Wave Propagation In Pipe Research Articles

Influence of temperature on fouling removal for pipeline based on eco-friendly ultrasonic guided wave technology

When industrial pipelines are used to transport production materials, the scale can easily form on the inner wall of a pipeline due to long-term contact with the liquid medium. Scaling in industrial pipelines is a common problem that poses a great threat to the production process and environmental protection. In this paper, the influence of temperature on the fouling removal process in pipes is studied. A finite element simulation model was established for guided wave propagation in pipes with different temperatures to obtain the acoustic pressure distribution along the pipes, showing that when the temperature increases, the acoustic pressure value on the solid–liquid surface of the pipes increases, and the cavitation threshold decreases. The experimental system for pipe descaling at different temperatures was established, when the temperature is from 20 to 60 °C, the descaling rate in the inner wall of the pipe far from the transducer is increased from 77.49 to 93.71%, the descaling rate in the inner wall of the pipe near the transducer is increased from 87.01 to 97.02%. The experimental results showed that the descaling performance is better when the pipeline temperature is higher.Compared with the traditional technology, the pipeline descaling technology based on ultrasonic guided waves is highly efficient, safe and eco-friendly, which can remove the fouling inside pipeline online without affecting the transportation. The above conclusions could provide a reference for further popularizing the application of the descaling technology based on ultrasonic guided wave. Graphical abstractLabVIEW program was written by computer to generate 10Vp-p sinusoidal continuous wave digital signal, and then the digital signal is converted into analog voltage signal by using a data acquisition card (DAQ), and then the analog voltage signal is amplified to 300Vp-p by input power amplifier. The amplified analog voltage signal is applied to the transducer, and the transducer converts the voltage signal into vibration signal to generate ultrasonic guided waves in the pipeline and remove dirt in the pipeline.

Research on the Impediment to Vibration Wave Propagation of Pipe from a vibration isolation mass

In order to control the pipe vibration, the performance of flexible connection with vibration isolation mass in impeding vibration wave propagation is studied. Based on the principle of impedance mismatching and numerical analysis method, the influences of vibration isolation mass and rotational inertia on the vibration wave propagation in pipe were discussed. The results show that the isolation mass is good at reducing the vibration of wave transmission in intermediate and high frequency domain. Meanwhile, The larger rotational inertia of the isolation mass, the better the damping effect. A useful reference was provided for the application of flexible connection to the vibration isolation and noise reduction of ship pipe.

Identification of multiple leaks in pipeline II: Iterative beamforming and leak number estimation

Abstract This paper considers the problem of detecting multiple leaks in a water-filled pipe using transient waves. A previous paper by the authors proposes a maximum likelihood (ML) method for leak detection based on an approximate linear model of wave propagation in pipe and shows that it is efficient, robust with noise, and super-resolved. However, that ML method needs to solve an N-parameter optimization problem (N is the leak number) which is high dimensional, non-convex and has many local maxima when N is large. The present paper deals with the multiple-leak detection problem where the leak number is high. A ML based iterative procedure, known as the iterative beamforming (IB) method, is proposed. Given an initial value of model parameter (locations and sizes of leaks) in each iteration, the complex inverse problem with 2 N unknown parameters is decomposed into N one-dimensional optimization problems, which largely decreases the computational complexity. More specifically, IB iteratively estimates the contributions from various leaks to the pressure head measurement and then performs a 1-D ML method on these estimates. In order to estimate the unknown number of leaks, model selection methods, known as Akaike information criterion (AIC) and Bayesian information criterion (BIC), are used and they are proven to be efficient to estimate the actual leak number. Numerical simulations show that five leaks can be accurately identified with super-resolution and the leak number can be correctly estimated using the methods proposed in this paper.

