Tube Vibration Research Articles

Modelling of fluidelastic instability in tube bundles under two-phase bubbly flow conditions

One of the major factors affecting the integrity of tube bundles in a steam generator undergoing excessive vibrations is fluidelastic instability. Currently, a comprehensive model for predicting fluidelastic instability in tube bundles under two-phase cross flow has not been developed. Accurate design guidelines on fluidelastic instability in tube bundles is crucial to avoid tube failure due to tube vibrations. Therefore, this study presents a model for the fluidelastic instability (FEI) of a two-phase flow in a normal square tube bundle. The model focuses on the bubbly flow regime of a two-phase flow. This complex flow across the bundle is simplified as a one-dimensional inviscid flow in channels. The liquid is treated as a continuous phase while the gas bubbles are treated as compressible dispersed particles. The motion of each individual bubble is tracked in time domain simulations. Bubble-to-bubble interaction, bubble break-up, and bubble coalescence mechanisms are considered in the current model. The continuity equation is solved using the local instantaneous void fraction. The momentum equation is then solved to calculate the fluid forces on the tube. Using this technique, it was possible to calculate the change in the flow density around the tube. Prediction of the stability threshold showed very promising results when compared with the experimental data.

Investigation of Fluid-Induced Vibration and Heat Transfer of Helical Elastic Coiled Tube

The study of fluid-induced vibration of helical elastic coiled tubes to enhance heat transfer is very important for engineering practice and energy saving. Fluid-induced vibration and enhanced heat transfer of a helical elastic coiled tube heat exchanger were analyzed based on its finite element model, by using a two-way fluid–solid coupling method. Vibration response of the helical elastic coiled tubes, heat transfer coefficient per unit volume, and Nusselt number in vibration and nonvibration were studied at different entrance velocities and winding numbers. The results illustrate that there are a lot of vortexes in the heat exchanger and around the helical elastic coiled tubes. In the range of the entrance velocity , the vibration frequency is constant, whereas the vibration amplitude increases, and the tube vibration enhances the heat transfer of the helical elastic coiled tubes by 0.38%, 0.89%, 1.93%, and 13.65%, respectively. As the winding number increases from 5 to 9, it has a greater effect on the vibration amplitude, and the tube vibration enhances the heat transfer of the helical elastic coiled tubes by 1.93%, 3.39%, and 3.59%, respectively.

Thermally Induced Vibration Analysis of Flexible Beams Based on Isogeometric Analysis

Spacecraft flexible appendages may experience thermally induced vibrations (TIV) under sudden heating loads, which in consequence will be unable to complete their intended missions. Isogeometric analysis (IGA) utilizes, in an isoparametric concept, the same high order and high continuity non-uniform rational B-splines (NURBS) to represent both the geometry and the physical field of the structure. Compared to the traditional Lagrange polynomial based finite element method where only C0-continuity across elements can be achieved, IGA is geometrically exact and naturally fulfills the C1-continuity requirement of Euler–Bernoulli (EB) beam elements, therefore, does not need extra rotational degrees-of-freedom. In this paper, we present a thermally induced vibration analysis framework based on the isogeometric method where thermal and structural behaviors are coupled. We fully exploited the higher order, higher continuous and geometric exactness of the NURBS basis with both benchmarks and sophisticated problems. In particular, we studied the thermally induced vibrations of the Hubble Space Telescope (HST) solar panel where main factors influencing thermal flutters are studied, and where possible improvements of the analytical reference methods are discussed. Additionally, thermally induced vibrations of the thin-walled lenticular tubes are studied and two new configurations of the tube are proposed to effectively suppress the thermally induced vibrations. Numerical examples of both benchmarks and sophisticated problems confirm the accuracy and efficiency of the isogeometric analysis framework for thermally induced vibration analysis of space structures.

