Fluid Structure Interaction Analysis on a Transient Pitching Hydrofoil

2009 ◽  
Author(s):  
Antoine Ducoin ◽  
Jacques Andre´ Astolfi ◽  
Franc¸ois Deniset ◽  
Jean-Franc¸ois Sigrist
Keyword(s):  
Experimental Approach ◽  
Interaction Analysis ◽  
Structural Response ◽  
Leading Edge ◽  
Video Camera ◽  
Cavitating Flows ◽  
Structure Interaction ◽  
Laminar To Turbulent Transition ◽  
Turbulent Transition ◽  
Edge Vortex

In this paper, the structural behavior of a deformable hydrofoil in forced pitching motion is analyzed through an experimental approach. The experimental study is based on the measurement in a hydrodynamic tunnel of the foil displacement obtained with a video camera. Tip section displacement is compared to the hydrodynamic loading obtained on a rigid hydrofoil using wall pressure measurement. The structural response appears to be strongly linked to hydrodynamic phenomena such as laminar to turbulent transition and leading edge vortex shedding. The influence of pitching velocity is discussed. Finally, the paper presents displacement measurements in cavitating flows.

Design Optimization of a Piezocomposite Morphing Multi-Element Airfoil

2020 ◽  
Author(s):  
Cody Wright ◽  
Onur Bilgen
Keyword(s):  
Leading Edge ◽  
Elastic Behavior ◽  
Interaction Method ◽  
Suction Surface ◽  
High Lift ◽  
Structure Interaction ◽  
Laminar To Turbulent Transition ◽  
Turbulent Transition ◽  
Fuel Burn ◽  
Natural Laminar Flow

Abstract A slotted natural-laminar-flow airfoil design is a two-element airfoil design that employs a slot between the fore and aft elements. This slot alters the pressure recovery condition on the suction surface of the fore element, minimizing skin-friction and inhibiting the laminar to turbulent transition. These benefits reduce overall aircraft drag and increase wing lift. This allows smaller planforms, in turn, reducing fuel burn. This paper investigates the proposal that by help of piezocomposite surface actuation the aft element can be moved, rotated, and morphed to be used as a high-lift effector for take-off and landing conditions. A theoretical analysis is performed using a coupled fluid-structure interaction method assuming static aero-elastic behavior. During analysis the fore-element of the multi-element airfoil is assumed rigid. Thus, shape optimization is limited exclusively to the aft element. Airfoil morphing is achieved by way of piezocomposite actuating elements applied to the pressure and suction sides of the aft element. A genetic algorithm is used to independently optimize substrate thicknesses for each piezocomposite actuator as well as voltage, chord position and piezocomposite length. The nominal and leading edge substrate thicknesses of the airfoil are also varied. The optimized geometry for the high lift configuration is presented.

A Tailored Nonlinear Slat-Cove Filler for Airframe Noise Reduction

2018 ◽  
Author(s):  
Gaetano Arena ◽  
Rainer Groh ◽  
Alberto Pirrera ◽  
William Scholten ◽  
Darren Hartl ◽  
...  
Keyword(s):  
High Strain ◽  
Interaction Analysis ◽  
Effective Means ◽  
Leading Edge ◽  
Structural Behavior ◽  
Deployable Structures ◽  
Airframe Noise ◽  
Structure Interaction ◽  
Slat Noise ◽  
Displacement Constraints

Exploiting mechanical instabilities and elastic nonlinearities is an emerging means for designing deployable structures. This methodology is applied here to investigate and tailor a morphing component used to reduce airframe noise, known as a slat-cove filler (SCF). The vortices in the cove between the leading edge slat and the main wing are among the important sources of airframe noise. The concept of an SCF was proposed in previous works as an effective means of mitigating slat noise by directing the airflow along an acoustically favorable path. A desirable SCF configuration is one that minimizes: (i) the energy required for deployment through a snap-through event; (ii) the severity of the snap-through event, as measured by kinetic energy, and (iii) mass. Additionally, the SCF must withstand cyclical fatigue stresses and displacement constraints. Both composite and shape memory alloy (SMA)-based SCFs are considered during approach and landing maneuvers because the deformation incurred in some regions may not demand the high strain recoverable capabilities of SMA materials. Nonlinear structural analyses of the dynamic behavior of a composite SCF are compared with analyses of similarly tailored SMA-based SCF and a reference, uniformly thick superelastic SMA-based SCF. Results show that by exploiting elastic nonlinearities, both the tailored composite and SMA designs decrease the required actuation energy compared to the uniformly thick SMA. Additionally, the choice of composite material facilitates a considerable weight reduction where the deformation requirement permits its use. Finally, the structural behavior of the SCF designs in flow are investigated by means of preliminary fluid-structure interaction analysis.