Acoustic Wave Propagation in Air-Filled Pipes Using Finite Element Analysis

The major objective of this work is to develop an efficient Finite Element Analysis (FEA) procedure to simulate wave propagation in air-filled pipes accurately. The development of such a simulation technique is essential in the study of wave propagation in pipe networks such as oil and gas pipelines and urban water distribution networks. While numerical analysis using FEA seems superficially straight forward, this paper demonstrates that the element type and refinement used for acoustic FEA have a significant effect on the accuracy of the result achieved and the efficiency of the computation. In particular, it is shown that the well-known, better overall performance achieved with 3D solid hexahedral elements in comparison with 2D-type elements in most stress and thermal applications does not occur with acoustic analysis. In this paper, FEA models were developed taking into account the influence of element type and sizes using 2D-like and 3D element formulations, as well as linear and quadratic nodal interpolations. Different mesh sizes, ranging from large to very small acoustic wavelengths, were considered. The simulation scheme was verified using the Time of Flight approach to derive the predicted acoustic wave velocity which was compared with the true acoustic wave velocity, based on the input bulk modulus and density of air. For finite element sizes of the same order as acoustic wavelengths which correspond to acoustic frequencies between 1 kHz and 1 MHz, the errors associated with the predictions based on the 3D solid hexahedral acoustic elements were mostly greater than 15%. However, for the same element sizes, the errors associated with the predictions based on the 2D-like axisymmetric solid acoustic elements were mostly less than 2%. This indicates that the 2D-like axisymmetric solid acoustic elements are much more efficient than the 3D hexahedral acoustic elements in predicting acoustic wave propagation in air-filled pipes, as they give higher accuracies and are less computationally intensive. In most stress and thermal FEA, the 3D solid hexahedral elements are much more efficient than 2D-type elements. However, for acoustic FEA, the results show that 2D-like axisymmetric elements are much more efficient than 3D solid hexahedral elements.

Investigation of guided wave propagation in pipes fully and partially embedded in concrete.

The application of long-range guided-wave testing to pipes embedded in concrete results in unpredictable test-ranges. The influence of the circumferential extent of the embedding-concrete around a steel pipe on the guided wave propagation is investigated. An analytical model is used to study the axisymmetric fully embedded pipe case, while explicit finite-element and semi-analytical finite-element simulations are utilised to investigate a partially embedded pipe. Model predictions and simulations are compared with full-scale guided-wave tests. The transmission-loss of the T(0,1)-mode in an 8 in. steel pipe fully embedded over an axial length of 0.4 m is found to be in the range of 32-36 dB while it reduces by a factor of 5 when only 50% of the circumference is embedded. The transmission-loss in a fully embedded pipe is mainly due to attenuation in the embedded section while in a partially embedded pipe it depend strongly on the extent of mode-conversion at entry to the embedded-section; low loss modes with energy concentrated in the region of the circumference not-covered with concrete have been identified. The results show that in a fully embedded pipe, inspection beyond a short distance will not be possible, whereas when the concrete is debonded over a fraction of the pipe circumference, inspection of substantially longer lengths may be possible.

Model Optimization and Flow Rate Prediction in Electro-injectors of Diesel Injection Systems

Modelling and control of the injection process in common rail Diesel engines has attracted the interest of many researches also in recent years. This paper adds a new contribution for accurately modelling electro-injectors. Namely, not only nonlinear dynamics of the fuel flow and electro-mechanical aspects are considered but also a different representation of high-pressure wave propagation in pipes that feed the injector volumes. Model parameters are optimized by an evolutionary technique and a simulation study analyzes the prediction capability of the optimized model. The optimized model shows a superior fitting to experimental data than a nominal and a conventional model, and then it could be profitably used for injection control.

