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

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 496
Author(s):  
Hongbo Li ◽  
Guomin Han ◽  
Jingbo Yang ◽  
Nong Li ◽  
Jie Zhang

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.

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Ali Behrouzifar ◽  
Masoud Darbandi

Abstract The fluid–structure interaction (FSI) is generally addressed in multimegawatt wind turbine calculations. From the fluid flow perspective, the semi-analytical approaches, like actuator disk (AD) model, were commonly used in wind turbine rotor calculations. Indeed, the AD model can effectively reduce the computational cost of full-scale numerical methods. Additionally, it can substantially improve the results of pure analytical methods. Despite its great advantages, the AD model has not been developed to simulate the FSI problem in wind turbine simulations. This study first examines the effect of constant (rigid) cone angle on the performance of the chosen benchmark wind turbine. As a major contribution, this work subsequently extends the rigid AD model to nonrigid applications to suitably simulate the FSI. The new developed AD-FSI solver uses the finite-volume method to calculate the aerodynamic loads and the beam theory to predict the structural behaviors. A benchmark megawatt wind turbine is simulated to examine the accuracy of the newly developed AD-FSI solver. Next, the results of this solver are compared with the results of other researchers, who applied various analytical and numerical methods to obtain their results. The comparisons indicate that the new developed solver calculates the aerodynamic loads reliably and predicts the blade deflection very accurately.


Author(s):  
Yukari Hamamoto ◽  
Makoto Toyoda

Global warming is caused by the emission of greenhouse gases, like CO2. Nuclear energy is one of the main sources of low-carbon energy. In the events of serious accidents, a nuclear power plant may emit radioactivity that is harmful to human health. Nuclear power should be used after enough evidence of its safety is provided. Measures for safety of nuclear power plants, such as autogenous control and LBB, have been developed. Moreover, there is requirement with respect to the design, safety, equipments components and systems of nuclear plant. For example, it is necessary to place components that restrain pipe whip behavior, and to design peripheral equipments that may be affected by high-pressured fluid in pipe rupture accidents [1], [2]. In the case of pipe rupture that occurs to structures such as nuclear plants and steam generators, a pipe deforms releasing its inner high-pressured fluid. In previous studies, the pipe whip behavior analyses have been performed by using blowdown thrust force that is estimated by fluid analysis. In this study, we simulate pipe whip behavior and reduction of blowdown thrust force by releasing inner fluid to the atmosphere. The analysis model is an elbow pipe and high-pressure fluid running inside. We considered fluid-structure interaction effect in the analysis because ovalization of the cross-section of the elbow part as well as a change of the elbow torus radius affects fluid flow blowing out from the ruptured part of the pipe.


2017 ◽  
Vol 9 (1) ◽  
pp. 19
Author(s):  
Buyung Junaidin

This paper describes numerical simulation o f flexible High Altitude Long Endurance Unmanned Aerial Vehicle (HALE UAV)wingusing two-way fluid structure interaction (FSI) method. The HALE wing is designed with high aspect ratio. This configuration intended to reduce the vehicle induced drag and reduces the lift-loss at wingtip which caused by wingtip vortex. But the structure of the wing itself becomes more elastic that be able to give large deformation when the aerodynamic loads applied. This deformation changes the aerodynamic loads distribution on the wing that gives a new deformation to the wing structure and vice versa. This interaction in a couple process called as fluid structure interaction (FSI). ANSYS 15.0 software was used to simulate fluid structure interaction on the wing. The unsteadiness and viscous flows at low speed are evaluated using the solution o f timedependent Reynolds Averaged Navier-Stokes (RANS) with SST k-rn turbulent model. In addition, multiblock structured grids are generated to provide more accurate viscous result and to anticipate negative volume o f the mesh which may occur due to the deformation o f the wing during simulation. Five different o f simulations are performed with variation o f material characteristics including Young’s modulus and Poisson’s ratio.The results are global aerodynamic characteristics at various material characteristics.


2011 ◽  
Vol 115 (1167) ◽  
pp. 285-294 ◽  
Author(s):  
M. Guillaume ◽  
A. Gehri ◽  
P. Stephani ◽  
J. B. Vos ◽  
G. Mandanis

Abstract The Swiss Airforce is operating F/A-18C/D Aircraft since 1997. Since the aircraft’s structural design is different from the version operated by the US Navy it was necessary to carry out a structural integrity study (ASIP) which was done by The Boeing Company in St. Louis. To validate this study a full scale fatigue test facility was build at RUAG and operated from 2003 to 2005. When operating this facility difficulties were encountered with the aerodynamic loads data provided by Boeing (insufficient, not well documented, questionable data). As a result RUAG looked for alternative methods to provide the aerodynamic loads, and a large investment was made in the development of a Computational Fluid Dynamics (CFD) tool. The Navier Stokes Multi Block (NSMB) solver, which was developed in an international collaboration, was adopted. In a first phase the code was validated by comparing results of CFD calculations with wind-tunnel results, results from literature and flight test data results. In the second phase, discussed in this paper, a Fluid Structure Interaction (FSI) tool was developed to permit unsteady aero-elastic simulations. Particular attention is focused on the vertical tail since this component of the F/A-18 fighter is very sensitive to fatigue due to unsteady loads generated by buffeting phenomena.


Author(s):  
Raffaele Ardito ◽  
Federico Perotti ◽  
Simone Mandelli ◽  
Davide Novarina ◽  
Stefano Malavasi

The recent developments in numerical tools and computing resources seem to provide a suitable environment to perform numerical analyses of Fluid-Structure Interaction problems. The Co-Simulation technique, in particular, develops the idea of coupling a CFD software with a structural one in order to simulate complex FSI phenomena with a partitioned approach, stressing the concept of software modularity. In this way, it is possible to adopt software tools at the cutting edge of technology. Nonetheless, several difficulties may arise in the choice of the partitioning scheme and of the algorithmic details for the step-by-step time integration. This paper deals with the application of the Co-Simulation technique to a benchmark case experimentally investigated in previous works: the vortex-induced vibrations (VIV) of a beam supported sphere (that is, a sphere fixed to the end of a slender cantilever beam) in a free surface flow. This problem is challenging although apparently simple and it seems quite absent from literature so far. In this paper, the computational issues are thoroughly investigated and the model is validated by comparison with the experimental data. In this way, a robust framework is created in order to deal with VIV problems.


2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Yu Liu ◽  
Daogang Lu ◽  
Yuanpeng Wang ◽  
Hongda Liu

Spent fuel rack is the key equipment for the storage of spent fuel after refueling. In order to investigate the performance of the spent fuel rack under the earthquake, the phenomena including sliding, collision, and overturning of the spent fuel rack were studied. An FEM model of spent fuel rack is built to simulate the transient response under seismic loading regarding fluid-structure interaction by ANSYS. Based on D’Alambert’s principle, the equilibriums of force and momentum were established to obtain the critical sliding and overturning accelerations. Then 5 characteristic transient loadings which were designed based on the critical sliding and overturning accelerations were applied to the rack FEM model. Finally, the transient displacement and impact force response of rack with different gap sizes and the supporting leg friction coefficients were analyzed. The result proves the FEM model is applicable for seismic response of spent fuel rack. This paper can guide the design of the future’s fluid-structure interaction experiment for spent fuel rack.


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