Vortex structure analysis of unsteady cloud cavitating flows around a hydrofoil

2016 ◽  
Vol 30 (02) ◽  
pp. 1550275 ◽  
Author(s):  
Yu Zhao ◽  
Guoyu Wang ◽  
Biao Huang
Keyword(s):  
Vortex Structure ◽  
Cavity Growth ◽  
Leading Edge ◽  
Lower Surface ◽  
Cavitating Flows ◽  
Suction Surface ◽  
Trailing Edge ◽  
Numerical Predictions ◽  
Moderate Reynolds Number ◽  
Edge Vortex

In this paper, time dependent vortex structures are numerically analyzed for both noncavitating and cloud cavitating flows around a Clark-Y hydrofoil with angle of attack [Formula: see text] at a moderate Reynolds number, [Formula: see text]. The numerical simulations are performed using a transport equation-based cavitation model and the large eddy simulation (LES) approach with a classical eddy viscosity subgrid scale (SGS) model. Compared with experimental results, present numerical predictions are capable of capturing the initiation of cavity, growth toward the trailing edge and subsequent shedding process. Results indicate that in noncavitating conditions, the trailing edge vortex and induced positive vortex shed periodically into the wake region to form the vortex street. In cloud cavitating conditions, interrelations between cavity and vortex induce different vortex dynamics at different cavity developing stages. (i) As attached cavity grows, vorticity production is greatly enhanced by the favorable pressure gradient at the leading edge. The trailing edge flow does not have a direct impact on the attached cavity expansion process. Furthermore, the liquid–vapor interface that moves toward the trailing edge enhances the vorticity in the attached cavity closure region. (ii) When the stable attached sheet cavity grows to its maximum length, the accumulation process of vorticity is eventually interrupted by the formation of the re-entrant jet. Re-entrant jet’s moving upstream leads to a higher spreading rate of the attached cavity and the formation of a large coherent structure inside the attached cavity. Moreover, the wavy/bubbly cavity interface enhances the vorticity near the trailing edge. (iii) As the attached sheet cavity breaks up, this large vortex structure converts toward the trailing edge region, which will eventually couple with a trailing edge vortex shedding from the lower surface to form the cloud cavity. The breakup of the stable attached cavity is the main reason for the vorticity enhancement near the suction surface.

Combined Asymptotic Method for Soil-Structure Interaction Analysis

2010 ◽  
Vol 5 (4) ◽  
pp. 340-350 ◽  
Author(s):  
Alexander G. Tyapin ◽  
Keyword(s):  
Contact Surface ◽  
Time Domain ◽  
Soil Structure ◽  
Interaction Analysis ◽  
Structural Response ◽  
Soil Structure Interaction ◽  
Impedance Method ◽  
Rigid Base ◽  
Structure Interaction ◽  
Seismic Input

The author upgrades the well-known impedance method for seismic soil-structure interaction (SSI) analysis. The author suggests accounting in the time domain for the frequency dependence of the “true impedances” by means of the modification of the seismic input on the platform. The criterion for this modification is that it must provide the same structural response with approximate “platform” impedances as for the “true” frequency-dependent impedances in case of a rigid base mat. The entire analysis is performed for the linear system (no nonlinear effects occur in the soil, in the structure, or on the contact surface). In the process of modification, one first obtains the “true” seismic response of the rigid contact surface. If the actual contact surface can be considered stiff (e.g., the base mat is reinforced by dense walls) and the internal forces in the base mat itself are not important, then this “true” motion may be applied directly to the base mat. This simplified option goes without the modification of the seismic input. Another option is to use the “platform” model with “soil” springs and dashpots but to put to the platform the excitation modified in such a way as to provide a response base mat motion similar to the “true” one. The proposed method is called “combined” because it combines frequency-domain and time-domain calculations. This method is also called “asymptotic” because it becomes rigorous for rigid base mats.

A Study on Fluid-Structure Interaction Performance of a Flexible Hydrofoil

2018 ◽  
Author(s):  
Zheng Huang ◽  
Ying Xiong ◽  
Ye Xu ◽  
Shancheng Li
Keyword(s):  
Center Of Pressure ◽  
Separation Bubble ◽  
Fluid Structure Interaction ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Fluid Structure ◽  
Maximum Deformation ◽  
Structure Interaction ◽  
Turbulent Transition

To research the flexible hydrofoils’ hydroelastic response, the fluid-structure interaction (FSI) characteristic investigation is conducted on the basis of the analysis of a rigid hydrofoil’s hydrodynamic performance. For a rigid cantilevered rectangular hydrofoil, the pitching hydrodynamic performance is calculated using boundary motion with remeshing strategy. The Laminar Separation Bubble (LSB) and turbulent transition are captured. Numerical flow analysis revealed that the LSB occurs at 0.8c when pitching at initial angle of attack. As the angle increases to 5.1°, the laminar to turbulent transition occurs and the lift presents an inflection. For a geometric equivalent flexible hydrofoil, the static FSI characteristic is researched using oneway and two-way FSI method. The lift decreases and the drag increases using two-way compared to one-way FSI. The center of pressure and the maximum deformation move from trailing edge to leading edge as the angle of attack increases, showing the necessary of two-way FSI calculation. The transient FSI characteristic of the flexible hydrofoil is then studied using LES model. The lift fluctuation at 8° in frequency domain is calculated . The dry mode and wet mode natural frequency of the flexible hydrofoil are calculated to simulate the vibration performance, which meet the experiment data quite well, laying foundation for further research on the hydroelastic vibration response.

