Fluid-structure Interaction Vibration Research Articles

Simulation Analysis and Experimental Investigation on the Fluid–Structure Interaction Vibration Characteristics of Aircraft Liquid-Filled Pipelines under the Superimposed Impact of External Random Vibration and Internal Pulsating Pressure

This paper investigated the fluid–structure interaction vibration response of an aircraft liquid-filled pipeline under external random vibration and internal pulsating pressure. First, the fluid–structure interaction solution is theoretically analyzed, and the advantages and disadvantages of the direct coupling method and the separation coupling method are compared, with the latter chosen as the simulation analysis method in this study. Second, taking the U-shaped oil pipeline of an aircraft engine as an example, simulation modeling was performed to compare and analyze the fluid–structure interaction vibration response of aircraft liquid-filled pipelines under different working conditions, obtaining the vibration response characteristics of stress danger points under various conditions. Finally, a test bench for an aircraft liquid-filling pipeline was built to explore the influence of external random vibrations with different kurtoses, different pipe wall thicknesses and different working conditions on the vibration response danger points of aircraft liquid-filling pipelines, verifying the simulation conclusions and providing a basis for aircraft liquid-filling pipeline design.

Investigation of the Difference Between Ordinary and FSI Numerical Solution for Flutter of Tandem Compressor

This research aims to analyze and compare the flutter of turbine compressor blades from experimental, numerical, and fluid structure interaction (FSI) derived data. The results proved that the FSI solution results are closer to the experimental results. A reduced velocity parameter of 5 can be regarded as the flutter boundary in the bending flutter. Additionally, the incidence angle parameter equal to 1.5 can be characterized as the torsional flutter boundary. Tandem leads to strengthening the load applied on the compressor blades, reducing the number of compressor stages, and ultimately reducing the weight of the engine. Adding tandem to the rotor increases the vibration bending frequency by a factor of 2. Increasing the compressor velocity caused the FSI vibration frequency to be close to the experimental results. It was found that the vibration range of the main rotor is greater than that of the tandem. The vibration of the rotor and the tandem is damped for approximately 0.1 s to reach a constant frequency.

Time-varying mechanism of fluid-structure interaction vibration effects and dynamic characteristics of the cross-over pipeline when the medium flows

The time-varying mechanism of fluid-structure interaction (FSI) vibration effects and dynamic characteristics of the cross-over pipeline with the flowing of the crude and natural gas mixture two-phase medium were revealed in this study. An active fluid finite element method (FEM) model was built for the medium that exhibited a volume ratio 1:1 and flowed through the pipeline under a velocity of 2 m/s. The standard turbulence κ-ε model was modified by incorporating the flow velocity and pressure fluctuation changes with the floating of the medium. The pipeline's FSI vibration effects and the pipeline-crossing system's dynamic characteristics were determined and then analyzed. As indicated by the research results, the medium was affected by frictional damping at the pipeline wall and energy transfer losses at the phase interface, such that irregular flow regimes were generated (i.e., slug flow and wavy flow). The flow velocity was further reduced in the 280 s, and the intervals between pressure fluctuations gradually increased. The FSI vibration effects in the middle section of the cross-over pipeline were significant, with a peak displacement response reaching 45.7538 mm while the medium flow. Notable differences and complex changes were identified in the acceleration response among the monitoring sections of the first and second spanning sections. The dynamic properties of the pipeline-crossing system changed significantly with time. The natural frequencies of the 1st to 7th modes decreased with time.In contrast, the natural frequencies of the 8th to 12th modes tended to decline with complex time-varying characteristics more notably. The methods in the respective direction exhibited time-varying characteristics. Specifically, their relative proportions of the effective mass ratio varied with time. As the research concludes, The research concludes that the flowing mechanical behavior can be more accurately expressed by modifying the standard κ-ε turbulence model using the medium's velocity changes and pressure fluctuation curves. This study can lay a theoretical foundation for gaining insights into the time-varying mechanism of the FSI vibration effects and dynamic characteristics in the cross-over pipeline.

