused. [ABSTRACT FROM AUTHOR]

Copyright of Energy Policy Journal / Polityka Energetyczna is the property of Mineral & Energy Economy Research Institute of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, a nonlinear model was developed for a cantilevered piezoelectric pipe conveying fluid that included geometric nonlinearity and electromechanical coupling. The Galerkin method discretized the system in order to characterize its behavior. Critical flutter velocity and its associated unstable mode can be determined based on linear analysis. Due to the presence of piezoelectric materials, the critical flutter velocity depends on the resistive piezoelectric damping and electromechanical coupling. This added resistive piezoelectric damping tends to decrease the flutter velocity. Comprehensive simulations were also conducted to characterize the post-flutter behaviors. System parameters including amplitude, deformed pipe shape, and collected voltage in piezoelectric materials were calculated. The system will undergo limited cycle oscillation when the fluid velocity passes the flutter velocity. Parametric studies were conducted as well to investigate the system responses under different flow velocities. Physical insights can be collected from these simulation results to conduct piezoelectric pipe design and performance predictions for future pipe vibration control and energy harvesting applications. [ABSTRACT FROM AUTHOR]

Abstract This investigation is focused on understanding and modeling the effects of specific structural uncertainties in nearly-straight and uniform pipes conveying fluid on the dynamic response and stability of these pipes. The structural uncertainties of interest here are those that affect directly the fluid flow and its feedback on the structural response, e.g., uncertainties on/variations of the inner cross-section and curvature of the pipe. Owing to the complexity of introducing such uncertainties directly in finite element models, it is desired to proceed directly at the level of modal models by randomizing simultaneously the appropriate mass, stiffness, and damping matrices. The maximum entropy framework is adopted to carry out the stochastic modeling of these matrices with appropriate symmetry constraints guaranteeing that the nature, e.g., divergence or flutter, of the bifurcation is preserved when introducing uncertainty. To support the formulation of this stochastic reduced order model (ROM), a series of finite element computations are first carried out for pipes with straight centerline but inner radius varying randomly along the pipe. The results of this numerical discovery effort demonstrate that the dominant effects originate from the variations of the exit flow velocity, induced by the change in inner cross-section at the pipe end, with the uncertainty on the cross-section at other locations playing a secondary role. Relying on these observations, the stochastic reduced order model is constructed to model separately the uncertainty in inner cross-section at the pipe end and at other locations. Then, the fluid related mass, damping, and stiffness matrices of this stochastic ROM are all determined from a single random matrix and one additional random variable. The predictions from this stochastic ROM are found to closely match the corresponding results obtained with the randomized finite element model. It is finally argued that this stochastic ROM also accounts for the small effects due to uncertainty in pipe curvature. [ABSTRACT FROM AUTHOR]

This study aims to mitigate CaCO3 scale formation in pipes under influence of vibration and oxalic and formic acid additives. The vibration of the pipes was generated mechanically by an electrical motor and controlled by a computer program. CaCO3 scale was synthesized by CaCl2 and Na2CO3 reagents. The scale deposition was examined at a temperature of 35°C and vibration frequencies of 0.00, 3.00, and 6.00 Hz. The mass of scale deposit was found as 3.3211 g, 3.8358g, and 4.4705 g. Fourier Transform Infra Red spectroscopy analysis proved that the additives successfully diffused into the crystal lattice and retarded carbonate anion formation, which consequently retarded the scale formation. In addition, the use of oxalic acid made the morphology of vaterite-changed. However, the formic acid was added, a new habit of hexagonal thin-plate vaterite-could be observed and a fewer carbonate scale was obtained. [ABSTRACT FROM AUTHOR]