The Study of Tubing Vibration Mechanism in High Pressure Gas Well

Deep gas wells and gas fields have the characteristics of high pressure. The vibration of the tubing string during the production of gas wells causes the string to be subjected to severe stress and even dynamic fatigue failure. Therefore, this article is based on the dynamic finite element theory, aiming at the characteristics of large-size tubing strings in deep gas wells. The finite element mechanics model and mathematical model of the tubing string vibration of the packer of high-pressure gas wells were established, and the ANSYS software was re-developed. The finite element analysis program for the vibration dynamics of the unbuckled and buckled strings of gas wells was compiled with APDL, and the displacement of the longitudinal vibration of the tubing string of high-pressure gas wells was studied. According to different sizes of tubing strings currently used in deep gas wells and gas fields, simulation calculations are carried out, and the axial impact load and buckling damage laws of the tubing strings of the entire well section under different production rates are obtained. It provides a theoretical basis for the prediction of tubing string vibration law and measures to prevent tubing string vibration.

Effect of material on fluid elastic instability of parallel triangular tube array subjected to water cross

The effect of tube material and structure on fluid elastic instability is examined experimentally using a parallel triangular finned tube array with a P/D ratio of 1.78. Flow-induced vibration is a common cause of failure in shell and tube heat exchangers, and it may result in substantial harm to the heat exchanger as well as significant financial loss. There are different mechanisms responsible for flow induced vibration out of which fluid elastic instability and vortex shedding are the most severe due to their sudden occurrence and high amplitude of vibration. Different parameters affect the tube vibration when the tube array is subjected to water crossflow. In this paper effect of tube material and fin are examined for fluid elastic instability. Experimentation was performed to measure demanding velocity at fluid elastic instability for plain and finned tubes for steel, aluminum and copper material. A fully flexible tube array with a cantilever end condition and with a constant pitch ratio subjected to water cross flow was considered. Testing was done with a gradually increasing water flow rate from 5 m3/hr and increases up to 75 m3/hr to obtain fluid elastic instability. The relationship between the critical velocity at fluid elastic instability and the mass damping parameter was investigated using Connor's equation. The amplitude response of vibration concerning the change in velocity shows that the addition of fins, as well as the material change, greatly affects the fluid elastic instability. A small peak before the occurrence of fluid elastic instability was observed. This is maybe due to vortex shedding which further required to be verified using the Strouhal number.

Neuromodel of the "Crusher mill" Mechatronic Complex

To create a mechatron model of vacuum tube vibration system for rock cutting by flat auger tools based on physical and mechanical properties of processed array and kinematic characteristics of the instrument. The analytical model of the fracture process of rock cutting by tool vibration with considering of plastic properties of the massif were developed. The main technological parameters of massif vibrating cutting with normal variations were modeled: dependences of normal and tangential pressure in the zone of working body interaction with the medium, normal and shear stresses in the zone of destruction, rock characteristics of the medium, vibration parameters dependences on the characteristics of mechatronic system geometry of the contact area of flat incisors treated with medium. The choice of the computational model of the vibration rock cutting with the normal to the direction of movement of the working body fluctuations with considering arising from processes at once or disorders: the occurrence of compressive and tensile stresses were backgrounded. Main stages and interconnection options in the simulation of vibration cutting were established. Scientific novelty lies in the development of a method of analysis of contact interaction of roller working body molding machine with an array taking into account the changes in the stabilization process of physical and mechanical properties of the treated medium, the aim of which is to predict the required voltage and depth of the formed layer. The theoretical basis of rock cutting by flat auger tool taking into account the normal component of the vibration with respect to the movement direction allowing for the deformation of the rock mass and the contact interaction with the working body were established, that allows to improve the technology of drilling wells by reducing the power consumption of the cutting process. The results enable us to determine the parameters of power and kinematic conditions for the occurrence of the vibration cutting.

