Tube Vibration Research Articles

Flow-induced vibration of a flexible tube with squeeze film in an otherwise rigid tube array subjected to cross-flow

Flow-induced vibration of a flexible tube with squeeze film in an otherwise rigid tube array subjected to cross-flow

Numerical investigation of the effect of the structure and number of spiral baffles on the vibration and heat transfer coefficient of spiral tubes within spiral tube heat exchangers

In response to the advantages of compactness and high efficiency of spiral elastic tube heat exchanger and its easy-to-vibrate characteristics, this study aims to further improve its heat transfer efficiency by utilizing fluid-induced vibration-enhanced heat transfer technology, so a design scheme of reverse baffle spiral tube heat exchanger (RB-STHE) is proposed to enhance the turbulence characteristics of the shell-side fluid by installing spiral baffles, thus promoting the vibration of the spiral tube. In this study, four new types of the RB-STHE (Model A, B, C, and D) were used as research objects, and the two-way fluid–structure coupling calculation method (using CFX and Transient Structure software) was adopted to systematically investigate the effect of fluid-induced spiral tube vibration on the comprehensive heat transfer coefficient (HTC) of the RB-STHE under different flow velocities and structure schemes, and based on the research data, the objective of no reduction in the comprehensive HTC and savings in the use of materials is taken as the goal, so as to put forward the improved Model C-1. The results show that: although the fluid-induced spiral tube vibration can effectively improve the HTC of the spiral tube, it also increases the pressure drop in the RB-STHE, and the larger the amplitude, the higher the degree of influence; among them, Model C is most affected by the spiral tube vibration, and its HTC and pressure drop are maximally enhanced by 6.33% and 5.85%, respectively. The change in the number of baffles has a significant effect on the comprehensive HTC of the RB-STHE. Compared to the Model D without a spiral baffle, the maximum improvement in the comprehensive HTC of Model C with one spiral baffle installed in the RB-STHE is 14%, while the Model A with four spiral baffles and the Model B with two spiral baffles have a maximum reduction in the comprehensive HTC of 20% and 3%, respectively. In addition, compared to Model C, the structure improved Model C-1 significantly reduces the size of the spiral baffle while effectively maintaining the comprehensive HTC of the RB-STHE, making the structure more reasonable, which provides a reference for heat exchanger design.

Modeling and control design of a bronchoscope robotics system

For the pulmonary nodule biopsy problem, this paper investigates an intervention robotics system based on the bronchoscope. To achieve precise control of the system, the mathematical model is established at first. The system mainly consists of an inserting tube and a tube tip, which are modeled based on a moving flexible beam and a soft robot, respectively. In order to reduce the harm to the patient during the operation, the robot system should suppress the vibration of the inserting tube during the process of tracking the desired trajectory in the bronchus. Therefore, we use the boundary control algorithm to design a controller capable of suppressing vibration for the inserting tube. Meanwhile, in order for the robot system to accurately select the bronchus corresponding to the branch, we designed a soft robot controller that can bend or deflect the soft robot to a specified posture. Finally, we used theoretical proof and numerical simulation to verify the conclusion.

Study on failure mechanism of suspension lug elbow in an ethylene cracking pyrolyzer