Analysis of Vibration Characteristics of Cross-Type Hydraulic Pipeline Based on Finite Element Method

Branched hydraulic lines are prone to leakage and break under complex working conditions. The coupling vibration problem caused by the fluid pressure beat and external mechanical excitation of the pump at the junction of the branch of the cross-type hydraulic pipeline is very common. So a method combining finite element simulation and fluid-structure interaction vibration experiments is proposed for research. First, the possibility of the finite element method in solving the pipeline vibration problem is verified, and then the modal analysis and harmonious response analysis of the cross-type pipe are carried out to discuss the influence of fluid pressure and solid elastic modulus on pipeline vibration. The results show that as the fluid pressure and pipeline elastic modulus change, different modes of different orders will be affected. Under external excitation, only a portion of the order is sensitive to external excitation.

Analysis of the Influence of Single-Walled Carbon Nanotubes on the Fluid–Structure Interaction Vibration Control in Bionic Hydraulic Pipelines

In previous research, a bionic hydraulic pipeline (BHP) with a three-layer structure for absorbing pulsation was invented. This paper proposes to disperse single-walled carbon nanotubes (SWCNTs) in the elastic layer material, namely silicone rubber (RTV), to enhance its ability to absorb pulsation. Firstly, the RTV-SWCNTs composite specimens with different SWCNT proportions are prepared and tested. It was found that the mechanical property is optimal when the volume content of the SWCNTs is 0.5 vol%. On this basis, BHPs with RTV-SWCNTs composite material as the elastic layer are fabricated to study the influence of the thickness and length of the elastic layer on the absorption flow pulsation. The results show that the addition of SWCNTs significantly improves the mechanical properties of silicone rubber and reduces the friction between the elastic material and oil, so that the BHP can absorb the pressure pulsation better. With the appropriate thickness and length of the elastic layer, the addition of SWCNTs can increase the pulsation suppression effect by 20%. Moreover, to analyze the influence of nanomaterials on pipeline friction, a comprehensive fourteen-equation model for describing the fluid–structure interaction (FSI) of the pipe conveying fluid considering friction coupling is established. And through numerical analysis and modal tests, the evaluation error for the modified dynamic model of the BHP is less than 5%, verifying the correctness of the proposed model and solution method.

Study on Vibration Characteristics of Hydraulic Pipes in Case of Internal Pulsating Fluid Excitation

The influence of transverse external periodic force on the fluid-structure interaction vibration of hydraulic pipe was researched. Through stress analysis on the pipe under the effect of internal flow, the Bernoulli-beam model in the paper was selected. The equation of fluid-structure interaction vibration was established. By comparing the simulation results of load and no load the transverse external periodic force, a length of hydraulic pipe was analyzed using ansys cfx. The results were shown that the transverse external periodic force strengthened the hydraulic oil’s pressure fluctuation of the pipe internal and the fluid-structure interaction vibration.

Analysis of Double Inverted Flag Energy Harvesting System in Pipe Flow

This technical note numerically and experimentally studies a vibration energy harvester (VEH) consisting of a set of two parallel elastic steel sheets (ESSs) and piezoelectric patches (PZTs) in pipe flow. The roots of the elastic steel sheets are fixed on the base with the PZTs to form a double inverted flag vibration energy harvesting system (DIF-VEHS). In this note, a semi-circular receiving device (receiver) was added to the free end of the elastic steel, and a cylinder was installed upstream to generate a periodic oscillating flow field in the pipeline to obtain better electric energy generation efficiency. This study reveals the effect of different factors on the energy harvesting system, such as the distance between the ESSs, the diameter of the cylinder, etc. This study uses ANSYS software to simulate the fluid–structure interaction vibration of ESSs to determine the feasibility of this design. An experimental setup is then implemented to find the most effective combination of factors for the system. The results of this study show that with all parameters configured properly, the electric energy generation reaches a maximum average value of 1.6657 V per minute. In the future, such devices could be installed in sewers, pipes or rivers, allowing the flow energy of the fluid to be recycled to generate more energy.

Study on fluid-structure interaction vibration characteristics of absorber feed tank based on micro vibration monitoring

