scholarly journals Fluid Structure Interaction Modelling of Tidal Turbine Performance and Structural Loads in a Velocity Shear Environment

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1837 ◽  
Author(s):  
Mujahid Badshah ◽  
Saeed Badshah ◽  
Kushsairy Kadir
Keyword(s):  
Fluid Dynamic ◽  
Turbine Blades ◽  
Fluid Structure Interaction ◽  
Angular Position ◽  
Uniform Flow ◽  
Velocity Shear ◽  
Power Coefficient ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Stress And Deformation

Tidal Current Turbine (TCT) blades are highly flexible and undergo considerable deflection due to fluid interactions. Unlike Computational Fluid Dynamic (CFD) models Fluid Structure Interaction (FSI) models are able to model this hydroelastic behavior. In this work a coupled modular FSI approach was adopted to develop an FSI model for the performance evaluation and structural load characterization of a TCT under uniform and profiled flow. Results indicate that for a uniform flow case the FSI model predicted the turbine power coefficient CP with an error of 4.8% when compared with experimental data. For the rigid blade Reynolds Averaged Navier Stokes (RANS) CFD model this error was 9.8%. The turbine blades were subjected to uniform stress and deformation during the rotation of the turbine in a uniform flow. However, for a profiled flow the stress and deformation at the turbine blades varied with the angular position of turbine blade, resulting in a 22.1% variation in stress during a rotation cycle. This variation in stress is quite significant and can have serious implications for the fatigue life of turbine blades.

scholarly journals Stochastic fluid structure interaction of three-dimensional plates facing a uniform flow

2016 ◽  
Vol 794 ◽  
Author(s):  
O. Cadot
Keyword(s):  
Fluid Structure Interaction ◽  
Angular Position ◽  
Three Dimensional ◽  
Uniform Flow ◽  
Steady States ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Fluid Forces ◽  
Long Time ◽  
Order Of Magnitude

An experiment on a flat rectangular plate facing a uniform flow at $Re=264\,000$ shows the importance of the base pressure loading on the asymmetric static modes of the turbulent wake. The plate is free to rotate around its short symmetry axis. For plates with aspect ratio ${\it\kappa}<6$, the angular position exhibits strong random discontinuities between steady states of non-zero angles. The steady states have long time durations, more than one order of magnitude greater than the convective time scale. The discontinuities, comparable to rare and violent events, are due to strong fluid forces associated with a drastic global change of the three-dimensional wake – mainly the switching between the static asymmetric modes. A clear transition occurs at ${\it\kappa}=6$, for which the angular fluctuations are minimum, leading for ${\it\kappa}>6$ to a classical fluid structure interaction with periodic fluctuations. The transition is supported by a recent global stability analysis of rectangular fixed plates in the laminar regime.

Thermo-Fluid-Dynamic Design of Reciprocating Compressor Cylinders by Fluid Structure Interaction (FSI)

2011 ◽  
Author(s):  
Riccardo Traversari ◽  
Alessandro Rossi ◽  
Marco Faretra
Keyword(s):  
High Speed ◽  
Fluid Dynamic ◽  
Fluid Structure Interaction ◽  
Classical Equation ◽  
Flow Coefficient ◽  
Reciprocating Compressor ◽  
Complex Situation ◽  
Fluid Structure ◽  
Associated Gas ◽  
Structure Interaction

Pressure losses at the cylinder valves of reciprocating compressors are generally calculated by the classical equation of the flow through an orifice, with flow coefficient determined in steady conditions. Rotational speed has increased in the last decade to reduce compressor physical dimensions, weight and cost. Cylinder valves and associated gas passages became then more and more critical, as they determine specific consumption and throughput. An advanced approach, based on the new Fluid Structure Interaction (FSI) software, which allows to deal simultaneously with thermodynamic, motion and deformation phenomena, was utilized to simulate the complex situation that occurs in a reciprocating compressor cylinder during the motion of the piston. In particular, the pressure loss through valves, ducts and manifolds was investigated. A 3D CFD Model, simulating a cylinder with suction and discharge valves, was developed and experimentally validated. The analysis was performed in transient and turbulent condition, with compressible fluid, utilizing a deformable mesh. The 3D domain simulating the compression chamber was considered variable with the law of motion of the piston and the valve rings mobile according to the fluid dynamic forces acting on them. This procedure is particularly useful for an accurate valve loss evaluation in case of high speed compressors and heavy gases. Also very high pressure cylinders, including LDPE applications, where the ducts are very small and MW close to the water one, can benefit from the new method.