The cracking of a suspension lug elbow caused a shutdown in a certain petrochemical enterprise. In this study, the authors conducted physical and chemical analysis to investigate the cracking mechanism. Macroscopic observations indicated no signs of corrosion or thinning on the inner and outer surfaces of the head, and the cracks were distributed in the body of the head and the ear. Chemical composition analysis revealed that the main chemical components of the failed elbow met the standard requirements. Metallographic observations showed significant creep damage in the substrate material, and after long-term high-temperature service, both the room temperature and high-temperature mechanical properties of the failed elbow significantly deteriorated. The failure sample exhibit a fracture elongation of 0 %, and the high-temperature creep performance of the head material was only 6.868 h, both lower than the standard requirement of a fracture elongation of 4 % and 120 h of high-temperature creep performance. Fracture surface observation revealed obvious creep voids and fatigue striations, indicating severe creep damage and the influence of alternating loads on the head. Field observations indicated that the head experienced significant shaking inside the furnace. Therefore, simulation analysis suggested that the maximum stress coincided with the crack location, ranging from 121 MPa to 131 MPa, far exceeding the tensile strength at the operating temperature when the elbow was subjected to alternating loads generated by left–right and back-forth swinging. In conclusion, the failure of the suspension lug elbow was caused by creep-fatigue cracking. This study reveals that, even when the internal medium is in single gaseous phase, elbows are still susceptible to cracking under the combined effects of high temperature vibration and creep interaction. To avoid future failures, strengthening the monitoring of the cracking furnace operation, controlling the load appropriately, and preventing severe vibration and shaking of the furnace tube are recommended.

Numerical and Experimental Study of Low-Frequency Membrane Damper for Tube Vibration Suppression

In modern days, low-frequency vibration is still challenging to suppress due to its high vibrational energy. A typical suppression method is to increase the object’s mass to reduce the amplitude of the vibration, but such a way is unsuitable in many cases. Membrane dampers can potentially eliminate the limitation and offer lightweight and compact damper. The idea is to decrease the stiffness and add additional mass to increase the dissipation of the vibration energy. For that, the membrane and an extra mass made of silicone rubber were used for the damper. Finite element eigenfrequency simulation showed the transformation of each mode to the damper mode, where the tube displacement was zero. Also, it showed the bandgap between modes in the frequency range from 106 Hz to 158 Hz. The experimental verification of clamped from both ends of the tube showed the predicted bandgap and absence of the resonance peak of the bare tube. Overall, the membrane damper showed good efficiency in extremely low frequencies and seems promising for vibration suppression.

Emergency Pump-Rate Regulation to Mitigate Water-Hammer Effect—An Integrated Data-Driven Strategy and Case Studies

Pump-rate regulation is frequently used during hydraulic fracturing operations in order to maintain the pressure within a safe range. An emergency pump-rate reduction or pump shutdown is usually applied under the condition of sand screen-out when advancing hydraulic fractures are blocked by injected proppant and develop wellhead overpressure. The drastic regulation of the pump rate induces water-hammer effects—hydraulic shocks—on the wellbore due to the impulsive pressure. This wellbore shock damages the well integrity and then increases the risk of material leakage into water resources or the atmosphere, depending on the magnitude of the impulsive pressure. Therefore, appropriate emergency pump-rate regulation can both secure the fracturing operation and enhance well-completion integrity for environmental requirements—a rare mutual benefit to both sides of the argument. Previous studies have revealed the tube vibration, severe stress concentration, and sand production induced by water-hammer effects in high-pressure wells during oil/gas production. However, the water-hammer effect, the induced impulsive pressures, and the mitigation measures are rarely reported for hydraulic fracturing injections. In this study, we present a data-driven workflow integrating real-time monitoring and regulation strategies, which is applied in four field cases under the emergency operation condition (screen-out or near screen-out). A stepwise pump-rate regulation strategy was deployed in the first three cases. The corresponding maximum impulsive pressure fell in the range of 3.7~7.4 MPa. Furthermore, a sand screen-out case, using a more radical regulation strategy, induced an impulsive pressure 2 or 3 times higher (~14.7 MPa) than the other three cases. Compared with the traditional method of sharp pump-rate regulation in fields, stepwise pump-rate regulation is recommended to constrain the water-hammer effect based on the evolution of impulsive pressures, which can be an essential operational strategy to secure hydraulic fracturing and well integrity, especially for fracturing geologically unstable formations (for instance, formations near faults).