Highlights • Simulation and shaking table test was done to identify the vibration characteristics of drain pipe. • Natural frequency, mode shape, and transmissibility were determined and compared. • The new design is expected to successfully suppress the vibration response. • Additional design change may be needed for further vibration reduction. Abstract The drain pipe of the steam generators in nuclear power plants is designed to remove the remaining reactor coolant when the nuclear power plant stops. In the normal electricity generating condition of the nuclear power plant, the drain pipe acts as the pressure boundary between the primary coolant system and outside, which forbids the radioactive coolant to be leaked. Therefore, it is important to assure the structural integrity of the drain pipe, which is closely related with the vibration characteristics of the drain pipe. In this paper, the vibration characteristics of the previous and newly designed drain pipes are investigated by simulation and measurement with the shaking table test. The purpose of the new design was to suppress the excessive vibration in the interested low and high frequency ranges, which were observed in the power uprating of plants. From the measured results, in y direction, the first three modal frequencies are increased by 5, 18, and 50 Hz in the low frequency region, and the higher order modes are excluded in the interested high frequency region with the adoption of the new design. Further design modification is required to reduce the high frequency vibration in x direction with other approaches. In general, it is expected from the result that the newly designed drain pipe is more robust to the existing vibration compared with the previous one. [ABSTRACT FROM AUTHOR]

Abstract Realistic multi-span fluid-conveying pipe may contain various accessories such as valves, clamps, flanges, elastic supports and vibration absorbers under complex boundary conditions in engineering applications. The dynamic response of the multi-span pipe may be affected by the presence of accessories, giving rise to complex mode shapes. Simplified and reliable methods for multi-span mode shapes calculation from eigenvector of the characteristic equation are widely applied in the pipeline engineering community. However, current methods are not valid when it comes to the amplitude of the eigenvector with a resonance frequency. Consequently, corresponding stresses cannot be further evaluated exactly. To address the above mentioned issues, a novel Frequency Response Function (FRF)-based method is proposed in this paper for the calculation of the mode shapes exactly. Furthermore, a method combining the Spectral Analysis Method (SAM) and Transfer Matrix Method (TMM) is first proposed in this paper to obtain the natural frequencies and transient response for the cascaded pipeline. The results calculated by the present method are validated by comparing them with those obtained from existing literature and conventional Finite Element Method (FEM). The effects of the accessories on the vibration characteristics of the multi-span pipes are further analyzed. [ABSTRACT FROM AUTHOR]

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, an improved Fourier series method is employed to analytically model the coupled vibration characteristics of the fluid-conveying pipe system with arbitrary elastic boundary supports. By introducing two types of boundary restraining springs at both ends of the pipe, all the classical boundary conditions as well as their combination can be easily realized by setting the stiffness coefficients accordingly. The transverse vibrational displacement of the fluid-conveying pipe is expanded as the superposition of standard Fourier series and the boundary smoothed supplementary functions, to ensure that the displacement function is sufficiently smooth in the entire region [0, L], Through solving the governing equations and the elastic boundary conditions simultaneously, the standard eigen-value matrix problem is obtained. Numerical examples are then given to validate the proposed model in predicting the modal characteristics of fluid-conveying pipe. Based on the model established, the influence of the boundary stiffness on the coupled vibration characteristics of fluid-conveying pipe is discussed and analyzed. The current model is efficient and accurate, which can provide a tool of analysis for the study of vibration characteristics with complex boundary constraints. [ABSTRACT FROM AUTHOR]

The original noninvasive method for measuring the flow rate of liquids proposed in this work relies on the ability of the piezoelectric sensors embedded into pipes or pipe bends to detect the pressure fluctuations of turbulent flow. As the pressure fluctuation is directly related to the flow velocity, the electric responses of the piezoelectric sensors are correlated to the flow rate. Plastic pipes and pipe bends of different curvature radius with embedded piezoelectric ceramics of lead zirconate titanate (PZT) were used for measuring the flow rate of water. The piezoelectric sensors are placed close to the inner surface of pipe to increase their sensitivity to the pressure fluctuations of turbulent flow. Measurements of pipe vibration with accelerometers were also performed for comparison purposes. Frequency domain analyses demonstrate that the response of the piezoelectric sensors is mainly related to the pressure fluctuation of turbulent flow. Preliminary results of tests with straight acrylic pipes and 90° pipe bends made of polyvinyl chloride (PVC) demonstrate the effectiveness of the proposed technique. An interesting sensing performance to flow was observed for the PZT sensors installed in bends of small curvature radius. The disturbances to flow generate high pressure fluctuations in short radius bends, consequently improving the sensitivity to flow rate of the PZT sensors. Volumetric flow rates lower than 0.1 l/s were detected using a 90° bend of r/d = 0.5, with inside diameter d = 21 mm and integrated PZT sensors. As the pressure fluctuation is responsible for the pipe bend vibration, the sensitivity to flow rate of the accelerometers was also significantly improved. [ABSTRACT FROM AUTHOR]

