Flutter is a self-sustained vibration which could create serious damage to compressor *** the efficiency and accuracy of fluid-structure interaction(FSI)method is crucial to flutter *** efficient FSI method which comb...
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Flutter is a self-sustained vibration which could create serious damage to compressor *** the efficiency and accuracy of fluid-structure interaction(FSI)method is crucial to flutter *** efficient FSI method which combines a fast mesh deformation technology and Double-Passage Shape Correction(DPSC)method is proposed to predict blades flutter under traveling wave ***,regarding the fluid domain as a pseudo elastic solid,the flow mesh deformation and blade vibration response can be quickly obtained by solving the governing equations of the holistic system composed of blade and pseudo elastic ***,by storing and updating the Fourier coefficients on the circumferential boundary,the phase-lagged boundary condition is introduced into the computational ***,the aerodynamic stability for the blades of an axial compressor under various Inter-Blade Phase Angle(IBPA)is *** results show that the proposed method can effectively predict the characteristics of aerodynamic damping,aerodynamic force and blade *** a conceptual model is proposed to describe the motion behavior of the shock *** with the multi-passage method,the proposed method obtains almost the same unstable IBPA interval and the blade displacement error is less than 3.4%.But the calculation time is significantly shortened especially in small IBPA cases.
In this article the UDF script file in the Fluent software was rewritten as the "connecting file" for the Fluent and the ANSYS/ABAQUS in order that the joined file can be used to do aero-elastic computations. In thi...
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In this article the UDF script file in the Fluent software was rewritten as the "connecting file" for the Fluent and the ANSYS/ABAQUS in order that the joined file can be used to do aero-elastic computations. In this way the fluid field is computed by solving the Navier-Stokes equations and the structure movement is integrated by the dynamics directly. An analysis of the computed results shows that this coupled method designed for simulating aero-elastic systems is workable and can be used for the other fluid-structure interaction problems.
Due to the flexibility of the envelope of large stratosphere airships, the aerodynamic solution of such airship is closely related to its shape and the external aerodynamic forces which lead to the structural deformat...
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Due to the flexibility of the envelope of large stratosphere airships, the aerodynamic solution of such airship is closely related to its shape and the external aerodynamic forces which lead to the structural deformation. It is essentially one of the fluid-structure interaction (FSI) problems. This article aims at the numerical investigation of nonlinear airship aeroelasticity in consideration of aerodynamics and structure coupling, using an iteration method. The three-dimensional flow around the airship was numerically studied by means of the SIMPLE method based on the finite volume method. Nonlinear finite element analysis was employed for geometrically nonlinear deformation of the airship shape. Comparison of aerodynamic parameters and the pressure distribution between rigid and aeroelastic models was conducted when an airship is in a trimmed flight state in specified flight conditions. The effect ofaeroelasticity on the airship aerodynamics was detailed.
Free-surface flows, especially those associated with fluid-structure interactions(FSIs), pose challenging problems in numerical simulations. The authors of this work recently developed a smoothed particle element meth...
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Free-surface flows, especially those associated with fluid-structure interactions(FSIs), pose challenging problems in numerical simulations. The authors of this work recently developed a smoothed particle element method(SPEM) to simulate FSIs. In this method, both the fluid and solid regions are initially modeled using a smoothed finite element method(S-FEM) in a Lagrangian frame, whereas the fluid regions undergoing large deformations are adaptively converted into particles and modeled with an improved smoothed particle hydrodynamics(SPH) method. This approach greatly improves computational accuracy and efficiency because of the advantages of the S-FEM in efficiently treating solid/fluid regions showing small deformations and the SPH method in effectively modeling moving interfaces. In this work, we further enhance the efficiency of the SPEM while effectively capturing local fluid information by introducing a multi-resolution technique to the SPEM and developing an effective approach to treat multi-resolution element-particle interfaces. Various numerical examples demonstrate that the multiresolution SPEM can significantly reduce the computational cost relative to the original version with a constant ***, the novel approach is effective in modeling various incompressible flow problems involving FSIs.
fluid-structure interaction (FSI) problems in microchannels play a prominent role in many engineering applications. The present study is an effort toward the simulation of flow in microchannel considering FSI. The b...