Coupling vibration analysis of heat exchanger tube bundles under different stiffness conditions

A two-dimensional tube bundles fluid–structure coupling model was developed using the CFD approach, with a rigid body motion equation and the Newmark integral method. The numerical simulations were performed to determine the vibration coupling properties between various tube bundles of stiffness. Take the corner square tube bundles with a pitch ratio of 1.28 as the research object. The influence of adjacent tubes with different stiffness on the vibration of the central target tube was analyzed. The research results show that the vibration characteristic of tube bundles is affected by the flow field dominant frequency and the inherent frequency of tube bundles. The vibration of adjacent tube bundles significantly impacts the amplitude and frequency of the central target tube. The equal stiffness and large stiffness tubes upstream or downstream inhibit the vibration displacement of the target tube to some extent. The low-stiffness tubes upstream or downstream significantly enhanced the amplitude of the target tube. The findings can be used to provide a basis for reasonable design and vibration suppression of shell-and-tube heat exchangers.

Voltage-controlled non-axisymmetric vibrations of soft electro-active tubes with strain-stiffening effect

Material properties of soft electro-active (SEA) structures are significantly sensitive to external electro-mechanical biasing fields (such as pre-stretch and electric stimuli), which generate remarkable knock-on effects on their dynamic characteristics. In this work, we analyze the electrostatically tunable non-axisymmetric vibrations of an incompressible SEA cylindrical tube under the combination of a radially applied electric voltage and an axial pre-stretch. Following the theory of nonlinear electro-elasticity and the associated linearized theory for superimposed perturbations, we derive the nonlinear static response of the SEA tube to the inhomogeneous biasing fields for the Gent ideal dielectric model. Using the State Space Method, we efficiently obtain the frequency equations for voltage-controlled small-amplitude three-dimensional non-axisymmetric vibrations, covering a wide range of behaviors, from the purely radial breathing mode to torsional modes, axisymmetric longitudinal modes, and prismatic diffuse modes. We also perform an exhaustive numerical analysis to validate the proposed approach compared with the conventional displacement method, as well as to elucidate the influences of the applied voltage, axial pre-stretch, and strain-stiffening effect on the nonlinear static response and vibration behaviors of the SEA tube. The present study clearly indicates that manipulating electro-mechanical biasing fields is a feasible way to tune the small-amplitude vibration characteristics of an SEA tube. The results should benefit experimental work on, and design of, voltage-controlled resonant devices made of SEA tubes.

Experimental study of parametric vibrations of arc-shaped tubes with pulsating fluid flow

The dynamics of curved tubes with fluid flow fixed on both sides was studied experimentally. Two cases were studied in which the curved tubes differed in curvature. Tests were performed with the flow without pulsation to determine the natural frequencies and with pulsation to determine the interesting dynamic phenomena occurring in the system. Two alternative measurement systems were used to study the motion of the tubes, a contact one based on accelerometers and a non-contact one based on optical technology. Acceleration and displacement time-series were analysed to determine the nature of the motion of the tubes. It was confirmed that the eigenfrequencies of the curved systems are insensitive to flow velocity which is consistent with the extensible centreline hypothesis. The interesting dynamics of tubes with pulsatile flow, the possibility of excitation of simple, combination parametric resonances, including several different combination resonances simultaneously, were identified. The vibrations in the simple resonances were polyharmonic and in the combination resonances quasi-periodic. The motion of the tubes was three-dimensional in nature and its complexity increased with increasing excitation amplitude. It was found that increasing the curvature of the tube reduced the possibility of excitation of parametric vibration.

