Fluid-filled Pipe Research Articles

Vibration analysis of piping system coupled with conical-cylindrical combined shells

Fluid-filled piping system are widely used in power cooling, fuel transportation and underwater vessel, which not only produce vibration along the system, but also transmit to the connecting structure to generate noise in ambient environment. Most investigations have concentrated on either the vibration characteristics of piping systems or of combined shells separately. In this work, an analytical impedance synthesis method (ISM) is proposed to analyze the vibration characteristics of a pipe-hull coupled system, in which the hull can be simplified to a combined conical-stiffened cylindrical-hemisphere shell. The piping system is modeled by fluid-filled beams in three-dimensional configuration. Wave function and power series solution are used to describe the displacements of cylindrical and conical shell respectively. Based on exact analytical solutions, the impedance matrix of each segment is established separately and assembled in the global coordinate by displacement continuity and force balance boundary conditions. Forced responses are compared with the experimental results to verify the correctness of the method.

Comparative Analysis of Water Hammer Performance in Different Pipe Parameters with FSI

Water hammer (WH) is a critical phenomenon in fluid-filled piping systems that can lead to severe pressure surges and structural damage. The characteristics of the pipe material, geometry, and support conditions play a crucial role in the fluid–structure interaction (FSI) during WH events. This study investigates the impact of various pipe parameters, including material, length, thickness, and diameter, on the WH behavior using an FSI-based numerical approach. A comprehensive computational model was developed based on the algorithm presented in Delft Hydraulics Benchmark Problem (A) to simulate the WH phenomenon in pipes made of different materials, such as steel, copper, ductile iron, PPR (polypropylene random copolymer), and GRP (glass-reinforced plastic). This study examines the influence of pipe parameters on WH performance in pipelines, utilizing FSI to analyze the phenomenon. The results show that the pipe material has a significant influence on the pressure wave speed, stress wave propagation, and the overall system response during WH. Pipes with lower modulus of elasticity, such as PPR and GRP, exhibit lower pressure wave speeds but higher stress wave speeds compared with steel pipes. Increasing the elastic modulus, pipe wall thickness, length, and diameter enhances the pipe’s stiffness and impacts the timing, magnitude of pressure surges, and the likelihood of cavitation. The findings of this study provide valuable insights into the design and mitigation of WH in piping systems.

Sparse reconstruction of ultrasonic guided wave signals of fluid-filled pipes by multistrategy hybrid DBO-OMP using dispersive Hanning-windowed chirplet model

Ultrasonic guided waves (UGWs) in fluid-filled pipes are subject to more severe dispersion and coherent noise than those of vacant pipes, posing significant challenges for defect identification and localization. To this end, a novel sparse signal decomposition method called multistrategy hybrid dung beetle optimization based orthogonal matching pursuit (MHDBO-OMP) using dispersive Hanning-windowed chirplet model was proposed, of which the model not only represents the nonlinear frequency and asymmetric envelope of the dispersive UGW, but also contains the mode and propagation distance information, and this model exhibits better matching and interpretability than the other UGW models. For dispersive perturbed UGW signals with multiple modes and features, MHDBO-OMP achieves high reconstruction accuracy in both signal reconstruction (RES < 0.3) and propagation distance estimation (RES < 3 cm). When applied to experimental UGW signals obtained from water/oil-filled pipes containing cracks and corrosion pits, MHDBO-OMP successfully reconstructs dispersion-compensated signals that solely contain feature signals, and the minimum location error is 0.72 cm while the average location error is 2.65 cm. © 2001 Elsevier Science. All rights reserved.