Nonlinear vibration and dynamic response of nano composite conical tube by conveying fluid flow

Modeling of tubes containing fluid flow is widely used in the study of heat exchangers, nuclear reactors, micro and nano tools, etc. This system is structurally simple but very complex in terms of dynamic behavior and vibrations. In this paper, an analytical relationship for nonlinear vibrations of self-excitation of a nanocomposite conical tube containing fluid flow is extracted, one end of which is free and the other side is fixed and is under gravitational force. The base material is assumed to be 1200 series aluminum, which is reinforced with carbon nanotubes. The Hamiltonian equations are obtained, assuming the Euler–Bernoulli beam theory and the use of the Galerkin method, dissected the partial derivative equations into Ordinary Differential Equations (ODE), then solved by MATLAB coding and investigated the effect of various parameters on system behavior. As the fluid velocity increases, the amplitude of the vibration increases and the nonlinear effects of the system increase, so more modes are needed to converge the responses. In a conical tube, the βT coefficient increases with increasing inner diameter along the tube and the system becomes more stable. Increasing the length of the pipe makes the opening conical pipe more stable and the closing conical pipe more unstable. The change in length has no effect on the stability of the cylindrical tube.

Fatigue investigation of tubing string in high-yield curved wells

In view of the fatigue failure of tubing string caused by fluid-induced vibration (FIV) in high-yield curved well, a nonlinear vibration model of tubing string is established using energy method and Hamilton principle, which considers the longitudinal/lateral coupling effect of tubing string and the nonlinear contact collision effect of tubing-casing and verified by a similar experiment of tubing vibration. The cumulative damage theory (Miner's Law) is used to establish the fatigue life prediction method of the tubing string in high-yield curved well combined with the stress response which was determined by the proposed vibration model and the S–N curve of the tubing material (13Cr-L80) which was measured by fatigue experiment. Based on that, the fatigue life of the tubing in two typical horizontal well and directional well was analyzed under different production rate (0.4–1.6 million square/day) and different tubing diameter (3.5-in and 4.5-in). The result shows that the most dangerous position of the tubing string appears between 3/4 position of the tubing string and the packer. The critical production rate of 4.5-in tubing string in horizontal well is 1.08 million square/day to satisfy the life requirements of gas reservoir tubing (20 years), and which is 0.45 million square/day in directional well. The fatigue life of 4.5-in tubing string is higher than that of 3.5-in tubing string in both horizontal and directional wells. The research results provide a theoretically sound guidance for designing and practically sound approach for effectively improving the service life of tubing string in high-yield curved wells.

Vibration and damping analysis of flexible aluminum tube under the variation of support plate geometry using low speed water tunnel

Vibration response and damping effects on flexible aluminum tube placed in tube-bundle under fluid interaction velocity of 0.5 m/s using water tunnel, is analyzed experimentally for drag and lift direction. The study is undertaken to reduce the flow-induced instabilities in heat-exchanger, proposing low-vibrating design approach. Therefore, three tube bundles in triangular arrangement using distinct support plate thickness of 2 mm, 2.8 mm, and 3.6 mm under (P/D) ratio of 1.45 are developed, respectively. The vibrations are sensed through tri-axial accelerometer mounted at top of central-tube. The damping factors are assessed for monitored/central tube of each tube-bundle at tuned natural frequencies of 9, 8, 7, and 6 Hz, respectively. Whereas, tube-vibration response is further analyzed in terms of RMS-acceleration and dimensionless magnitude at fixed natural frequency of 8 Hz. The results highlight that, the damping factors (under all four natural frequencies) exhibit increasing and the tube-vibrations show decreasing trend with increase in support plate thickness, respectively. Moreover, successive decrease in natural frequency of tube (9-6 Hz) influence the damping factors to increase for each tube bundle. Based on assessment, it is noted that tube-bundle comprising 3.6 mm thick support plate along 8 Hz natural frequency, shows maximum stability for given setup.