Continuous Evaluation of Roller Pump Occlusion Pressure Due to Pump Tube Vibration

Continuous Evaluation of Roller Pump Occlusion Pressure Due to Pump Tube Vibration

Study on Vortex-Induced Vibration Response of Riser under the Action of Oscillating Flow Superposition

Based on the slicing method and overlapping grid method, the bidirectional and sequential coupling of the fluid domain and riser structure is realized by UDF programming. A numerical model of vortex-solid coupling is constructed to study vortex-induced vibration characteristics of risers with different velocity ratios and different oscillation frequencies under the effect of superimposed oscillating flow. With the increase of the velocity ratio, a higher order formation appeared in the transverse vibration envelope of the riser. Meanwhile, with the increase of oscillation frequency, the vertical tube vibration envelope changed from “symmetrical up and down” to “wide up and narrow down”. There is an obvious process of “establishment”, “locking” and “decay” in the transverse-flow displacement of the riser to dimensionless, and the proportion of the “locking” phase increases gradually with the flow rate ratio, changing from 0.50 to 0.62. The effect of the oscillation frequency of the superimposed flow on the proportion of the “locked” stage is not evident. When the oscillation frequency is 0.25f1, the proportion of the “locked” stage of the riser reaches 50%.

Dynamic 3D Measurement without Motion Artifacts Based on Feature Compensation.

Phase-shift profilometry (PSP) holds great promise for high-precision 3D shape measurements. However, in the case of measuring moving objects, as PSP requires multiple images to calculate the phase, the movement of the object causes artifacts in the measurement, which in turn has a significant impact on the accuracy of the 3D surface measurement. Therefore, we propose a method to reduce motion artifacts using feature information in the image and simulate it using the six-step term shift method as a case study. The simulation results show that the phase of the object is greatly affected when the object is in motion and that the phase shift due to motion can be effectively reduced using this method. Finally, artifact optimization was carried out by way of specific copper tube vibration experiments at a measurement frequency of 320 Hz. The experimental results prove that the method is well implemented.

Study on water hammer effect and tubing string vibration in high-pressure high-production gas wells

The transient internal flow in high-pressure high-production gas wells generates severe water hammer and tubing string vibration, which accelerates fatigue damage, joint wear, thread loosening, and other wellbore integrity problems. Based on the analysis of transient flow in gas wells, a mathematical model for fluid pressure surge and the induced tubing string vibration is developed and validated by similarity experiments. This method considers fluid-structure interaction, initial loads of tubing string, and compressibility of natural gas, and can fill the gap in quantification of water hammer pressure and tubing sting dynamic load in high-pressure high-production gas wells. On this basis, the effects of valve closure time, production rate, liquid content, and tubing string structure on transient flow and tubing string characteristics are analyzed systematically. The calculations show that wellhead pressure increases rapidly, and pressure wave propagates along tubing string to induce vibrations in the string after an instantaneous shut-in at the wellhead. During this transient process, fluid pressure and axial stress at wellhead reach their maximum valves. Owing to the fixed constraint effect of wellhead and downhole packer, the lack of restrictions on tubing distant from wellhead and packer enhances the severity of axial vibration. As valve closure time increases, the maximum wellhead pressure, tubing vibration displacement, and velocity gradually decrease. Therefore, the most direct way to control water hammer effect and tubing string vibration is to extend the shut-in time or prevent a rapid shut-in of gas well. The methods used in this study and the results obtained therein can serve as both a theoretical framework and practical foundation for the prediction and control of water hammer effect and tubing string vibration in high-pressure high-production gas wells.

Prediction Framework of Vortex-Induced Vibration of Steel Tubes in Transmission Towers Based on Generalized Wake Oscillator Model