The main idea of this paper is to assess a simpler and faster procedure leading to the evaluation of the fluid flow rate through a pipe. Currently, several methods are available and they involve ad-hoc instruments. All these methods are characterized by high accuracies and dynamic responses, but they are intended to be inserted within the pipe under investigation, bringing to well-known insertion effects, compromising the reliability of the measurements performed. The authors illustrate a newer methodology for the measurement of flow rates by means of the processing of the vibration signals of pipe walls, inferred by the flow turbulence. Previous studies of the same authors showed a linear dependence between the amplitude of the most prominent peak of the vibration spectra and the flow rate. In this work, the authors relate the power content of the processed signals (by introducing the signal Root Mean Square value) to the flow rate. [ABSTRACT FROM AUTHOR]

For the purpose of protection of a hydraulic actuator of land traction vehicles of unauthorized mission of power fluid in case of breakage of pipelines of high pressure the analysis of the existing condition of a hydraulic system of traction vehicles was carried out, the causes of the destruction of high-pressure hoses are revealed and a technical solution on elimination of the mentioned shortcoming is developed. It is suggested to increase the efficiency of protection of a hydraulic actuator in case of unauthorized emission of power fluid after breakage of high-pressure hoses by introduction of additional elements of pressure stabilization in hydraulic system, to provide speed, operational reliability and ecological safety of hydraulic actuator of vehicles. For the realization of an objective the ball-type pressure reducing valve supplied with circular groove and clamp in the form of thread gauge with submerged spring-applied core with tapering point, and also the plunger supplied with stop disk with solid cage which is reported with pressure pipe supplied with the locking gate is installed in the drain adapter of the locking device. [ABSTRACT FROM AUTHOR]

Fuel pipes popularly used in automotive industry applications carry fuel from the fuel tank to the engine and work under variable vibrations having different magnitude and frequency parameters due to the engine’s rotation frequency and road profile’s spontaneous change. Considering that the transfer of the fuel to the engine in the desired way has a crucial importance on the driving performance, any problem that may exist because of the vibrations cannot be acceptable in the pipe assembly. Because of this reason, all manufactured fuel pipes have to be well tested in terms of some industrial standards. The fluid excitement test is a very useful and commonly accepted method in the industry. However, this method produces enormous amount of noise that does not allow to obtain healthy pressure values from the sensors. In this study, Kalman filtering method has been used to interpret the data that have been obtained from the sensors. The usefulness and effectiveness of the proposed Kalman filtering method have been shown and discussed based on the test results. [ABSTRACT FROM AUTHOR]

Leaks have been detected and localized in water distribution in many countries for years, by using the cross-correlation of pipe vibration measured either side of a suspected leak and/or by using listening sticks. However, in modern plastic pipes this is problematic because of the strong coupling between the water and the pipe which results in significant attenuation of the coupled fluid-pipe wave, which in turn is responsible for the propagation of leak noise. Hence leak noise does not propagate as far as it did in older metallic pipes. This paper discusses how the vibro-acoustic behavior of the water-pipe-soil system influences leak noise propagation. To investigate this, a numerical model is developed, and the results are compared with those from an analytical model for two water pipe systems, one in the UK and one in Brazil. Experimental results are also presented. It is shown that the important difference between the two systems is the shear stiffness of the surrounding soil, which has a profound effect on both the speed of leak noise propagation and the attenuation of the noise along the pipe. [ABSTRACT FROM AUTHOR]