From Radio to In-Pipe Acoustic Communication for Smart Water Networks in Urban Environments: Design Challenges and Future Trends

The smart management of water resources is an increasingly important topic in today’s society. In this context, the paradigm of Smart Water Grids (SWGs) aims at a constant monitoring through a network of smart nodes deployed over the water distribution infrastructure. This facilitates a continuous assessment of water quality and the state of health of the pipeline infrastructure, enabling early detection of leaks and water contamination. Acoustic-wave-based technology has arisen as a viable communication technique among the nodes of the network. Such technology can be suitable for replacing traditional wireless networks in SWGs, as the acoustic channel is intrinsically embedded in the water supply network. However, the fluid-filled pipe is one of the most challenging media for data communication. Existing works proposing in-pipe acoustic communication systems are promising, but a comparison between the different implementations and their performance has not yet been reported. This paper reviews existing works dealing with acoustic-based communication networks in real large-scale urban water supply networks. For this purpose, an overview of the characteristics, trends and design challenges of existing works is provided in the present work as a guideline for future research.

Measurement of the transmission loss of a rubber hose

Flexible rubber hoses can provide significant attenuation of vibro-acoustic energy in fluid-filled piping systems. The vibro-acoustic performance of rubber hoses can be measured by using a variation of a water-filled impedance tube, using the two-source method, to determine the impedance and transmission loss. This paper presents the test method and results from measurements performed to characterize the vibro-acoustic behavior of a water-filled, 1.5 m length of DN100 fiber reinforced rubber hose, with beaded and flanged terminations, at two pressures. The test results indicated that the rubber hose test specimen achieved a fluid-borne transmission loss of at least 5-10 dB at low frequencies increasing to more than 45 dB at 1kHz.

Propagation characteristics analysis of high-frequency vibration in pumped storage power station based on a 1D fluid-solid coupling model

High-frequency pressure fluctuation is a common hydraulic phenomenon in pumped storage power station (PSPS), which is caused by the rotor-stator interaction in the pumped turbine. The propagation of the high-frequency vibration (HFV) could transmit the vibration energy to the upstream headrace tunnel, inducing severe environmental vibration and noise pollution. This study aims to establish an applicable numerical model to investigate the propagation characteristics of HFV, and evaluate the vibration magnitude of both solid and fluid in the headrace tunnel of the PSPS. In this study, a one-dimensional (1D) numerical model is established for the fluid solid interaction (FSI) behavior of the pipe, where the equations of solid and fluid are solved intuitively in the time domain by the Finite Difference Method (FDM) and Method of Characteristics (MOC), respectively. Detailed discretization schemes and solution procedures are deduced and presented in this study. Four validation cases are carried out to examine the established model. The results demonstrate that the established mode is applicable for predicting the vibration in the fluid-filled pipe (FFP). The non-reflect boundary conditions are proposed to eliminate the influence of the reflected wave from the boundary. The propagation characteristics of the high-frequency vibration (HFV) in FFP are comprehensively analyzed and summarized based on a real PSPS. And magnitude distributions of the pressure fluctuation, axial and radial vibration along the pipeline axis are presented and discussed.

Numerical Investigations of a Two-Way Coupled Fluid–Structure Interaction Approach for Fast Transients in Fluid-Filled Flexible Piping Systems

Numerical Investigations of a Two-Way Coupled Fluid–Structure Interaction Approach for Fast Transients in Fluid-Filled Flexible Piping Systems

Influence of transverse vibration induced by fluid-structure interaction on pipeline strength

The transverse vibration of a pipe induced by fluid–structure interaction can cause abnormal fluctuation, buckling and flutter. In this paper, the effect of fluid–structure interaction on the transverse vibration of nuclear power pipelines is analyzed theoretically and numerically. Firstly, a theoretical model of the nuclear power pipe and the fluid that flows internally is established based on Hamilton’s principle. Then, an analytical solution of the transverse vibration differential equation considering the fluid–structure interaction is obtained. Next, a finite element analysis of the transverse vibration of nuclear power pipe due to fluid–structure interaction is carried out. In the end, the analytical solutions of natural frequency, vibration performance, mechanics characteristic of pipes are compared with the finite element solution. The results show that the analytical solutions of transverse vibration of pipes are consistent with the finite element solutions. In addition, the results show that the negative effect of transverse vibration due to fluid–structure interaction on the pipe strength is worthy of attention only at a high internal pressure or velocity. It is of great significance to improve the safety and economic benefits of fluid-filled pipes.