Steel tube members with high slenderness ratios in transmission towers are susceptible to vortex-induced vibration (VIV), which can lead to fatigue damage once the vibration amplitude exceeds a certain threshold. This study proposes a VIV prediction framework for transmission tower steel tube members with semi-rigid constraints, based on the developed generalized wake oscillator model (GWOM). Firstly, the GWOM is established by coupling the nonlinear Van der Pol oscillator with the Euler–Bernoulli beam equation and incorporating semi-rigid boundary conditions. Meanwhile, the identification methods for the rotational stiffness and empirical parameters in the GWOM are presented, respectively. Second, a numerical solution scheme of the GWOM is derived based on the central difference method, and then a VIV prediction framework for steel tube members with arbitrary structural configuration is established. Comparisons with published experiments demonstrate that the proposed GWOM-based prediction framework has a promising accuracy in estimating the lock-in range and maximum VIV amplitude. The influence of semi-rigid constraints on the VIV of steel tube members is mainly manifested in the critical wind speed, but it has little effect on the amplitude branch. The proposed framework provides an efficient and cost–effective alternative to traditional experimental methods and computational fluid dynamics CFD simulations for predicting the VIV of steel tube members in transmission towers.

Design of Heat Pipe Air Preheater for 10 t/h Gas-Steam Boiler

This design is aimed at energy -saving and designed a heat pipe air preheat to recover 10T/H steam gas boiler flue heat waste heat, thereby increasing the efficiency of the boiler and reducing gas consumption. This article first introduces the thermal pipe, heat pipe heat exchange, and boiler thermal system, and then focus on the design and optimization of the heat pipe air heater. This design optimizes the thermal pipe specifications of the heat pipe air heater and the parameters of the fins. At the same time, the sealing structure, the fixed structure, and the airport structure are optimized. Subsequently, the UG software created a three -dimensional physical model model and rendering model, and finally proposed corresponding countermeasures on equipment corrosion, thermal pipe life and tube vibration problems. This design uses Excel software to make design calculation tables. Through input parameters, the results of the results of the number of thermal pipes can be obtained.

Numerical study of transient flow characteristics of gas-liquid two-phase flow in inclined upward tube under periodic vibration

The transient flow characteristics of gas-liquid two-phase flow in inclined upward tubes exhibit a high degree of complexity. The tube vibration caused by multiple uncertain factors, such as seawater impacts or subsea earthquakes, poses more significant challenges for flow safety assurance. Thus, it becomes increasingly crucial to explore the transient flow characteristics of gas-liquid two-phase flow in inclined upward tubes under various vibration conditions. In this paper, the transient flow characteristics of gas-liquid two-phase flow in an inclined upward tube under different vibration conditions are numerically studied based on CFD dynamic mesh technique. In the current study, the studied parameters include vibration direction (heaving, transverse and coupling), vibration amplitudes (0.5D, 1.0D and 1.5D), and inlet velocity (jsg=0.5∼1.0m/s; jsl=0.1∼1.0m/s). The transient flow structure, cross-sectional void fraction and pressure drop are analyzed. The findings indicate that the transient flow structure of the slug flow demonstrates periodic variation characteristics under transverse and coupling vibrations, and the cross-sectional void fraction increase. For transition flow, the cross-sectional void fraction increases under transverse and coupling vibrations, while displays an increase initially and subsequently a decrease significant with an increase in the heaving vibration amplitude. Additionally, all considered vibration conditions intensify the pressure drop of the transition flow and decrease the cross-sectional void fraction of the turbulent flow.

Comparison of various thin-walled composite beam models for thermally induced vibrations of spacecraft boom

A sufficiently accurate, yet computationally efficient prediction of thermomechanical behavior is essential for the structural design of spacecraft. This paper presents a novel modeling approach for thermally induced vibrations of thin-walled composite tubes in spacecraft, in which the generalized beam theory is employed, and meanwhile, the non-conventional shear and extension modes are introduced into it. Furthermore, a cross-sectional temperature model in terms of harmonic functions is developed to provide more accurate temperature field, which is performed by taking into account the strong couplings between average and perturbation temperatures and between perturbation temperatures. Combining the beam model and the temperature model, a thermal–structural finite element formulation for composite boom in space environment is established. By comparison to the finite shell element, the accuracy and characteristic feature of these new models are illustrated. The results show that the additional deformation modes may play a significant role in thermal–structural analysis of thin-walled composite beams.