In the present study, a modal parameter-based technique has been presented to identify damage in steel cylindrical pipes under real measurement condition. For this purpose, an analytical formulation has been presented considering radial vibration of the pipe following Prescott’s equation and the relation of its damage with its dynamic properties has been established. The proposed approach and its efficacy have been numerically illustrated and localization as well as comparative quantification of severity of damage has been performed. The difference of modal parameters between the damaged and undamaged cross section of pipe successfully identifies the location of damage. In laboratory environment, specimens of pipes with various anomalies have been introduced to replicate various damage scenarios. Changes in frequency have been observed and tabulated. Ongoing experiments aim to observe similar outputs for different damage conditions. The accuracy of final methodology will rely on accurate extraction of modal parameters of the specimens. [ABSTRACT FROM AUTHOR]

Defect resolution using transient-based detection methods (TBDDM) improves as frequency bandwidth of injected signals increases. High-frequency waves (HFW) excite radial and azimuthal modes, however, making the 1D water-hammer ineffective for these phenomena. This paper focuses on idealized HFW in inviscid, slightly compressible fluid in rigid, unbounded, circular conduits. HFW waves are generated by an axisymmetric wave source. High-order 2D finite volume scheme is developed for HFW. Results show that injected probing waves containing a cut-off frequency exhibit significant wave dispersion, and group velocity varies over a wide range of speeds, resulting in wave-energy spatial spreading with large amplitude reduction. Injected signals without any cut-off frequency remain spatially separated. Size of wave source significantly affects energy distribution within wave modes. Practical implications are that probing wave and defect resolution effectiveness may be increased using (i) probing HFW without cut-off frequencies contained in the bandwidth of the injected probing signal, and (ii) larger power sources for the injection of probing wave signals. [ABSTRACT FROM PUBLISHER]

This study presents a simulation of interactions between sound and a surrounding pipe structure conveying fluid flows. A sound-attenuating structure using layered metamaterials of cylindrical shells is proposed and verified. Numerical simulations based on the finite difference method after considering steady fluid flow in the pipe were performed. The effective wave speed and density of the fluid required to determine acoustic characteristics were calculated from the transfer matrix method. This enabled estimation of noise reduction capability. The metastructure layers were lined parallel to the pipe walls to minimize flow resistance. The effective density was negative near the resonance frequency of the layers. The transmission loss predicted for a moving fluid medium was smaller than that for a stationary medium due to boundary layer formation. The proposed method can be used to design silencers to reduce the transmitted noise in pipe systems. [ABSTRACT FROM AUTHOR]

Structural model for a slender and uniform pipe conveying fluid, with axially moving supports on both ends, immersed in an incompressible fluid, is formulated. Free vibration and stability of the system are studied through numerical calculation. First, the equations of motion of the system are derived in an absolute coordinate system. An "axial added mass coefficient" is adopted to amend the forces caused by the external fluid. Boundary conditions are fixed by using coordinated conversion. Then, numerical results of the natural frequency are obtained via the Galerkin method, both for pinned-pinned and clamped-clamped supports. The critical speeds of supports and several instability types are discussed. Last, the effects of the system parameters on the dynamics and instability of the system are investigated. [ABSTRACT FROM AUTHOR]

The transportation of dry fine powders is an emerging technologic task, as in biotechnology, pharmaceutical and coatings industry the particle sizes of processed powders get smaller and smaller. Fine powders are primarily defined by the fact that adhesive and cohesive forces outweigh the weight forces, leading to mostly unwanted agglomeration (clumping) and adhesion to surfaces. Thereby it gets more difficult to use conventional conveyor systems (e.g. pneumatic or vibratory conveyors) for transport. A rather new method for transporting these fine powders is based on ultrasonic vibrations, which are used to reduce friction between powder and substrate. Within this contribution an experimental set-up consisting of a pipe, a solenoid actuator for axial vibration and an annular piezoelectric actuator for the high frequency radial vibration of the pipe is described. Since amplitudes of the radial pipe vibration should be as large as possible to get high effects of friction reduction, the pipe is excited to vibrate in resonance. To determine the optimum excitation frequency and actuator position the vibration modes and resonance frequencies of the pipe are calculated and measured. Results are in good accordance. [ABSTRACT FROM AUTHOR]