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fluid-structure interaction (FSI) problems in microchannels play a prominent role in many engineering applications. The present study is an effort toward the simulation of flow in microchannel considering FSI. The bottom boundary of the microchannel is simulated by size-dependent beam elements for the finite element method (FEM) based on a modified cou- ple stress theory. The lattice Boltzmann method (LBM) using the D2Q13 LB model is coupled to the FEM in order to solve the fluid part of the FSI problem. Because of the fact that the LBM generally needs only nearest neighbor information, the algorithm is an ideal candidate for parallel computing. The simulations are carried out on graphics processing units (GPUs) using computed unified device architecture (CUDA). In the present study, the governing equations are non-dimensionalized and the set of dimensionless groups is exhibited to show their effects on micro-beam displacement. The numerical results show that the displacements of the micro-beam predicted by the size-dependent beam element are smaller than those by the classical beam element.
Background The mitral valve is essential for proper heart function. Patient-specific simulations may provide insights into valve function and provide hemodynamic information for treatment planning. This study presents...
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Background The mitral valve is essential for proper heart function. Patient-specific simulations may provide insights into valve function and provide hemodynamic information for treatment planning. This study presents a framework for patient-specific mitral valve hemodynamic prediction and the validation of the simulation model against echocardiographic and MRI data. Methods Ten healthy volunteers (age range/median: 1–37/13 years) underwent echocardiographic exams, of which five also underwent cardiac MRI. Patient-specific mitral valve geometries were segmented from 3D echocardiograms, while mass flow boundary conditions were derived from left ventricular volume data obtained via echocardiography and MRI. The mitral apparatus, including the chordae, was modeled in a simplified left heart and simulated in a computational model using fluid-structure interaction. Results The simulations captured the valvular behavior and hemodynamics of the left heart throughout the cardiac cycle. We found an average difference of 3.6 ± 29 % and 8.3 ± 22 % in the maximum and mean transvalvular velocity compared to Doppler data. Echocardiography underestimated end-systolic and end-diastolic volumes by 1.8 ± 20 % and 19 ± 3.8 % compared to MRI. The average maximum principal strain over the mitral valve was 5.8 % during systole and 6.7 % during diastole, consistent with literature. Conclusions A computational framework for clinically feasible patient-specific prediction of mitral valve hemodynamics was developed and validated in vivo in the largest cohort presented to date. Computational time was acceptable for clinical planning. This is a step towards personalized surgical planning of valve repair and an increased understanding of the hemodynamics and mitral valve function after intervention.
This paper experimentally studies the cavitating fluid-structure interaction of composite hydrofoils with different ply *** synchronous measurement system with high-speed camera and for laser Doppler vibrometer(LDV),t...
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This paper experimentally studies the cavitating fluid-structure interaction of composite hydrofoils with different ply *** synchronous measurement system with high-speed camera and for laser Doppler vibrometer(LDV),the feedback pressure regulation system,and the flow rate control system are *** experimental results of the cavitation evolution show that,compared with the rigid hydrofoil,the composite hydrofoils with+45°ply angle and 0°ply angle accelerate the cavitation inception,and the composite hydrofoil with−45°ply angle delays the cavitation *** the same cavitation number,the cloud cavitation of the+45°laminated hydrofoil is the most severe,followed by that of the 0°laminated hydrofoil,and that of the−45°laminated hydrofoil is relatively weak and close to that of the rigid *** analyses of the structural vibration of the composite hydrofoils in different cavitation stages show that the three composite hydrofoils have no significant vibration at the incipient cavitation and the supercavitation,but relatively significant vibration is observed in the sheet and cloud *** vibration amplitude of the composite hydrofoil with+45°ply angle is the largest,followed by those of the−45°,0°laminated *** the sheet cavitation,the dominant frequencies of the structural vibration velocity of the+45°laminated hydrofoil and the−45°laminated hydrofoil are the first and second modal frequencies,but no explicit dominant frequency is observed for the 0°laminated *** the cloud cavitation,the dominant frequencies of the three composite hydrofoils mainly include the first modal frequency,the second modal frequency,and the cavity shedding frequency.