scholarly journals FSI in Wind Turbines: A Review

2020 ◽  
Vol 8 (3) ◽  
pp. 37
Author(s):  
Yogesh Ramesh Patel
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Fluid Structure Interaction ◽  
Arbitrary Lagrangian Eulerian ◽  
Wind Turbine Blades ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Deformable Structure

This paper provides a brief overview of the research in the field of Fluid-structure interaction in Wind Turbines. Fluid-Structure Interaction (FSI) is the interplay of some movable or deformable structure with an internal or surrounding fluid flow. Flow brought about vibrations of two airfoils used in wind turbine blades are investigated by using a strong coupled fluid shape interplay approach. The approach is based totally on a regularly occurring Computational Fluid Dynamics (CFD) code that solves the Navier-Stokes equations defined in Arbitrary Lagrangian-Eulerian (ALE) coordinates by way of a finite extent method. The need for the FSI in the wind Turbine system is studied and comprehensively presented.

Sequential Fluid-Structure Interaction of a Large-Scale Gas Control Valve

2010 ◽  
Vol 455 ◽  
pp. 146-150
Author(s):  
Fang Cao ◽  
Yong Wang ◽  
Y.T. An
Keyword(s):  
Large Scale ◽  
Fluid Structure Interaction ◽  
Fluid Pressure ◽  
Control Valve ◽  
Practical Significance ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Gas Control ◽  
Stress And Deformation ◽  
Pressure Stress

According to the real structure and work condition of a large-scale gas control valve used in recycling generating electricity project, a sequential fluid-structure interaction system model of control valve is set up, the coupling of fluid and valve plug is studied. The complicated fluid pressure, stress and deformation of balanced valve plug and stem at different control valve openings are investigated. The root cause of plug vibration by fluid is revealed. The natural frequency and modes of vibration are obtained, which could verify whether the design overcomes resonance. All of these are in favor of realizing design optimization in fluid-structure interaction and are of great practical significance for advancing study on large-scale control valves.

Analysis of Fluid-Structure Interaction of an Elastic Blade in Cascade

2002 ◽  
Author(s):  
R. C. K. Leung ◽  
Y. L. Lau ◽  
R. M. C. Si
Keyword(s):  
Numerical Technique ◽  
Fluid Structure Interaction ◽  
Uniform Flow ◽  
Frequency Parameter ◽  
Generation Process ◽  
Noise Generation ◽  
Fluid Structure Interactions ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Normalized Frequency