Pipe structures are widely applied in industries, and different kinds of defects may occur in the structures during their long-time service. For non-destructive testing of defects in pipes of small diameter, it has to be conducted from the inner side of the pipe when there is no space for detection from the outside or the geometry of the outside tube surface is too complicated. In this work, a flexible film type Electromagnetic acoustic transducer (EMAT) probe with a dual coil configuration is developed. The new probe is flexible and can be inserted into the pipe for inspection. First, the feasibility of the new probe was studied through numerical simulation. Then the feasibility of the proposed flexible EMAT for detection of wall thinning in small diameter pipe was verified experimentally. It was found that the new EMAT method is suitable for the detection of wall thinning defects for small pipes. [ABSTRACT FROM AUTHOR]

The enhancement of axial heat and mass transfer by laminar flow oscillation in pipes with axial gradients in temperature and concentration has been studied analytically for the cases of insulated and conducting walls. The axial diffusivity can exceed its molecular counterpart by many orders of magnitude, with a quadratic scaling on the pressure-gradient amplitude and the Prandtl or Schmidt number, and is a bimodal function of oscillatory frequency: quasi-steady behavior at low frequencies and a power-law decay at high frequencies. When the pipe wall is conductive and of sufficient thickness, and the flow oscillation is quasi-steady, the axial diffusivity may be enhanced by a further factor of about ten as a result of increased radial diffusion, for liquid and gas flows in pipes with walls with a wide range of thermal conductivities. Criteria for the wall thickness required to achieve this additional enhancement and for the limits placed on the validity of these solutions by viscous dissipation are also deduced. When the heat transfer per unit flow work achieved by oscillatory pipe flow is contrasted with that of a conventional parallel-flow heat exchanger, it is found to be of comparable size and the ratio of the two is shown to be a function only of the pipe geometry, heat-exchanger mean velocity, and fluid viscosity. [ABSTRACT FROM AUTHOR]

Drillstring and down-hole tool failure usually results from failing to control one or more of the vibration mechanisms. The solution starts with the ability to measure different modes of vibration, hence identifying different vibration mechanisms. Lateral, torsion and axial are vibration modes that take place when drill pipes run into problems downhole. Due to the three modes of vibration mechanisms such as bit bounce, stick-slip, lateral shocks, bit and bottom hole assembly (BHA) whirl, parametric and torsional resonance occur. Understanding the causes of the destructive loads is the main step towards developing approaches to prevent or reduce their effects, hence improving drilling performance. Vibration modes and mechanisms lead to failure of the drill pipes, BHA and drill bits. Drill pipes fatigue failure is very common due to capability of producing all vibration modes and mechanisms. Drill pipe and downhole tool assembly failure usually result from failing to have power over one or more of these vibration mechanisms. A novel in house experimental setup has been developed to mimic downhole axial, lateral and torsional vibration modes and mechanisms in drilling operations. In this paper, we focus on the design and construction of the testing facility. A number of tests were conducted to validate the capability and performance of the test setup. Drill pipe fatigue failure due to lateral cyclic stresses induced in the drill pipe has also been investigated and presented in this paper. The results show that operating on a rotation speed higher than 90% of the drillstring critical speed leads to yielding in the drillstring. [ABSTRACT FROM AUTHOR]