Effective Models of PZT Actuators for Numerical Simulation of Elastic Wave Propagation

In this study, to accurately identify the functions of piezoelectric actuators and sensors for the generation and collection of elastic waves in typical engineering structures, several effective models of surface-bounded flat PZT disks are further developed and validated for numerical modelling of elastic wave propagations. Based on these models, a series of finite element models of elastic waves in plates are devised using both implicit and explicit dynamics analysis techniques and those numerical simulations are conducted and verified one another. The results flowed from the present research is being used to study the elastic wave propagation in pipes and develop an online structural health monitoring (SHM) system with an integrated piezoelectric actuator-sensor network.

Real-time multibody application for tree harvester truck simulator

A real-time simulator for a tree harvester has been developed for training in more effective vehicle and cutter operation and tree management. The equations of motion of the constrained mechanical system of the tree harvester are expressed using a recursive formulation. The hydraulic actuator modelling of the harvester is based on lumped fluid theory, in which the hydraulic circuit is divided into discrete volumes where pressures are assumed to be distributed equally, while pressure wave propagation in pipes and hoses is assumed to be negligible. For modelling purposes, valves are broken up into a number of adjustable restrictors, which can be modelled separately. The contact model used comprises two parts: collision detection and response. Collision detection identifies whether, when and where moving bodies may come in contact. Collision response prevents penetration when contact occurs and identifies how it should behave after collision. A penalty method is used in this study to establish object collision events. The major achievement of this study is combining these three modelling methods in the application of a real-time simulator.

Guided wave propagation in single and double layer hollow cylinders embedded in infinite media

Millions of miles of pipes are being used for the transportation, distribution, and local use of petroleum products, gas, water, and chemicals. Most of the pipes are buried in soil, leading to the significance of the study on the subject of guided wave propagation in pipes with soil influence. Previous investigations of ultrasonic guided wave propagation in an elastic hollow cylinder and in an elastic hollow cylinder coated with a viscoelastic material have led to the development of inspection techniques for bare and coated pipes. However, the lack of investigation on guided wave propagation in hollow cylinders embedded in infinite media like soil has hindered the development of pipe inspection methods. Therefore the influence of infinite media on wave propagation is explored in this paper. Dispersion curves and wave structures of both axisymmetric and nonaxisymmetric wave modes are developed. Due to the importance of the convergence of numerical calculations, the requirements of thickness and element number of the finite soil layer between hollow cylinder and infinite element layer are discussed, and an optimal combination is obtained in this paper. Wave structures are used for the mode identification in the non-monotonic region caused by the viscoelastic properties of coating and infinite media.

A system for magnetostrictive transduction of guided waves in fluid-filled pipes of small diameter

This paper is concerned with the design of magnetostrictive transducers for the excitation and detection of guided waves in metal pipes of small diameter (mm) and their application to the study of wave propagation in pipes filled with water or supercritical CO(2). Optimized system design is based on a simulation of the overall signal pathway which includes the electric circuit conditions at the transducers, mode excitability, and the wavenumber filtering effect of the spatial distribution of the exciting alternating magnetic field. A prototype system was built, and experimental observations on small diameter pipes indicated good agreement with expected results from simulations. The reassigned spectrogram has been used to compare expectation on the basis of guided wave dispersion curves for fluid-filled pipes with experimental data.

금속 배관의 연성된 음향 전파 특성

The circular cylinder pipes are used in the many industrial areas. In this paper, the acoustic wave propagation in the pipe containing a gas is researched. First of all, the theory for the coupled acoustic wave propagation in a pipe is investigated. Acoustic wave propagation in pipe can not be occurred independently between the wave of the fluid and the shell. It requires complicated analysis. However, as a special case, the coupled wave in a high density pipe containing a light density medium is corresponded closely to the uncoupled in-vacuo shell waves and to the rigid-walled duct fluid waves. The coincidence frequencies of acoustic and shell modes contribute to the predominant energy transmission. The coincidence frequency means the frequency corresponding to the coincidence of the wavenumber in both acoustic and shell. In this paper, it is assumed that the internal medium is much lighter than the pipe shell. After the uncoupled acoustic wave in the internal medium and uncoupled shell wave are considered, the coincidence frequencies are found. The analysis is successfully confirmed by the verification of the experiment using the real long steel pipe. This work verifies that the coupled wave characteristic of the shell and the fluid is occurred as predominant energy transmission at the coincidence frequencies.