Absorber feed tank (AFT tower) is a kind of reinforced concrete structure supported steel tank. It is a composite structure used for desulfurization and cleaning in power industry. A large amount of slurry is sumped in the steel tank, and oxidation air is blown into the tank through a pipe to impact the slurry surface, then the agitator vibrates and disturbs the slurry in the tank. The structure has obvious vibration in daily operation, which is not conducive to the safety of the structure, but also brings greater psychological burden to the staff. Therefore, field monitoring and numerical simulation analysis are carried out for the AFT tower. The field investigation of AFT tower is also carried out. The video monitoring and local monitoring are used to monitor the AFT tower, and the corresponding laws of vibration are explored. A simplified simulation method for this kind of structure is proposed. The model is established with the aid of the fluid structure coupling function of ADINA finite element analysis software to study the vibration characteristics of AFT tower. The results show that the motion trajectory of AFT tower can be determined quickly by video monitoring. The local monitoring can demonstrate that the effect of mixer is the main factor of structural vibration, and the blowing in of oxidation wind intensifies the structural vibration response, resulting in different degrees of damage to the infilled wall between the columns of the structure. By comparing the numerical simulation results with the monitoring results, the reliability of the simplified model is verified, which provides a reference for analyzing the vibration response, damage mechanism and reinforcement design of this kind of structure.

Frequency Domain Analysis of Fluid–Structure Interaction in Aircraft Hydraulic Pipe with Complex Constraints

This paper focuses on the frequency domain fluid–structure interaction (FSI) vibration characteristics of aircraft hydraulic pipe with complex constraints. The linear partial differential fourteen-equation model is applied to describe the nonlinear FSI dynamics of pipes conveying fluid with high-speed, high-pressure, a wide Reynolds number, and the vibration frequency range. The excitation, complex boundary, and middle constraint models of liquid-filled pipes are analytically established and added into the global model of the pipe system. These resulting models are solved by the improved Laplace transform transfer matrix method (LTTMM) in the frequency domain. Then, the dynamic response characteristics of an aircraft hydraulic pipe containing diverse constraints are investigated numerically and experimentally under four types of working conditions, and the improvement conditions for the numerical instabilities are presented. In general, the present method is highly efficient and convenient for rapid model parameter modifications, in order to be fully applicable to different pipe systems and analysis cases. The results reveal the complex resonant laws regarding aircraft hydraulic pipes with complex constraints in the broad frequency band, which can also provide theoretical reference and technical support for FSI vibration analysis and the control of aircraft hydraulic pipes.

Fluid–Structure Interaction Vibration Experiments and Numerical Verification of a Real Marine Propeller

Abstract The design of lifting blade shapes is a key engineering application, especially in domains such as those of marine propellers, hydrofoils, and tidal energy converters. In particular, the excitation frequency must be different from that of the structure to avoid resonance. The natural frequency in the cases where the fluid–structure interaction (FSI) is considerably different if considering the coupling added mass (AM) of the water. In this study, vibration experiments were performed using a real propeller in air and water. The modal parameters, natural frequencies, and mode shapes were determined. Validations were performed using 3D solid and acoustic elements in a direct coupling finite element format. The modal results and AM ratios were in agreement with the experimental results. Convenient application and high efficiency are basic requirements for an engineering application. Therefore, an empirical formula was established for the first-order FSI natural frequency to enable rapid estimation, thereby satisfying this requirement.

Modal characteristics and fluid–structure interaction vibration response of submerged impeller

Turbo pump is one of the elements with the most complex flow of liquid rocket engine, and as an important component of turbo pump, an impeller is the weak point affecting its reliability. In this study, a noncontact modal characteristic identification technique was proposed for the liquid oxygen pump impeller. Modal characteristics of the impeller under three different submerged media, air, pure water, and brine with same density as liquid oxygen, were tested based on the noncontact modal identification technology. Submersion state directly affects the modal frequencies and damping ratio. The transient vibration response characteristics of the impeller excited by the unsteady flow field was achieved combining with unsteady flow field analysis and transient dynamic analysis in the whole flow passage of the liquid oxygen pump. Vibration responses at different positions of the impeller show 10X and 20X frequencies, and the amplitude at the root of short blade is significant, which needs to be paid more attention in structural design and fatigue evaluation.

Axial Vibration Characteristics of Fluid-Structure Interaction of an Aircraft Hydraulic Pipe Based on Modified Friction Coupling Model

This paper aims at studying the axial vibration response characteristics of Fluid-Structure Interaction (FSI) vibration of aircraft hydraulic pipe when considering the friction coupling. Based on the Brunone empirical model and the Zielke weighting function, an expression of fluid shear stress of the hydraulic pipeline is presented for a wide range of Reynolds number, and the friction model of the FSI 14-equation for high-speed and high-pressure hydraulic pipeline is modified. On this basis, a left-wing hydraulic pipeline of the C919 airplane is taken as the verification object and modeled, then the FSI vibration 14-equation is solved using frequency-domain transfer matrix method in MATLAB to analyze the modal and the axial vibration characteristics of the pipeline. Ultimately, a test experiment is given and discussed by being compared with the numerical simulation results, which confirmed the correctness of the friction model and demonstrated that the analytic accuracy of axial velocity response of FSI vibration could be improved by considering the friction coupling.