A major problem of utilizing co-firing technique is controllably distributing fuel mixtures of pulverized coal and granular biomass in a common pipeline. This research related into particle velocity distribution in the vertical pipe after a right angle elbow was undertaken using the Laser Doppler Anemometry (LDA) technique and a coupled computational fluid dynamics (CFD)-discrete element method (DEM) simulation. According to the similarity criterion of Stokes Number, three types of glass beads were used to model the dilute gas-solid flow of pulverized coal or biomass pellets. In the vertical pipe after an elbow (R/D = 1.3, R is the bend radius as 100 mm and D is pipe diameter as 75 mm), a horseshoe shape feature has been found on cross-sectional distributions of the axial particle velocity for all three types of glass beads on the first section which is 15 mm away from the blend exit. At the further downstream sections, the horseshoe-shaped feature is gradually distorted until it completely disappears. The distance for total disintegration is about 300 mm away from the first section for the first type of glass beads, 150 mm away for the second type and 75 mm away for the third one. As for particle number rate, its cross-sectional distribution on the first section shows that a rope is formed at the pipe outer wall where the maximum particle number rate occurs. On the whole, the rope formed by the first type of glass beads can be still observed at the section which is 450 mm away from the first section. For the second type of glass beads, the rope will disintegrate from the section (300 mm away) according to the cross-sectional distributions of the dimensional value of particle axial velocity divided by air conveying velocity. Overall, the roping characteristic is not obviously shown in the gas-solid flow of the third type of glass beads after the first section. All of these indicate that ropes formed from larger particles disperse more easily, for reasons perhaps related to their higher inertia. In addition, CFD-DEM analysis was employed to determine the particle characteristics to confirm this assumption. The numerical results indicated that the flow pattern has the highest axial velocity near the elbow to form the ‘horseshoe’ pattern. As the particles with lower Stokes Number were easier to follow the air flow, this is the reason why the horseshoe pattern of smaller particles was more obvious than larger particles. [ABSTRACT FROM AUTHOR]

The use of Pipe Belt Conveyor (PBC) has gained more and more popularity in bulk solids handling. Compared to the traditional trough conveyors, PBC can allow tighter curves and steeper gradients of conveyor routes and thus better suits the applications in difficult terrains. It has many unique mechanical characteristics which are not well understood yet. This paper proposes a coupled finite element model (FEM) and discrete element method (DEM) model to investigate the mechanics of a PBC system, with particular reference to the distribution of contact force in the pipe section. This FEM/DEM model considers comprehensively the formation of pipe from a flat belt and the microscopic structure of discrete particles under gravity, and thus can well describe the states of both conveyor belt and bulk solids. The predictions of the contact forces are shown to agree well with the previous experimental data under different conditions. Using this approach, the distribution of contact forces under different load conditions, i.e. zero gravity (ZG), empty pipe (VF 0%), volume fill of 40% (VF 40%) and 80% (VF 80%) are obtained and their dependencies on the rotation angle of pipe are investigated. [ABSTRACT FROM AUTHOR]

The axial vibration of liquid-pipes, considering the fluid-structure interaction (FSI), can be described by a four-equation model consisting of two equations for the fluid and the other two for the pipe wall. When distributed friction and damping were neglected, the model could be solved with an exact solution developed from the method of characteristics (MOC). The exact solution with a simple recursion process was presented instead of meshing the distance-time plane, introducing no numerical error, while the only weakness was the high time cost. An improved method based on this exact solution is proposed in this work, using the time-line interpolation rather than the recursive algorithm to speed the calculation. As numerical diffusion and oscillation affect the accuracy a lot, various interpolation techniques are investigated and compared. The mean absolute error (MAE) and the structural similarity index measure (SSIM) are employed to assess the accuracy of proposed methods, and the latter was originally developed for the image quality assessment. A hybrid interpolation scheme, mixing the cubic spline and linear interpolation, is proposed and achieves the highest accuracy and the quadratic-linear interpolation is found to be a good choice considering both accuracy and efficiency. The solution method developed here improves the efficiency significantly while retains an acceptable level of the accuracy, especially suitable for the long duration event. [ABSTRACT FROM AUTHOR]