Fixed offshore wind turbines usually have large underwater supporting structures. The fluid influences the dynamic characteristics of the structure system. The dynamic model of a 5-MW tripod offshore wind turbine cons...
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Fixed offshore wind turbines usually have large underwater supporting structures. The fluid influences the dynamic characteristics of the structure system. The dynamic model of a 5-MW tripod offshore wind turbine considering the pile-soil system and fluidstructureinteraction (FSI) is established, and the structural modes in air and in water are obtained by use of ANSYS. By comparing low-order natural frequencies and mode shapes, the influence of sea water on the free vibration characteristics of offshore wind turbine is analyzed. On basis of the above work, seismic responses under excitation by E1-Centro waves are calculated by the time-history analysis method. The results reveal that the dynamic responses such as the lateral displacement of the foundation and the section bending moment of the tubular piles increase substantially under the influence of the added-mass and hydrodynamic pressure of sea water. The method and conclusions presented in this paper can provide a theoretical reference for structure design and analysis of offshore wind turbines fixed in deep seawater.
Small and micro unmanned aircraft are the focus of scientific interest due to their wide range of *** often operate in a highly unstable flight environment where the application of new morphing wing technologies offer...
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Small and micro unmanned aircraft are the focus of scientific interest due to their wide range of *** often operate in a highly unstable flight environment where the application of new morphing wing technologies offers the opportunity to improve flight *** investigated concept comprises port and starboard adjustable wings,and an adaptive elastoflexible membrane serves as the lifting *** focus is on the benefits of the deforming membrane during the impact of a one-minus-cosine type *** a low Reynolds number of Re=264000,the morphing wing model is investigated numerically by unsteady fluid-structure interaction ***,the numerical results are validated by experimental data from force and moment,flow field,and deformation ***,with the rigid wing as the baseline,the flexible case is investigated,focusing on the advantages of the elastic *** all configurations studied,the maximum amplitude of the lift coefficient under gust load shows good agreement between the experimental and numerical *** the decay of the gust,they differ more the higher the aspect ratio of the *** considering the flow field,the main differences are due to the separation behavior on the upper side of the *** flow reattaches earlier in the experiments than in the simulations,which explains the higher lift values observed in the *** at one intermediate configuration does the lift amplitude of the rigid configuration exceeds that of the flexible by about 12%,with the elastic membrane resulting in a smaller and more uniform peak load,which is also evident in the wing loading and hence in the root bending moment.
An experimental setup was developed for channel driven cavity flow in order to study the fluid- structureinteraction and provide benchmark data for validation of numerical fluid-structure interaction models. The chan...
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An experimental setup was developed for channel driven cavity flow in order to study the fluid- structureinteraction and provide benchmark data for validation of numerical fluid-structure interaction models. The channel driven cavity flow is a modification from lid-driven cavity flow. To examine the fluid-structure interaction, the bottom side of the cavity is a deformable flat plate. All other boundaries are rigid. The fluid-structure interaction inside the cavity is driven by flow through a thin channel topside of the cavity. Water is used as the fluid. fluid-structure interaction for different deformable plates during constant flow is quantified using a variety of strain and displacement measurement techniques. To establish suitable boundary conditions for numerical analysis of the experiment, the inlet velocity of the channel driven cavity flow is known. Outlet pressure is constant atmospheric. Numerical results are obtained using ANSYS's CFX and structure analysis.
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