Experimental estimation of equivalent loads on upward two-phase crossflow in tube bundles via Kalman filtering

Tube bundles of heat exchangers are permanently exposed to flow-induced forces, which may lead to high amplitude vibrations compromising the lifetime. In this context, Flow-induced vibration (FIV) is the most crucial dynamic issue to deal with in the design and operation of shell-and-tube heat exchangers. The experimental investigation of FIV requires determining the nature of flow-induced forces and their consequences, which are given by the characteristics of tube vibration. However, the measurement of flow-induced forces is challenging due to space restrictions within a tube bundle and their intrinsic spatially-distributed nature, often represented by equivalent point forces. The present work aims to estimate the equivalent flow-induced forces in tube bundles due to two-phase crossflow using Virtual Sensing principles. In order to do that, a device is designed and constructed to replace a tube within a normal triangular (transversal pitch to diameter ratio of 1.26) tube bundle, which is subjected to two-phase flow with void fractions ranging from 30% to 95% and a wide range of mass velocities. The device is instrumented with two couples of accelerometers and strain sensors, aligned with drag and transverse directions. The measured dynamic responses are discussed in terms of void fraction, mass velocities, and flow patterns. The results confirm the severity of FIV under Intermittent-type flow patterns. Further, the equivalent force estimation is performed via the Augmented Kalman Filter (AKF), which requires a model approximation (based on EMA techniques) and the system’s outputs. The values of the input covariance matrix are determined through the L-curve regularization method. Finally, the quality of the estimated equivalent force is tested by simulating system accelerations, whose RMS values are compared with measured data. The results suggest better acceleration predictions in the transverse direction than in the main flow direction for relatively low mass velocities and Bubbles flow pattern.

Torsional vibration of a flexoelectric nanotube with micro-inertia effect

The modified strain gradient theory (MSGT) with flexoelectric and micro-inertia effects is developed to study the free vibration of tube made of elastic centrosymmetric materials. Within this theory, the internal energy density is the function of the strain tensor, deviatoric part of stretch gradient and rotation gradient tensors, dilatation gradient, polarization vector, and electric quadrupoles. The linear coupled governing equations and boundary conditions are derived from the Hamilton variation principle. The torsional vibration problem is analytically solved for non-piezoelectric nanotube with fixed edges. The effect of the nanotube geometry, flexoelectric coefficient, micro-inertia, and micro-stiffness parameters on the natural frequency is studied.

Incremental harmonic balance method for multi-harmonic solution of high-dimensional delay differential equations: Application to crossflow-induced nonlinear vibration of steam generator tubes

Diverse science and engineering problems are governed by delay differential equations (DDE). Seeking periodic solutions of DDEs is crucial for many nonlinear dynamic systems. The incremental harmonic balance (IHB) method is an efficient semi-analytical approach for periodic solutions of DDE. Among various DDE systems, flow-induced vibration (FIV) of tube bundles with loose support is unique, in the sense that the added damping cancels out structural damping in the vicinity of critical velocity, making it extremely slow to retain a convergent solution if numerical integration (NI) is utilized. Despite the efforts of developing IHB for various mechanical vibration problems with time-delay, no attempt has been made to employ IHB to nonlinear FIV problems. Here we fill this blank by separately combining two spatial discretization strategies, i.e., discretization via linear vibration modes or via finite element method (FEM), with IHB to capture limit cycle solutions after the onset of instability. Within the range of gap velocity of interest, the IHB demonstrates excellent convergence by increasing harmonic terms, and good agreement is obtained between IHB results and the results by NI method. An 18 degree-of-freedom (DOF) nonlinear DDE system was readily dealt by integrating FEM and IHB, each DOF being approximated by three harmonics. This is the first attempt to employ IHB for multi-harmonic solution of high-dimensional FIV problems, which opens a door for solutions of other DDEs. All the codes used in this paper could be downloaded via: https://github.com/XJTU-Zhou-group/IHB.