A time-marching numerical model for the analysis of fluid-structure interaction caused by oncoming alternating vortices has been developed by Jadic et al. (1998). Its applicability to analyzing realistic fluid–structure interaction problems has successfully been established in a recent experimental work of a flat plate in a circular cylinder wake (Lau et al. 2002). Using the model, So et al. (1999) have predicted that, under the excitation of oncoming Karman vortex street (KVS) vortices, an elastic airfoil/blade in inviscid uniform flow exhibits two types of fluid–structure resonance, namely aerodynamic and structural resonance. Aerodynamic resonance is of pure aerodynamic origin and occurs with rigid airfoil/blade excited at normalized frequency parameter c/d = 0.5, 1.5, 2.5 etc., where c is the blade chord and d is the streamwise separation between two neighboring vortices. For an elastic airfoil/blade, as a result of coupled fluid–structure interaction, structural resonance occurs at a normalized frequency close to the natural frequency in vacuo of the airfoil/blade. The occurrence of fluid-structure resonance has also been shown critical in noise generation process (Leung & So 2001). The present study extends the scope of the analysis to fluid–structure interactions occurring in axial–flow turbomachine cascade. When the flow is passing through the rotor, it generates wakes containing KVS vortices behind the rotor blades. The convecting wake will induce perturbations on the downstream stator blades at a wake passing frequency (Rao 1991). Such wake–blade interaction is important in determining the fatigue life of the blades and noise generation of the cascade. The cascade analysis starts with modeling the two-dimensional turbine stator by five high–loading blades evenly separated by s in inviscid uniform flow. Oncoming KVS vortices are released upstream to represent the passing wake originating from the rotor, and are allowed to pass through the stator blades. The blade pitch to blade chord ratio s/c and normalized frequency parameter c/d are important parameters of the problems. Fluid–structure interactions are fully resolved by the same numerical technique (Jadic et al. 1998, So et al. 1999). The combined effects of s/c and c/d on the aerodynamic and structural responses of the central blade are studied and discussed.

Fluid–Structure Interaction Models of Bicuspid Aortic Valves: The Effects of Nonfused Cusp Angles

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Karin Lavon ◽  
Rotem Halevi ◽  
Gil Marom ◽  
Sagit Ben Zekry ◽  
Ashraf Hamdan ◽  
...  
Keyword(s):  
Flow Direction ◽  
Fluid Dynamic ◽  
Fluid Structure Interaction ◽  
Jet Flow ◽  
Elastic Behavior ◽  
Principal Stresses ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Biomechanical Models ◽  
Hyper Elastic

Bicuspid aortic valve (BAV) is the most common type of congenital heart disease, occurring in 0.5–2% of the population, where the valve has only two rather than the three normal cusps. Valvular pathologies, such as aortic regurgitation and aortic stenosis, are associated with BAVs, thereby increasing the need for a better understanding of BAV kinematics and geometrical characteristics. The aim of this study is to investigate the influence of the nonfused cusp (NFC) angle in BAV type-1 configuration on the valve's structural and hemodynamic performance. Toward that goal, a parametric fluid–structure interaction (FSI) modeling approach of BAVs is presented. Four FSI models were generated with varying NFC angles between 120 deg and 180 deg. The FSI simulations were based on fully coupled structural and fluid dynamic solvers and corresponded to physiologic values, including the anisotropic hyper-elastic behavior of the tissue. The simulated angles led to different mechanical behavior, such as eccentric jet flow direction with a wider opening shape that was found for the smaller NFC angles, while a narrower opening orifice followed by increased jet flow velocity was observed for the larger NFC angles. Smaller NFC angles led to higher concentrated flow shear stress (FSS) on the NFC during peak systole, while higher maximal principal stresses were found in the raphe region during diastole. The proposed biomechanical models could explain the early failure of BAVs with decreased NFC angles, and suggests that a larger NFC angle is preferable in suture annuloplasty BAV repair surgery.

Numerical Study on Fluid Structure Interaction of Slug Flow in a Horizontal Pipeline

2016 ◽  
Vol 819 ◽  
pp. 319-325
Author(s):  
Abdalellah Omer Mohmmed ◽  
Mohammad Shakir Nasif ◽  
Hussain Hamoud Al-Kayiem ◽  
Zahid Ibrahim Al-Hashimy
Keyword(s):  
Slug Flow ◽  
Maximum Stress ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Fluid Structure Interaction ◽  
Water Velocity ◽  
Design Stage ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Model Code