High resolution acoustic identification of clusters of small blockages in fluid-filled pipe using maximum likelihood estimation

This paper presents a method for identifying a cluster of small blockages (i.e., blockages with length on the order of centimeters and radial extent on the order of millimeters and separated by a distance on the order of few centimeters) in pressurized fluid-filled pipes using sound waves. This focus on defects with small scale, and, thus, small scattering strength is exploited to develop a Neumann series solution for the scattered acoustic wave field. The probing waves are such that the Helmholtz number (ratio of blockage longitudinal length scale and probing acoustic wavelength) is of order 1 or larger. A high resolution inverse technique for identifying a cluster of small blockages based on the maximum likelihood estimation principle is developed. The proposed technique uses two-dimensional search space to resolve each blockage in the cluster and requires a single measurement point only. The method is successfully tested through both numerical and laboratory experiments. The proposed methodology allows an early identification of a cluster of small defects and leads to reliable condition assessment of pipelines, which is necessary to inform decisions as to when remedial actions are required.

Effect of axial stresses on longitudinal guided waves in a fluid-filled pipe.

This paper describes the study of the acoustic field of a fluid-filled pipe subjected to axial stress based on the acoustoelastic theory. The pipe with applied axial stresses can be approximated as a transversely isotropic pipe, and hence, its acoustic fields can be expressed using potential functions. The velocity changes of longitudinal wave modes with applied stresses are analyzed for the pipe filled with oil by an analytical method. It was found that the longitudinal mode velocity changes almost uniformly with the applied stresses. The high speed and low frequency plateaus of longitudinal wave modes are sensitive to stress. The relationship between stress and the velocity change of the guided wave is given. The results indicate that non-destructive testing techniques using longitudinal wave modes have strong potential to identify and monitor the stress levels in pipe structures.

A study on acoustic performance of dissipative silencer for fluid-filled pipe system according to acoustic models of absorbing material

In many industrial systems involving pipe or duct structures, sound transmission modeling is critical to noise treatment and control. A typical noise treatment method applied to pipe structures is to use a silencer. In particular, a dissipative silencer with a sound absorbing material has a noise control ability to reduce noise through successive sound reflections by impedance mismatch while dissipating incident sound energy as heat. In this study, the acoustic performance of a dissipative silencer lined with multi-layered absorbing materials for fluid-filled pipe system is investigated. Herein, the absorbing materials are modeled applying poroelastic and viscoelastic theories. In the analysis, the eigenvalues and eigenfunctions in the dissipative silencer are determined from the rigid wall boundary condition and the interfaces between the absorbing materials, and then the acoustic performance is compared by obtaining the transmission loss using the mode matching method. Also, a parametric study is conducted to investigate the effect of the number and arrangement of layers on the acoustic performance of the silencer according to the absorbing material properties.

A study of the frequency response of fluid-structure interactions in a three-dimensional fluid-filled pipe system using an impedance synthesis method

Fluid-filled pipelines are widely used in engineering and industry. An analysis of the frequency dynamic responses of three-dimensional pipes is presented in this paper. A general formulation is developed based on an impedance matrix transmission approach in which a T-shaped pipe system can be assembled from three straight pipes. For validation purposes, numerical results are compared with data given by finite element method (FEM) software, previous literature, and an experiment. In the experiment, the three-dimensional pipe system is suspended horizontally on spring wires and is excited in the X and Y directions. It is found that the results calculated using the proposed method match the experimental results well. A dimensionless analysis of Poisson’s coupling is then carried out, and the junction coupling of the branch pipe is analyzed as a function of its angle. Through this work, it is shown that the proposed method is efficient and can be used to predict the vibration of three-dimensional pipes.