Safety evaluation method of tubing strings in high-pressure, high-temperature and high-yield gas wells based on FIV analysis

In view of the failures of tubing string caused by the flow-induced nonlinear vibration (FINV) in high-pressure, high-temperature and high-yield (3H) gas wells, a FINV model of tubing string is established using micro-finite element and energy methods, as well as Hamilton variational principle, and verified by a similar experiment of tubing vibration. Moreover, in order to effectively evaluate the safety of the tubing string, the buckling stability and strength damage evaluation method of tubing string are proposed. Thus, the influences of production rate, inclination angle, well section length, and centralizer position on the tubing string safety were systematically analyzed. The failure mechanism of tubing string in 3H gas wells is elucidated, and the safety control methods of field tubing string are proposed; which suggest that, firstly, with the increase of production rate, the safety of the tubing string decreases, and there exists a sudden value, which can be determined using the proposed analysis method, such that the field production allocation should be far away from the sudden production rate. Secondly, in the well trajectory design, the vertical section length should be reduced, while that of kick-off section and the angle of stable inclined section should be increased. Thirdly, there is an optimal position for the centralizer in the field, which is related to the well structure, downhole tool size, etc. and should be determined by the proposed analysis method to enable the design of the centralizer on-site. The research results provide a theoretically method for safety evaluation and practically sound approach for effectively improving the service life of tubing string in 3H gas wells.

Dynamic Behaviour of Flexible Silicone Tube Subjected to Pulsatile Flow

Flexible Silicone tubes possess superior qualities such as higher corrosion resistance, purity, strength, and inertness compared to other flexible tubes. Hence, these tubes own broad applicability in medical applications as well as other industrial applications. An unsteady flow through the flexible tube can induce severe internal excitation, which results in the flow-induced vibrations. Such vibrations at resonance can cause severe damage to the structure. Concerning the flexible tubes used in sophisticated medical applications, it is imperative to eliminate the structural vibrations, as far as possible. The present study examines the dynamics of the silicone tube under internal excitation due to pulsatile flow. It includes the investigation of the effect of pre-stretch and mean flow velocity on the dynamic behaviour of flexible tube by conducting parametric studies using the operational modal analysis technique. The influence of the mean flow velocity in the flexible tube is a proportional variation in the magnitude of vibration concerning fluid flow rate. An advance in pre-stretch causes a decrease in sagging, and the tube tends to retrieve its original circular cylindrical shape. Owing to this, when the tube is excited due to internal pulsation, the difference between the magnitude of vibration in the horizontal and vertical plane at resonance condition reduces, and the natural frequencies at different planes nearly become equal at higher pre-stretch, where sagging is negligible. The study reveals that for flexible tubes, the tube vibration always stabilizes in an arbitrary plane under excitation due to pulsation. This investigation exhibits that impact hammer excitation is better than constrained external excitation to find the fundamental frequencies of the flexible tube conveying fluid.

Radial Vibration Characteristics of Piezoelectric Ceramic Composite Ultrasonic Transducer

Different from the existing equivalent circuit analysis method of the transducer, based on the vibration theory of the mechanical system and combined with the constitutive equation, this paper analyzes the radial vibration characteristics of the transducer. The piezoelectric ceramic composite ultrasonic transducer is simplified as a mechanical model of a composite thick wall tube composed of a piezoelectric ceramic tube and a metal prestressed tube. The mathematical model of radial vibration of the transducer is established, which consists of the wave equation of radial coupling vibration of the piezoelectric ceramic tube and the metal prestressed tube, the continuity conditions, and the boundary conditions of radial vibration of composite thick wall tube. The characteristic equation and the mode function of radial vibration are derived. The calculated results of natural frequency are in good agreement with the existing experimental results. Based on the analytical method and the difference method, the numerical simulation models of radial vibration are established, and the amplitude-frequency characteristic curves and the displacement responses are given. The simulation results show that the amplitude-frequency characteristic curves and the displacement responses of the two methods are the same, which verifies the correctness of simulation results. Through the simulation analysis, the influence rule of the transducer’s structure sizes on its radial vibration natural frequency is given: when the thickness of the metal prestressed tube and the piezoelectric ceramic tube are constant, the natural frequency decreases with the increase of the inner diameter of the piezoelectric ceramic tube; when the outer diameter of the metal prestressed tube and the inner diameter of the piezoelectric ceramic tube are constant, the natural frequency decreases with the increase of the thickness-to-wall ratio. The calculation method of natural frequency based on elastic vibration theory is clear in concept and simple in calculation, and the simulation models can analyze the mechanical vibration of the transducer.