A new technique for modal acoustic emission pipeline leak location with one sensor

Due to the multi-mode and dispersion characteristics of acoustic wave propagation in a pipeline, traditional crosscorrelation techniques do not perform well for acoustic leak location. Based on the theory of modal acoustic emission (MAE), a technique of MAE pipeline leak location with one sensor is proposed. With the dispersion characteristics of guided wave propagation in pipe, two modes in the acoustic leak signal are isolated. Using the two modes isolated from one sensor, a leak location model is proposed. Leak location experiments have proved the validity of the one sensor MAE pipeline leak location technique.

Analysis of flexural mode focusing by a semianalytical finite element method.

Focusing is one of the most promising techniques for the detection of small defects in pipe works, in which guided waves including longitudinal and flexural modes are tuned so that ultrasonic energy can be focused at a target point in a pipe, and analysis of reflected waves gives information on defects such as location and size. In this paper, the focusing technique is discussed by way of a simulation of guided wave propagation in pipe by a semianalytical finite element method (SAFE). Experiments and SAFE calculations were compared for waveforms transmitted by a single transducer and received at different circumferential positions initially, and then the focusing phenomena were experimentally observed using focusing parameters obtained by calculations. Calculation and visualization were conducted to clarify focusing phenomena in pipe in investigating the potential of the focusing technique. These results show that the time-reversal idea helps in understanding focusing and that resolution of focusing is strongly affected by incident waveforms as well as the number of channels available in an experiment.

FEM Analysis of Circumferential Ultrasonic Wave Propagation in Pipes and Sizing of Axial Defects.

Circumferential wave propagation within pipe wall has been analyzed with an explicit finite element method under plane strain for thin walled steel pipes with an axial slot on the outer or inner surface as an artificial flaw. In the analysis, a plastic wedge of large attenuation is also taken into consideration to simulate the real pitch-catch measurement configuration with angle beam transducers. The numerical results show the pulse energy is not propagated along the path predicted by the ray theory. Namely, the pulse is propagated macroscopically along the circumference, however, the energy is carried locally along the radial direction. At the inner and outer surfaces of the pipe, the reflected and mode-converted waves are excited, thus the wave train becomes longer after multiple reflections. The numerical results of the received signal amplitude for various slot depths are in good agreement with the measured.

Finite element simulation of ultrasonic wave propagation in pipe and pressure vessel walls

Ultrasonic wave propagation is studied through application of finite element methods. Results for several time steps are plotted in color and a 16 mm animation film is made in order to visualize the sound wave propagation in materials. 2 MHz longitudinal and transversal wave paths are observed for the case of an imperfection between steel and stainless steel cladding. Application of finite element analysis together with color animation is established as a useful technique for further applications.

Dissipative and nondissipative fluid wave propagation in pipes

This presentation focuses on the pressure response at various locations along a finite fluid‐filled pipe to changes in the conditions at one end of the pipe. Initiated changes in the conditions represent valve operations that may be sudden valve closure or opening, or a gradual valve operation. The properties of the fluid are calculated via an equation of state, and the model presented is capable of simulating nondissipative and dissipative fluid dynamics. In addition, varying pipe diameters are considered along with pipe elasticity. For the nondissipative (no friction losses in the pipe) configuration, the numerical model is compared with a newly derived analytical solution, which describes the water hammer phenomena along the pipeline in response to a sudden valve closure. The pressure response propagates at the speed of sound through the fluid and oscillates in a combination of step changes. For the dissipative (with friction losses along the pipe) configuration, the kinetic energy is transformed into elastic energy of fluid and pipe by the valve operation. Also, the pressure response declines due to the friction energy losses. This model may apply to any pipeline setting such as transportation pipelines, oil, gas and water wells, water distribution systems, and plant circulating systems.