Influence of Shear Effects on the Characteristics of Axisymmetric Wave Propagation in a Buried Fluid-Filled Pipe

The acoustic propagation characteristics of axisymmetric waves have been widely used in leak detection of fluid-filled pipes. The related acoustic methods and equipment are gradually coming to the market, but their theoretical research obviously lags behind the field practice, which seriously restricts the breakthrough and innovation of this technology. Based on the fully three-dimensional effect of the surrounding medium, a coupled motion equation of axisymmetric wave of buried liquid-filled pipes is derived in detail, a contact coefficient is used to express the coupling strength between surrounding medium and pipe, then, a general equation of motion was derived which contain the pipe soil lubrication contact, pipe soil compact contact and pipe in water and air. Finally, the corresponding numerical calculation model is established and solved used numerical method. The shear effects of the surrounding medium and the shear effects at the interface between surrounding medium and pipe are discussed in detail. The output indicates that the surrounding medium is to add mass to the pipe wall, but the shear effect is to add stiffness. With the consideration of the contact strength between the pipe and the medium, the additional mass and the pipe wall will resonate at a specific frequency, resulting in a significant increase in the radiation wave to the surrounding medium. The research contents have great guiding effect on the theory of acoustic wave propagation and the engineering application of leak detection technology in the buried pipe.

Band gap analysis of composite fluid-filled pipe with periodically axial support or dynamic vibration absorbers

Two kinds of periodic composite pipes with support or dynamic vibration absorber are designed based on the theory of phononic crystals. Axial vibration and band gaps of composite fluid-filled pipe are calculated by using transfer matrix method and Bloch wave theory. The present fluid–structure interaction model and frequency domain calculation method are validated by comparing the velocity of fluid from a FEM model. The results show that the stop bands frequency of velocity responses are in good agreement with band gap. Longer length of a single cell decreases the beginning frequency and width of both two kinds’ band gaps.

Numerical analysis of vibroacoustic beamforming gains for acoustic source detection inside a pipe conveying turbulent flow

This study concerns a monitoring technique based on vibration measurements for identifying the presence of an acoustic source in a fluid-filled pipe conveying turbulent flow. In such situation, the source-induced vibrations can be smeared with the flow-induced vibrations, which hinders the source detection. To increase the signal-to-noise ratio (SNR), beamforming techniques can be applied to the vibrations measured by an array of accelerometers mounted on the pipe. However, the current problem is more complex and challenging than most typical beamforming applications due to strong fluid–structure coupling and to the presence of resonant modes and internal flow excitations. Numerical vibroacoustic methods are presented to predict the vibratory response of a pipe excited by a monopole source and/or a turbulent boundary layer (TBL). The cross-spectral matrices of the computed radial accelerations induced by the monopole source to be detected and by the TBL are used for assessing the performance of two vibroacoustic beamforming techniques. The array gains using both, the conventional and the MaxSNR beamforming approaches are estimated. Results indicate superior performance of the MaxSNR, which leads to significantly higher array gain.

Reduction of flexural vibration of a fluid-filled pipe with attached vibration absorbers

Dynamic vibration absorbers (DVAs) are often used to reduce vibrations in narrow frequency ranges. To reduce the flexural vibrations of a fluid-filled pipe system in a broader frequency band, several DVAs are attached to the pipe periodically to constitute a system akin to a locally resonant phononic crystal. Each DVA is analyzed based on mechanical impedance theory, and Bloch wave theory and the transfer matrix method are used to investigate the wave propagation in such a periodic system. The validity and accuracy of the natural frequencies and dynamic responses obtained are verified by comparing the present numerical results with results from the finite-element method. Also analyzed are the band-gap formation mechanism and how various system parameters influence the band-gap behavior, such as how the lattice and absorber properties influence the location and width of the lowest band gap. Lastly, a mass–spring DVA is designed and attached periodically to find the existence of locally resonant band gaps. The analytical and experimental results show that the mechanical impedance of the DVA is the main factor for the band-gap formation mechanism. When the DVAs are periodically arrayed, it can more effectively control flexural pipe vibration by broadening the bandwidth they attenuate and increase the magnitude of vibration attenuation.