Large amplitude free vibrations of FGM shallow curved tubes in thermal environment

In the current investigation, large amplitude free vibration behavior of shallow curved pipes (tubes) made of functionally graded materials is investigated. Properties of the tube are distributed across the radius of the tube and are obtained by means of a power law function. It is also assumed that all thermo-mechanical properties are temperature dependent. The governing equations of the tube are obtained using a higher order shear deformation tube theory, where the traction free boundary conditions are satisfied on the top and bottom surfaces of the tube. The von Karman type of geometrical non-linearity is included into the formulation to consider the large displacements and small strains. Uniform temperature elevation of the tube is also included into the formulation. For the case of tubes which are simply supported in flexure and axially immovable, the governing equations are solved using the two-step perturbation technique. Closed form expressions are provided to obtain the small and large amplitude fundamental natural frequencies of the FGM shallow curved tubes in thermal environment. Numerical results are given to explore the effects of thermal environment, radius ratio, and length to thickness ratio of the tube on the fundamental linear and non-linear frequencies.

Experimental study of the vibration of vertical rod in liquid flow

Vibration of the vertical tube, induced by an axial flow, were studied experimentally. Experiments were carried out using the sensors based on the electrical impedance. The time chronology of the pass of the tube axis was reconstructed using four sensors. For various flow rates different modes of fluctuations were found. The amplitude, shape, and characteristic frequencies of signals were found to change depending on the liquid flow rate.

Electrostatically tunable axisymmetric vibrations of soft electro-active tubes

Due to their unique electromechanical coupling properties, soft electro-active (SEA) resonators are actively tunable, extremely suitable, and practically important for designing the next-generation acoustic and vibration treatment devices. In this paper, we investigate the electrostatically tunable axisymmetric vibrations of SEA tubes with different geometric sizes. We consider both axisymmetric torsional and longitudinal vibrations for an incompressible SEA cylindrical tube under inhomogeneous biasing fields induced by radial electric voltage and axial pre-stretch. We then employ the state-space method, which combines the state-space formalism in cylindrical coordinates with the approximate laminate technique, to derive the frequency equations for two separate classes of axisymmetric vibration of the tube subjected to appropriate boundary conditions. We perform numerical calculations to validate the convergence and accuracy of the state-space method and to illuminate that the axisymmetric vibration characteristics of SEA tubes may be tuned significantly by adjusting the electromechanical biasing fields as well as altering the tube geometry. The reported results provide a solid guidance for the proper design of tunable resonant devices composed of SEA tubes.

Coriolis meter density errors induced by ambient air and fluid temperature differentials

Coriolis metering technology is widely applied throughout industry. In addition to the mass flow rate, a Coriolis meter can measure fluid density based on the resonant frequency of the flow tube vibration. There is currently increasing interest in utilising this density measurement capability as the primary process value in applications such as precision control for fluid property conditioning, and fluid contamination monitoring.However, within these applications, ambient temperature variation can be significant.This paper details research data obtained using NEL's ‘Very Low Flow’ single-phase facility. The rig was modified to include a programmable temperature enclosure in which a Coriolis meter was installed. Two commercial meter models from the same manufacturer were tested. Both meters showed fluid density errors when subjected to fluctuations in the surrounding ambient air temperature. The fluid properties of the test medium were confirmed to be stable using NEL's UKAS standard reference instrumentation.Previous temperature effects research for Coriolis meters have focussed on the process fluid temperature and there is little published data on the effects of ambient temperature.