scholarly journals NON-LINEAR DYNAMIC SOIL‐STRUCTURE INTERACTION ANALYSIS OF BUILDINGS

2007 ◽  
Vol 13 (4) ◽  
pp. 266-271 ◽  
Author(s):  
Abdelhacine Gouasmia ◽  
Kamel Djeghaba
Keyword(s):  
Dynamic Response ◽  
Soil Structure ◽  
Interaction Analysis ◽  
Soil Layer ◽  
Structural Response ◽  
Soil Structure Interaction ◽  
Frequency Content ◽  
Structure Interaction ◽  
Lateral Displacements ◽  
Input Motion

The objective of this research is to evaluate the effects of soil‐structure interaction (SSI) on the modal characteristics and on the dynamic response of structures. The stress had an impact on the overall behaviour of five storeys reinforced concrete (R/C) buildings typically encountered in Algeria. Sensitivity studies are undertaken in order to study the effects of frequency content of the input motion, frequency of the soil structure system, rigidity and depth of the soil layer on the dynamic response of such structures. This investigation indicated that the rigidity of the soil layer is the predominant factor in soil‐structures interaction and its increases would definitely reduce the deformation of the R/C structures. On the other hand, increasing the period of the underlying soil will cause an increase in the lateral displacements at storey levels and create irregularity in the distribution of storey shears. Possible resonance between the frequency content of the input motion and soil could also play an important role in increasing the structural response.

scholarly journals Stiffness Adjustment of Surface-Piercing Hydrofoils Within Fluid-Structure Interaction

2020 ◽  
Vol 3 (3) ◽  
pp. 189-204
Author(s):  
Darin Majnarić ◽  
Albert Zamarin
Keyword(s):  
Stainless Steel ◽  
Numerical Analysis ◽  
Interaction Analysis ◽  
Fluid Structure Interaction ◽  
Structural Response ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Hydrodynamic Loading ◽  
Future Prediction ◽  
Stiffness Adjustment

This paper presents results from numerical analysis of the fluid and structure interaction of two different hydrofoil models, Model 1 and Model 2. Analyzes were performed with stainless steel, aluminium and composite materials for Model 1, and Model 2 was created from composite with aluminium reinforcement. Models were analyzed for three different angles of attack (10, 20, 30 degrees) and for each angle three different speeds were tested (2, 4, 6 m/s). At first, the whole set of analysis was run for entirely submerged hydrofoils and later on for immersed hydrofoils to the draft h. Described numerical analysis was performed in order to adjust stiffens of hydrofoils based on different operational loads. Two-way fluid-structure interaction analysis was used which combines FEM and CFD solvers. Presented results are based on 44 analysis with which all planned conditions of hydrofoil operation were tested. Numerical analysis showed a correlation between stiffens of material i.e. structural response and hydrodynamic loading. Besides mentioned, based on analysis of Model 2 future prediction are given in a way of hydrofoil design or particularly placement for hydrofoils reinforcement.

INFLUENCE OF THE PLATE LEADING-EDGE SHAPE AND THICKNESS ON THE BOUNDARY LAYER LAMINAR-TURBULENT TRANSITION IN HYPERSONIC FLOW

2019 ◽  
Vol 50 (5) ◽  
pp. 461-481
Author(s):  
Sergei Vasilyevich Aleksandrov ◽  
Evgeniya Andreevna Aleksandrova ◽  
Volf Ya. Borovoy ◽  
Andrey Vyacheslavovich Gubernatenko ◽  
Vladimir Evguenyevich Mosharov ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Hypersonic Flow ◽  
Leading Edge ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

Flight

2018 ◽  
Author(s):  
Anders Hedenström
Keyword(s):  
Bird Species ◽  
Leading Edge ◽  
Micro Air Vehicles ◽  
Leading Edge Vortex ◽  
Confined Spaces ◽  
Unsteady Aerodynamic ◽  
Maneuvering Flight ◽  
Edge Vortex ◽  
Lifting Surfaces ◽  
Animal Flight

Animal flight represents a great challenge and model for biomimetic design efforts. Powered flight at low speeds requires not only appropriate lifting surfaces (wings) and actuator (engine), but also an advanced sensory control system to allow maneuvering in confined spaces, and take-off and landing. Millions of years of evolutionary tinkering has resulted in modern birds and bats, which are achieve controlled maneuvering flight as well as hovering and cruising flight with trans-continental non-stop migratory flights enduring several days in some bird species. Unsteady aerodynamic mechanisms allows for hovering and slow flight in insects, birds and bats, such as for example the delayed stall with a leading edge vortex used to enhance lift at slows speeds. By studying animal flight with the aim of mimicking key adaptations allowing flight as found in animals, engineers will be able to design micro air vehicles of similar capacities.

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