The effect of vibrations over a flow tube from a solar water heating collector was studied in order to enhance the heat exchange. First, a hydrodynamic model for the internal flow of the tube was proposed, in order to obtain the pattern for the relative motion of the liquid. The results highlighted a strong exchange of liquid volumes between the upper and the lower part of the pipe over the transversal section of the tube for a vertical displacement of the flow. In order to validate the positive effect of the internal motion over the heat transfer between the pipe and the water flow, an experiment was accomplished. The flow tube filled with liquid was introduced in a water recipient and vibrated at several frequencies. The water temperatures inside and outside the tube were recorded. The values for water temperatures measured during the warming and cooling intervals confirm that by vibration, the time for heat exchange is decreasing if the vibrating frequencies near the resonance frequency are considered. [ABSTRACT FROM AUTHOR]

Consideration is given to dynamic behavior of cylindrical pressure pipe with elastic boundary conditions. Based on Sanders’ shell theory and Hamilton principle, the system equations are established for integrating the uniform distributed pressure into the elastic boundary condition. In the analytical formulation, the Rayleigh–Ritz method with a set of displacement shape functions is used to deduce mass, damping, and stiffness matrices of the pipe system. The displacements in three directions are represented by the characteristic orthogonal polynomial series and trigonometric functions which are satisfied with the elastic boundary conditions, which are represented as four sets of independent springs placed at the ends including three sets of linear springs and one set of rotational spring. The pressure pipe always suffers a uniform distributed pressure in radial direction. To verify the accuracy and reliability of the present method, several numerical examples with classical boundary condition, including free and simply supported supports are listed and comparisons are made with open literature. Then the influences of boundary restraint stiffness and the distributed pressure on natural frequency and the forced vibration response are studied: The natural frequencies increase significantly as the restraint stiffness or the distributed pressure increases. Compared to the rotational spring stiffness, the stiffnesses of axial, radial, and circumferential springs have more significant effect on natural frequency. And the lower modes are more sensitive on restraint stiffness than higher modes. But the variation of natural frequency with respect to the spring stiffness decreases monotonically with the increasing distributed pressure. The forced vibration response is also affected by the restraint stiffness. [ABSTRACT FROM AUTHOR]

The resistance offered by the inner soil to the vertical oscillation of an end-bearing pipe pile is studied analytically. The differences in the resistance to pile vibrations associated with the inner soil and the outer soil are underlined via example applications and theoretical considerations. Simplified, reduced solutions are also derived, to further investigate the wave propagation mechanisms governing the problem. [ABSTRACT FROM AUTHOR]

This paper treats the two-phase flow-induced vibration in pipes. A broad range of two-phase flow conditions, including bubbly, dispersed and slug flow, were tested in a clamped-clamped straight horizontal pipe. The vibration response of both transversal directions for two span lengths was measured. From experimental results, an in-depth discussion on the nature of the flow excitation and flow-parameters influence is presented. The hydrodynamic mass parameter is also studied. Experimental results suggest that it is proportional to mixture density. On the other hand, two analytical formulations were developed and tested against experimental results. One formulation predicts the quadratic trend between standard deviation of acceleration and shear velocity found in experiments. The other formulation indicates that the peak-frequency of vibration response depends strongly on void fraction. It provides accurate predictions of peak-frequency, predicting 97.6% of the data within ±10% error bands. [ABSTRACT FROM AUTHOR]

The vibration of pipes supported by a flexible tank wall is analyzed taking into account the hydroelastic vibration of the tank and the nonlinearity caused by the support clearances. Because the support clearances increase the pipe displacement, it is important to examine whether the support clearances augment the pipe stress. We illustrate that the support clearances can cause an increase in the pipe stress not only due to the increase in pipe displacement but also to the difference between elastic behaviors of the tank wall and pipes. The tank wall and pipes are dominated by membrane and bending deformations, respectively. Furthermore, we illustrate that the support clearances render a stress reduction method ineffective. In this study, a semi-analytical method is applied, rather than a full finite element analysis. The semianalytical method is helpful not only for computationally efficient analysis but also for gaining physical insight into the clearance-nonlinearity-induced stress behaviors noted above. [ABSTRACT FROM AUTHOR]