Study on Amplitude and Flatness Characteristics of Elastic Thin Strip under Fluid–Structure Interaction Vibration Excited by Unsteady Airflow

Based on unsteady airflow excitation and elastic thin strip vibration theory, a SI-FLAT flatness meter was taken as the research object, and an amplitude–residual stress simulation analysis model of the cold rolling strip under aerodynamic loads was established by using ANSYS Workbench. First, the influences of fluid–structure interaction on the strip amplitude distribution and the flatness calculation deviation were analyzed. It was found that the analysis with fluid–structure interaction matched the actual measurement of the flatness meter better. Then, the influences of different aerodynamic loads and tensions on the strip midpoint amplitude and the flatness calculation deviation were analyzed. It was found that when alternating aerodynamic loads increased, the strip amplitude increased in the form of a quadratic polynomial. However, when the tensions decreased, the strip amplitude decreased exponentially. The strip dimensions also influenced the amplitude of vibration: The wider and thinner the strip, the larger the amplitude. Finally, the influences of different flatness defects on the strip amplitude distribution and the flatness calculation deviation were analyzed. The deviation was serious on the strip edge, and the fluctuation characteristics of the deviation were opposite to those of the initial flatness defects.

Influences of wind and rotating speed on the fluid-structure interaction vibration for the offshore wind turbine blade

For the 5MW offshore wind turbine blade, the control and discrete equations of the fluid domain and structural domain were established respectively, and the calculation formulas of blade loads and damping coefficient were given. Furthermore, the blade entity modeling was completed by using UG and ANSYS Workbench. Based on it, the numerical calculation of blade vibration characteristics under different wind and rotating speeds was carried out, and the reliability verification was conducted by the wind tunnel test. The results of calculation indicate that the numerical results of the first principal stresses at the blade surface along the span-wise direction are consistent with the results of wind tunnel test, which verifies the reliability of the theory and numerical models. Both the influences of the bidirectional fluid-structure interaction (BFSI) and the rotation effect on the characteristics of blade vibration should be underlined. The increase of wind or rotating speed results in the nonlinear increase of the maximum span-wise displacement of the blade and of the Mises-stresses. Under different wind or rotating speed, the blade’s maximum displacement occurs at its tip, its maximum Mises-stresses appear at the relative wingspan of 0.55, and the contribution of rotating speed and average wind speed to the displacement or Mises-stress along the span-wise direction is similar.

Study on the integrated calculation method of fluid–structure interaction vibration, acoustic radiation, and propagation from an elastic spherical shell in ocean acoustic environments

A modeling method based on the wave superposition method is studied in this paper. Different underwater acoustic propagation models are used in the near and far field. Taking the acoustic radiation field calculation of an elastic spherical shell as an example, the near and far field can be analyzed as a unified system, using this method. Many studies use FEM/BEM (finite element method/boundary element method) to calculate acoustic radiation fields of elastic structures, but only a few of these methods can be applied when considering finite ocean depth, seafloor reflection loss, and sound velocity profile. In this study, the Green function is calculated differently in the near and far field to significantly simplify calculations. The virtual source method is used to calculate the acoustic radiation field in the near field and source strength, while the normal mode method is used in the far field. The results are compared with those obtained using the COMSOL finite element software, which showed that this method was both computationally efficient and accurate. Based on numerical examples, the influence of sea surface, seafloor, and sound velocity on the acoustic radiation field of elastic structures in an ocean acoustic environment is quantitatively analyzed.

Fluid–structure interaction analysis of fluid pressure pulsation and structural vibration features in a vertical axial pump

Current studies on the operation of the axial pump mainly focus on hydraulic performances, while the coupled interaction between the fluid and structure attracts little attention. This study aims to provide numerical investigation into the vibration features in a vertical axial pump based on two-way iterative fluid–structure interaction method. Three-dimensional coupling model was established with high-quality structured grids of ADINA software. Turbulent flow features were studied under design condition, using shear–stress transport k-ω turbulence model and sliding mesh approach. Typical measure points along and perpendicular to flow direction in fluid domain were selected to analyze pressure pulsation features of the impeller and fixed guide vane. By contrast, vibration features of equivalent stress in corresponding structural positions were investigated and compared based on fluid–structure interaction method. In order to explore fluid–structure interaction vibration mechanism, distribution of main frequencies and amplitudes of the measure points was presented based on the Fast Fourier Transformation method. The results reveal the time and frequency law of fluid pressure pulsation and structural vibration at the same position in the vertical axial pump while additionally provide important theoretical guidance for optimization design and safe operation of the vertical axial pump.