Time and frequency domain analyses of fluid force fluctuations in a normal triangular tube array in forced vibrations

Vibrations of tube bundles in heat exchange equipment, such as nuclear steam generators and tube-and-shell type heat exchangers, are often caused by unsteady fluid forces. The study of flow-induced vibration excitation forces on tubes is necessary for understanding the fluid-elastic instability phenomenon. In this paper, a forced vibration method is introduced to investigate unsteady motion-dependent fluid forces in a normal triangular tube array with the pitch ratio of 1.32 that is subjected to water crossflow. Fluid force behaviors of a single flexible central tube and its lift response spectra are investigated in various forced vibration modes. In a seven-tube kernel unit, coupling effects of surrounding tubes on the central tube are also discussed. Results show that the lift force on a flexible vibrating tube mainly depends on the vibration amplitude of tube itself in the lift direction, and is less affected by the degree of freedom, the rotation direction and the main vibration direction of tube vibration. The frequency spectrum of lift responses is dominated by two main frequencies: the vortex alternating frequency and the tube natural frequency. Surrounding flexible tubes increase higher order harmonics of the periodic lift force fluctuations of the central tube. Compared with rear-column tubes, vibrations of the front-column tubes have more significant effects on lift force responses of the tube kernel, which facts causes strong coupling to promote the fluid-elastic instability of tubes.

Internal resonance analysis of a fluid-conveying tube resting on a nonlinear elastic foundation

This study used a fluid-conveying nonlinear beam and a nonlinear spring to simulate the vibration of a fluid-conveying tube placed on an elastic foundation. The centripetal force and tangential force of fluid acting on the tube wall were considered. In this paper, Hamilton’s principle is used to derive the equation for the nonlinear flow-structure coupled motion, where the method of multiple scales is used to derive the frequency response of each mode under the fixed point (steady state), and the amplitude of each mode is used to examine internal resonance. This study added (tuned mass dampers) TMDs of different masses, spring constants and damping coefficients at different locations in the system to observe the effect of the shock absorber in avoiding the internal resonance of the flow-structure coupled system and reducing the vibration of the system. Poincare map, maximum amplitude contour plots, and basin of attraction are used to analyze and compare the system to verify the correctness of our theory. The stability of the system is analyzed by changing the flow velocity of the fluid. The results show that under a certain combination of elastic foundation spring constants and flow speeds, the 1:3 internal resonance between the first and third modes of the main system will occur. In addition, the stability range of any case will increase significantly after TMD is added, indicating that TMD plays an important role.

Vibration of a liquid-filled capillary tube

Liquid-filled capillary tubes are common structures in nature and engineering fields, which often function via vibration. Although liquid-solid interfacial tension plays important roles in the vibration behavior of the liquid-filled capillary tube, it remains elusive how the interfacial tension influences the natural frequency of capillary tube vibration. To address this, we developed a theory of beam-string structure to analyze the influence of liquid-solid interfacial tension on the vibration of a liquid-filled capillary cantilever. We used glass capillary tubes as a demo and experimentally validated the theory, where the reduced liquid-solid interfacial tension in a capillary tube decreases the natural frequencies of small-order modes. We then performed theoretical analysis and found that the change of elastocapillarity number, slenderness ratio and inner/outer radius ratio of capillary tubes enables: in higher order modes, a nonmonotonic change of natural frequency due to mode transformation between a beam and string; for lower order modes, decrease in the natural frequency to zero (increase from zero) due to mode disappearance (appearance). The developed theory would provide guidelines for high-accuracy design of capillary sensors.

Perforating Gun Detonation Monitoring System Based on Tubing Vibration

This paper describes a perforating gun detonation monitoring system developed to meet the need for real-time monitoring of perforation effect in the petroleum industry. A high-sensitivity acceleration sensor, serving as the response module of the physical characteristics of the tubing vibration, acquires a set of vibration signals of the whole physical process during the impact after the detonation of the shaped charge. The jump point in the monitoring process is extracted by comparing the signal's short-time energy. The amplitude, energy, and envelope characteristics of the signal are then evaluated. From the time-frequency characteristics of the tubing vibration upon the detonation of the perforating gun, a judgment is made as to whether the perforating gun has detonated. Tubing vibration experiments were conducted involving different perforating guns. The results suggested that the proposed monitoring method is able to monitor perforating guns of different shaped charges with a perforating depth between 500m-3500m and in oil wells with an inclination of 0° - 90°. As a means of vibration detection, this method also works well in other types of vibration monitoring.