Analysis of flow induced valve operation and pressure wave propagation for single and two-phase flow conditions

The flow induced valve operation is calculated for single and two-phase flow conditions by the fluiddynamic computer code DYVRO and results are compared to experimental data. The analysis show that the operational behaviour of the valves is not only dependent on the condition of the induced flow, but also the pipe flow can cause a feedback as a result of the induced pressure waves. For the calculation of pressure wave propagation in pipes of which the operation of flow induced valves has a considerable influence it is therefore necessary to have a coupled analysis of the pressure wave propagation and the operational behaviour of the valves. The analyses of the fast transient transfer from steam to two-phase flow show a good agreement with experimental data. Hence even these very high loads on pipes resulting from such fluiddynamic transients can be calculated realistically.

Turbomachines hydrauliques Essais industriels et méthodes de calcul

Static and dynamic load data for steady and transient conditions are basic design requirements for the machines considered in this report. Tests and calculation are complementary as a source of this information, the former in supplying the basic calculation assumptions and confirming the "representativeness" of the mathematical model. Turbomachine structures are subjected to both hydraulic and mechanical loads. Mechanica1 loads mainly result from weight and inertia effects (centrifugal and prestress loads), which are fairly easily determined. Hydraulic loads are of two distinct kinds, one being associated with pressure and its fluctuations caused by water-hammer and wave propagation in pipes, and the other with flow forces through the bladings. Overpressure and overspeed values to take into account in connection with machine disconnection overloads are determined with the aid of a general transient condition calculation program for turbines, pumps and pump-turbines. Stationary pressure distributions around guide-vanes and runner blades are calculated by a blading flow program. Having defined the loads and checked them by model and industrial tests, strength calculations are carried out with general or specific programs, depending on the considered turbine component and type of stress. In addition, calculated data are checked against experimental data obtained on models and, especially, machines operating in the power station. The latter tests take place when a unit is started up, or during operation if a particular problem requires investigation. The first requirement for experimental investigation of dynamic machine behaviour is to determine the natural modes of its main components, e.g. stay-vanes, guide-vanes and runner, in both air and water. This is usually done by harmonic excitation (Figs. 1, 3, 4 and 6). In addition, basic frequency can be determined by impact (Fig. 5). The most important quantities measured in industrial tests include displacement, velocity, acceleration, pressure, stationary and moving component stresses and operating parameters, e.g. guide-vane and runner blade settings, electric power, levels, etc. Typical instrumentation for bulb units and pump-turbines is illustrated in Figures 7, 9 and 11. Runner stresses and pressure (Figs. 8 and 10) and flexural and torsional shaft stresses (Figs. 12 and 13) are determined by radio signal transmission. Radial and axial thrust on vertical-shaft units is measured by strain gauges on the bearing support and thrust bearing. The strain gauges are calibrated by applying radial load to the runner and lifting the rotor. Fig. 14 shows thrust behaviour for the pump-turbine at Sainte-Croix during load rejection when operating as a turbine. After magnetic recording of the data, the energy density spectra and inter-spectra are calculated by a correlator operating in conjunction with a numerical Fourier transformer (Fig. 2). The origin and type of pulsation associated with a given effect are determined by spectrum analysis (Fig. 15). The connection between tests and calculation is illustrated by an example of experimental and theoretical stress determination on a Francis turbine runner model (Figs. 16, 17 and 18). The calculation programs relate mainly to investigation of stress and elastic or plastic strain and determination of natural mode, response and structural stability. The methods used are based on integral equations and finite elements (Fig. 19). These programs are preceded by pre-processing programs, i.e. automatic meshing, band width minimalisation, calculating and positioning of loads, and are followed by data-plotting programs (Figs. 20, 21 and 22).

Acoustical Wave Propagation in Pipes

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