Fluid-Structure-Interaction Analysis of an Aero Hydraulic Pipe Considering Friction Coupling

A hydraulic pipe is a basic component of the aero hydraulic system, while high pressure and high speed lead to the enhancement of multiple field coupling effects, such as the structure, fluid, heat, and sound of the aero hydraulic pipe. A larger elastic deformation of the pipe and the more common unsteady flow of fluid can aggravate the vibration and noise of the hydraulic pipe system. Based on the 14-equation model of fluid-structure-interaction (FSI) vibration of aero hydraulic pipe, a model suitable for a wide Reynolds number range is proposed by comparing and analyzing various kinds of friction coupling models. This model is used for the FSI dynamic behavior analysis of aero hydraulic pipes, which improves the accuracy of FSI frequency-domain solutions under high Reynolds number conditions. Second, based on the 14-equation model of FSI vibration of aero hydraulic pipe and the transfer matrix method, the mathematical model of airframe deformation load of an aero hydraulic pipe is established, and the evolution law of the FSI dynamic behavior of the aero hydraulic pipe under different airframe deformation loads is analyzed. All the above analysis results were verified by the experimental analysis. The error of the analysis results of the FSI vibration frequency is smaller than 5% compared with the experimental results. The results show that the proposed method is feasible and effective for predicting the hydrodynamic behavior of the aero hydraulic pipes under load conditions.

Dynamic analysis of offshore wind turbine blades under the action of wind shear and fluctuating wind

Aiming at large-scale offshore wind turbine blades, governing equations in fluid domain and motion equations in structural domain with geometric nonlinearity were built by the aid of ALE method. A three dimensional model under fluid-structure interaction (FSI) was established by using UG software and Geometry module, and numerical calculation for FSI vibration characteristics of wind turbine blades under the effects of wind shear and fluctuating wind was carried out based on ANSYS Workbench. The results indicate that the contribution of the combined action to displacement and Mises stress chiefly derives from the wind shear effect, which not only causes a comparatively larger increase for the maximum displacement and Mises stress, but also becomes bigger and bigger with the increase of average wind speed, and the fluctuating wind effect is insignificant. The maximum value of Mises stress in the blade section appears at the relative wingspan of 0.55, the maximum Mises stress varying with relative span length decreases progressively from the middle to both sides of the blade, and the contribution of wind shear effect alone, the combined action or wind speed increment to stress also shows the same change rule. Furthermore, in the maximum stress section along wingspan, Mises stress along the direction of blade thickness or chord length respectively presents two distribution laws, and reaches the maximum on the blade surface.

A measurement criterion for accurate mass detection using vibrating suspended microchannel resonators

In this paper, a measurement criterion is presented to ensure the accuracy of mass detection using suspended microchannel resonators. The dynamic characteristics of the microchannel resonator with an added suspended particle are investigated to analyze and clarify the measurement principle for mass detection. It indicates that the vibration properties of the suspended particle have a significant effect on the measurement accuracy and the generation of systematic error. The fluid-structure interaction vibration of the particle driven by the resonator is solved by the lattice Boltzmann method integrated with the immersed boundary method. The effects of several important factors, including the particle density, fluid viscosity, and oscillating frequency, are studied and discussed. The results demonstrate that the Reynolds number and the density ratio are the two crucial parameters which affect the measurement accuracy and error generation. As the Reynolds number or the density ratio increases, the measurement precision degrades. Moreover, once the Reynolds number decreases to a critical value, the systematic error of mass detection reduces to zero. The measurement criterion can be taken as the guide to accurately detect the mass of suspended particle in the resonator.

Research Status and Trends on Fluid-structure Interaction Vibration Mechanism and Control of Hydraulic Pipeline

Research Status and Trends on Fluid-structure Interaction Vibration Mechanism and Control of Hydraulic Pipeline