Broadband bandgap and shock vibration properties of acoustic metamaterial fluid-filled pipes

This paper describes the design of an acoustic metamaterial fluid-filled pipe with periodically variable materials. The aim of this design is to improve the broadband vibration attenuation frequency range of fluid-filled pipes by combining the mechanism of local resonance (LR) and Bragg scattering bandgaps (BGs). The vibration bandgap (BG) of the pipe is investigated using the transfer matrix method. It is demonstrated that the coupling of LR and Bragg scattering BGs produces a remarkable improvement in effective bandwidth. Additionally, the external shock excitation effect on pipe vibration is calculated using the finite element method. This indicates that the strongest interaction between the LR and Bragg BG is achieved when the LR is located in the center of the softer material. However, this strong coupling effect may cause some degeneration in the Bragg BG. Moreover, in practical applications, the position of the LR BG should be determined according to the vibration BG requirements. Experimental samples are prepared, and an experimental test and verification procedure is conducted. The positions and widths of the BG and the shock vibration properties measured during the experiment agree well with the theoretical results. This research provides a technical and theoretical basis for the attenuation design of vibration reduction systems for fluid-filled pipes that may be subjected to explosive loads.

In-plane wave propagation analysis of fluid-filled L-Shape pipe with multiple supports by using impedance synthesis method

In order to reduce the vibration of planar pipe systems assembled by multiple segments, bends and supports, an impedance synthesis method, which is based on the Timoshenko beam theory, is used to analyze vibration and wave propagation characteristics. Due to junction coupling at unanchored bends, there exists interesting hydraulic and structural wave transmission and reflection. By comparing the natural frequencies and dynamic responses with results available in the literature and with results of the finite-element method, the present calculation method is validated. Based on the relation between the wave number and the propagation band gap, parametric studies of a pipe system with periodic supports are presented. In addition, novel experiments are carried out to validate the present method and to investigate the dynamic response of a pipe system with periodic supports. The results of this paper may provide guidance for vibration reduction of supported pipe systems with elbows.

Transformation between damped and undamped waterhammer waves

This paper derives a mathematical relation between the damped and undamped waves propagating in a fluid-filled pipe. The damping considered is caused by the steady and unsteady friction and the pipe wall visco-elasticity. The derived relation is solved so that the idealized undamped pressure wave signal is obtained from the measured damped pressure signal. Physically, the proposed transformation is an amplification operation that adds back the energy that was lost due to the damping. This means that measurement errors will also be amplified under the transformation, making the problem ill-posed. The truncated singular value decomposition method is used to regularize the transformation. Both numerical and laboratory experiments are conducted to show the validity of this transformation. The results show that the transformation can accurately predict the shape and size of the reflections that were distorted due to the wave dissipation and dispersion.

The leak noise spectrum in gas pipeline systems: Theoretical and experimental investigation

This paper is concerned with a theoretical and experimental investigation into the pressure spectrum in a pressurised fluid-filled pipe containing a leak. A general theoretical framework for predicting the leak noise spectrum is derived. A simple relationship is developed between the leak noise pressure spectrum in the pipe and the velocity spectrum at the leak orifice. Measurements of the leak noise spectrum are also presented from a pipe rig with air under pressure. The variation in noise spectrum is investigated for various leak orifice diameters and pipe pressures and compared against predictions from the theoretical model. The model is shown to predict the general shape of the pressure spectrum when the turbulence quantities are appropriately chosen. The variation in overall noise with leak orifice radius and exit velocity is also well-captured by the theoretical model.