A pile is a fundamental part of fixed type platform which commonly used to support superstructure rig in the offshore area. A seamless pipe is usually used as the pile structure. However, this seamless pipe is a high-priced pipe and scarce to find in Indonesia. ERW (Electric Resistant Welded) pipe can be used for an alternative selection of the seamless pipe for piling structure. However, ERW pipe production may have a defect in the form of a cold weld and a hook crack. This paper studies the possibility of ERW pipe utilization as the piling structure. A case study was conducted for ERW pipe NPS 24 and length of 6 m. This research conducted by using eta-FEMB and LS-DYNA software to examine the effective stress of the pile structure during installation. Numerical simulations were carried out on the pile structure with crack modelling and withstand multiple impact loading. The result was compared with failure criterion based on API RP 2A WSD. Those criteria include Axial Allowable Tensile Stress (AATS), Axial Allowable Compressive Stress (AACS) and Critical Hoop Buckling Stress (CHBS). Based on this preliminary analysis, we hypothesize that the ERW pipe with defect length up to 5 mm can be used for the piling structure. However, this analysis need further investigation in order to be a recommendation for substituting seamless pipe for piling structure. [ABSTRACT FROM AUTHOR]

The transducer most widely used for vibration measurement is the piezoelectric accelerometer. This application has been explored for flow rate measurement, since some studies have verified the narrow correlation between ratio of flow and vibration. The technique consists of measure the vibration induced by the flow in the pipeline, has been considered as promising, in the sense of enabling the development of a sensor that presents advantageous characteristics such as non-intrusiveness, non-invasiveness and reduced cost. This paper shows the method of measurement of flow in pipe based on vibration caused by transit of water, without the need of flow interruption or opening of pipe for installation of water meters. Further are present experimental measurements and metrological validation in laboratory accredited for calibration of flowmeters. [ABSTRACT FROM AUTHOR]

Overcut is a critical issue in pipejacking, especially for the cases with difficult geology conditions or with a curved alignment. For those cases, lubricants are frequently applied to fill the gap or to reduce the friction between soil and pipes. However, it is very difficult to quantitatively determine the real contact condition between the soil and pipe. New technology for soil-pipe interaction measurement is still scarce and requires further development. There are only indirect methods practically available for soil-pipe interaction, and engineering judgment is required for those measurements. In this study, the finite element software ABAQUS is used for the numerical analysis of the pipejacking, including the influence of lubricant property and the overcut on the soil-pipe interaction. The results show that lubrication can significantly reduce the stress concentration surrounding the pipe, the disturbing of the pipejacking on the surrounding soil was increased as the overcut increasing, the soil stress was decreased but the disturbance on the excavation face will be increased. [ABSTRACT FROM AUTHOR]

The problems arising during the use of ribbed pipes at the Angarsk Petrochemical Complex and the process of formation of deposits and their effect on the technology of products manufacture are studied. [ABSTRACT FROM AUTHOR]

Many studies have aimed to characterize pressurized transient hydraulics. However, it remains difficult to assess the importance of dynamic effects in a robust manner, and modeling is further complicated by the tension between computational efficiency and physical accuracy. To address such challenges for incompressible flows, this article presents an adaptive modeling approach that combines a novel hybrid formulation, termed the hybrid global gradient algorithm (HGGA), with a variable time step (VTS). The HGGA combines the generalized and rigid water column global gradient algorithms, so it can adapt to inertially-dominated flows and those without such effects. Computational efficiency and physical accuracy are balanced by adjusting the formulation according to the simulated hydraulics. Three physically-based indicators are then introduced to characterize unsteady flow: these actively inform the HGGA of how to model a system. Two pipe networks are used to demonstrate the current work. The first illustrates the utility of the inertial indicators, and the second comprises an extended period simulation with the VTS scheme. Although more computationally intensive than conventional modeling, the methodology is shown to provide a better representation of dynamic hydraulics. [ABSTRACT FROM AUTHOR]