It is well-known that when slug flow occurs in pipes it may result in damaging the pipe line. Therefore it is important to predict the slug occurrence and its effect. Slug flow regime is unsteady in nature and the pipelines conveying it are indeed susceptible to significant cyclic stresses. In this work, a numerical study has been conducted to investigate the interaction between the slug flow and solid pipe. Fluid Structure Interaction (FSI) coupling between 3-D Computational Fluid Dynamic (CFD) and 3-D pipeline model code has been developed to assess the stresses on the pipe due to slug flow. Time – dependent stresses results has been analyzed together with the slug characteristic along the pipe. Results revealed that the dynamic behavior of the pipelines is strongly affected by slug parameters. The FSI simulation results show that the maximum stresses occurred close to the pipe supports due to slug flow, where the pipe response to the exerted slug forces is extremely high. These stresses will subsequently cause fatigue damage which is likely reduce the total lifetime of the pipeline. Therefore a careful attention should be made during the design stage of the pipeline to account for these stresses. The system has been investigated under multiple water velocities and constant air velocity, the maximum stress was obtained at the water velocity of 0.505 m/s. Moreover, when the water velocity is increased from 0.502 to 1.003 m/s the maximum stress magnitude is decreased by 1.2% and when it is increased to 1.505 m/s the maximum stress is diminished by 3.6%.

scholarly journals Coupled Fluid-Structure Interaction Modelling of Loads Variation and Fatigue Life of a Full-Scale Tidal Turbine under the Effect of Velocity Profile

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2217 ◽  
Author(s):  
Mujahid Badshah ◽  
Saeed Badshah ◽  
James VanZwieten ◽  
Sakhi Jan ◽  
Muhammad Amir ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Velocity Profile ◽  
Fluid Structure Interaction ◽  
Angular Position ◽  
Thrust Coefficient ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Tidal Turbine ◽  
The Mean ◽  
Mean Cycle

Velocity profiles in tidal channels cause cyclic oscillations in hydrodynamic loads due to the dependence of relative velocity on angular position, which can lead to fatigue damage. Therefore, the effect of velocity profile on the load variation and fatigue life of large-scale tidal turbines is quantified here. This is accomplished using Fluid Structure Interaction (FSI) simulations created using the ANSYS Workbench software, which couples the fluid solver ANSYS CFX to the structural solver ANSYS transient structural. While these load oscillations only minimally impact power and thrust fluctuation for rotors, they can significantly impact the load variations on individual rotor blades. To evaluate these loadings, a tidal turbine within a channel with a representative flow that follows a 1/7th power velocity profile and an onset turbulence intensity of 5% is simulated. This velocity profile increases the thrust coefficient variation from mean cycle value of an individual blade from 2.8% to 9% and the variation in flap wise bending moment coefficient is increased from 4.9% to 19%. Similarly, the variation from the mean cycle value for blade deformation and stress of 2.5% and 2.8% increased to 9.8% and 10.3%, respectively. Due to the effect of velocity profile, the mean stress is decreased, whereas, the range and variation of stress are considerably increased.

A fluid–structure interaction approach to investigate the quenching characteristics of a steel tube with temperature dependent properties

2016 ◽  
Vol 05 (04) ◽  
pp. 1650018
Author(s):  
Pratik Sarker ◽  
Uttam K. Chakravarty
Keyword(s):  
Residual Stress ◽  
Fluid Structure Interaction ◽  
Steel Tube ◽  
Transient Temperature ◽  
Temperature Dependent ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Stress And Deformation ◽  
Temperature Dependent Properties ◽  
Residual Stress And Deformation

Quenching is commonly used for improving material properties of steel tubes because of their numerous applications. However, quenching generates some residual stress and deformation in the material due to rapid temperature fluctuations. The properties of the steel are strong functions of these variable temperatures and therefore, the estimated stress and deformation by constant property or static quenching analysis are not very realistic. This study describes the first extensive study of the quenching process of a steel tube including temperature dependent properties by three liquid quenchants using the dynamic fluid–structure interaction quench model. The cooling characteristics of the three liquid quenchants are compared to each other along with the transient temperature distributions in the steel tube. The time-varying nodal, axial, and radial residual stress and deformation of the tube are studied. It is found that, the effectiveness of quenching does not depend only on a particular quenchant, but also on the temperature-varying properties of the steel and the uniformity of the cooling which ultimately determine the criteria for selecting a suitable quenchant for a specific purpose.

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